GI Radiology Flashcards
3 causes of ascites
- cirrhosis
- CHF
- hypoprotienemia
4 causes of exudative ascites
- abscess
- pancreatitis
- peritonitis
- bowel perforation
X-ray sign for ascites
- bowel loops filled with air
- hazyness look to the film
- diffuse increased density
ascites on CT
- water is designated as 0
- simple serous ascites is 0 to -10
- if >45 think hemorrhage
free air in the peritoneal cavity (pneumoperitoneum)
- perforated hollow viscous until proven otherwise
- may be normal for 3-4 days after surgery but anything after that is abnormal
- usually on right side
- if a person cannot stand do a left lateral decubitus
best image modality for free air
- CT
dilated small bowel
- 2.5-3 cm
dilated colon
- > 5 cm
dilated cecum
- > 8cm
- if > 10 cm look for perforations and treat aggressively
adynamic ileus
- diffuse paralytic ileus
- non-obstructive
- commonly caused by drugs, surgery
dynamic ileus
- stasis above a physical obstruction
- usually a tumor, adhesion, or stricture
common causes of small bowel obstructions
- adhesions (#1 cause in US)
- incarcerated hernia (#1 cause everywhere else)
- malignancy
- intussususception
common causes of large bowel obstructions
- colon carcinoma (50-60%)
- metastatic disease
- diverticulitis
- fecal impaction (nursing homes)
- volvulus
- adhesions
3 causes of fatty infiltration of the liver
- alcoholism (#1 cause)
- obesity
- diabetes
diagnosis of fatty liver on CT
- The spleen and liver should be equal density on CT
- if the liver is lower density (not as bright) suggests diffuse fatty infiltration
diagnosis of fatty liver on US
- liver becomes brighter then the kidney
- echogenicity of liver is significantly greater than kidney
most common malignant mass in the liver
- metastatic lesion
- most from GI tract, breast and lung
most common primary tumor of the liver
- HCC
- most common cause of HCC is cirrhosis
preferred screening method of the biliary tree
- US
- US and CT are highly sensitive in detecting dilation of bile ducts but less effective for determining the cause
MRCP findings for static fluid
- any static fluid will be bright such as ascites or hepatic cysts
- takes advantage of long T2 characteristics of bile
HIDA scan
- normal gallbladder shows progressive accumulation of radionuclide activity over 30min to 1 hour
- considered positive with normal activity in liver and bowel with no activity at 4 hours
- may be considered positive at 1 hour if morphine utilized
major imaging modalities of the spleen
- CT and US
fluoroscopy
- useful in the evaluation of ulcerative disease
malignancy of duodenal lesions
- in duodenal bulb, 90% of lesions are benign
- in 2nd and 3rd portion, 50% are benign
- in 4th portion, most are malignant
duodenal ulcers
- caused by H. pylori
- most often occur in the duodenal bulb
preferred method for small bowel evaluation
- enteroclysis (small bowel enema)
- CT complements the barium exam
most common small bowel neoplasm
- carcinoid
- Carcinoid > adenocarcinoma > lymphoma
imaging modality for acute appendicitis
- CT
- US is the alternative
GI bleeding scan
- utilizes in vitro Tc 99m tagged RBCs, should be done during active bleeding, can be imaged up to 24 hours
common causes of hepatomegaly
- ALCOHOL USE
- CHF
- HEPATITIS
- TUMOR (METASTASIS)
- STEATOSIS
acute cholecystitis
- ACUTE INFLAMMATION OF THE GALLBLADDER
- 90% CAUSED BY GALLSTONES OBSTRUCTING CYSTIC DUCT
- NUCLEAR MEDICINE AND ULTRASOUND HAVE COMPARABLE SENSITIVITIES AND SPECIFICITIES
screening for colorectal cancer
- CT colonography is an alternative to colonoscopy to screen for colorectal cancer.
imaging modality for colon
- Double-contrast enema is favored over barium method
most common malignancy of GI tract
- colorectal cancer
gastric emptying studies
- Solid or liquid foods are labeled with a radiotracer and consumed by patient
- Images acquired and time activity curves obtained
- Normal t ½ is less than 90 minutes, if longer than 90 think gastroparesis
