Radiology Midterm Flashcards
Capsule endoscopy
Phleboliths
Gastric lap band
Upright abdominal radiography
Supine Abdominal Radiography
Emphysematous cholecystitis
Paralytic ileus
Continous Diaphragm Sign
Secondary to pneumoperitoneum
Small bowel obstruction
Describe how a small bowel obstruction would look on x-ray.
Proximal - dilated
transition point - obstruction
distal - collapsed
How do you treat a small bowel obstruction?
Lysis of adhesions
Differentiate valvulae conneventes from haustra on x-ray.
Valvulae are continuous (connect)
Haustra don’t
What constitutes a dilated small bowel on CT with contrast?
>2.5-3 cm
Diffuse dilation of the small and large bowel on x-ray?
Paralytic ileus
What is the modality of choice to diagnose renal, ureteral and bladder calculi?
CT abdomen without constrast
How do you follow/monitor renal calculi in family practice?
U/S - don’t want to expose somone to too much radiation, when you already know they have stones
What are phleboliths?
Calcification of the pelvic veins
Will you see the diaphragm on a supine (AP) or upright (PA) abdominal x-ray?
Upright - air under the diaphragm
Where does the air rise to in an upright abdominal x-ray?
Fundus of the stomach AND hepatic and splenic flexures
Where does the air rise to in a supine abdominal x-ray?
Body of the stomach and transverse colon
T/F: If you see an emphysematous cholecystitis on x-ray, confirm with U/S?
False - SURGICAL EMERGENCY - gas forming anaerobic infection in the wall of the gallbladder
What is the test of choice for diagnosing gallstones?
U/S - abdominal x-rays miss most stones
What will you see on an x-ray in a person with a pneumoperitoneum?
Continous diaphragm sign - air within the peritoneal cavity, under the diaphragm
When should you see the valvulae conneventes on an x-ray?
Abnormal - i.e. dilated portion proximal to an obstruction
What is the name of the large bowel fold pattern?
Haustrations/Haustra
What is the name of the small bowel fold pattern?
Valvulae conneventes
What is the name of the stomach fold pattern?
Rugae
What is the most commonly performed radiologic examination?
Chest x-ray
Explain the basic principles of a radiograph?
- A light source emits light photons towards the patient
- The photons penetrate the patient, depending on their density of the organs (some are transmitted, some are attenuated)
- Transmitted photons are captured by the detector, while attenuated photons cast a shadow on the detector.
Does air filled tissue (i.e. lungs) attenuate or transmit photons?
Transmit - maximally exposes the detector
Does dense tissue (i.e. bone) attenuate or transmit photons?
Attenuates - minimally exposes the detector
Does soft tissue (i.e. heart, vessels) attenuate or transmit photons?
Variable
What are the 5 radiographic densities?
Air
Fat
Fluid, soft tissue
Bone, calcium
Metal
T/F: Soft tissue and fat have the same density on x-ray?
False - soft tissue and FLUID have the same density on x-ray
What color is the original x-ray film? What color will be displayed on the radiograph if the beam is attenuated by a tissue?
The original x-ray film is white
If the beam is attenuated, it is absorbed by the tissue, and the resulting radiographic image will be white (i.e. bone)
Define radiolucent.
Black, lucency, dark, decreased density
Define radioopaque.
White, opacity, density, consolidation, increased density
(things that absorbed the x-ray beam)
Of the 5 radiographic densities, which are radiolucent?
Air
Fat
Of the 5 radiographic densities, which are radioopaque?
Fluid, soft tissue
Bone, calcium
Metal
Should the lungs be black void, like the atomospheric air?
No
If you see a very dense and calcified nodule in the lung, how what can you compare it to, to determine if it is a TB granuloma?
Adjacent rib - if the nodule is denser (whiter) than the adjacent rib, then you can diagnose it as a TB granulom
2 objects of DIFFERENT radiographic densities touch/border each other
Radiographic interface
2 objects of the SAME radiographic density touch/border each other
Silhouette sign - the border disappears
If there is fluid in the lungs (i.e. alveoli) and it is bordering the heart (soft tissue), there will be a silhouette sign where there should be an interface
What are the standard chest radiograph views? What type of patients are they used for?
PA & Lateral - patient who can stand
AP - supine patient
Semi-erect AP
What does “PA” chest radiograph mean?
Posterior to anterior - describes the direction of the beam through the patient (posterior to anterior) towards the detector
If you were not able to determine if the patient were standing or supine based on the air in the stomach/colon, where could you cheat and look?
At the arm - if they are in a bear hug the patient is standing PA
If they are by the patient’s side, they are supine
Is the heart size more acurate in a PA (upright) or supine radiograph? What is the ratio?
PA (upright) - 1:1 ratio - because the chest is directly against the detector
Is the PA (upright) or supine chest radiograph more sensitive for free air (i.e. pneumothorax)?
PA (upright)
If you are looking for free air in the colon, should you look under the right or left lung?
Right lung - so not to confuse any air in the colon with the air in the gastric air bubble (fundus)
How should the patient stand for a lateral chest radiograph?
Right to left (beam goes through the right then the left)
What should you do if you see a mass on radiograph?
Triangulate in the orthogonal plane (Rotate 90 degrees - Lateral chest radiograph)
When you see a mass you want to confirm it is a mass by triangulating it in the orthogonal plane because a mass will be spherical in all planes
Is the PA (upright) or supine chest radiograph less sensitive for fluid and free air?
AP (supine)
In which radiograph will the heart be magnified? Why?
Supine (AP) - manification increases with increased distance of the object from the detector
Which radiograph technique is the most sensitive for picking up fluid? The least?
Most - lateral decub (only need 5 mL of fluid)
Lateral (erect) - 75 mL
PA (erect) - 150 mL
Least - AP (supine) - (need 300 mL)
Which lung segment is in contact with the right heart border? Left heart border?
Right - middle (right) lobe
Left - lingula (left)
On PA CXR, which lung is being imaged? Anterior, postior, or both?
Anterior and posterior lungs - superimposed on PA and AP radiographs
On AP CXR, which lung is being imaged? Anterior, postior, or both?
Both antertior and posterior lungs - superimposed on PA and AP radiographs
What is the pneumonic to determine technical adequacy of looking at a CXR?
PAIR
Penetration
Angulation
Inspiration
Rotation
What is ideal penetration when looking at a CXR?
Adequate photos penetrate the patient and expose the radiograph - able to see the spine through the heart shadow
What is underpenetration when looking at a CXR? Who does this occur in?
Falsely increased opacity (white) in the retrocardiac region and bases
Vessels become more prominent
Occurs in overweight patients
What is overpenetration when looking at a CXR?
Falsely decreased opacity - pulmonary nodules disappear
Simulates emphysema or PTX
What is ideal rotation (R) of a CXR?
The spinous processes should lie equidistant from the medial ends of each clavicle
What is distorted when there is rotation in a CXR?
Triple H
Heart - False cardiomegaly
Hilum - spurious hilar masses
Hemi - falsely elevated hemidiaphragm
What is the orientation of the anterior ribs on CXR?
Downward
What is the orientation of the posterior ribs on CXR?
Horizontal
Counting up to which anterior and posterior ribs indicates okay, adequate and excellent inspiration?
6
9
10
What is an angulation technique for CXR?
AP lordotic view:
Clavicles are projected superiorly
Ribs are more horizontal
Mediastinal anatomy distorted
Can be intentional to visualize structions in the apex (i.e. pancoast tumor)
What is the order in which you should interpret a CXR?
- orientation
- technical adequacy (PAIR)
- heart size
- silhouetting
- lungs
- bones
- soft tissues
Is wood radiographically visible?
No - radiographically invisible
Right middle lobe pneumonia
(left) Silhouetting of the right heart border –> something must be wrong with the middle lobe
(right) Major fissure is marginated by the consolidation
Silhouetting of the left hemidiaphragm due to pleural effusion
Right lower lobe atelectasis
“Spine sign” - paradoxically increased density of the lower spine seen on lateral chest x-ray indicative of a posterior RIGHT lower lobe process (i.e. pneumonia)
it is right and not left because you can see the spines, and not the left diaphragm
Bilateraly lymphadenopathy silhouetting the trachea and hila - SARCOID
Right pneumothorax
Describe how an pneumothorax will look on an upright (AP) CXR.
Air will rise to the apex
Thin visceral pleural white line
Black air (absent lung markings) lateral/above the pleural line
Describe how a pneumothorax will look on a supine CXR?
Air collects anteriorly
Hyperlucent lung
Deep sulcus sign
What type of radiograph is used specifically to diagnose a pneumothorax?
Inpsiration expiration radiograph
Perihilar “batwing” pattern
s/p pulmonary edema, pnuemocystic pneumonia, ARDS,
hemorrhage, inhalation injury
Revere batwing patterns - peripheral subpleural
s/p eosinophilic pneumonia, radiation, contusion, sarcoid
Diffuse consolidation (white out)
s/p pulmonary edema, pneumonia, ARDS (white out)
Posterior right upper lung, lung cancer
Where could you place a central venous catheter?
Internal jugular vein
Subclavian vein - high risk of pneumothorax
Femoral vein
Ideal placement: tip in the SVC
Pneumothorax
How far above the carina should an endotracheal tube be placed?
3-5 cm
ETT within the right mainstem bronchus with left lung collapse
What study is ordered for TRAUMATIC back pain?
Thoracic or lumbar series radiography - NOT a chest radiograph
What study is ordered for TRAUMATIC chest pain?
Rib radiograph serious - NOT a chest radiograph
Emphysema - hyperinflation, flattened diaphragm, increased retrosternal space, increased AP diameter (not seen)
Why is it preferred to place a central venous catheter through the internal jugular vein over the subclavian vein?
Subclavian has a high risk for a pneumothorax
Nasogastric tube
What are the most common causes of CHF in the US?
CAD and HTN
How do we grade CHF on CXR?
I: Vascular redistribution
II: Pulmonary interstitial edema
III: Pulmonary alveolar edema
At what zone of the lungs are the artery and bronchus equal?
At the hilum
What is PCWP? Normal?
Pulmonary capillary wedge pressure - indirect way of measuring left atrial pressure
Normal = 6-12 mmHg
What occurs when there is vascular redistribution secondary to CHF?
PCWP increases to 13-18 mmHg
Cardiomegaly
Peribronchial cuffing - thick bronchus from increased fluid and pressure
Pulmonary vasculature is engorged - no longer equal to the bronchi
What occurs on CXR from pulmonary interstitial edema secondary to CHF?
PCWP increased to 18-25 mmHg
Lines - as fluid goes into the interstitium, you can see lines that aren’t normally there
What are Kerley A/B lines? What grade of CHF do they appear in?
II: pulmonary interstitial edema
A: long lines coming out of the hilum
B: short lines horizontally oriented from the periphery of the lung
What occurs on CXR during pulmonary alveolar edema secondary to CHF?
PCWP > 25 mmHg
Consolidation = clouds
How can you differentiate pneumonia consolidation from CHF pulmonary alveolar edema on CXR?
CHF: edema quickly clears in 24 hours with medication
If it does not clear in 24 hours - pneumonia
Pulmonary interstitial edema
Where do bone/metal, water, air, soft tissue and fat measure on the Hounsfield scale?
- 1,000 air
- 40-90 fat
0-20 water
+30-90 blood and soft tissue
+1,000 bone and metal
What would be the Hounsfield unit of ascites, urine, CSF, or a pleural effusion?
0-20
How can you differentiate ascites vs. blood in the abdomen?
Blood will measure higher on the Housfield scale (+40-90) then ascities (0-20)
How do CT window settings differ depening on the density of the organ?
The higher the density the smaller the window setting
How do we image using CT scan?
Trans-axially (transverse plane - slicing through the body horizontally)
T/F: I can reconstruct the coronal and sagittal planes from the transverse plane of an MRI?
False - I can only do this with a CT
How many CXRs are equivalent to 1 CT scan in terms of radiation?
500 CXR = 1 CT scan
What type of contrast should you order when evaluating for acute appendicitis on CT scan?
Oral and IV - should fill the appendix in 1.5 hours
What is the maximum size that the lumen of the appendix should be?
6 mm
What type of oral contrast should you NOT give if you suspect a bowel perf? Why?
Dilute barium sulfate - causes peritonitis
What type of oral contrast should you NOT give if a patient is at risk of aspirating? Why?
Water-soluble iodinated contrast (gastrograffin) - cause pneumonitis
What are the requirements for receiving IV contrast?
Normal renal function (GFR >40)
No history of anaphylaxis to IV contrast
What is the 3rd leading cause of hospital-acquired acute renal failure?
Contrast induced nephropathy - ARF within 48 hours of IV contrast due to previously abnormal renal function
(#1 surgery, #2 hypotension)
What are nephrotoxic medications that should not be given with IV contrast?
NSAIDs
Cisplatin chemo
Aminoglycoside abx
Iodinated contrast within the last 72 hours
Can you give IV contrast to a dialysis patient?
Yes - give it to them 24 hours before their dialysis
Which drug should be stopped at the time of IV contrast administration? When can it be given again?
Metformin - stopped at the time of IV contrast administration and resumed 48 hours
T/F: Allergy to shellfish is a predictor of increased risk of a reaction to IV contrast?
False!
Which medications can be given before IV contrast to prevent an allergic reaction?
Prednisone
Diphenhydramine
When should you do a CT scan in a patient suspected to have an aortic dissection?
Pre and post IV contrast
(non contrast CT of the chest to see if there is a hematoma, then contrast CT of the chest and abdomen to look for the dissection)
Can a mom breastfeed if she received IV contrast? VQ scan?
Breastfeeding: should express and discard the milk for 24 hours
VQ: don’t hold the baby close to her for 24 hours, but she can pump and have someone else feed the baby
T/F: IV contrast is indicated for evaluation of mediastinal or hilar masses?
True
T/F: IV contrast is indicated for trauma?
True
How do you evaluate a mass in the kidney?
Pre and post contrast CT abdomen - measure the pre and post Hounsfield unit
If it increases by 15, it is a mass
T/F: IV contrast is indicated to evaluate a pulmonary nodule?
False - noncontrast CT chest
T/F: IV contrast is indicated to evaluate a pneumothorax?
False - noncontrast CT
T/F: IV contrast is indicated to evaluate a ureteral calculi?
False - noncontrast CT abdomen
T/F: IV contrast is indicated to evaluate a pneumoperitoneum?
False - noncontrast CT abdomen
T/F: IV contrast is indicated to evaluate a retroperitoneal hemorrhage?
False - noncontrast CT abdomen
T/F: IV contrast is indicated to evaluate for a stroke?
False - noncontrast CT head to make sure there is not a bleed before administering tPa
What is the basic physics of MRI?
A magnetic field is used to manipulate the electromagnetic activity of the hydrogen atom, which releases energy in the form of a radiofrequency signal
What is T1 in terms of an MRI?
Longitudinal relaxation time
bright, hyperintense, short relaxation
Fat
Blood (depening on age)
Protein
Melanin
Gadolinium contrast
What is T2 in terms of an MRI?
Transversal relaxation time
Bright, hyperintense, long relaxation
Water (ascites, pleural effusion, urine, CSF, cysts)
Blood (depending on age)
Edema
Inflammation/infection
What is the unit that measured magnetic field strength? What is the equivalent to the Earth’s magnetic field?
Tesla
1 Testla = 20,000x Earth’s magnetic field
What are some contraindications for MRI?
Pacemakers
Metallic foreign body in the eye
Deep brain stimulator
Swan Ganz catheter
Bullets (Bullets shot in the US are MRI compatible)
Cerebral aneurysm clips
Cochlear implants
Magnetic dental implants
Who cannot receive gadolinium? Why?
A patient with a GFR < 40 - can cause nephrogenic systemic fibrosis
What are early signs of a stroke on CT?
Hypoattenuating brain tissue (whiter than normal)
Loss of sulci (due to swelling)
Dense MCA sign
Obscured lentiform nucleus
“Insular ribbon” sign
Loss of sulcal effacement s/p stroke
Dense MCA sign s/p stroke
What is the most sensitive sequence for stroke imaging?
Diffuse weighted image (DWI) on MRI
Diffuse weighted image
If a patient has had a stroke, what should the ADC look like corresponding to the DWI?
Dark - if it is bright on DWI and ADC, it is artifact, not a stroke
What should you give a patient if you want to evaluate a mass on MRI?
MRI contrast - gadolinium
T/F: IV contrast is needed for MRA circle of willis?
False - no IV contrast
T/F: IV contrast is needed for MRA neck?
True - need IV contrast to evaluate a carotid stenosis
T/F: IV contrast is needed for diagnosis of a spinal cord compression emergency?
False - IV contrast is not required to evaluate the spine UNLESS a mass is suspected
What does MRI with contrast give me that CT doesn’t?
Contrast Resolution
T/F: IV contrast is needed to evaluate any mass on MRI?
True
T/F: IV contrast is needed to evaluate soft tissue structures on MRI?
False
Exceptions: IV contrast needed for abscesses, osteomyelitis, and sarcoma (mass)
What is unique about the U/S transducer?
It transmits and receives the signal
What is the imaging modality that is the most operator dependent?
U/S
How much of an U/S beam is reflected at a tissue-air interface?
99% (none is available for further image)
Which organ in the abdomen is the most hyperechoic? The least?
Most: pancreas (bright white due to fat globules)
Least: kidneys
What happens when an U/S beam travels through a fluid filled structure?
Fluid is anechoic (dark), so the beam will travel fast through the fluid, causing posterior acoustic enhancement (white cast underneath the fluid)
What is the maximal thickness that the gallbladder wall should be?
3mm
How can you be sure you are seeing a gallstone on U/S?
The echogenic stone will cast a clean shadow under the stone
T/F: U/S pelvis has more contrast resolution than a CT?
True - CT doesn’t have contrast resolution
If you are evaluating a woman for ovarian torsion what will you see on U/S?
Will see ABSENT blood flow inside of the arteries and veins
What is a “ying-yang” appearance on color doppler indicative of?
Postcatherization pseudoaneurysm
What will you see on grey-scale in a patient with postcatheterization pseudoaneurysm?
Expansion of fluid collection during systole
Contraction of fluid collection during diastole
