9) Abdominal Organs Flashcards
Liver imaging key concepts
- Plain radiographs may show liver calcifications, but have limited use in liver imaging
- Nuclear medicine
- CT with IV contrast
- Hepatic angiography
Nuclear medicine
- Technetium “hida” scan is performed for functional and morphologic information
- Today has been virtually replaced by ultrasound, CT, and MRI
CT with IV contrast
- Imaging method of choice for imaging the liver parenchyma
MRI is valuable in the imaging of primary tumors and liver metastases
Hepatic angiography
- Reserved for those patients who need detailed evaluation of the hepatic vasculature
Benign tumors
- Hepatic adenoma
- Focal nodular hyperplasia
- More common in young and middle aged women who have been taking birth control pills or hormonal replacement therapy
Hepatocellular carcinoma
- Hepatoma
- More common in cirrhotic patients
The most common benign liver tumor
- Cavernous hemangioma
Hepatic cysts and abscesses key concepts
- These are two nonneoplastic liver masses
- Easily diagnosed with cross-sectional imaging techniques
- Ultrasound for hepatic cyst
- Percutaneous aspiration for liver abscess
At ultrasound a hepatic cyst appears
- Sharply defined round mass
- Thin wall that is echolucent
Diagnosis of a liver abscess is usually confirmed by
- Percutaneous aspiration
- Performed by a radiologist using CT or ultrasound guidance
Blunt liver trauma
- Most commonly caused by MVA’s (motor vehicle accidents) and falls
Penetrating liver trauma
- Caused by stab wounds, gunshot wounds, and liver biopsy complications
Liver trauma key concepts
- CT with oral and IV contrast is the imaging method of choice for liver trauma
- Unstable patient should be imaged at the bedside with portable ultrasound
Cirrhosis, splenomegaly, and ascites key concepts
- Cirrhosis resulting from chronic alcoholism will alter the size, shape, contours, or density of the liver
- CT is the imaging method of choice for cirrhosis, and may show splenomegaly (from portal hypertension), and ascites
Splenic trauma key concepts
- The spleen is the organ most frequently injured during blunt abdominal trauma
- CT is the imaging method of choice for splenic trauma
- Unstable patient should be imaged at the bedside with portable ultrasound
Gallstones in cholelithiasis
- Appear in ultrasound as echogenic, with acoustic shadows
- Only 10% of gallstones are radiopaque and may be imaged by plain films
Imaging method of choice for evaluating gallbladder disease
- Ultrasound
- 95% accuracy rate in the detection of gallstones
Acute cholecystitis (or acute inflammation of the gallbladder)
- 90% of cases caused by obstruction of the cystic duct by gallstones
Emphysematous cholecystitis can be see radiographically with
- Air in the gallbladder wall
Porcelain gallbladder can be seen with
- Calcification of the gallbladder wall
Oral cholecystogram (OCG)
- Rarely done today
- Patient ingests a contrast material the night before the exam
Cholescinctigraphy key concepts
- Nuclear medicine imaging of the liver and gallbladder
- Also known as the HIDA (hepatobiliary iminodiacetic acid) scan
- Because the cystic duct is nearly always occluded in acute cholecystitis, there is generally no visualization of the gallbladder, even on delayed images
Obstruction of the biliary tree imaging options
- Ultrasound
- Cholescintigraphy
- CT
- Percutaneous transhepatic cholangiography (PTC)
- Endoscopic retrograde cholangiopancreatography (ERCP)
Percutaneous transhepatic cholangiography key concepts
- Carried out by injection of a water soluble contrast material directly into the liver through the skin
- The biliary tree is seen in great detail, as well as a site of biliary obstruction
Pancreas key concepts
- Pancreas is not visible on plain films, but pancreatic calcifications may be evident in some patients (usually diagnostic of chronic pancreatitis)
- Ultrasound may show pancreatic masses, peudocysts, and pancreatic duct dilation, but pancreatic anatomy is more clearly delineated with CT
Endoscopic Retrograde Cholangiopancreatography (pancreas key concepts)
- Involves cannulization, under fluoroscopic control, of the common bile duct and the pancreatic ducts via the ampulla of Vater during upper endoscopy
- When ultrasound or angiographic studies of suspected panceatic disease is uncertain, ERCP is usually conclusive
Imaging method of choice for patients suspected of having pancreatic cancer, pancreatitis, pancreatic abscesses, and pancreatic trauma
- CT
Courvoisier’s law (Courvoisier’s sign)
- A statement that the gallbladder is smaller than usual if a gallstone blocks the common bile duct, but is dilated if the common bile duct is blocked by something other than a gallstone, such as pancreatic cancer
Renal diseases
- Renal cysts
- Polycystic renal disease
- Pyelonephritis
- Renal masses
CT scan of a fractured kidney
- Slice at the level of the
kidneys shows no laceration,
but reveals blood in the
perirenal space, surrounding the kidney
Summary
- CT of the GI tract demonstrates conditions that alter the thickness of the bowel wall
- CT with contrast is the imaging method of choice for most abdominal organs (with the exception of the gallbladder)
- Ultrasound is the imaging method of choice for most gallbladder pathology
