Anatomy The true (lesser) pelvis is divided from the false (greater) pelvis by an oblique plane extending across the pelvic brim from the sacral promontory to the symphysis pubis. The true pelvis contains the rectum, bladder, pelvic ureters, and prostate and seminal vesicles in males, or vagina, uterus, and ovaries in females. The false pelvis is open anteriorly and is bounded laterally by the iliac fossae.…

Basic Principles CT complements endoscopy and barium examination of the gastrointestinal (GI) tract by demonstration of intramural and extraintestinal components of GI disease, including disease in the mesentery, peritoneal cavity, lymph nodes, and liver. CT is used to diagnose the presence of GI disease, evaluate its nature and extent, and demonstrate complications such as abscess, phlegmon, fistula, and perforation. CT is excellent for determining the extent…

The adrenal glands are the primary focus of diagnostic attention in three clinical circumstances. A patient may be referred for imaging because a clinical diagnosis of adrenal hormone hyperfunction has been made. CT is then used to identify and characterize the lesion. The adrenal glands are commonly imaged to detect suspected metastatic disease, especially when the primary tumor, such as lung carcinoma, commonly metastasizes to the…

Kidneys Anatomy of the Retroperitoneal Space A detailed understanding of the retroperitoneal fascial planes and compartments is a prerequisite for accurate interpretation of abdominal CT. The retroperitoneum is the anatomic compartment between the posterior parietal peritoneum and the transversalis fascia extending from the diaphragm to the pelvic brim. It is divided into three distinct compartments—anterior pararenal, perirenal, and posterior pararenal spaces—by the anterior renal fascia and…

With high-resolution multidetector CT and dynamic multiphase postcontrast protocols, an increasing number of splenic lesions are being detected. These require characterization by combination of imaging findings with clinical data. Many spleen lesions are nonspecific in appearance. At a minimum, splenic lesions should be characterized as benign or potentially malignant. Anatomy The spleen occupies a relatively constant position in the left upper quadrant of the abdomen. It…

Multidetector CT is the imaging method of choice for evaluation of pancreatitis and competes with magnetic resonance imaging (MRI) for detection and staging of pancreatic tumors. Rapid CT acquisition times allow high-resolution multiphase scanning of the entire pancreas within a single breath hold in most instances. CT Technique CT evaluation of pancreatitis is usually performed as a routine abdomen scan with extension of CT scanning of…

Biliary Tree Primary imaging of the biliary tree depends increasingly on CT, ultrasonography, magnetic resonance imaging, and magnetic resonance cholangiopancreatography, and with diminishing reliance on invasive endoscopic retrograde cholangiopancreatography. Multidetector CT (MDCT) with thin sections and multiplanar reformats can clearly demonstrate the normal anatomy, anatomic variants, stones, tumors, and inflammatory disease of the biliary system. Anatomy The bile ducts arise as biliary capillaries between hepatocytes. Bile…

Anatomy In 2000 the Terminology Committee of the International Hepato-Pancreato-Biliary Association refined the accepted terminology of hepatic anatomy and liver resections. The international classification system divides the liver into eight independent segments (Couinaud [pronounced “kwee-NO”] segments) ( Fig. 11.1 , Tables 11.1 and 11.2 ). Each segment is a self-contained unit that can be surgically resected without damaging the remainder of the liver. Each segment has…

Multidetector CT (MDCT) is the imaging method of choice for the diagnosis of intra-abdominal injury following blunt abdominal trauma. Treatment is directed by characterization of the precise nature of the injury, or by the reliable demonstration of the absence of significant injury. CT is particularly valuable when physical examination of the abdomen is equivocal or unreliable, such as with head trauma or impairment of consciousness caused…

Peritoneal Cavity Anatomy The various recesses and spaces of the peritoneal cavity are easiest to recognize on CT when ascites is present. Identifying the precise compartment that an abnormality is in goes a long way toward identifying the nature of the abnormality and deciding on a plan for intervention. The peritoneum is a thin membrane that produces serous fluid, which lubricates the abdominal and pelvic cavity.…

Despite marked advances in limiting image times for magnetic resonance imaging, CT remains the primary modality for most indications for imaging the abdomen and pelvis. The technology of multidetector CT (MDCT) scanners continues to advance, with progressive increases in the number of detectors, now exceeding 128 detector rows, and progressive decrease in acquisition times. Concern is now focused on CT radiation dose and overuse as thin-slice…