▪ Prostate Anatomy The prostate gland is a walnut-shaped gland that sits in the base of the pelvis. The base of the gland is the broad superior portion and the apex is the narrow inferior portion ( Fig. 11.1 ). The prostate gland has zonal anatomy ( Fig. 11.2 ). The peripheral gland is made up of the peripheral zone, which accounts for approximately 70% of…
▪ Introduction The evaluation of the adnexa pivots on the unique spectroscopic capability of magnetic resonance (MR) to differentiate between lesions of different tissue composition, such as lipid (dermoid cyst), water (functional ovarian cyst), and hemorrhage (endometrioma). Improved tissue contrast elevates the sensitivity for neoplastic and malignant features compared with other modalities. The most common indications for MRI of the ovaries and adnexa include characterization of…
▪ Introduction Magnetic resonance imaging (MRI) serves as the most comprehensive and conclusive imaging modality available to image the female pelvis. The inherent zonal anatomy of the uterus is exquisitely depicted as a function of the different water content and histology of each mural layer. The predictable MR appearance of the uterus renders identification of abnormalities straightforward ( Fig. 9.1 ). Improved tissue contrast elevates the…
▪ Introduction Although computed tomography (CT) has been and still is the mainstay for imaging the gastrointestinal (GI) tract, small bowel and colorectal magnetic resonance (MR) applications have been developed and increasingly adopted in recent years. MR enterography evaluates the small bowel for inflammatory processes, such as Crohn’s disease, neoplasms, and etiologies of obstruction and bleeding. Colorectal applications include rectal cancer staging, anal fistula evaluation, and…
▪ Introduction Extreme sensitivity to the microscopic lipid—present in the form of cholesterol and cholesterol/lipid-based derivatives and adrenal adenomas—and the ability to detect other substances, such as hemorrhage, are the major reasons why MRI is so useful in adrenal imaging. Deviation from either normal Y-shaped morphology or microscopic lipid content generally connotes pathology. Typical indications for MRI in renal and adrenal imaging include indeterminate adrenal lesion…
▪ Introduction The tissue contrast and spectroscopic properties of magnetic resonance imaging (MRI) recommend its use as a problem solver for renal and urinary imaging. The unsurpassed ability to discriminate cystic from solid lesions and higher sensitivity to solid, neoplastic elements explains the superiority of MRI compared with other imaging modalities for imaging the kidney. Regarding the collecting system, ureters, and bladder, MRI features exquisite tissue…
▪ Pancreas Anatomy and Function The pancreas is a nonencapsulated organ of the digestive system located within the retroperitoneum, posterior to the stomach and anterior to the spine. The pancreas is approximately 2 inches wide and 6 to 8 inches in length. The pancreas can be subdivided into the head, uncinate process, neck, body, and tail ( Fig. 5.1 ). The head and uncinate process are…
▪ Gallbladder Anatomy The gallbladder is an ovoid cystic organ along the undersurface of the liver at the interlobar fissure, between the right and the left lobes of the liver. Although the size and shape of the gallbladder vary with the fasting state, it is approximately 10 cm long and 3 to 5 cm in diameter. The normal capacity of the gallbladder is approximately 50 mL.…
▪ Introduction Diffuse liver processes range from incidental signal and/or enhancement derangements, such as steatosis or transient hepatic intensity differences (THIDs), to serious, and potentially end-stage parenchymal disorders, such as cirrhosis and Budd-Chiari Syndrome (BCS). Segmental, or geographic lesions typically fall into one of two categories—(abnormal) signal or enhancement lesions. Diffuse liver disorders stratify into either: 1) primarily signal, 2) fundamental morphology, or 3) imaging occult…
▪ Introduction Magnetic resonance imaging (MRI) is the most comprehensive and definitive noninvasive modality for evaluating the liver. A combination of enhancement characteristics and exquisite tissue contrast allows for the characterization of liver lesions. Unique artifacts—such as susceptibility and chemical shift—allow for sensitive detection of hepatic iron and lipid deposition, respectively. Common indications for liver MRI include liver lesion characterization, hepatic steatosis quantification and surveillance, liver…
▪ Magnetic Resonance Imaging: What is the Objective? Magnetic resonance imaging (MRI) exploits the inherent magnetism of the protons that constitute the human body in a creative way—through manipulation with radiofrequency (Rf) energy in the presence of a strong magnetic field. This manipulation induces the protons to emit energy, which is detected and reconstructed into an image. The human body—not ostensibly magnetic—is effectively magnetized by a…
In this chapter entities such as disk disease and the osseous structures of the spinal canal will be discussed again, as well as postoperative spine changes. The appearances of the bones in the setting of some systemic diseases are additional descriptions in this chapter as are the incidentally encountered abnormalities in the axial skeleton and ribs when evaluation of chest-abdomen-pelvis imaging is performed. Metallic implants and…
Introduction The advent of increasing numbers of rows of detectors has expanded the utility for CT technology. Multidetector CT (MDCT) has the ability to produce near-isotropic voxel images that allow multiplanar reformations and faster data acquisition. This technique is particularly valuable in the setting of trauma, for which conventional radiographs can be difficult to obtain because patients may be unable to comply with positioning requirements. Volume-rendered…
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…