Background-CT Colonography (CTC) is a non-invasive option for colorectal cancer (CRC) screening. The accuracy of CTC as a screening tool among asymptomatic adults has not been well defined.

Fat accumulation is one of the most common abnormalities of the liver depicted on cross-sectional images. Common patterns include diffuse fat accumulation, diffuse fat accumulation with focal sparing, and focal fat accumulation in an otherwise normal liver. Unusual patterns that may cause diagnostic confusion by mimicking neoplastic, inflammatory, or vascular conditions include multinodular and perivascular accumulation. All of these patterns involve the heterogeneous or nonuniform distribution of fat. To help prevent diagnostic errors and guide appropriate work-up and management, radiologists should be aware of the different patterns of fat accumulation in the liver, especially as they are depicted at ultrasonography, computed tomography, and magnetic resonance imaging. In addition, knowledge of the risk factors and the pathophysiologic, histologic, and epidemiologic features of fat accumulation may be useful for avoiding diagnostic pitfalls and planning an appropriate work-up in difficult cases.

Computed tomography (CT) was used to guide percutaneous fine-needle biopsy in 150 cases of difficult thoracic lesions; in 76 cases, nondiagnostic bronchoscopy (n = 62) and fluoroscopic biopsy (n = 14) had previously been performed. CT was indicated for guidance when the pulmonary or pleural lesions were small (0.3-2.5 cm); in a juxta-vascular location, either hilar or mediastinal; not seen or poorly visualized on conventional radiographs; or considered inaccessible. A diagnosis was made in 124 of 150 cases (82.7%) (107 of 124 malignant and 17 of 26 benign lesions), including 86 of 107 lung nodules (80.4%), 28 of 31 mediastinal lesions (90.3%), and ten of 12 pleural masses (83.3%). Complications included pneumothorax (n = 64), hemoptysis (n = 5), hemothorax (n = 2), and pericarditis (n = 1). The high rate of pneumothorax, its treatment, and advantages of its immediate radiologic management are discussed. Use of CT guidance considerably expands the scope of thoracic lesions amenable to percutaneous biopsy.

Fat stranding adjacent to thickened bowel wall seen at computed tomography (CT) in patients with acute abdominal pain suggests an acute process of the gastrointestinal tract, but the differential diagnosis is wide. The authors observed "disproportionate" fat stranding (ie, stranding more severe than expected for the degree of bowel wall thickening present) and explored how this finding suggests a narrower differential diagnosis, one that is centered in the mesentery: diverticulitis, epiploic appendagitis, omental infarction, and appendicitis. The characteristic CT findings (in addition to fat stranding) of each of these entities often lead to a final diagnosis. Diverticulitis manifests with mild, smooth bowel wall thickening and no lymphadenopathy. Epiploic appendagitis manifests with central areas of high attenuation and a hyperattenuated rim, in addition to its characteristic location adjacent to the colon. In contrast, omental infarction is always centered in the omentum. The most specific finding of appendicitis is a dilated, fluid-filled appendix. Correct noninvasive diagnosis is important because treatment approaches for these conditions range from monitoring to surgery.

Chronic liver disease is a major public health problem worldwide. Liver fibrosis, a common feature of almost all causes of chronic liver disease, involves the accumulation of collagen, proteoglycans, and other macromolecules within the extracellular matrix. Fibrosis tends to progress, leading to hepatic dysfunction, portal hypertension, and ultimately cirrhosis. Liver biopsy, the standard of reference for diagnosing liver fibrosis, is invasive, costly, and subject to complications and sampling variability. These limitations make it unsuitable for diagnosis and longitudinal monitoring in the general population. Thus, development of a noninvasive, accurate, and reproducible test for diagnosis and monitoring of liver fibrosis would be of great value. Conventional cross-sectional imaging techniques have limited capability to demonstrate liver fibrosis. In clinical practice, imaging studies are usually reserved for evaluation of the presence of portal hypertension or hepatocellular carcinoma in cases that have progressed to cirrhosis. In response to the rising prevalence of chronic liver diseases in Western nations, a number of imaging-based methods including ultrasonography-based transient elastography, computed tomography-based texture analysis, and diverse magnetic resonance (MR) imaging-based techniques have been proposed for noninvasive diagnosis and grading of hepatic fibrosis across its entire spectrum of severity. State-of-the-art MR imaging-based techniques in current practice and in development for noninvasive assessment of liver fibrosis include conventional contrast material-enhanced MR imaging, double contrast-enhanced MR imaging, MR elastography, diffusion-weighted imaging, and MR perfusion imaging.