Chapter 11 Intensive Care Unit

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CHAPTER 11 • Intensive Care Unit Imaging

FIGURE 11-18. Normal anatomic structures visualized on an axial abdominal CT.

Findings Relevant to Specific Organs Kidneys and Ureters The visibility of the kidney on the KUB view depends on the amount of perinephric fat and overlying bowel gas. The combination of kidney enlargement and calcification suggests urinary tract obstruction or polycystic kidney disease. If nephro- lithiasis is suspected, the renal outlines and course of both ureters should be carefully inspected for cal- culi (visible in up to 85% of cases). Identifying gas in the renal pelvis is uncommon but is indicative of emphysematous pyelonephritis seen most often in poorly controlled diabetics. Gas-producing infec- tions of the bladder are also seen occasionally. Pancreas and Retroperitoneum Asymmetric obliteration of the psoas shadows or retroperitoneal fat lines suggests a retroperitoneal process (most commonly pancreatitis or hemor- rhage from a leaking aorta). Similar changes can be seen with spontaneous hemorrhage or traumatic disruption. Although the pancreas is not normally seen on the plain radiograph, calcifications may occur in chronic alcoholic pancreatitis. Localized

or postoperative change. Free air is much more com- monly seen as the result of upper GI (stomach or duodenum) perforation rather than from colonic per- foration (diverticulitis, appendicitis, colon cancer). The KUB view is a poor indicator of liver size, and when in question, should not supplant careful physical examination or CT evaluation. The gall- bladder is inadequately defined on the KUB view unless it is very distended or calcified. Less than 15% of gallbladder calculi are visible. Gas appearing in the biliary ducts is highly suggestive of infectious cholangitis but can occur following endoscopic ret- rograde cholangiopancreatography. The ingestion of massive amounts of carbonated beverages, or intake of compounds that can generate gas when mixed with gastric acid (e.g., sodium bicarbonate), can also cause bile duct gas. Hepatic calcifications, although rare, may occur due to healed infection, hemangi- oma, or metastatic carcinoma. Films taken in differ- ent positions may help sort out the location of right upper quadrant calcifications. Calcifications within the kidney or liver maintain a relatively fixed posi- tion, whereas stones within the gallbladder are usu- ally mobile. Use of the KUB view in the diagnosis of the “acute abdomen” is discussed in Chapter 36.