TCM 2 Exam - Second Semester Flashcards
2 causes of dilated bowel
- Paralytic ileus
2. Bowel obstruction (small or large)
Radiologic findings of paralytic ileus?
Distended bowel with multiple air-fluid levels
Gas seen in the rectum
Common causes of paralytic ileus
Inflammation of the peritoneum (post-abdominal surgery, appendicitis, pancreatitis, etc.)
Normal postoperative ileus lasts ___ hours.
48
Common causes of small bowel obstruction (4)
Post-operative adhesions
Gallstone ileus
Intussusception
Tumors
Common causes of large bowel obstruction (3)
Colon cancer
Fecal impaction
Diverticulitis
How should bowel obstruction be evaluated with imaging?
Screening - plain film
CT of the abdomen
Radiologic findings of small bowel obstruction?
Multiple air-fluid levels
Stacked
Centrally located loops of intestine
Dilated small bowel greater than 3 cms visible with valvulae conniventes; colon not dilated
String of pearls sign (small bubbles trapped)
Absence of colon gas (collapsed colon)
Radiologic findings of large bowel obstruction?
Peripherally located distended bowel with haustral markings
Dilated loops of small and large bowel
No air distal to site of obstruction
Mass might be seen
Compare small vs. large bowel (location)
Small - central abdomen
Large - peripheral abdomen
Compare small vs. large bowel (appearance)
Small - valvulae conniventes crosses the entire width
Large - haustra, bubbly appearance of feces, diverticula
Findings of acute pancreatitis on abdominal CXR?
Calcification Mass from a pseudo cyst Sentinel loop (dilation of duodenum) Colon cut off (dilated colon to the mid-transverse colon, no air beyond the splenic flexure) Diffuse ileus (small bowel dilation) Left pleural effusion
Findings of acute pancreatitis on abdominal CT (contrast-enhanced)?
Enlargement due to edema Peripancreatic inflammation (linear strands in the surrounding fat) Phelgmon Hemorrhagic Necrosis (decreased or no enhancement) Fluid in the paracolic gutter Fluid collections Pseudocysts Abscesses
What is the normal size of the pancreas?
Same width as the abdominal aorta (2.5 cm in diameter)
How does the pancreas appear on CT compared to the liver and spleen?
Similar enhancement with contrast
How does an edematous pancreas appear on CT compared to the liver and spleen?
Less dense
More dense if hemorrhagic
How does pancreatitis appear on ultrasound?
Edematous pancreas Gallstones Dilated common bile duct Pseudocyst Poorly defined
The normal pancreas is in the ___peritoneum, ___cm long, and located in the ___.
Retro; 12-15; epigastrum
What surrounds the head of the pancreas?
Duodenum
What vein runs along the posterior inferior groove of the pancreas?
Splenic vein
The ___ duct traverses through the head of the pancreas and joins with the pancreatic duct at the ___ to empty bile into the descending part of the duodenum.
Common bile; ampulla of Vater
Imaging findings of chronic pancreatitis
Calcifications
Pseudocysts
Imaging of choice for pancreatitis
CT with IV contrast
Useful imaging procedures to evaluate pancreatic cancer
CT scan (evaluate tumor, stage) US/nuclear medicine (biliary obstruction)
Neoplasm in the ___ of the pancreas can compress the common bile duct, causing an extra-hepatic biliary obstruction.
Head
Cancer in the ___ of the pancreas may obstruct the splenic vein or cause mass effect.
Tail
What is indicated for initial study of a patient who presents with jaundice?
Abdominal US (dilated bile ducts or presence of a mass in the head suggests tumor)
CT is useful in patients who are not jaundiced and in those in whom intestinal gas interferes with US
What is indicated when CT and US do not reveal a mass lesion within the pancreas, and when chronic pancreatitis is suspected?
ERCP
What are common malignant liver masses?
Metastatic tumors, HCC, cholangiocarcinoma
What are common benign focal liver lesions?
Cysts (congenital, parasitic - echinococcal), cavernous hemangiomas, focal nodular hyperplasia, hepatic adenomas, abscesses
What is the best imaging modality to evaluate liver masses?
CT
When is ultrasound useful to evaluate liver masses?
Intra-operatively
When is MRI useful to evaluate liver masses?
Delineating vascular involvement and identifying additional intra-abdominal lesions
True or false - normal biliary ducts are not seen on CT.
True (only seen when dilated)
What are the imaging findings of hepatoma on CT?
Single or multiple masses or diffuse involvement Low attenuation lesions Hemorrhage, fat, necrosis Calcification Hypodense capsule or rim Enhancement seen with contrast Can invade portal and hepatic veins
How do hepatomas appear on MRI?
Mass with low intensity on T1 and high signal on T2
How do liver cysts appear on CT?
Oval, well-defined
Imperceptible or thin wall
Water density
No enhancement
How do liver cysts appear on US?
Well-defined, anechoic (echogenic if fluid filled)
How does a liver cyst appear on MRI?
Mass with low intensity on T1 and high signal on T2, may be indistinguishable from hemangioma without IV contrast
Common primary source sof liver metastases
Colon carcinoma, breast, kidney
What is the imaging procedure of choice to evaluate the liver for mets?
CT scan with IV contrast
Liver tumors are usually hypodense on CT with IV contrast performed in ___ phase (70 seconds). However, tumors may be hyperdense on CT in ___ phase (15 seconds).
Standard portal venous phase; arterial
Compare the density of the normal liver and spleen on non-contrast CT.
Approximately the same
What is the diagnostic procedure of choice for cirrhosis?
CT with IV contrast
How does a cirrhotic liver appear on CT?
Small liver with nodular margins
Ascites
Common renal masses (4)
Simple renal cyst
Renal cell carcinoma
PCKD
Abscess
What is the initial imaging procedure of choice for a renal mass?
US (distinguish between a cyst and a solid mass)
What are the three major criteria for a single simple cyst on US?
- Round mass, sharply demcarted with smooth walls
- No echoes (anechoic) within the mass
- Strong posterior wall echo indicating good sound transmission through the cyst
What US findings suggest a renal malignancy?
Solid or complex Internal echoes Irregular walls Calcifications or septae Multiple cysts clustered (could mask underlying carcinoma)
When is CT and MRI used in evaluating a renal mass?
CT (with and without IV contrast) - next appropriate step
MRI - if patient is unable to receive IV contrast, useful to evaluate vascular invasion
How does renal carcinoma appear on CT?
Hypodense (unless hemorrhagic)
Cystic
Calcified
Most enhance after contrast administration, but less than normal kidney enhnacement
Thickened or irregular walls of the cystic portion
Thickened or enhanced septae within the cystic mass
Multilocular mass
Invasion of renal vein and IVC
Nodes
Normal size of the kidney, normal appearance of kidney on US
9-11 cm
Same extent of echoes as the liver
Central echoes in the kidney are from ___ surrounding the renal pelvis and are white.
Fat
The ___ of the kidney is hypoechoic and appears dark.
Medulla (can distinguish it from fluid filled calyces, as there will be no increased transmission of sound beyond)
How do kidneys appear in acute renal failure?
Normal
How do kidneys appear in chronic renal failure?
Smaller than normal, surface may be irregular, cortex is thinned and hyperechoic compared to the liver due to scar tissue
How do kidneys appear in hydronephrosis?
Dilated anechoic calyces with increased posterior transmission of sound, cortex is normal, separation of hyperechoic fat within the central renal sinus
How does AAA appear on ultrasound?
Widened aortic lumen >3 cm
How does AAA appear on CXR?
Calcification of both walls at the same level with increased diameter
How does AAA appear on CT?
Calcification of the wall, may show chronic erosion of adjacent vertebrae
How does ruptured AAA appear on CT without IV contrast?
High density blood
What is the role of interventional radiology in the management of AAA?
Permanent stent placement
What is the procedure of choice in adults to diagnose acute appendicitis?
Abdominal and pelvic CT with IV contrast
What are the findings of acute appendicitis on CT?
Appendicolith
Dilated appendix with thick wall
Periappendiceal fluid, abscess (indicated by an air pocket)
Where should a Dobhoff feeding tube tip go?
Junction of the second and third parts of the duodenum
5 types of intracranial hemorrhage
Subdural hematoma Epidural hematoma Subarachnoid hemorrhage Intracerebral hemorrhage Intraventricular hemororhage
Optimal imaging procedure to evaluate suspected intracranial hemorrhage?
Pre-contrast CT
Defined as a collection of blood between the inner table of the skull and the dura
Epidural hematoma
Common etiology of epidural hematoma?
Head trauma, often in children
Epidural hematoma often demonstrates what finding on XR?
Fracture line (parietal) across the middle meningeal artery
Findings of epidural hematoma on pre-contrast CT?
Biconvex/lens shape
Acute blood is hyperdense
Does not cross suture line
Mass effect
Defined as a collection of blood between the dura and the arachnoid
Subdural hematoma
Common causes of subdural hematomas
Head trauma (child abuse), coagulopathy
Compare the appearance of acute, chronic, and subacute subdural hematomas on CT.
Acute - blood appears hyper dense
Chronic - blood appears hypodense
Subacute - isodense
Subdural hematoma is common in patients with brain atrophy - why?
Superficial veins are stretched over a greater distance and more prone to rupture with rapid head movement
Findings of an acute subdural hematoma on CT?
History of recent fall Hyperdense blood Crescentic shape (medial margin is less convex) Crosses suture lines Mass effect
Findings of a chronic subdural hematoma on CT?
Bilateral chronic subdural hygromas produce slight compression of the adjacent sulci
Hypodense blood
Blood within the CSF subarachnoid space
Subarachnoid hemorrhage
How does a subarachnoid hemorrhage typically present?
Worst headache of my life
Spontaneous subarachnoid hemorrhage is most often caused by what?
Rupture of arterial aneurysms, which release blood into the CSF; most common cause overall is trauma
Type of hematoma with a lucid interval followed by deterioriation
Epidural hematoma
Common causes of intracerebral hemorrhage
HTN, trauma, rupture of aneurysm, rupture of AVM
Most intracranial aneurysms occur in what artery?
Anterior communicating artery
How does ICH appear on CT?
Round shape
High density
CT findings of SAH?
Subarachnoid blood in subarachnoid space
Normal sulci filled with low density normal CSF and appear dark
Sulci filled with blood appear hyperdense
Common causes of stroke
Ischemic (atherosclerotic disease, embolus, inadequate cerebral blood flow) Hemorrhagic Venous sinus thrombosis Vasculitis Traumatic arterial dissection
Imaging modality of choice to rule out hemorrhagic stroke
CT
Imaging modality to diagnose acute stroke
MRI (CT does not detect)
Does a normal CT rule out stroke?
No
Acute infarct appearance on Non-contrast CT
Large hypodense area Effacement of gyri and sulci Can be normal Loss of gray-white matter differentiation Blurred basal ganglia Insular ribbon sign Dense MCA sign
How does edema and infarction appear on CT?
Low density (black)
How does edema and infarction appear on MRI?
High signal intensity on T2 and FLAIR
How does edema appear on T2?
Bright, high intensity
What is FLAIR?
Equivalent to T2
An abnormality such as a tumor or infarct that is dark on T1 becomes bright after IV gadolinium contrast. What does this indicate?
Breakdown of BBB
Acute infarct appearance on DWI MRI?
Hyperintense
Wha causes the bright signal of an infarct using DWI?
Restriction of the ability of water protons to diffuse extracellularly
How does a glioblastoma appear on T1 MRI (post-contrast)?
Ring-enhancing lesion
What is the on the differential for a ring enhancing lesions?
Glioblastoma
Metastatic tumor
Abscess
Imaging test of choice for metastatic tumors to the brain?
MRI
What are common malignant tumors that met to the brain?
Lung
Breast
Melanoma
Renal
Most common intracranial benign tumor
Meningioma
How does meningioma appear on MRI?
Mass involving the floor of the anterior cranial fossa
Dural-based tumor, extra-axial
Enhances like a light bulb on T1 MRI post-contrast
How does a pyogenic abscess appear on T1 MRI post contrast?
Ring enhancing lesion
Edema surrounding the abscess is hypointense on T1
How does MS appear on FLAIR?
Asymmetrical, abnormal high signal weight matter lesions in the periventricular and subcortical areas
Diagnostic imaging of choice for MS?
MRI
DDX white matter lesions
White matter infarctions (HTN, DM)
MS
HIV-related infections
Radiation or chemo induced leukoencephalopathy
How does a spine compression fracture appear?
Vetebral body is wedge shaped, flattened, higher density
Compare the appearance of osteoblastic and osteolytic spinal lesions on CXR
Osteoblastic: bone production and sclerotic, hyperdense, white bone
Osteolytic - lucent, hypodense
Best study to evaluate possible spinal cord compression?
MRI
