Classics Flashcards
What is the incidence of myelomalacia? What are the myelographic signs?
- Cumulative incidence of <1% over 7 years
- Findings:
- Can be normal
- Focal swelling resulting in thinning of the contrast column
- Contrast-staining of the spinal cord; can be subtle or extensive
What is the location of this contrast?
Subdural - characterized by smooth dorsal border and irregular ventral border of the contrast column; tend to accumulate dorsally in the vertebral canal; believed to be within the region of the structually weak dural border cells (subdural space)
Can reduce risk by:
- Use small needle size
- Bevel placed across both levels
During myelography, injection at what location is more likely to result in central canal opacification? What causes this? Is this associated with clinical signs?
- Lumbar punture cranial to L5
- May be due to inadvertent communication between subarachnoid space and central canal, such as with trauma, IVDD, neoplasia, or pressure induced leakage around the needle
- Usually incidental. Could be associated with neurologic deterioration, particularly if injected rapidly
- Dachshunds may be more at risk due to increased size of central canal and narrower subarachnoid space
Is CT, angiographic CT, myelography, or CT myelography most sensitive for diagnosis of acute canine myelopathy?
- CT myelography had highest agreement and sensitivity for identifiction of compression, lesion localization, and lateralization
- No imaging techniques definitively diagnosed spinal cord infarction or meningomyelitis, but both myelography and CT myelography ruled out surgical lesions in these cases
Dennison VRU 2010
What type of IVDD lesion is conventional CT most capable of identifying?
Mineralized Hansen type 1 discs in chondrodystrophic breeds
Hansen type 2 were rarely mineralized
Dennison VRU 2010
In what cases is CT myelography often necessary for diagnosis of acute canine myelopathy?
- If no lesion is identified on conventional or angiographic CT
- The dog is not chondrodystrophic
- Plegia due to extradural compression and concurrent spinal cord swelling
What are the categories of corpus callosal abnormalities? In what portion of the corpus callosum do abnormalities most commonly occur?
- Categories (human lit)
- Hypoplasia - small, but normal shape
- Hypoplasia w/ dysplasia - small with distorted shape
- Agenesis
Rostral portion is most commonly affected; severity and type of abnormality varies
Regarding corpus callosal abnormalities, what other concurrent abnormality can be seen? How frequently is it noted?
Concurrent fusion of midline structures rostral to the corpus callosum; these regions are also involved in regulation of thirst and may be responsible with the clinical sign of adypsia
Seen in most dogs
This appearance of the lateral ventricles is often associated with what condition?
Associated with complete or partial corpus callosal aplasia
“Upturned, pointed dorsal corners of lateral ventricles; bat-wing appearance”
What criteria can differentiate ventriculomegaly from clinically relevant hydrocephalus?
- Ventricle-brain index (>0.6) is discriminator between the two
- Additional findings associated with relevant hydrocephalus
- Elevation of the corpus callosum
- Dorsoventral flattening of interthalamic adhesion
- Periventricular edema
- Dilation of the olfactory recesses
- Thinning of the cortical sulci and/or subarachnoid space
- Disruption of the internal capsule adjacent to the caudate nucleus
Is post-contrast T1w imaging or subtraction imaging better for detection of the meninges? Where (anatomically) was the enhancement predominately located?
Subtraction imaging allows clear visualization of the meninges
Appears as
- Faint, small rounded foci within the sulci
- Large, round foci at dorsal aspect of cerebral cortex
- Thin curvilinear enhancement around the brain
Located in dura
What factor affects visualization of meningeal enhancement in post-gadolinium images?
Fat saturation was most useful (allowed definite diagnosis/characterization of meningeal enhancement in 50%)
Delay of image acquisition did not improve characterization of meningeal enhancement
No imaging features significantly allowed differentiation between neoplasia and inflammatory disease, but:
- Inflammation - enhancement more diffuse, leptomeningeal
- Neoplasia - thicker meninges, increased contrast ratio
What are MRI findings of idiopathic oculomotor neuropathy in dogs?
- Unilateral
- Variable enlargement of the oculomotor nerve
- Variable contrast enhancement (absent, focal, or diffuse)
What clinical signs are associated with oculomotor neuropathy? What is the prognosis?
Signs: unilateral internal ophthalmoplegia and external ophthalmoparesis
Good prognosis - clinical signs do not deteriorate and can improve even without immunosuppressive treatment
What is the sensitivity and specificity for VIBE and post-gadolinium T1w MRI for detecting facial nerve abnormalities in dogs with facial neuropathy?
- VIBE: high sensitivity and specificity
- T1w: low to moderate sensitivity, excellent specificity
MRI was not sensitive for detecting concurrent vestibulocochlear nerve abnormalities
Where is this lesion? What imaging sequence is best for identifying this lesion?
Facial nerve; VIBE was more sensitive than T1w post-contrast for detection of facial neuropathy in dogs
Also - facial nerve can be visualized throughout its length (brainstem to stylomastoid foramen) in VIBE; best visualization proximally
What is the prognosis of return of facial and vestibular nerve function with neuropathy of unknown origin? What CSF finding was seen?
Guarded return to function without tx; complete resolution of signs in 1/3rd and 15% relapsed
Facial and vestibulocochlear neuropathy evolve independently
Albuminocytologic dissociation on CSF - suggests inflammatory etiology
Label the vasculature
- Rostral cerebral artery
- External ophthalmix artery
- Middle cerebral artery
- Caudal cerebral artery
- Rostral cerebellar artery
- Internal carotid artery
- Basilar artery
- Ventral spinal artery
Is 3D FLASH or 3D TOF better to visualie the cerebral arterial circle (Circle of Willis)?
TOF is better to visualize the cerebral arterial circle (arteries as small as 0.4mm)
Describe the CT appearance of brachial plexus tumors? What is the smallest mass that was identified?
- Vary from well-circumscribed to infiltrative
- Most enhance; rim-enhancement with a non-uniformly enhancing or hypodense center is most common
- Muscle atrophy
- 1 cm was the smallest identified
Do CT appearance and histopathologic findings of brachial plexus tumors correlate?
No. No relationship between appearance and histopathologic relationship
Describe the CT and MRI appearance of carotid body tumors in dogs
- CT: hypoattenuating to muscle, strong heterogeneous enhancement
- MRI: hyperintense to muscle in T1w and T2w images, strong heterogeneous enhancement
What is the biologic behavior of carotid body tumors in the dog?
Locally invasive in 9/16 dogs –> invaded basilar portion of the skull, tymapnic bulla, cranial cavity, internal jugular vein, external jugular vein, maxillary and linguofacial veins
How can carotid body tumors be differentiated from other cervical neoplasms?
Centered on carotid bifurcation
More cranial than thyroid and displaces medial retropharyngeal LN caudally
What types of cats are over-represent in open-mouth jaw locking? What underlying conditions predispose to open-mouth jaw locking?
Brachycephalic
- TMJ dysplasia
- Trauma
- TMJ or symphyseal laxity
CT findings in acromegalic cats
- Thickened bones (frontal, parietal, mandibular rami)
- Thickened soft tissue and subcutis
- Larger distance between zygomatic arches
- Smaller nasopharyngeal cross-sectional area
- Prognathia inferior
- TMJ malformation - cats are not clinical
- Pituitary macroadenoma (94%), but some did not have a visible mass
What is the normal bronchial wall thickness-to-pulmonary artery diameter in dogs?
- Must be measured in cranial lungs; = 0.6
- If larger than 0.6 = chronic bronchitis (sensitivity 77%, specificity 100%)
Qualitative and quantitative CT findings in dogs with bronchiectasis
Qualitative
- lack of peripheral airway tapering
- lobar consolidation
- bronchial wall thickening
- bronchial lumen constriction
Quantitative
- larger bronchoarterial ratio > 2 (previous study defines normal at 2.0)
What is the normal bronchial lumen-to-pulmonary artery ratio in cats?
- <0.91 is normal regardless of lung lobe
- If >0.91 - bronchiectasis
Is conservative balloon valvuloplasty in Bulldogs with pulmonic stenosis and R2A anomaly associated with mortality? Is there any improvement in clinical signs?
Conservative ballon valvuloplasty (ballon size = PA annulus size) may be safe and improve quality of life
In study, no dogs died; there was only a mild improvement in the pressure gradient, but PA/Ao VTI ratio improved
What is R2A anomaly?
Single right coronary artery from which the left circumflex and left paraconal arteries originate and encircle (potentially constrict) the RVOT close to the level of the pulmonic valve
Label the anatomy
Cerebral sinus anatomy in transverse plane
- Dorsal sagittaly sinus
- Transverse sinus
- Sigmoid sinus
- Temporal sinus
- Maxillary vein
Label the vasculature
Cerebral sinus system sagittal plane
- Dorsal sagittal sinus
- Straight sinus
- Transverse sinus
- Temporal sinus
- Sigmoid sinus
Label the vasculature
Cerebral sinus system dorsal plane
- Dorsal sagittal sinus
- Dorsal cerebral vein
- Transverse sinus
- Sigmoid sinus
What are common variations in the dorsal venous sinus system?
- Transverse sinus asymmetry (58%)
- Aplasia
- Hypoplasia
- Variation in the dorsal sagittal sinus (70%)
- Deviation from midline
- Collateral branches from dorsal sagittal sinus or dorsal cerebral vein
- Presence of occipital sinus (connect transverse and signmoid sinuses) (10%)
Name these abnormalities
A - transverse sinus hypoplasia
B - transverse sinus aplasia
Name these abnormalities
Deviation of dorsal sagittal sinus from midline and hypoplastic transverse sinus
Name this abnormality
Single occipital sinus
Name the abnormalities
- Deviation of DSS from midline
- Two DSS collateral vessels
- Partial aplasia of transverse sinus
What is the distribution of astrocytomas and oligodendrogliomas within the brain?
Predominately found in the cerebrum or thalamus, but astrocytomas can also be found in the cerebellum or caudal brainstem.
Young VRU 2010
What are the MRI features of astrocytomas? Oligodendrogliomas?
No MRI features reliably distinguish the two
Common:
- Associated with both gray and white matter
- T1w hypointense, T2w hyperintense
- Contrast enhancement (often ring-like)
- Cystic regions
- Hemorrhage
- Contact the lateral ventricles
Oligodenrogliomas - more likely to contact the meninges
What is the most common MRI finding with astrocytomas and oligodendrogliomas?
Contact lateral ventricle
Is the presence of contrast enhancement in a astrocytoma or oligodendroglioma associated with grade?
Contrast was more common in high grade tumors (breakdown of BBB)
A 5yo MN DSH presents for paraparesis, flaccid tail and bladder, pain on palpation, unresponsive anus and decreased flexor reflexes. What is the neurolocalization? What is this lesion most likely to be?
L4-S3
Intramedullary disc extrusion - note the linear GRE susceptible tract extending from the dorsal annulus
An indoor/outdoor cat presents for peracute paraparesis following recent trauma. What should be on your ddx list? What is the prognosis for this condition?
Acute non-compressive nucleus pulposus extrusion; 75% of cats had a history of known or suspected trauma
Prognosis is good - all non-ambulatory cats were ambulatory and most regained urinary and fecal incontinence
What is the most common location of ANNPE in the cat? In the dog?
Cat:
- L3-4 and L5-6
- Previous studies report mid- to caudal lumbar +/- cervical
Dog:
- T12-13 and T13-L1
Taylor-Brown JFMS 2015
In Great Danes, which radiographic vertebral ratio is associated with spinal cord compression as identified on MRI?
Ventrodorsal ratio (A/B in figure)
VD ratio was associated with spinal cord compression at all cervical sites; every 0.1 increase in the ratio corresponded to a 65% reduction in risk of spinal cord compression
The ventrodorsal ratio used for cervical spondylomyelopathy in great danes was significantly smaller in affected dogs (vs normal dogs) at which sites?
- C5-6 and C6-7
Do intra- and intervertebral ratios differ between normal Dobermans and Dobermans affected with CVM?
No. There was no difference in either ratio between normal and abnormal Dobermans
In Dobermans, which IVD sites had smaller intra- and intervertebral ratios (both normal and abnormal dogs)? What factors were associated with smaller ratios?
Smaller ratios in caudal cervical spine (C6-7 and C7) compared to cranial
Age (older dogs) and male dogs had smaller ratios
In dynamic MRI of CVM dobermans, how did linear traction affect the site of compression? Were there any deleterious effects?
- Reduced the compressive lesion
- No neuro deterioration
Which parameters of caudal fossa morphology were associated with neurologic signs in CKCS?
Syringohydromyelia (severity of SHM is correlated with severity of neuro signs
Caudal fossa:Cranial cavity volume –> paper doesn’t tell you how to measure this; also, contradictory things said about occipital hypoplasia (I assume they’re attributing the small caudal fossa to hypoplasia, but they also say occipital hypoplasia doesn’t correlate to neuro signs)
What percentage of CKCS had caudal fossa morphologic changes? What percentage of CKCS evaluated had neurologic signs? What were common abnormalities seen and were these of clinical importance?
- 92% of CKCS evaluated had morphologic changes
- 25% of CKCS evaluated had clinical signs
Cerebellar herniation and occipital dysplasia were commonly seen, but not associated with neuro signs
What is the most important conclusion regarding canine and feline CNS coccidioides granulomas on MRI?
MRI features overlap with gliomas, meningiomas, and round cell neoplasia; include on differential list if in endemic area or travel history to/from endemic area
What feature may help to distinguish meningioma from coccidioides granuloma?
Meningiomas generally have well-defined borders and coccidioides granulomas generally have poorly defined borders
What MRI features distinguish neoplasia from inflammatory and vascular disease?
Strong contrast enhancement, extra-axial, T2w FLAIR mixed intensity, and defined lesion margins
(This basically describes meningiomas, which we haven’t had trouble differentiating from inflammatory or vascular intra-axial disease, so I think this is silly)
What MRI features distinguish inflammatory disease from neoplasia and vascular disease?
Multifocal, irregular lesions with meningeal ehancement
What MRI features distinguish vascular disease from inflammatory and neoplastic disease?
None
What anesthetic protocol was associated with increased standard value uptake (SUV) of the occipital and frontal lobes compared to the brainstem in FDG PET/CT?
All anesthetic protocols resulted in increased SUV of the frontal and occipital lobes relative to the brainstem
This is possibly due to increased glucose usage by the cortex
Which anesthetic protocol resulted in overall higher brain standard uptake value (SUV) compared to propofol/isofluorane?
- Medetomidine/tiletamine-zolazepam
When evaluating cerebral glucose metabolism in the anesthetized dogs undergoing FDG PET/CT, what factor may influence the standard uptake value (SUV)?
Anesthesia protocol
Is MDCT better than echocardiogram at detecting cardiac masses in dogs with pericardial effusion?
No. They are equal. The benefit of MDCT is to identify thoracic metastasis and extrathoracic neoplasia in one modality.
What are common findings in dogs with spirocercosis?
Aortic mineralization and aneurysm formation. CT is good at characterizing these lesions
In a dog with spirocercosis, the finding of an esophageal mass and aortic mineralization is of what clinical significance?
May indicate malignant transformation
T/F: In regards to adrenal neoplasia, CT findings reflected their biological behavior, but was of limited utility to distinguish tumor type due to overlapping characteristics between tumor types.
True.
In regards to adrenal neoplasia, what findings suggested benign behavior? What findings suggests aggressive behavior?
Benign: contrast enhancing pseudocapsule suggested benign or low-grade neoplasia
Aggressive: Vascular invasion; more likely with pheochomrocytoma, but adenocarcinoma can also do it
Enhancement patterns of pancreatic insulinoma using CEUS
All nodules had different enhancement patterns
Utility of CEUS may increase conspicuity of pancreatic insulinoma nodules
What is the optimal portal vein attenuation for maximizing GI wall conspicuity using dual phase contrast-enhanced CT?
43-150 HUs
Distinct mucosal surface enhancement in the small intestine occurred how many seconds following contrast administration in CT? What about gastric mucosal enhancement?
Small intestinal mucosal enhancement at 30s
Gastric mucosal enhancement was not specifically evaluated, but appears to be late (>60 s postcontrast)
What are CT patterns of muscular metastasis in dogs and cats?
Postcontrast CT characteristics included well-demarcated, oval-to-round lesions with varying enhancement patterns
What are CT patterns of cardiac muscle metastasis?
Isodense pre-contrast, hyodense post-contrast
What CT feature is most predictive of true length of appendicular osteosarcoma?
Length of intramedullary/endosteal abnormalities
Is CT, MRI, or US considered the best imaging modality for detection of wooden foreign bodies in the canine manus?
CT > US > MRI
What is an antomical limitation in US detection of wooden foreign bodies in the canine manus?
The metacarpal pad creates shadowing artifact, which hindered evaluation in some cases
What is the sensitivity and specificity of CT fore identification of wooden foreign bodies?
Moderate sensitivity, high specificity
What are CT features suggesting acute wooden foreign body? CT features suggesting chronic?
Acute: presence of a wound and gas
Chronic: draining sinus, cavitary lesions, fat stranding, visualization of the foreign material, regional periosteal reaction
What is the broncial wall-to-pulmonary artery ratio in the dog? Where is it used?
- >/= 0.6 - good sensitivity, excellent specificity for predicting the presence of canine bronchitis
- Use in cranial lung lobes; caudal lung lobes were found to have smaller ratios in bronchitis and normal dogs
Optimized MDCT protocol for the canine brain when using 120 kVp and 10cm FOV:
- Scan mode
- mAs
- Slice thickness
- Tube rotation time
- Reconstruction algorithm
- Correction software
- Sequential mode
- 300 mAs
- 1mm thickness
- 1s tube rotation time
- Medium image reconstruction algorithm
- Applied beam-hardening correction software
In the horse, which cranial nerves are not identified individually?
- CN 3, 4, 6
- CN 9, 10, 11 identified as a group in most horses (one horse couldn’t see, but could see where they exited the skull)
In normal dogs, how do tracheal dimensions change between inspiration and expiration? Are these changes uniform throughout the length of the trachea?
- Tracheal dimension changes most in the cervical region between inspiration and expiraiton (24%) > intrathoracic > thoracic
- The tracheal area was associated with body weight in all regions
CT findings suggesting a benign or low-grade malignant adrenal neoplasm
- peripheral contrast-enhancing rim
- absence of signs of vascular invasion
T/F: Vascular invasion by an adrenal mass identified on CT was associated with malignancy, most commonly pheochromocytoma.
- True. Pheo is most common, but can occur with adenocarcinoma. No CT features differentiate between the 2
Which modality (CT or fluoroscopy) resulted in the largest tracheal diameter and lowest variability measurement? In what dimension is the trachea measured for evaluation of tracheal stent size and why?
- CT resulted in the greater tracheal diameter and lower variability
- Stent size is based on the maximum height of the trachea as it is greater than the width regardless of which modality was used
A Yorkshire Terrier presents for tracheal collapse non-responsive to medical management. You recommend tracheal stenting. Which of the following statements regarding measuring for tracheal stent is false?
- A: Proper stent size is typically chosen with a diameter 10-20% greater than the maximal diameter of the trachea measured on fluoroscopy or radiography with positive pressure ventilation.
- B: There is are statistically significant differences in measurements of maximum tracheal diameter obtained via fluoroscopy and CT, resulting in statistically significant differences in stent size selection.
- C: There is no statistical significance in tracheal diameter measurements obtained from radiographs and CT in cadaveric dogs.
- D: Maximum tracheal height tends to be larger than tracheal width regardless of whether it is measured on fluoroscopy or CT.
C: There is no statistical significance in tracheal diameter measurements obtained from radiographs and CT in cadaveric dogs.
What are 6 CT findings associated with eosinophilic bronchopneumopathy? Which is the most common?
- Pulmonary parenchymal abnormalities (93% of dogs had any abnormality and all of those had PP abnormality)
- Ground glass
- Consolidation
- Bronchial wall thickening
- Plugging of bronchial lumen by mucous/debris
- Bronchiectasis
- Pulmonary nodules
- Lymphadenopathy
In a study by Or et al. Vet Surg 2016, all portoazygous shunts arose from what two veins? Where did the shunts insert? Which portion of the shunt was consistently the narrowest?
- All shunts arose from the left or right gastric veins (L>R)
- All insert on the thoracic azygous
- Insertion was commonly the smallest diameter
Regarding CTA for aortic and hepatic enhancement, how does rate of injection affect in enhancement in cats vs. dogs?
- Cats - only changes in Ao
- Faster injection protocol- Time to peak is faster (earlier)
- Higher HU peak enhancement higher
- Duration of aortic enhancement shorter
- Dogs -
- Faster injection protocol - shorter duration of Ao enhancement
- TTP and PE not affected
- Bronchial lumen-to-pulmonary diameter ratio:
- Dogs
- Cats
- Bronchial wall-to-pulmonary artery diameter in dogs
- Bronchial lumen-to-pulmonary artery diameter ratio
- Dogs: 2
- Cats: 0.91; any lung lobe
- Dogs: wall to artery ratio - 0.61; cranial lung lobes only
