Secret deck Flashcards
What dose of barium contrast medium is recommended in cats to achieve adequate filling of the stomach?
10 mL/kg Morgan VRU 1981
In regards to Upper GI studies in cats, how does the position of the stomach vary with respiration?
Deep inspiration caused stomach to shift caudally a distance of 1 vertebral body Morgan VRU 1981
What influences gastric emptying in the cat during upper GI studies?
Dependent on the volume of contrast medium If received over 10 mL/kg –> more complete emptying and minimal residual streaking at 30 min
Does laparoscopic assisted gastropexy alter GI transit times in the dog?
No Balsa JVIM 2017
GI transit times with Barium in the dog
- Gastric - 30 to 120 min
- Time to reach duodenum 15 min
- Time to reach jejunum - 30 min
- Time to reach ileum - 60 min
- Time to reach ICJ (aka SITT) - 90 to 120 min
- SI empty - 3-5 hours
GI transit times with Barium in the cat
- Gastric - 30 to 60 min (within 30 min if use 10ml/kg)
- SITT - 30-60 min
Dose of Barium in large dog (>20kg)? Small dog (<20kg)?
- 30% w/v (dilution of normal 60%-100% w/v)
- Large - 5-7 mL/kg
- Small - 8-12 mL/kg
What is this most consistent with?
Settling - irreversible process caused by barium coming out of suspension
What position is best for esophageal contrast studies?
Sternal position - faster transit time and increased stimulation of primary peristaltic waves for both liquid and kibble compared to lateral recumbency
Bonadio JVIM 2009
What are the 4 measured parameters of pharyngal function in the dog? How are these parameters affected in dogs with cricopharyngeal achalasia?
- Maximum caudal contraction of the pharynx
- Opening of the cranial esophageal sphincter
- Closure of the cranial esophageal sphincter
- Re-opening of the epiglottis
Opening and closing of the cranial esophageal sphincter was significantly delayed during both liquid and kibble swallows in dogs with cricopharyngeal achalasia.
Pollard VRU 2000
Which cranial nerves govern the oropharyngeal phase of swallowing?
- Trigeminal
- Facial
- Glossopharyngeal
- Vagus
- Hypoglossal
How is the pharyngeal constriction ratio calculated?
Area of pharynx at MAXIMAL constriction/area of pharynx at rest
Pollard VRU 2007
How does the pharyngeal constriction ratio differ between normal dogs and dogs with weak pharyngeal contraction?
Normal dogs have smaller PCR than dogs with weak pharyngeal contraction
Pollard VRU 2007
How does PCR change with diminished pharyngeal contractility?
As pharyngeal contractility diminishes, the PCR approaches 1
What are the most common imaging findings in cats undergoing video fluoroscopy?
- Hiatal hernia
- Esophageal stricutre
- Esophageal dysmotility
T/F: oropharyngeal and cricopharyngeal causes of dysphagia were not identified in the cat
True
Which view has the highest sensitivity for identifying pneumothorax?
Right lateral HB projection had the highest rate of detection and gradation of severity for pneumothorax
Which radiographic view is best for detection of pneumoperitoneum?
Left lateral view - gas accumulates dorsally near fluid-filled fundus
What type of stent is this? What are its indications?
Balloon-expanding metallic stent (BEMS) - premounted onto a balloon dilation catheter and balloon inflation deploys the stent at the target. The BEMSs are typically made of stainless steel and used in veterinary IR for palliation of nasopharyngeal stenosis or stenting of the right ventricular outflow tract
What type of stent is this? What are its indications?
Self-expanding metallic stent (SEMS)
Common indications for SEMSs in veterinary IR include tracheal, vena caval, and urethral stents
What are the types of self-expanding metallic stents (SEMS)?
- Woven SEMS:
- Stainless steel or nitinol
- Forshorten (compressed stent longer than deployed stent)
- Reconstrainable for correction of improper positioning if less than 60-70% of the stent has been deployed
- Laser-cut SEMS:
- Nitinol
- Do not forshorten
- Are not reconstrainable
What is the difference between these 2 stents (can come in both BEMS and SEMS)?
D - Covered form or stent graft; help to constrain tissue proliferation and luminal restenosis, but may act as a nidus for infection
E - Bare-metal form
B - cutting balloon dilator
C - conventional balloon dilator
What are the phases of excretory urography?
- Arteriogram
- Nephrogram
- Pyelogram
- Cystogram
What are contraindications for IVP?
- Dehydration
- Previous contrast reaction
- Oliguria/anuria
- Multiple myeloma
What phases of IVP are these kidneys in?
A - before
B - nephrogram
C - pyelogram
T/F: 4 mL/kg sufficiently distends bladder to eliminate wall thickening due to incomplete filling, but does not eliminate mucosal irregularity due to cystitis
True
Wall should not be >2mm in thickness at this degree of distention
Describe normal appearance of equine myelogram in neutral, flexed, and extended positions
NEUTRAL
- Dorsal column is wider and more uniform than ventral column
- Dorsal column widens at the caudal aspect of each foramina
- Ventral column usually narrows and is slightly elevated at intervertebral disc spaces
FLEXION:
- Dorsal contrast column remains the same
- Ventral column becomes even narrower at the disc spaces
EXTENSION:
- Dorsal column remains the same
- Ventral column becomes slightly wider C5
Sensitivity and specificity of myelography for identifying CVM in horses
Sensitivity of myelogram is low and specificity is moderate no matter the criteria used
Sensitivity and specificity appear higher for C6-7 than mid-cervical sites
What are described measurements for myelography in CVM horses? What is the accuracy of each?
- 50% reduction of the dorsal contrast column at the intervertebral disc space
- Recently been shown to have false positive results
- 70% reduction of the dorsal column necessary to avoid false positives
- >20% reduction in dural diameter
- more accurate in neutral views
- 2 mm reduction in the dorsal contrast column signify significant compression
- Not recommended
At C6-7, what percent reduction in dorsal contrast column height and dural diameter have a high sensitivity and specificity?
At C6-7, reduction of the dorsal contrast column height by 70% or reduction in dural diameter by 25% have a high sensitivity and specificity
What are the most common sites of compression in CVM horses?
- C3-4 > C6-7 > C5-6 > C4-5
- Rarely detected at the other sites in the cervical spine
- 29% of compressive horses had it in multiple sites
Papageorges 1987
Which stent is recommended by Weisse for urethral stenting due to obstruction by tumor? Due to recurrent stricture?
Obstruction - Self-expanding metallic stent (SEMS), laser cut, uncovered
Stricture - SEMS, laser cut, covered
Calculate the tracheal stent size needed given that your raw radiographic measurement (not corrected for magnification) measures 13mm in the cervical trachea and 10mm in the intrathoracic trachea. The marker measures 11mm in length. The length of the trachea requiring stenting is ~85mm.
Choose a 14mm diameter stent (to be 2-3mm greater in diameter than the maximal measure)
A 14 x 58 mm stent expanding between 9mm and 12mm (calculated from radiograph) will be approximately 85mm in length once expanded
What fatal complications is automatic tru-cut biopsy of the liver associated with in cats?
Fatal hypotension and bradycardia within 15 minutes of biopsy
How do different anesthetic protocols affect uptake of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) by the brain in PET/CT imaging?
- Standard uptake value (SUV) for the frontal and occipital lobes was significantly higher than in the brainstem in all dogs regardless of protocol
- Dogs receiving medetomidine/tiletamine-zolazepam also had significantly higher whole brain SUVs than the propofol/isoflurane group
What is the radiopharmaceutical uptake caused by?
Peroneal nerve block
This occurs in approximately 50% of blocked limbs and can mimic a tibial lesion on the lateral view in approximately 20% of blocked limbs. Associated with higher dose of anesthetic.
How does acepromazine influence count density in horse limbs?
- Intravenous administration of acepromazine increases peripheral blood flow causing an earlier onset of the vascular phase during the three-phase bone scan; increased count density of vascular phase
- Acepromazine did not increase the count density of the bone phase scintigrams
In regards to trans-splenic portoscintigraphy, are there any distinguishing features differentiating between single intrahepatic and single extrahepatic shunts?
No distinguishing features
What is the morphology of this shunt?
Portoazygous - Tc bolus traveled dorsally, running parallel to the spine and entering the heart craniodorsally
What is the morphology of this shunt?
Splenocaval - bolus ran from the area of the portal vein/splenic vein junction in a linear fashion toward the caudal vena cava entering the heart caudally
What are the 3 identified shunt morphologies with trans-splenic portography?
- Porto-azygous
- Spleno-caval
- Internal thoracic
What is the most common distribution of feline thyroid disease?
Bilateral asymmetric
T/F: multifocal thyroid disease will develop in a few cats that have ectopic thyroid disease or thyroid carcinoma
True. Ectopic thyroid disease and thyroid carcinoma are relatively uncommon in hyperthyroid cats
Which thyroid scintigraphy measurement has the highest sensitivity for diagnosis of hyperthyroidism in cats?
T/S ratio had the accurary
Which thyroid scintigraphic parameter is the best parameter to predict the functional volume and metabolic activity of the feline adenomatous thyroid gland?
Percent thyroidal uptake of Tc (TcTU)
List differentials for generalized osteosclerosis in the cat?
- Osteopetrosis
- FeLV
- Lymphoblastic leukemia, lymphoma
- C-cell tumor
- Myeloproliferative disorders
- Chronic renal failure
Does head and neck position have an effect on nasopharyngeal size in horses? If so, which results in the smallest diameter?
- Significant influence of head and neck position on pharyngeal diameter, with head position having the major effect; neck position was less important, but still significant
- Smallest pharyngeal diameter was found at the dorsal, flexed position
What head and neck position in the horse results in the largest nasopharyngeal diameter?
Largest pharyngeal diameter was found at the extended midway position
Are intra- and intervertebral ratios good for differentiating normal from CVM in Dobermans? How do the ratios change with location along the cervical spine (general)?
- No difference in either the intervertebral or intravertebral ratio between normal vs. affected dogs
- In all dogs (normal and CVM), ratios decreased progressively along the cervical spine, being smallest at C6–C7 and C7
What signalment parameters are associated with small intra- and intervertebral ratios in Dobermans?
- Increasing age
- Males
Left cranial vena cava
- Pathophysiology
- Clinical significance
Most commonly encountered anatomic variant, but not clinically significant
- Failure of left anterior cardinal vein regression
- Can occur alone or with a normal right cranial vena cava
- Left cranial vena cava enters the right atrium caudally (see image)
- Has no detrimental effect but assumes importance during surgery as catheterization of left jugular can cause catheter to take unexpected path
- Transpositional venous anomalies often seen in patients with transpositional arterial anomalies (i.e., left cranial vena cava and persistent right aortic arch)
What are the standard views for evaluation of the foot in cows?
- Dorsal 65 proximal-palmarodistal and a lateral 30 dorsal-mediodistal oblique
- Allow the pedal bone and distal sesamoid bone, as well as the distal interphalangeal joint, to be displayed and evaluated in 2 different planes
DOI: https://doi.org/10.1016/j.cvfa.2013.11.003
Where was the injection made? Label the anatomy.
Right atrium
Left image
- Right auricle
- Right ventricle
- Pulmonary sinus of Valsalva
- MPA
- LPA
- RPA
Right image
a. Pulmonary v.
b. Left atrium
c. Left ventricle
d. Sinus of Valsalva
e. Ascending aorta
f. Brachicephalic trunk
g. Left subclavian a.
Where was the injection made? Label the anatomy.
Injection made in vena cava
Left image:
- Right atrium
- Right ventricle
- Pulmonary sinus of Valsalva
- MPA
- Right auricle
Right image:
a. Left atrium
b. Left ventricle
c. Left auricle
d. Aorta
e. Brachiocephalic trunk
f. Left subclavian
Where was the injection made? Label the anatomy.
Injection made in vena cava
- Vena cava
- Right atrium
- Right auricle
- MPA
- Right ventricle
- MPA
Label the anatomy
- Left atrium
- Left ventricle
- Ascending aorta
- Descending aorta
- Brachiocephalic trunk
Label the anatomy
What are the two commonly used balloon-dilator catheters for pulmonic stenosis as described in Weisse?
- TYSHAK
- Thin, minimally compliant
- Relatively low maximal burst pressure
- Low profile
- Most sizes can accomodated a 0.035” guide wire
- Commonly selected for BPV in dogs
- Z-MED
- Thicker –> require larger introducer size
- Greater maximal burst pressure
What are the 3 types of esophageal stents?
- Biodegradable (BDS) made of PDS suture
- SEMS
- Self-expanding plastic stents (SEPS)
They are either uncovered, partially covered, or fully-covered. The advantages of a covered stent is a lower rate of re-obstruction, especially with strictures, but a higher rate of migration, due to the failure of tissue in-growth. Esophageal stents have a dumb-bell shape at each end, to aid in preventing migration, and the covered stents, since they are intended for short-term use, have a string around each end so that they can be removed endoscopically with a grasping instrument.
What stent is recommended for tracheal stenting?
Mesh, self-expanding metallic stents are most commonly used for tracheal stenting procedures,as balloon-expandable and laser-cut stents have been ssociated with unacceptable risks of migration and fracture, respectively
Label the anatomy of the digital flexor tendon sheath.
Which tendon of the shoulder is this?
Supraspinatous
Infraspinatous
Biceps tendon
Features of insulinoma on different modalities (CEUS, CT, and MRI)
- CEUS
- Variable enhancement patterns, but generally increases conspicuity of the nodule
- CT (variable reports)
- Hyperattenuating to normal pancreas in arterial phase
- Variable in venous and delayed phases
- MRI
- T2w fat-saturation hyperintense
- Post-gad T1w fat-saturation isointense
Which equine intercarpal ligaments were visible with CT arthrogram
- Medial and lateral palmar intercarpal ligaments
- Radiocarpal ligament
- Transverse intercarpal ligaments
- Palmar carpal ligament
In dogs, mean ratio of kidney length to the second lumbar vertebra length is dependent on what?
Skull type - brachycephalic dogs had the highest median LK/L2 ratio and dolichocephalic dogs the lowest. Mesaticephalic dogs were in the middle
Using the right lateral view, what is the mean ratio of kidney length to the second lumbar vertebra length for different skull types?
- Brachycephalic dogs - LK/L2 ratio of 3.1
- Dolichocephalic dogs - 2.8
- Mesaticephalic dogs 2.97
T/F: A mean ratio kidney to L2 length of >3.5 was found only in mesaticephalic dogs on the ventrodorsal view
True
How did the mean ratio of kidney length to L2 length correlate with body weight?
- Small dog = larger ratio
In the Latimer et al. paper regarding lung lobe torsions in juvenile dogs (<12 mo), which lung lobes were affected most commonly and in what order?
- Left cranial lung lobe
- Right middle lung lobe
- Right cranial lung lobe
This paper consisted of mostly pugs, which are predisposed to L Cr LLT. The two non-pugs in this paper did not have torsions of L Cr.
In D’Anjou et al., was there a predilection for site of lung lobe torsion and weight?
Yes.
- Large dogs - Right middle lung lobe
- Small dogs - Left cranial lung lobe
- Cats (n=2) - right cranial and right middle
What is the most-likely diagnosis?
Lung lobe torsion
- Vesicular gas pattern
- Abrupt tapering of bronchus
- Mild pleural effusion
In Lang et al. (1986), which radiographic view was most sensitive for detecting pulmonary metastasis?
- R lateral > Left lateral > VD
- Recommend two-viewers review all met checks or, if only one reviewer, a 3-view study should be used
What side do these cranial lobar vessels belong to in this left lateral radiograph?
Right pulmonary vessels - The pulmonary vessels in the right cranial lung lobe are more conspicuous in a left lateral than in a right lateral radiograph. This is caused mainly by the dorsal displacement of the right cranial lobe that occurs when the patient is in right lateral recumbency resulting in the right cranial lobar vessels being superimposed on the left cranial lobar vessels.
Thrall 6 ed.
Which is left and right?
T/F: An enlarged left atrium causes bronchial collapse resulting in coughing
FALSE. No association between moderate‐to‐severe left atrial enlargement and left bronchial collapse (Singh and Johnson, JVIM)
How does 40mcg/kg dexmedetomidine IM influence the size of the cardiac silhouette on different views in cats?
Dexmedetomidine was associated with a small but significant increase in cardiac silhouette size:
- Right lateral (vertebral heart score)
- VD/DV (percentage width)
Enlargement may be persistent at a minimum of two hours postdexmedetomidine reversal
Radiographic appearance of non-cardiogenic pulmonary edema
- Mixed
- Symmetric
- Peripheral
- Multifocal
- Bilateral
- Dorsal lung
Can be asymmetric and unilateral
A Bulldog presents for dyspnea after a collapse episode and you suspect NCPE. On radiographs, you see asymmetric, unilateral, and dorsal pulmonary interstitial to alveolar pattern. What is the most likely cause of this distribution of NCPE?
Post-obstructive pulmonary edema
When the distribution was unilateral, pulmonary infiltration involved mainly the right lung lobes
What criteria can be used to assess the pulmonary veins in dogs with MMVD (Oui et al., 2015)?
Normal dogs:
- Pulmonary arteries and veins are similar in size
- Cranial lobar vessel diameter smaller than 4th rib (lateral)
- Right caudal PV <1.22x width of 9th rib (VD)
Right caudal pulmonary vein can be enlarged without distention of cranial pulmonary vein
What is the most likely diagnosis?
Laryngeal paralysis –> air-filled laryngeal ventricles (Stadler VRU 2011, Figure 3)
Magic angle
- 55 degrees relative to B0
- Short TE (PD, STIR, T1w)
- Occurs in neutral and angled limbs
- Increasing the TE to >40ms in spin echo sequences and >80ms in TSE sequences, eliminates the magic angle effect in tendons
- Other paper says that magic angle is reversed at TE 140ms, but 120 ms had the best balance bt image quality and magic angle artifact
Werpy
T/F: Due to the configuration of the fibers, ligaments more susceptible to magic angle effect than tendons
True - ligament fibers have a more complex organization than tendons
MRI features of coccidioides granulomas
- Difficult to determine location (intra- vs. extra-axial location)
- Variable MR features, many of which overlap with neoplasia
- Variably enhancing, may be marked
- Often poorly defined borders –> this will differentiate between meningiomas, which have sharp margins
Bentley VRU
Newer paper out of AZ (Spoor VRU 2019) describes a different appearance - bilateral, symmetric T2w hyperintensities, faint/wispy enhancement in the caudate nucleus, frontal lobe, and rostral internal capsule. Impressive brain atrophy once the infection resolved.
CT and MRI features of carotid body paragangliomas (Mai VRU 2015)
- Centered on carotid body
- CT
- hypoattenuating to adjacent muscles
- strong, heterogeneous enhancement
- MRI
- hyperintense to muscles in T1- and T2-weighted MRI
- strong, heterogeneous enhancement
- Invasion of adjacent structures - most common was basilar portion of skull; others included regional vessels, tympanic bulla, cranial cavity
Carotid body paragangliomas
- Common presenting complaint
- Signalment
- Most common reason for imaging was a palpable cervical mass or respiratory signs (i.e., dyspnea or increased respiratory noises
- Most commonly affected breed was Boston terrier (n = 5)
- Predominately male castrated
- Median age was 9 years [range 3–14.5].
7‐year‐old male neutered domestic short‐haired cat had depression for 5 months and acute blindness
Pituitary apoplexy
A dog presents for hindend weaknes. On MRI you see heterogeneous STIR hyperintensity in the hindlimb muscle and the majority of the STIR‐hyperintense region does not enhance indicating poor perfusion. What is the most likely diagnosis?
Ischemic myopathy
Which MRI sequence is best for evaluating facial neuropathy?
VIBE (sensitivity 86-96% and the specificity 87-92%)
Conventional T1-weighted images yielded a sensitivity of only 39-65% and a specificity of 94-96%
T/F: MRI was not a sensitive detector of vestibulocochlear nerve abnormalities
True
A pelvic width reaching ____ was observed in several dogs and cats with clinically normal renal function that were not receiving IV fluids
3 mm (D’Anjou VRU 2011)
Mean pelvic width increased in polyuric animals or animals receiving IV fluids; increased further with pyelonephritis
What width of the renal pelvis has been suggested as a cut-off for predicting animals with urinary outflow obstruction?
13mm
What measurements are considered normal, indicative of hyperplasia, or indicative of neoplasia regarding parathyroid US per Wisner VRU 2005?
- >4mm = adenoma or carcinoma
- 2-4mm = hyperplastic
- <2mm = normal
The strength of a sound wave depends on:
- Amplitude
- Intensity
Amplitude
- Maximum variation along the y-axis
- In diagnostic US, positive compression amplitude exceeds the negative rarefaction amplitude (asymmetric, non-sinusoidal waveform)
Intensity
- Concentration of energy (power) per unit of area (W/cm2)
- Inversely related to wave width
- Intensity of the beam is greatest where the beam is narrowest (i.e., focal point)
- Higher intensity beam = increased risk of adverse biological effects
Wavelength (λ)
- Distance between 2 areas of compression (rarefaction)
- Determines penetration power and image resolution along the beam
- large λ = low frequency
- small λ = high frequency
Frequency (f)
- Number of cycles per unit of time (Hz)
- Inversely related to wavelength
How do image resolution and penetration vary with changing frequency?
- Low frequency (large wavelength) = high penetration, but low resolution
- High frequency (small wavelength) = low penetration, but high resolution
_____ and _____ are dependent on the propagation medium, but ____ is not dependent on the propagation medium
Wavelength and speed are both depended on the propagation medium, but frequency is not dependent on the propagation medium
Acoustic velocity depends on:
- Density - increased density —> slower speed
- Stiffness - increased stiffness –> faster speed
- More important than density
- Compressibility - increased compressibility = slower speed
- Inverse of stiffness
Rank soft tissues, air, and bone in order of acoustic velocity (propagation speed) from fastest to slowest
Bone (4,080 m/sec) > soft tissue (1,540 m/sec) > air (331 m/sec)
Focusing the beam improves _____ resolution
- Lateral (narrower beam)
- Elevational (less important)
Advantages of harmonic imaging
- Increased lateral resolution
- Increased signal to noise ratio
- Decreased artifacts:
- Reverberation
- Refraction
- Scatter
- Noise
- Side lobes
As the angle (insonation angle) between the transmitter and interface approached ____ degrees, the accuracy of the estimation of velocity decreases
90 degrees. Only the sound waves parallel to the beam contributes to Doppler effect. In general, use an insonation angle <60 degrees to give accurate estimate of velocity. May have increased artifact if the angle is less than 30 degrees
Strain elastography
- Aka compressive elastography
- Stress is applied by repeated manual compression of the transducer and the amount of lesion deformation relative to the surrounding normal tissue is measured and displayed in color
- Largely dependent on the examiner’s experience, and significant interobserver variability has been found
Shear-wave elastrography
- Uses an acoustic radiation force impulse created by a focused ultrasound beam, which allows measurement of the propagation speed of shear waves within the tissue to locally quantify its stiffness
- Kilopascals or meters per second
- Highly reproducible
- Potential for an increase in artifacts caused by reflection and refraction
The Doppler frequency shift is defined as:
- A. The difference between the Doppler frequency and the imaging frequency
- B. The difference between the transmitted and received frequencies
- C. The time between the transmitted and received pulses
- D. The rate at which the transducer emits pulses
B. The difference between the transmitted and received frequencies.
The Doppler effect causes the transmitted Doppler frequency to be altered when it encounters a moving reflector. The frequency is increased if the reflector is moving toward the beam and decreased if the reflector is moving away from the beam. The difference that occurs between the transmitted frequency and the altered frequency that is reflected back is known as the frequency shift.
While performing a Doppler study, the measurement of the Doppler angle of incidence was underestimated. What error will result from this mistake?
- A. The frequency shift will be underestimated.
- B. No Doppler frequency shift will be detected.
- C. Mirror imaging of the Doppler spectrum will occur.
- D. The velocity estimation will be inaccurate.
- E. Aliasing of the Doppler spectrum will occur
D. The velocity estimation will be inaccurate.
Power Doppler
- Uses the amplitude of Doppler signal to detect moving matter
- Independent of velocity and direction of flow, so there is no possibility of signal aliasing
- Independent of angle, allowing detection of smaller velocities than color Doppler
- Higher sensitivity than color Doppler, which makes a trade-off with flash artefacts
In the cat, normal measurements of:
- Esophageal wall
- Cardia wall
- Pyloric wall
- Pyloric muscularis layer
- Length of duodenal submucosal thickening
- Esoph - 4.9 mm
- Cardia - 5 mm
- Pyloric wall - 4.4 mm
- Pyloric mucosal layer - 2.5 mm
- Length of duodenal SM thickening - 4.7 mm
In Zwingenberger JVIM 2011, muscularis thickening on ultrasound correlated with cellular infiltration of what layers? Lymphadenopathy was associated with infiltration of what layers?
- Muscularis thickening - mucosal and submucosal
- Lymphadenopathy - mucosal and submucosal OR mucosal, submucosal and muscularis
T/F: In cats with infiltrative bowel disease, disease confined to the mucosa and lamina propria was not associated with ultrasonographic changes
True
What is this artifact and why does it occur?
- Twinkle
- Occurs behind a strongly reflective interface, such as those produced by urinary tract stones or parenchymal calcifications, and appears as a quickly fluctuating mixture of Doppler signals with an associated characteristic spectrum of noise
- Narrow-band signal error generated by highly echogenic interfaces seems to be the primary cause
- Enhanced with rough surfaces
In vivo, which factors influence the appearance of Twinkling artifact
- Gain
- Surface roughness
- Stone size
Ultrasonographic appearance of lipiduria in cats
- Suspended +/- gravity independent echoes
- No artifact
Clumping of suspended echoes in lipiduric cats is associated with ________
- Type of lipid - diacylglycerol (DAG)
Label the anatomy in this Gelding
- Arrows - ureters
- Arrowheads - deferent ducts
Label the anatomy in this mare
- Arrows - ureters
- Arrowheads - vagina
Label the anatomy in this Stallion
- Arrows - ureters
- Arrowheads - ampullae
In horses, what is the normal ureteral wall thickness and diameter of ureter (contracted vs. expanded)?
- Ureteral wall thickness 1.0 - 2.4mm
- Ureteral diameter contracted - up to ~9.5mm
- Ureteral diameter distended - up to 19mm
Normal urinary bladder thickness in horses
1 to 5 mm
Differences in enhancement pattern of the spleen between non-sedated dogs, dogs sedated with butorphanol, and dogs sedated with dexmedetomidine?
- Normal and butorphanol dogs were the same
- Initial phase - rapid, intense enhancement of small arteries
- Venous phase - heterogeneous enhancement of splenic parenchyma gradually becoming more homogeneous
- Wash-out phase - gradual, homogeneous decrease in intensity
- Dexmedetomidine
- Slower distribution of contrast medium
- Whole organ was diffusely hypoechoic during the first 30s
- Enhancement was weak and homogeneous throughout
T/F: Butorphanol does not cause subjective or objective effects during normal contrast-enhanced ultrasound of the spleen
True
Increased GB volume and reduction in GB ejection fraction were seen in which of the following groups:
- Normal
- Mobile sludge
- Immobile sludge
- Mucocele
Seen in all dogs with sludge or mucocele, but the mucocele group was most severely affected
T/F: Biliary stasis occurs not only in dogs with gallbladder mucocele but also in dogs with biliary sludge
True
CEUS adrenal gland enhancement patterns in normal dogs versus dogs with PDH
Normal:
- Initial enhancement of an artery within the medulla parallel to the long-axis of the gland
- Centrifugal enhancement of small arteries branching off the central artery
- Diffuse, homogeneous, intense enhancement
- Gradual washout - homogeneous loss of intensity
PDH
- rapid, chaotic, and simultaneous perfusion of US contrast agent into both the adrenal medulla and cortex
- Three enhancement patterns
- In all PDH dogs, regardless of these vascular patterns, there was a uniform distribution of the contrast agent during the late washin phase and the entire gland became iso-enhanced, followed by slow and progressive washout, similar to that of the remaining adrenal parenchyma
What are the 3 early wash-in enhancement patterns in the adrenal glands of dogs with PDH?
- Type 1
- only the central longitudinal artery of the medulla was seen, but it was barely visible
- dogs with <24ug/dl on ACTH
- Type 2
- perfusion of the adrenal gland by the contrast agent was so fast and disordered that the central longitudinal artery was not detectable, even in the initial washin stages
- ACTH-stimulated cortisol levels > 24ug/dl
- Type 3
- nodular pattern - presence of abnormal vessels forming nodular lesions together with homogeneous, but chaotic enhancement of the contrast agent within the whole adrenal parenchyma
Normal CEUS pattern of small intestine in healthy cats
- Initial rapid enhancement of serosal and submucosal layers
- Followed by a more gradual enhancement of the entire wall
- At peak enhancement, there was a lack of demarcation between wall layers
- Late phase, there was a gradual wash out of signal from the intestinal wall. The wash out of the submucosal layer occurred last
T/F: kVp, but not mAs influences the energy (quality) or the x-ray beam
True. kVp is the only factor to control quality (aka energy) of the x-ray beam
T/F: Both kVp and mAs control quantity of the x-ray beam
True.
What are heat units? How is this calculated?
Heat units describe maximum load (function of heat energy) that can be safely applied to an x-ray tube; heat energy determined by exposure factors
- Simple generator: HU = kVp * mA * exposure time (sec)
- For 3-phase generators - multiple by 1.35
- For constant potential generators - multiple by 1.4
Calculate the heat units for a simple generator with settings of 70 kVp, 100 mA, and 0.1 sec exposure time
70 * 100 * 0.1 = 700 HU
Calculate the heat units for a constant potential generator with settings of 70 kVp, 100 mA, and 0.1 sec exposure time
70 * 100 * 0.1 * 1.4 = 980 HU
What is the relationship between radiographic contrast and kVp?
- Inversely related
- Low kVp = high contrast
- Increased energy (kVp) photons are more likely to undergo scatter than photoelectric effect –> compton decreases image contrast (makes it gray)
What is this foramina?
Optic canal
Optic canal
Green - orbital fissure
Pink - rostral alar foramen
Bonus Q: What structure is indicated by the blue arrow
Rostral alar foramen
Blue arrow - indicates the rostral clinoid process, which is the rostral border of the sella turcica
Blue - round foramen
Green - alar canal
Bonus Q: What is the structure identified by the pink arrow
Oval foramen
Pink - caudal clinoid process, which is the caudal margin of the sella turcica
Internal acoustic meatus
Pink - jugular foramen
Green - petro-occipital fissure (aka temporo-occipital fissure)
Hypoglossal canal
What is this view? Name the tarsal bones.
Blue - talus
Black - calcaneus
Orange - central tarsal
Yellow - tarsal 3
Purple - tarsal 1 and 2
Pink - tarsal 4
Lateromedial
What is this view? Name the tarsal bones.
Blue - talus
Black - calcaneus
Orange - central tarsal
Yellow - tarsal 3
Pink - tarsal 4
Craniocaudal
What is this view? Name the tarsal bones.
Blue - talus
Black - calcaneus
Orange - central tarsal
Yellow - tarsal 3
Purple - tarsal 1 and 2
Pink - tarsal 4
PLDMO
What is this view? Name the tarsal bones.
Blue - talus
Black - calcaneus
Orange - central tarsal
Yellow - tarsal 3
Purple - tarsal 1 and 2
Pink - tarsal 4
DLPMO
What attaches at this site?
Superficial digital flexor tendon
What attaches at this site?
Common digital extensor tendon
What is the order of enhancement and order of peak enhancement with ocular CEUS?
- Initial enhancement
- Choroid retina —> iris and ciliary body
- Peak enhancement
- Retrobulbar –> ciliary body –> iris –> optic nerve (5 min)
How does ocular imaging with CEUS compare to Doppler?
CEUS - increased visualization of small vessels particularly in iris/ciliary body
What view is this? Label the anatomy.
Right parasternal long axis
What view is this? Label the anatomy.
Right parasternal long axis
What view is this? Label the anatomy.
Right parasternal short-axis view
What view is this? Label the anatomy.
Right parasternal short axis at the level of the mitral valve
- LVOT
- Right ventricle
- Mitral valve leaflets
What view is this? Label the anatomy.
Right parasternal short axis view at the level of the ventricles/papillary muscles
- Left ventricle
- Right ventricle
- Papillary muscles
What is the view? Label the anatomy
Left apical view - four chamber
- Right atrium
- Right ventricle
- Left ventricle
- Left atrium
What view is this? Label the anatomy.
Left apical view - 5 chamber
- Right atrium
- Right ventricle
- Left ventricle
- Left atrium
- Aorta
What is this view? Label the anatomy.
Left parasternal long- axis view
What is this view? Label the anatomy.
Left parasternal short axis view
FOAL
Umbilical vein
- Should be thin-walled with an anechoic lumen
- Diameter <10mm
FOAL
Umbilical arteries (1 and 3)
- Round, thicker wall
- Echogenic clot material
- Diamter <12mm (level of bladder)
Urachus (2)
- Normally a potential space between the two arteries; does not contain fluid
- Combined measurement with arteries <25mm
CALF
- Anechoic structure is the umbilical vein
- Lumen large near body wall (10-25mm)
- Urachus should never be seen
- Arteries should not extend beyond UB apex after 1 week
- Walled structures with central anechoic to hypoechoic tissue
Nephrogram: fair to good initial opacification that persists or becomes more opaque with time
- Adverse reaction to contrast media
- Systemic hypotension
- Acute tubular obstruction or necrosis
- Acute renal failure
Nephrogram: poor initial opacification that gradually fades
polyuric renal failure
Nephrogram: poor initial opacification that persists
glomerular or generalized renal disease
Nephrogram: poor initial opacification followed by intestification of the opacification
- Renal ischemia
- Renal hypotension
- Obstruction
List 4 benefits of spatial compound ultrasound?
- Reduced speckle
- Reduced artifacts
- Clutter
- Shadowing
- Echo drop-out
- Increased contrast resolution (increased signal to noise)
- Increased visibility of lesion margins
What is spatial compound imaging?
Method to improve sonographic image quality by combining several image frames to cancel out random variation
In Whatmough et al., VRU 2006, compound images were considered better with:
- Transmit-only, receive-only, or combined transmit/receive
- Sector, curvilinear, or linear transducers
- Combined transmit/receive
- Sector and curvilinear transducers
In Whatmough et al., VRU 2006, what properties of spatial compound imaging accounted for the higher quality compared to non-compound images?
- Improved border definition
- Increased signal to noise ratio
How does anisotropy affect renal cortical echogenicity in dogs? Does spatial compound imaging influence this?
- Echogenicity increased with a perpendicular insonation angle compared to a parallel insonation angle (cortical hyperechogenicity in the poles, greater cranially)
- Spatial compounding did not change this
Which CEUS agent has a hepatic sinusoidal phase?
Levovist
Which CEUS agent has been associated with anaphylactic reactions in dogs and other small animals?
Optison - has a human albumin shell
In the dog, which physes close by 5 months (~150 days)?
- Anconeal process
- Acetabulum
- Pubic symphysis
In the dog, which physes close by 6-8 months?
- Calcaneus
- Humeral condyle and medial epicondyle
- Distal metacarpals and metatarsals
- Phalanges
In the dog, which physes close by 7-10 months?
- Proximal radius
- Olecranon process
- Cranial vertebral body
In the dog, which physes close by 9-12 months?
- Distal radius and ulna
- All of the proximal tibia and fibula
- All of femur
- Caudal vertebral body
- Ischiatic tuberosity
In the dog, which physes close by 12-18 months?
- Distal tibia/fibula (12-15 months)
- Proximal humerus (12-18 months)
In the dog, when does the humeral condyle (intercondylar) close?
6-8 weeks
What is this lesion? What percentage of GSDs with cauda equina syndrome have this lesion?
- Sacral osteochondrosis - lesion in dorsal endplate
- ~30% of GSDs with CES have sacral OC
- Clinically normal with OC <18mo
- CES with OC >18mo
- Dogs with CES and OC were 2 years younger than CES dogs w/o OC
Which tissues concentrate 99mTc-pertechnetate?
- Thyroid
- Salivary glands
- Gastric mucosa
- Choroid plexus
T/F: In cats, optimal imaging of the thyroid gland is 20 min to 2 hours post-injection of 99mTcO4- while imaging after 4 hours may give a false diagnosis of hyperthyroidism.
True
Iodide trapping by normal thyroidal tissue is significantly enhanced by antithyroid medication and continues to be increased for _____ after withdrawal of the medication.
15 days
normal cats placed on methimazole will have an elevated thyroid:salivary ratio and a false impression of hyperthyroidism could be made on TcO, thyroid scintigraphy
What is the mechanism of action for methimazole?
- Inhibits the synthesis of thyroid hormones by blocking incorporation of iodine into tyrosyl groups to form thyroglobulin
- Inhibits coupling of iodotyrosines to form tetraiodothyronine (T4) and triiodothyronine (T3)
Methimazole does not directly affect the iodide pump which concentrates iodide in thyroid cells
What is the sentinel clot sign as described by Specchi et al., VRU 2017? Is it accurate? How does the attenuation compare to peritoneal effusion?
- Highest attenuation hematoma adjacent to a bleeding organ
- Accurately localized source of hemoabdomen in the majority of dogs
- Clot has a higher HU (43-70) compared to hemoabdomen (20-45)
What was a diagnostic limitation for identifying the sentinel clot sign?
- Too little peritoneal effusion
Things that are T1w hyperintense
Double fragmented medial coronoid process (FMCP) + N
- F - flow-related artifact
- F - fat
- M - methemoglobinemia
- M - melanin
- C - cholesterol
- C - calcification (iron, copper, manganese)
- P - proteinaceous fluid
- P - posterior pituitary
- N - necrosis
Hemorrhage on MRI
- Hyperacute (<7h) - It B
- Acute (7h - 3d) - Id D
- Early Subacute - B D
- Late Subacute - B B
- Chronic - D D
Are spinal MCT more likely to be intramedullary, intradural/extramedullary, or extradural? What is the typical distribution?
- All were extradural
- Can be epidural, paravertebral, or polyostotic (mimic MM)
Which of the following factors were associated with survival of dogs diagnosed with MUE?
- Absolute midline shift <0.3mm
- % Midline shift
- High CSF total nucleated cell count (TNCC)
- Age
- Age
- High CSF TNCC
Oliphant VRU 2017
Choose the correct statement regarding GFR measurement using 99mTc-DTPA renal scintigraphy:
- This method provides reliable, precise measurements of GFR with inherent variability of <0.01 ml/min/kg between scintigraphic studies of the same patient.
- GFR calculation is not affected by manually drawn ROIs around syringes, provided both pre- and post-injection syringes are accounted for.
- A value of + 0.4 ml/min/kg has been proposed as a suggested range of inherent variability between GFR studies of the same patient.
- Renal scintigraphy is the gold standard method for GFR assessment because it provides consistent GFR measures for a given patient, regardless of camera used, isotope, or observer’s level of experience.
- A value of + 0.4 ml/min/kg has been proposed as a suggested range of inherent variability between GFR studies of the same patient.
- GFR variability is affected by ROI drawing technique
- Renal scintigraphy is gold standard method of GFT, but it is defendent on the observer’s level of experience
Which of the following statements is correct? (Lee, VRU, 2016)
- Black blood cine acquisitions are useful to recognize MPA shunting lesion as turbulent flow causes MR signal loss.
- In human medicine, transcatheter or surgical closure are recommended if Qs/Qp ratio is superior to 1.
- A persistent left cranial vena cava occurs when the left-sided cranial venous cardinal system fails to evolve into the coronary sinus.
- Echocardiography is superior to cMRI for evaluating the minimal ductal diameter of a PDA.
- A persistent left cranial vena cava occurs when the left-sided cranial venous cardinal system fails to evolve into the coronary sinus.
- Black blood cine acquisitions are useful; do NOT cause signal loss
- Closure is recommended if Qs/Qp ration >2.0
- MRI is accurate in determining the shunt diameter
Which CT findings are statistically different between lipomas and infiltrative lipomas?
- shape
- margins
- presence and type of hyperattenuating components
What CT features were statistically different between benign fatty masses (lipoma and infiltrative lipoma) compared to liposarcoma?
- heterogeneous lesion, with a prevailing soft tissue component
- mineralization
- regional lymphadenopathy
LS neuroforaminal diameter is smallest using which techniques?
Oblique plane, hyperextended position
Which ligaments appear heterogeneous in MRI of the tarsal region in non-lame horses?
- Proximal suspensory ligament
- Accessory ligament of the DDFT
- Dorsal aspect of long plantar ligament
When interpreting MRI of the plantar tarsal region in horses, which structure has the most variable appearance?
A: DDFT
B: SDFT
C: Suspensory ligament
D: Long plantar ligament
C: Suspensory ligament
99mTc-sulfur
- What is it?
- What are its indications?
- How is it interpreted?
- What are its limitations?
- Colloid that localized in the reticuloendothelial system
- Given as an IV injection to evaluate for PSS; in dogs with PSS, a significant portion of colloid localizes in the lung
- PSS - reduced portal blood flow relative to arterial flow
- Limitations
- Localization in lung is non-specific for PSS - any hepatic insufficiency will cause the colloid to accumulate in the lung
- Cannot be used in cats because lung uptake is normal (resident macrophages)
Per-rectal portal scintigraphy
- Which radiopharmaceutical is used?
- How is it performed?
- What is its course in the normal animal? PSS?
- Sodium Petechnetate (Na+ 99mTcO4-)
- Insert catheter in distal colon to the level of the pelvic inlet
- Normal - flows to liver and then heart in 8-12 sec
- PSS - pertechnetate is seen in the heart before the liver
What are limitations of per-rectal portal scintigraphy?
- Cannot characterize shunt morphology
- Will not identify dogs with microvascular dysplasia
- Portal hypertension can result in poor absorption of pertechnetate from the colon
- Large amount of pertechnetate is required to overcome poor absorption in the colon (typically ~15% absorption)
Per-rectal portal scinitgraphy SHUNT FRACTION
- Normal
- Poor or slow absorption
- Congenital PSS
Bonus: Are shunt practions prognostic for response to surgical intervention?
- Normal - <5 %
- Poor or slow absorption - 15-20%
- Congenital PSS - >60% (usually 80-95%)
Shunt fractions have no prognostic significance and will not predict how an animal will respond to surgical intervention
What is portal streamlining in per-rectal portal scintigraphy? What are the 3 patterns of distribution?
- Non-uniform distribution of pertechnetate in the liver due to portal vein laminar flow patterns preventing homogenous mixing of the radiopharmaceutical
- 3 patterns of distribution:
- Dorsal hepatic –> right divisional branch of PV
- Central hepatic –> central divisional branch of PV
- Ventral hepatic –> left divisional branch of PV
What is the main advantage of trans-splenic portal scintigraphy over PRPS?
TSPS permits visualization of shunting vessel(s) in >90% of cases
What are advantages of TSPS over PRPS?
- Better absorption allows for a lower dose of radionuclide
- Improved count statistics
- Decreased personnel exposure
- Allows visualization of shunting vessel(s) and classification by termination site
Limitations of trans-splenic portal scintigraphy
- Possible reduced visualization of shunts located caudal to the splenic vein
- Does not allow identification of microvascular dysplasia
99mTc-mebrofenin
- What are clinical indications?
- How does it differ from pertechnetate?
- Used for trans-splenic portal scintigraphy
- High first pass extraction by the liver –> very little should continue beyond the liver into the heart in a normal animal
According to Lamb et al. VRU 2017, is this wooden foreign body likely to be acute or chronic?
Acute - gas in soft tissues was significantly associated with acute cases
According to Lamb et al. VRU 2017, what are CT features associted with chronic wooden foreign body?
- Visible foreign material
- Cavitary lesions
- Fat stranding
- Periosteal reaction of adjacent bones
According to Lamb et al. VRU 2017, what is the sensitivity and specificity of CT for identification of wooden foreign bodies?
- Moderate sensitivity (more false negatives)
- High specificity (few false positives)
Based on a study evaluating use of single-shot turbo spin echo (SSTSE) MRI sequences of the spine, increased suspicion of later development of progressive myelomalacia may be suggested by:
- A: Attenuation of CSF signal for >12 times the length of L2.
- B: Attenuation of CSF signal along dorsal margins of the spinal cord.
- C: Attenuation of CSF signal measuring <7 times the length of L2.
- D: Lack of attenuation of CSF signal on SSTSE images.
A: Attenuation of CSF signal for >12 times the length of L2.
>7.4x length of L2 is suggested cut-off
Gilmour VRU 2017
What is the optimal portal vein attenuation for maximizing GI wall conspicuity? When is the strongest mucosal surface enhancement seen in the small intestine? Stomach?
- 43-150 HUs
- Peak SI mucosal enhancement 30 second
- Peak gastric mucosal enhancement is in delayed phase (>60s)
What is the difference between scan field of view (SFOV) and display field of view (DFOV or FOV)? How do they influence resolution?
- SFOV - scanned area where the x-ray beam completely overlaps for 360 degrees; may not be selectable except for GE scanners
- DFOV - area of SFOV from which an image is reconstructed; cannot exceed the SFOV
- SFOV size has minimal effect on resolution, but DFOV should be kept as small as possible to improve resolution
For a 512 x 512 matrix, will a 40cm DFOV or a 15cm DFOV have better resolution? What is the pixel length for each?
- Smaller DFOV has better resolution, so 15cm will be better
- Pixel length = DFOV/matrix size
- 40/512 = 0.78mm
- 15/512 = 0.29mm
- Decreasing DFOV below 10cm does not further increase image resolution because of the geometry of the detectors
What is a matrix? How does matrix size influence spatial resolution and signal to noise ratio?
- The matrix is the number of pixels used to form an image
- The larger the matrix, the smaller the pixels
- Smaller pixels result in better spatial resolution, but decreased SNR (because larger matrix with smaller pixels means fewer x-rays pass through each voxel)
- 512 x 512 is common in CT
- 512 x 512 matrix = 262,144 pixels
Calculate to voxel size for a 15cm FOV, 5122 matrix, and slice thickness of 2mm
- Voxel size (mm3) = (FOV ÷ matrix) x slice thickness
- Example: what is the voxel size for a 2 mm slice thickness imaged with a 512 x 512 matrix over a 15cm FOV?
- Voxel size = (150mm2 ÷ 512) x 2
- Voxel size = 0.58mm3
In multi-dectector helical CT, what determines the minimal slice thickness possible? What are the advantages and disadvantages of a smaller thickness?
- Acquired slice thickness cannot be narrower than the detector width in MDCT
- Advantages:
- Decreased volume averaging, so better quality of MPR
- Disadvantages:
- Decreased signal to noise ratio
- Increased patient dose
- Longer scan time
- May affect tube heat capacity
How does an objects inherent contrast affect the slice thickness it should be viewed at?
- Good inherent contrast (i.e., bone, nasal turbinates, lung) is viewed with a wide window setting
- Poor inherent contrast (i.e., soft tissue, brain) is viewed with a narrow window setting
What is pitch and why is it significant?
- The increment in the z-axis the patient moves during one full gantry rotation
- Pitch is directly proportional to image blur
- Ex: high pitch –> blurry image
- In MDCT, the increment in the z-axis is discussed in 2 ways:
- Collimator pitch
- Detector pitch
What is the optimal pitch for a good quality reconstruction in a single slice scanner?
-
The optimal pitch is 1.4
- Provides compromise between coverage and detail
- Maximum pitch is 2; if the pitch is >2 –> skipped data
- A pitch smaller than 0.75-1 implies oversampling, longer scan time, and increased radiation dose to the patient
What is the effective dose for CT of the head, thorax, abdomen/pelvis?
Effective dose
- CT head: 2 mSv
- CT chest: 8 mSv
- CT abdomen/pelvis: 10 mSv
What factors influence radiation dose during CT (5)?
Factors that influence dose include:
- kVp
- mAs
- mAs is directly proportional to dose
- halve mAs –> halve the dose, BUT increase noise by the square root of 2
- Scan time
- Pitch
- indirect relationship
- Double the pitch –> halve the dose
- Volume examined
- Dose increase linearly
In a region with high inherent contrast, what algorithm and window settings would you choose?
- High inherent contrast - bone, lung
- Select a sharp algorithm (aka a high frequency algorithm)
- Select wide window settings
In a region of low inherent contrast, what algorithm and window settings would you choose?
- E.g., soft tissue, brain
- Smooth algorithm (aka low-medium frequency algorithm)
- Narrow window settings
What are window level and window width?
- Window level - central value of the window; should be selected for the HU of the tissue of interest
- Window width - range of HU values displayed
What window level and width would you select for a lung CT?
- C = 20, W = 320
- C = -230, W = 320
- C = -230, W = 2700
- C = -600, W = 1600
- C = -100, W = 1000
C = -600, W = 1600
Average lung attenuation is -950 to -550
What window width and level would you select for CT of soft tissue?
- C = 26, W = 1000
- C = 100, W = 150
- C = -50, W = 400
- C = 45, W = 400
C = 45, W = 400
Averge attenuation of soft tissue is 30-70
What window level and width would you select for brain?
- C = 35, W = 150
- C = 40, W = 450
- C = -50, W = 1500
- C = -500, W = 2000
C = 35, W = 150
Attenuation of brain
- White matter - 20-34
- Gray matter - 37-41
What window level and width would you select for bone?
- C = 500, W = 700
- C = 150, W = 1500
- C = -500, W = 150
- C = 450, W = >1500
C = 450, W = >1500
Attenuation of bone is >250
What is the optimal window level and width for imaging the pituitary gland?
C = 80, W = 250
How does CT appearance of hemorrhage change with phase?
- Resolves from outside in
- Peractue (<3d) - hyperattenuating
- Acute (<1 wk) - hyperattenuating center, hypo- outer ring
- Subacute (1-3wk) - ring contrast enhancement
- Chronic (>30d) - isoattenuating +/- contrast enhancement
What is the CT appearance of basihyoid thyroid carcinoma (aka sublingual thyroid carcinoma)?
- Oval-to-bilobed masses centered on the basihyoid bone with associated bone lysis
- Highly vascularized capsules with central poorly contrast enhancing areas (colloid)
- Laryngeal wall infiltration +/- invasion of the laryngeal lumen
- +/- metastasis to medial RPLN or lung
- 15-62% depending on the study
How do the clinical features of basihyoid thyroid carcinoma (aka sublingual thyroid carcinoma) differ from other thyroid carcinomas?
- Younger (7-9 yo depending on study)
- Less likely to have metastatic disease
- Specificly reported in Broome JVIM 2014
- Generally prolonged survival
- Less aggressive biologic behavior
What are CT features of muscular metastases? What is the most common location?
- Well-demarcated, oval-to-round or nodular lesions
- Isodense to normal muscle in the pre-contrast images
- Varying enhancement patterns:
- ring-enhancing (n = 16)
- heterogeneously enhancing (n = 8)
- homogeneously enhancing (n = 5)
- Usually multiple lesions
- Epaxial/paraspinal musculature > superficial muscles of thoracic wall
What is the incidence of muscular metastases in oncology patients are reported in Vignoli VRU 2013?
- Incidence of 2.1% in dogs
- Incidence of 3.1% in cats
T/F: Metastatic nodules in the cardiac muscle can appear isodense to muscle pre-contrast and hypodense to muscle post-contrast
True
Vignoli VRU 2013
T/F: The computed tomographic attenuation properties of hemorrhage are determined by hemoglobin
True
T/F: Oxyhemoglobin is diamagnetic and has long T1 relaxation times. This is the predominate form of hemoglobin in hyperacute hemorrhage.
True
What is the recommended reconstruction algorithm and window settings to reduce CT metal artifact in a seal gunshot model to improve evaluation of adjacent bone?
- High frequency reconstruction algorithm
- Wide to very wide window width
- ECTS raw data reconstruction technique
T/F: In a seal model for metallic gunshot head trauma, increasing the tube voltage from 120-140 kVp slightly increased the metal artifact magnitude.
True
T/F: In a seal model for metallic gunshot head trauma, a proprietary PFO filter reduced metal artifact
False - no significant reduction in metal artifact
What is the best diagnostic imaging method for gender determination in lizards?
- Contrast enhanced CT identified hemipenes in all males (100% accuracy)
- Contrast was administered into cloaca FYI
- Contrast radiography was second best
What is the CT appearance of feline nasopharyngeal polyps (pre- and post-contrast)?
- Precontrast
- Hypoattenuating to muscle, isoattenuating to soft tissue
- Homogeneous
- Ill-defined borders
- Postcontrast
- Rim enhancement, hypoattenuating to soft tissue centrally
- Homogeneous
- Ovoid with well-defined borders
- Expansion of the bulla with wall thickening
- Ipsilateral MRPLN enalrgement
T/F: There is substantial overlap in the pre- and postcontrast CT features of malignant and nonmalignant hepatic and splenic masses therefore dual-phase CT provides limited specific diagnostic information
True
In regards to a study by Jones and Lamb et al. (dual CT characteristics of hepatic and splenic masses), how did the appearance of splenic hematomas differ from nodular hyperplasia and hemangiosarcoma? Are there any similar characteristics between hematomas and hemangiosarcomas?
- Hematoma only had slight contrast enhancement in the early phase whereas hemangiosarcoma and nodular hyperplasia had marked enhancement
- Hematoma and (~75%) hemangiosarcomas showed enhancement patterns consistent with blood accumulation
Which CT characteristic is best at approximating the true length of canine appendicular osteosarcoma?
- Length of intramedullary/endosteal change
- Use submillimeter slice thickness (0.625mm)
Both the periosteal reaction length and contrast enhancement length over-estimated by ~10%
Which modality is the most useful for identifying wooden foreign bodies in the canine manus?
- CT
- Ultrasound evaluations were second, but limited by distal acoustic shadowing of the metacarpal pad
- MR is third
Which apect of MC3/MT3 in TB horses is predisposed to stress remodeling and fracture?
- Palmar-medial aspect of the condyle
What three pathologic changes preceed condylar stress fractures of the distal end of MC3/MT3 in Thoroughbred racehorses?
- Subchondral bone sclerosis
- Articular cartilage erosion
- Cartilage cracking
T/F: Subchondral bone changes CT and MRI are significantly correlated with grossly identified articular cartilage loss
True
T/F: Signal changes in articular cartilage detected on MRI were not significantly related to cartilage ulceration on gross examination
True
T/F: In TBs, condylar stress fractures typically propagate from the palmar/plantar third of the weight-bearing portion of distal MC3/MT3 to the level of the base of the sesamoids
True
What are the common locations of equine OC/OCD?
- Tarsocrural joint
- Distal intermediate ridge of the tibia (DIRT)
- Distal aspect of lateral trochlear ridge of the talus
- Medial malleolus of the tibia
- Metacarpophalangeal joint (Fetlock)
- Distal MC/MT 3
- Stifle
- Lateral trochlear ridge of the femur
- Distal patella
- Medial trochlear ridge of femur
- Intertrochlear groove
- Shoulder
- Caudal glenoid and humeral head
T/F: Regarding equine OC/OCD, it is common to have bilateral or quadrilateral lesions or multiple lesions within the same joint, but uncommon to have lesions concomitant lesions in different joints
True
What is T1 relaxation?
- Longitudinal relaxation (aka spin-lattice relaxation)
- Energy released from protons into the tissue around them (lattice) as they return to resting longitudinal magnetization (z-axis) after the RF pulse is discontinued
- T1 time = time it takes for 63% of T1 relaxation to occur
- From short to long T1: fat < white matter < gray matter < CSF
What is T2 relaxation?
- Tranverse magnetization (aka spin-spin relaxation)
- Occurs concurrently, but independent of T1 relaxation
- Describes the process of dephasing (protons becoming out of phase from phase coherence) due to proton interactions
- Faster than T1 relaxation
- T2 time is the time it takes for the protons to de-phase to 37% of original value
- From long to short: CSF > gray matter > white matter
What is time to repetition (TR)? What is time to echo (TE)
Time to repetition (TR)
- Time between 2 excitation pulses
- Determines T1w of the sequence
Time to echo (TE)
- Time at which we sample the signal
- Initially contrast in tissue is due to varying proton density, but over time it is due to differences in T2 relaxation
What sequences does each letter correspond to?
What are 3 parameters that define spatial resolution in MRI?
- Field of view (FOV)
- Slice thickness
- Bandwidth
- Slope of gradient magnetic field
- Size of the matrix
Basically the voxel determines spatial resolution
In what order are the gradients used to spatially encode an MRI signal?
- Slice
- Phase
- Frequency
U.S. Food and Drug Administration (FDA) guidelines refer to a magnetic field of __________ as the upper limit where the field strength is of no potential concern for the general public, including persons with implanted electronic devices.
- 5 G (0.0005 T)
- A line called the 5-G line is often drawn around the bore to show this limit
What is the difference between the following devices?
- MR safe
- MR unsafe
- MR conditional
- MR-safe devices are nonhazardous in all MR imaging environments
- MR-unsafe devices are considered to be contraindicated in any MR imaging environment
- MR-conditional device is MR imaging–compatible only in specific operating conditions:
- main magnetic field strength
- maximum magnetic field gradient
- maximum specific absorption rate (SAR)
- description of the testing conditions
The FDA limit for a permissible increase in body temperature during MRI is _________
1 degree C
Energy absorption due to the RF pulse is described in terms of a specific absorption rate (SAR; W/kg). How does SAR change with the following:
- Magnetic field strength
- Flip angle
- Patient size
Specific absorption rate increases with:
- Increasing magnet strength
- ex., 3T magnet has 9x the SAR of a 1T magnet
- Larger flip angle (more time needed)
- Bigger patient
What is quenching of the magnet? What are possible causes?
Quenching is when the superconductivity of the magnet is lost because of heating
Potential causes:
- Improper helium filling
- Running out of helium
- Large ferromagnetic objects
- Pressing the emergency button
- Can also happen for no apparent reason
What is the LEAST likely diagnosis?
- Aspiration pneumonia
- Canine influenza
- NCPE
- Interstitial lung disease
Aspiration pneumonia
The following are common radiographic features of canine influenza EXCEPT:
- Cranioventral interstitial and alveolar pattern
- Pleural effusion
- Mediastinal lymphadenopathy
Mediastinal lymphadenopathy and widening are not features of canine influenza
In MRI, slice selection relies on a gradient magnetic field applied during ______ whereas frequency encoding gradient relies on a gradient magnetic field applied during ________
In MRI, slice selection relies on a gradient magnetic field applied during the RF pulse whereas frequency encoding gradient relies on a gradient magnetic field applied during time of sampling (echo time)
Most artifacts occur in the _____ encoding direction because this step takes a long time
Most artifacts occur in the phase encoding direction because this step takes a long time
- Phase wrap
- Motion artifacts
How does gadolinium affect T1 relaxation time?
Shortens T1 relaxation time
What is the common localization (extradural, intradural/extramedullary, intramedullary) of spinal lymphoma? Multiple myeloma?
- Both are extradural
- Other extradural tumors include:
- OSA
- Fibrosarcoma
- Chondrosarcoma
- Hemangiosarcoma (can also be intramedullary)
- MCT
- Carcinoma metastasis
What is the localization (extradural, intradural/extramedullary, intramedullary) of peripheral nerve sheath tumors?
Can be any; can start as one and become any of the others
What spinal neuroanatomical localization is associated with ipsilateral Horner’s syndrome?
C6-T2
T/F: Intradural/extramedullary tumors are typically painful whereas intramedullary tumor may be non-painful
True. Intramedullary can be painful if there is expansion of the spinal cord resulting in stretching of nerve roots or compression of the dura
What are these vessels? This lesion (thrombus) may result in what pathology and clinical signs?
- A - Deep circumflex iliac artery
- B - External iliac artery
May result in ischemic myopathy to the hind limb with clinical signs of weakness and paresis
This lesion is most likely to be associated with what clinical signs? Bonus: what is this condition?
- Left-sided facial neuropathy
- Idiopathic facial neuritis
The _____ sequence attenuates signal from fat by exploiting the differences in T1-relaxation times of lipids and water.
STIR sequences offer good conspicuity of fluids and tissues with prolonged T2 relaxation, but suppress any substance with short T1 relaxation, including fat, mucinous or proteinaceous fluid, subacute hemorrhage, and enhancement
Chemical ________ exploits the chemical shift (i.e. the difference in the precessional frequencies) of fat and water protons
Fat saturation.
- With this technique, a frequency-specific preparation pulse is applied to excite lipid protons selectively, followed by a spoiling gradient pulse that dephases the fat signal. Once the initial fat-specific pulse is produced, the signal generated by the subsequent T1-weighted pulse sequence arises only from nonfatty, short T1 tissues, such as gadolinium-enhancing tissues
- Can be used with other types of weighting (T2, PD), which is not true for STIR
- Eliminates chemical shift artifact
What is the MR appearance of PNST in dogs?
- T2w: hyperintense to muscle, but hypointense to axillary fat
- T1w: isointense to muscle
- STIR: increased lesion conspicuity
- CE: often subtle and heteogeneous
- Authors suggest fat suppression may help
- Diffuse thickening or nodule/mass (about 50/50)
Remember - CT = rim enhancement with hypoattenuating center
What position is recommended for MR of brachial plexus PNST?
Dorsal recumbency with symmetrically positioned forelimbs
What imaging parameters are recommended for MR of PNST?
- 2 planes minimum
- Transverse views provide the vest definition of the mass and nature of spinal cord compression
- Sagittal plane - overview of the relationship of the brachial plexus lesion relative to the vertebral canal and thoracic cavity
- Dorsal - see lesion, but not helpful beyond that
- Large FOV view to see relationship of mass and vertebral column
- Smaller FOV of cervicothoracic spine to look for nerve root and foraminal involvement
- What is the sensitivity and specificity of TOF MR-angiography for identification of any PSS in dogs?
- Which type of shunt (single or multiple) were identified with higher sensitivity and specificity?
- What percentage of shunts were identified correctly as intra- or extrahepatic?
- What percentage had accurate origin identified? Insertion?
- TOF MRA sensitivity 80%, specificity 100% (no false positives)
- Single shunts were identified with higher sensitivity and specificity than multiple shunts
- 80% correctly identified as intra- or extra-hepatic
- Origin - 55%
- Insertion - nearly 100%
Seguin VRU 1999
MRA was found to be a specific imaging modality for diagnosis of PSS and a sensitive indicator of the anatomic location of single congenital PSS.
What is the most useful clinical application of MRA for PSS?
The most useful clinical application of MRA probably resides in patients where the presence of an intrahepatic shunt is suspected
Seguin VRU 1999
What are benefits of contrast-enhanced MRA over TOF MRA?
- Shorter acquisition time
- Better image quality
- Provides 3D anatomic detail of the portal vein and its tributaries
- Easy to cary out
Identified a single PSS in all dogs; they didn’t have dogs with multiple and only had one intra-hepatic shunt
What are pre- and post-contrast MRI findings in adult horses with septic arthritis?
Pre-contrast
- Diffuse hyperintenstiy within bone and extracapsular tissue on FS images
- Joint effusion, synovial proliferation, capsular thickening
- Bone sclerosis
- Cartilage and subchondral damage
Post-contrast
- Fibrin deposition
- Synovial enhancement
- Bone enhancement
What is the most common MR finding in adult horses with septic arthritis?
Diffuse hyperintensity within bone and extracapsular tissue on fat-suppressed images
What are 2 discriminating MR findings between foals with infectious arthritis and foals with non-infectious arthritis?
- Majority of foals with infectious arthritis had osseous lesions compatible with osteomyelitis; none of the foals with non-infectious arthritis had osseous lesions
- Majority of foals with infectious arthritis had heterogeneous synovial fluid; non-infectious arthritis had homogeneous synovial fluid
Describe the appearance of osseous lesions in foals with infectious arthritis
- Epiphyseal, physeal, or metaphyseal
- T2w/PD, STIR hyperintense foci with a hypointense halo
- 3D RSSG - entirely hyperintense; no hypointense halo
Fatty infiltration of the vertebral bodies occurs most commonly in (small/large) breed dogs and tends to be (focal/multifocal)
Fatty infiltration of the vertebral bodies occurs most commonly in small breed dogs and tends to be multifocal
MR findings of irregular endplates, endplate hyperintensity in T2w/STIR, reduced endplate signal in T1w, and endplate contrast enhancement are compatible with:
- Discospondylitis
- Reactive endplates
- Both
Both
What are two MR features unique to discospondylitis (compared to other vertebral endplate changes)?
- Contrast enhancement of the paravertebral soft tissue
- Contrast enhancement of the disc
Reactive endplate changes in dogs have a predilection for ______ disc space. They are associated with __________ and affect (older/younger) patients.
Reactive endplate changes in dogs have a predilection for the LS disc space. They are associated with intervertebral disc degeneration and affect older patients.
What is a Schmorl’s node? What is the MR appearance?
- Schmorl’s node is an intraosseous disc herniation
- Appear as a well-marginated, focal endplate defect contiguous with the disc and contains material isointense to disc material
- Localized centrally in the endplate
Vertebral osteochondrosis and Schmorl’s nodes both appear as an endplate defect. How does the location vary between the two?
- Osteochondrosis - defect in dorsal edge of dnplate with disc-isointense material filling the gap
- Schmorl’s node - localized centrally
What are the 2 most common vertebral endplate changes in dogs?
- Discospondylitis
- Fatty infiltration
In Carrera et al., characteristic MRI features of discospondylitis are:
- Involvement of ______ vertebral body(ies) and the adjacent disc
- T1-w _______
- STIR _______
- Contrast enhancement of the __________
- Two adjacent vertebral bodies and the adjacent disc
- T1-w hypointensity
- STIR hyperintensity
- Contrast enhancement of the vertebral bodies, intervertebral disk, paravertebral soft tissues and epidural space.
In Carrera et al., variable T2w intensity was seen in the endplates of dogs with discospondylitis. The authors hypothesize that the T2w hyperintensity is associated with (acute/chronic) disease and T2w hypointensity is associated with (acute/chronic) disease.
In Carrera et al., variable T2w intensity was seen in the endplates of dogs with discospondylitis. The authors hypothesize that the T2w hyperintensity is associated with acute disease and T2w hypointensity is associated with chronic disease.
The most likely diagnosis for the image on the right is? Left?
- Left - sacral osteochondrosis
- Right - Schmorl’s node (aka intravertebral disc herniation)
How does MRI appearance differ between acute and chronic canine distemper virus infection?
Both have T2w hyperintensity:
Acute
- Cerebellum and brainstem +/- temporal lobes
- Loss of of gray-white matter contrast
Chronic
- Bilaterally symmetric
- Cortical gray-white matter junction of parietal and frontal lobes, cerebellar arbor vitae, and pons
- Meningeal enhancement
Describe the MR appearance of FIP.
- T2w hyperintensity and contrast enhancement of the ventricular ependymal lining, choroid plexus, and meninges
- Hydrocephalus is common –> 4th ventricle especially
- +/- periventricular T2w hyperintensity
- +/- cerebellar herniation
- +/- syringohydromyelia
- +/- CSF suppression in FLAIR
Common signalment and MR distribution:
- GME
- NME
- NLE
- GME
- Young to middle-aged, toy breed dogs
- Commonly affects brainstem
- Predilection for white matter
- Variable CE
- NME
- Pugs, other small breed dogs
- Cerebrum
- Variable contrast enhancement
- NLE
- Yorkshire terrier
- Cerebrum and brainstem
- Variable contrast enhancement
What MR features of astrocytomas and oligodendrogliomas suggest high grade?
- Intratumoral hemorrhage
- Contrast enhancement
What is the typical MR appearance of ependymomas?
- T1w slightly hypointense to slightly hyperintense
- T2w hyperintense
- Usually minimal edema
- Marked, heterogeneous enhancement
- May have cysts or hemorrhage
Approximately ____% of choroid plexus tumors arise from the fourth ventricle and lateral apertures
50%
Choroid plexus tumors and ependeymomas have many overlapping MR features (variable T1w intenstiy, T2w hyperintense). In what ways do they differ?
- Mild to moderate edema with CP tumors (edema rare in ependymomas)
- Marked, homogeneous CE with CP (marked, heterogeneous with ependymomas)
CP are more common than ependymomas
What is the MR appearance of hepatocellular carcinoma using gadodextate disodium?
- All are hypointense to the surrounding liver parenchyma in 3D T1w GRE images due to impaired hepatocyte function
In which MR sequence is artifact caused by metallic material most severe?
- Artifact was most severe in T2* images
- Artifact severity is similar between T2w TSE and T1w images
For a symmetric metallic object, the maximal susceptibility artifact occurs parallel to the _____ gradient
For a symmetric metallic object, the maximal susceptibility artifact occurs parallel to the frequency-encoding gradient
Which of the following factors does not reduce the metallic artifact size?
- Position long-axis parallel to the main magnetic field
- Higher static magnetic field strength (B0)
- Higher gradient magnetic field strength
- Increase frequency-encoding bandwidth
- Select larger matrix size
- Decrease FOV
- Position long-axis parallel to the main magnetic field
- Lower static magnetic field strength (B0)
- Higher gradient magnetic field strength
- Increase frequency-encoding bandwidth
- Select larger matrix size
- Decrease FOV
A 10-year-old Samoyed presents with a right sided Zurich-type (titanium) total hip arthroplasty and a clinical suspicion of lumbosacral intervertebral disc disease. What would be the best advice be regarding the utility of MRI T2w turbo spin echo and T1-weighted spin echo images at 1.5T for the imaging of the lumbosacral junction?
- A: Signal voiding from the implants will likely obscure the lumbosacral region.
- B: Images of the lumbosacral region should be possible but there will likely be distortion of the anatomy that will reduce the diagnostic quality of the study.
- C: The implants are unlikely to impact the diagnostic quality of the study.
- D: There is a moderate risk of implant movement from the main magnetic field and an alternative imaging modality should be selected.
C: The implants are unlikely to impact the diagnostic quality of the study.
Titanium total hip implants were characteriz ed by up to 70% less signal voiding and image distortion than an equivalent stainless-steel total hip implant
Rank the following metals from most likely to cause artifact to least likely:
- Steel objects
- Surgical stainless steel
- Lead
- Titanium
Steel > surgical steel > titaniun > lead
What is the common MR appearance of thiamine deficiency in cats?
- Bilaterally symmetric, T2w and FLAIR hyperintensity
- Non-contrast enhancing
- Locations
- Lateral geniculate nucleus
- Caudal colliculus
- Facial nuclei
- Medial vestibular nucleus
- Resolve with supplementation
Which MR sequences provide the most diagnostic information regarding acute (<48h) head trauma in dogs?
T2w and FLAIR
What MR features of acute head trauma in dogs were associated with high mortality rate, major persistent neurological deficits, or need for surgical intervention?
- Caudal fossa involvement
- Marked midline shift
Following acute head trauma, fontanelle herniation is associated with a (good/poor) outcome
Good
What is the most common location of intracranial hemorrhage following acute head trauma in dogs? Where is the largest accumulation of hemorrhage?
- Most common location - subdural
- Largest accumulation - epidural
How does hemoglobin change over time?
- Hyperacute (<7h) - oxyhemoglobin
- Acute (7h to 3d) - deoxyhemoglobin
- Early Subacute (3d to 7d) - central methemoglobin
- Late Subacute (7d to 3w) - central and peripherla methemoglobin
- Chronic (>3w) - hemosiderin
Rank the following from highest ADC value to lowest ADC value:
- Meningioma
- Glial cell tumor
- Acute non-hemorrhagic infarct
- Chronic non-hemorrhagic infarct
- Pituitary tumor
Smallest ADC –> highest ADC
- Acute non-hemorrhagic infarct
- Pituitary tumor
- Glial cell tumor
- Chronic non-hemorrhagic infarct
- Meningioma
There is a wide range and overlap of ADC value within the disease groups –> unlikely that singular quantitative ADC values can be used to determine the histological type of canine intracranial disease
- What is the most common location of GIST?
- What ultrasonographic finding was associated with GIST?
- Where is the most common site of metastasis?
- Common location - Cecum
- Abdominal effusion seen with GIST more commonly than other smooth muscle tumors
- Mets to liver
Which of the following MRI system specifications offers the greatest potential for high image quality and fast image acquisition.
- A: 1.5T superconducting magnet, gradient amplitude 33 mT/m, gradient slew rate 170 T/m/s
- B: 1.5T superconducting magnet, gradient amplitude 34 mT/m, gradient slew rate 150 T/m/s
- C: 1.5T superconducting magnet, gradient amplitude 45 mT/m, gradient slew rate 200 T/m/s
- D: 1.5T superconducting magnet, gradient amplitude 33 mT/m, gradient slew rate 125 T/m/s
C: 1.5T superconducting magnet, gradient amplitude 45 mT/m, gradient slew rate 200 T/m/s
This image of a stifle is an example of application of a look up table (LUT) during acquisition, rather than post-processing. The resulting artifact is known as:
- A: Clipping
- B: Saturation
- C: Uberschwinger
- D: Quantum mottle
A: Clipping
Regarding radiographic diagnosis of pleural effusion, no significant difference in diagnosis and grade of pleural effusion were seen between views, although the _______ had both the highest rate of detection and grade of severity.
left lateral HB
Which radiographic views were best for best for detection and gradation of pneumothorax?
- Right and left lateral horizontal beam
- Left lateral vertical beam
RIGHT LATERAL HB IS BEST!!!
What layers of the hoof capsule are represented by the markers on thefollowing radiograph? (Goulet et. al, VRU, 2016)
- A: Stratum externum
- B: Stratum medium and stratum internum
- C: Stratum internum
- D: Stratum internum and Dermis parietis
D: Stratum internum and Dermis parietis
At what number of days pre-partruition can you first identify fetal mineralization radiographically in cats? (10.2460/javma.2003.223.1614)
- A: 10-14 days
- B: 18-22 days
- C: 25-29 days
- D: 35-39 days
C: 25-29 days
Cat gestational length: 58-67 days
At what number of days pre-partruition can you first identify fetal mineralization radiographically in dogs?
- A: 10-14 days
- B: 18-22 days
- C: 25-29 days
- D: 35-39 days
B: 18-22 days
Dog gestational length: 58-68 days
What is the ratio of iodine to osmotically active particles for the following iodinated contrast agents?
- Diatrizoate (Gastrografin)
- Iopamidol (Isovue)
- Ioxoglate (Hexabrix)
- Iotralan (Isovist)
- Diatrizoate (Gastrografin)
- Ionic monomer
- Iodine to osmotic particles= 3:2
- Iopamidol (Isovue)
- Non-ionic monomer
- Iodine to osmotic particles= 3:1
- Ioxoglate (Hexabrix)
- Ionic dimer
- Iodine to osmotic particles= 6:2 (aka 3:1)
- Iotralan (Isovist)
- Non-ionic dimer
- Iodine to osmotic particles= 6:1
What are two non-ionic, dimer iodinated contrast agents?
- Iotralan
- Iodixanol
What is the ionic, dimeric iodinated contrast agent?
Ioxoglate (Hexabrix)
What sonographic findings are suggestive of feline cholangitis?
- Hyperechoic liver parenchyma
- Hyperechoic gallbladder contents
- Increased pancreatic size
T/F: Most cats with cholangitis had sonographically normal liver size, echogenicity, and normal biliary systems
True
What is the most common US abnormality in dogs with renal lymphoma?
Pyelectasia
Other abnormalities
- loss of corticomedullary distinction
- renomegaly
- renal deformity
- renal nodules/masses hypoechoic or hyperechoic
- often bilateral
Which factors were associated with survival of dogs with PV thrombosis? Non-survival?
Survival
- Treatment with anticoagulant therapy
Non-survival
- Acute PVT
- Multiple thromboses
- SIRS
What are the most common radiographic findings in dogs with intrathoracic histiocytic sarcoma?
- Lymphadenopathy (TB and sternal > cranial mediastinal)
- Pulmonary masses
- Right middle is most common location
- Can have multiple pulmonary nodules
What is the least common radiographic finding in dogs with intrathoracic histiocytic sarcoma?
Pleural effusion
What four factors are associated with survival in dogs with non-tonsillar oral SCC?
- intraoral location
- listed in descending survival time: rostral > caudal > rostral and caudal)
- tumor recurrence (no > yes)
- relative portal size (less than 100 cmz/mz > greater than or equal to 100 cmz/m2)
- age at diagnosis
- less than or equal to 6y > greater than 6y
In dogs with pharyngeal neoplasia, which lymph nodes were most frequently affected with metastasis? What CT appearance suggests metastasis?
- Medial retropharyngeal LNs
- CT appearance
- marked enlargement
- rounded shape
- heterogeneous enhancement
T/F: CT features of pharyngeal neoplasms in the dog overlap and therefore CT cannot differentiate types of neoplasia
True
What is the function of a gamma camera collimator?
Collimator filters photons –> only allows gamma photons that travel perpendicular to the collimator to be accepted. Those travelling at an angle will hit the septum (usually lead), be absorbed and, therefore, not contribute to the image.
- What type of gamma camera collimator is this?
- Parallel hole
- Most common
What type of gamma camera collimator is this?
Diverging hole - allows a minified image
What type of gamma camera collimator is this?
Pin-hole = single-hole collimator for magnifying images of small objects
What type of gamma camera collimator is this?
Converging hole - magnifying the image
What is the importance of septal thickness for a gamma camera collimator? What type of thickness/energy would you need for 99mTc? What about 131I?
- Septal thickness must increase as photon energy increases to ensure maximum absorption of photons that hit the septae at an angle
- Parallel hole collimators are classified as
- Low energy = thin septae (0.3mm) = 99mTc (150 keV)
- Medium energy = 1mm = 131I (400 keV)
- High energy = thick septae (2mm) = 18F
A Low-Energy All-Purpose (LEAP) collimator is an example of what type of gamma camera collimator
Parallel hole collimator
How are resolution and sensitivity of a NM image affected by increased patient to collimator distance for the following collimators:
- Parallel hole Collimator
- Pinhole Collimator
Influence of increased patient to collimator distance:
- Parallel hole
- Decrease resolution
- No effect on sensitivity
- Pinhole
- Resolution and sensitivity decrease
Ultrasound of equine forelimb:
- Where is the image acquired?
- Label the anatomy
- Level of proximal MC3
Ultrasound of equine forelimb:
- Where is the image acquired?
- Label the anatomy
- Level of proximal P1
Ultrasound of equine forelimb:
- Where is the image acquired?
- Label the anatomy
- Middle third of P1
Label the anatomy
