Anatomic Radiology Flashcards
What can ‘appear’ as water density on radiographs
blood, pus and obviously..water
Pneumoperitoneum can be best seen on what radiograph position?
upright - free air rises to the most superior portion of the abdominal cavity
What position can detect air between the liver and right lower ribs in a radiograph?
left side down decubitus with a cross table lateral film - used for sick patients who cant stand
Where is air under the diaphragm best seen?
right side bc the liver offers a distinct outline between the free air and soft tissues
Why can the left side under the diaphragm be difficult to see if there is free air?
because of gastric bubbles in the stomach or splenic flexure
What color is air on a radiograph?
black
What is Rigler’s sign?
both sides of the bowel wall becomes outlined by air (double-wall sign)
Seen in supine radiographs
Lots of free air in abdomen
What part of the bowel is defined by air in normal conditions in the radiograph?
inner aspect
Free air can collect over the ___ on supine radiographs and outline edges of the ______ ______
liver
falciform ligament
What is Morrison’s pouch?
Place that free air can collect that is inferior to the liver and above the right kidney
What are the main causes of free air?
peforated viscus (peptic ulcer, penetrating trauma)
Inflammatory conditions (Toxic megacolon)
Iatrogenic (postsurgical)
Intrathoracic causes
Pneumatosis intestinalis
What can cause a lack of gas in an area that normally contains air in a radiograph?
Soft tissue mass that displaces bowel
You can see ________ on renal stones, gallstones, appendicolith, vas deferens, gallbladder walls, pancreas, etc
Calcifications/ossifications
Air in the _____ is always normal
stomach
What is the normal caliber of air in small bowel?
1-2 loops of air
abnormal is greater than 3 cm
Where do you ALMOST always see air in a normal radiograph
rectum and sigmoid
Describe normal air-fluid levels in the stomach, small bowel, and large bowel
stomach always seen unless supine
small: two or three levels allowed
large: not typically seen
Describe the small bowel in a radiograph
tends to be more centrally located
valvulae extend across the entire lumen
less than 3 cm in diameter
Describe the large bowel in a radiograph
tends to be peripherally located
haustra do not extend from wall to wall
What is illeus?
bowel dilation without mechanical obstruction due to metabolic disorders, medications, ischemia, localized abdominal pain due to appendicitis, pancreatitis etc
1-2 persistently dilated loops of small or large bowel
air in rectum or sigmoid
may see air fluid levels, but are nondifferential
may resemble early or partial SBO
What is mechanical SBO?
dilated small bowel loops
little gas in colon
absent in rectum
disproportionate air in small bowel
What is mechanical LBO?
air seen to point of obstruction
little to no air in rectum and/or sigmoid colon
little to no gas in small bowel, unless ileocecal valve is incompetent (large bowel may then decompress into small and cause apparent SBO)
What are the causes of SBO?
adhesions
hernias
cancer - intrinsic and extrinsic
volvulus
What is fluroscopy used for?
'live xray' incomplete colonoscopy post surgical changes esophagus diverticulosis, apple core lesion, scleroderma
What is ultrasound used for?
abdominal pain, especially to evaluate for cholelithiasis (gallstones)
hepatic steatosis and renal cell carcinoma
there is no radiation
Best option
however, not good for pancreas
What is CT used for?
Acute setting but also in workup of nonspecific abdominal pain
downside - radiation
contrast used if kidneys are okay
NO contrast if renal stones
easy to see renal stones w/o contrast anyways
What is MRI used for?
often used to evaluate specific issue seen on prior imaging studies
like a liver mass or renal mass
there is no radiation
