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Hepatic Variants

Technical Aspects Diagnostic imaging of the hepatobiliary system, with multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI), plays a major role in hepatobiliary surgery, helping to choose the best therapeutic approach, reduce complications, and identify the anatomy requiring special attention at surgery. Anatomic variants of the biliary and hepatic vascular anatomy are common; they dictate the surgical technique and also may predict the risk for…

Cholestatic Hepatic Disorders

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) are the two most common and well-characterized primary cholestatic disorders. In contrast to pathologic processes derived primarily from hepatocellular dysfunction, such as viral hepatitis and autoimmune hepatitis, the primary insult in cholestatic diseases centers on the bile duct epithelium. As with other diffuse liver diseases, PBC and PSC may progress to liver fibrosis, portal hypertension, cirrhosis, and/or…

Hepatic Veno-occlusive Diseases

The hepatic veno-occlusive diseases are a heterogeneous group of circulatory disorders characterized by obstruction of hepatic venous outflow at the sinusoidal or postsinusoidal levels. These disorders uniquely manifest portal hypertension before overt hepatic parenchymal disease and dysfunction, in contrast to other causes of hepatic disease in which hepatic dysfunction precedes portal hypertension. The focus in this chapter is on the most common types of sinusoidal (sinusoidal…

Cirrhosis and Hepatitis

Cirrhosis Etiology Virtually any chronic insult to the liver, if sufficiently severe and long-standing, may result in cirrhosis. In the United States, the most common causes are hepatitis C virus (HCV) infection and alcohol ingestion, whereas in Asia and sub-Saharan Africa, chronic hepatitis B virus (HBV) infection is the most frequent culprit. Nonalcoholic fatty liver disease (NAFLD) is increasing in prevalence and is now the third…

Hepatic Storage Disorders

The hepatic storage disorders are genetic conditions characterized by the accumulation of toxic substances within either hepatocytes or the hepatic extracellular matrix. This deposition causes secondary tissue damage, which may eventually progress to cirrhosis, portal hypertension, and hepatocellular carcinoma (HCC). As genetic conditions, their manifestations are wide-ranging and systemic, with hepatic involvement only one component of the larger illness. The most common of these disorders, hereditary…

Hepatic Iron Overload

Etiology Hepatic iron overload is a generic term that refers to the nonphysiologic accumulation of iron within the hepatic parenchyma. The most clinically significant cause of hepatic iron overload is hereditary hemochromatosis. Hereditary hemochromatosis is associated with several mutations in genes regulating iron metabolism, the most common of which are in the HFE gene. The HFE mutations result in dysregulated iron absorption, which may lead to…

Fatty Liver Disease

Etiology Fatty liver is a generic term that refers to the accumulation of lipids within hepatocytes. This chapter focuses on nonalcoholic fatty liver disease (NAFLD), the most common form of fatty liver. Histologically, it resembles alcoholic liver injury but occurs in patients who deny significant alcohol consumption. NAFLD encompasses a spectrum of conditions, ranging from benign hepatocellular steatosis to inflammatory nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis.…

Malignant Focal Lesions

Etiology Malignant liver tumors can be classified either by cell of origin as hepatocellular, cholangiocellular, or mesenchymal or by site of origin as primary or secondary. This chapter will describe the most frequently encountered malignant hepatic tumors arising in the noncirrhotic liver, including hepatocellular carcinoma (HCC), fibrolamellar HCC, epithelioid hemangioendothelioma (EHE), angiosarcoma, and metastatic disease. Also discussed are other rare primary liver tumors, such as lymphoma…

Benign Focal Lesions

Etiology Although benign hepatic tumors have been classified into several histiotypes according to their cell of origin (i.e., hepatocytes, biliary epithelium, or mesenchymal cells), our focus in this discussion is on those lesions most frequently encountered in clinical practice, including simple (nonparasitic) cyst, hemangioma, hepatocellular adenoma, focal nodular hyperplasia (FNH), large benign regenerative nodules, and hepatic abscess ( Table 36-1 ). TABLE 36-1 Clinical and Radiologic…

Imaging of the Liver

Ultrasound Technical Aspects Ultrasound is a widely accessible, noninvasive imaging method that has many advantages over other imaging methods. It is portable and relatively inexpensive with high spatial and temporal resolution. It does not involve ionizing radiation and can be repeated frequently. Despite increased use of other imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI), ultrasound remains, in many settings, the first-line…

Imaging of the Postoperative Bowel

Surgical procedures performed on the bowel are innumerable, and their detailed discussion is beyond the scope of this chapter. To understand the related imaging, it is important to be familiar with the postoperative anatomy. Our purpose in this chapter is to present tools to approach the postoperative bowel by discussing some commonly performed surgical procedures, their appearance on imaging, and common complications. Procedures Esophageal Resection All…

Colon Cancer and Screening Strategies

Etiology The causes of the development of colorectal carcinoma and its precursor lesion, the colonic adenoma, are multifactorial and include both genetic predisposition and environmental insults. Risk factors for colorectal carcinoma include familial polyposis syndrome, ulcerative colitis, family history of colorectal cancer, age, male gender, smoking, alcohol intake, and obesity. Prevalence and Epidemiology Colon cancer is the third most commonly diagnosed cancer and third most common…

Colonic Vascular Lesions

Etiology Vascular lesions of the colon are an important medical problem and have now been recognized as a significant cause of gastrointestinal bleeding. They can be solitary or multifocal, benign or malignant, or associated with a syndrome or systemic dis­order. There are three main groups: vascular malformations, neoplastic lesions, and non-neoplastic lesions ( Figure 32-1 ). Vascular malformations can be broadly classified into arterial, venous, and…

Inflammatory and Infectious Colonic Lesions

Etiology Colonic inflammation may be caused by numerous processes and is typically thought of as colitis. Some inflammatory conditions of the colon such as diverticulitis and epiploic appendagitis also represent inflammatory lesions of the colon and, on occasion, may be difficult to distinguish from each other and from neoplastic conditions. Colitis may be due to infection, autoimmune processes (Crohn's and ulcerative colitis), ischemia (low flow, emboli,…

Computed Tomographic Colonography

Technical Aspects Colorectal cancer is the second cause of cancer deaths in the United States, second only to lung cancer in men and breast cancer in women. Colorectal cancer screening can be used to identify adenomatous polyps, the precursor lesion to colon cancer for screening symptomatic patients. Computed tomographic (CT) colonography can be simply defined as a highly sophisticated technique that employs rigorous bowel preparation (cleansing)…

Colon Imaging: Conventional Imaging and Computed Tomography

Conventional Imaging Technical Aspects Before cross-sectional imaging, the double-contrast enema was the foremost radiologic method for detection of colonic mucosal lesions and precancerous polyps. Diagnostic high-quality double-contrast barium enema examination is an art, requiring skillful maneuvering of the patient and barium pool while optimally using fluoroscopy. With the advent of computed tomography (CT), intramural as well as extraluminal extension of colonic diseases can be detected. This…

Malignant Neoplasms and Wall Thickening of the Small Bowel

Small bowel neoplasms remain a diagnostic challenge for radiologists and clinicians. The small bowel represents 75% of the total length of the gastrointestinal tract and more than 90% of the mucosal surface, but less than 2% of all gastrointestinal malignancies originate in the small bowel. Malignant tumors of the small bowel may arise from the mucosal epithelium, lymphoid tissue, blood vessels, nerves, and muscle. Secondary involvement…

Benign Neoplasms and Wall Thickening of the Small Bowel

Normal intestinal wall thickness depends on the degree of bowel distention and the imaging modality. The normal jejunum wall thickness measures approximately 2 mm and the ileum 1 mm on enteroclysis. On computed tomography (CT), 3 mm is accepted as the upper limit of normal when the bowel is completely distended. The hallmark of benign wall thickening is homogenous or stratified wall thickening. The appearance is due to low…

Acute and Chronic Small Bowel Ischemia

Etiology Acute mesenteric ischemia of the small bowel has four major causes: (1) arterial embolism, (2) arterial thrombosis, (3) nonocclusive mesenteric ischemia, and (4) mesenteric venous thrombosis ( Table 26-1 ). Less common causes include aortic dissection, spontaneous dissection of the celiac or superior mesenteric artery (SMA), and vasculitis. The common end result is an acute reduction in splanchnic blood flow that can lead to bowel…

Small Bowel Obstruction

Small Bowel Obstruction: General Considerations Etiology Small bowel obstruction (SBO) is a common manifestation, and appropriate management continues to be a clinical challenge. The morbidity and mortality associated with acute SBO continue to be significant; however, there has been a decline in mortality from SBO in the last 50 to 60 years from 25% to 5%. The goal of treatment is to recognize the complications of…