CRC critical reviews in clinical radiology and nuclear medicine最新文献

Transerse axial tomography is a technique by which the spine is viewed radiographically in cross section. The tomographic apparatus, technique of examination, and radiation exposure will be discussed. Examples of normal and pathologic anatomy of the cervical, thoracic, and lumbar spine will be presented. In the lumbar spine cross-sectional views of stenotic canals due to facetal hypertrophy, congenital stenosis, spondylolithesis, and ventral overgrowth of spine fusions will be demonstrated. Measurements of the sagittal and interpedicular distances on conventional x-rays have correlated poorly with the anatomic state in lumbar stenosis. A high degree of correlation has been demonstrated by plotting the cross-sectional area configuration of the bony canal, as well as a new measurement, the interfacet distance, on axial tomograms. Transverse axial tomography is an exciting, new approach in neuroradiology for the evaluation of spinal disorders which have primarily axial distortion.

Tomographic cut is not synonymous to a roentgenogram of an anatomic cut. Blurring is inherent in the tomogram, and the edges do not appear as sharp as in the conventional roentgenogram. Part of the contrast is lost in tomography. Therefore, when tissue contrast is low, or when we intend to see an entire structure in one cut, zoneography is preferred. On the other hand, when many details are crowded in a small area and/or when the tissue contrast is high, a thin section tomography is indicated. Proper knowledge of the level of area of interest (focal plane) and proper spacing of the cuts decrease radiation and expenses. The Law of Tangent, namely, "The edge of a structure should be momentarily parallel to the beam at the focal plane, in order to show on the film," is an essential part of every tomographic study. The Law of Tangent applies equally to spheres and other curved surfaces. The effective tomographic angle is the angle described by the tube during exposure. The thickness of the cut depends on the effective tomographic angle. Prior viewing of conventional roentgenogram and proper knowledge of the mechanism of parasitic and phantom images help us to avoid mistaking these images as real structures.

This review defines the entity pseudomembranous colitis and briefly outlines the supposed etiologic causes of pseudomembranous colitis including antibiotics. The incidence, mortality rate, and natural history of antibiotic-related pseudomembranous colitis is contrasted with other forms and causes of pseudomembranous colitis. The clinical spectrum of antibiotic-related pseudomembranous colitis, ranging from a nonbloody, watery diarrheal state to a life-threatening condition mimicking an acute surgical abdomen, is reviewed. The classic proctoscopic and pathologic findings, as well as common problems encountered in interpretation, are discussed. A complete review of the spectrum of radiographic findings is presented from the nonspecific to the quite characteristic radiographic findings, including both plain film and contrast studies of the colon. These findings are contrasted with the X-ray features of other inflammatory and ischemic colitides and a differential diagnosis is discussed. A section dealing with the treatment of antibiotic-associated pseudomembranous colitis will be included. This section will review the various modes of therapy that have been employed. Finally, a brief section will speculate on the possible etiologic role that antibiotics play in pseudomembranous colitis, including the alteration of the bacterial flora and possible effect on bile salt metabolism.

The use of specific radiographic criteria in the investigation of an aneurysm of the aorta will enable the physician to determine its etiology with a high degree of accuracy. The etiology, location, type, and extent of an aneurysm determine the proper mode of therapy. Aortography, therefore, is the single most important examination for the diagnosis, and will predict the ultimate prognosis in a patient with an aortic aneurysm. This review critically evaluates major recent articles on aortic aneurysms, emphasizing radiographic findings which have a high degree of reliability and cautioning the reader about nonspecific signs which have been reported. Each type of aortic aneurysm is described in detail, stressing criteria which allow the radiologist to be as specific as possible in determining the etiology and extent of the aneurysm.

When a brain scan is abnormal, one can often describe the abnormality in terms of its location, shape, sharpness, brightness, and other descriptive parameters. Certain types of abnormality have been linked to certain specific diagnoses: for example, a crescent-shaped lesion would suggest subdural hematoma to many people, a wedge-shaped lesion would suggest cerebral vascular accident, etc. Some features thought to be characteristic of certain diseases are actually quite nonspecific. For example, the "doughnut" sign--at first believed to be characteristic of brain abscess--has also been found in primary and metastatic tumors, CVA, and subdural hematoma. The "crescent" sign that was at first thought to be specific for subdural hematoma occurs also in meningitis, scalp or skull trauma, meningioma en plaque, etc. Some features of abnormalities are highly specific for certain diseases; e.g., wedge- or flame-shaped lesions are rarely seen with disorders other than CVA, and lesions in the midline or in the posterior fossa are almost invariably tumors. This article reviews the features of abnormalities on brain scans that in the literature have been reportedly associated with specific types of disease and explores the strength and validity of the associations.

This article is a review of the recent literature on operative cholangiography. The objective is to summarize concisely the important contemporary viewpoints as an aid to students of radiology. To the practicing radiologist, it may offer a concise review of the subject and facilitate upgrading operative cholangiography in his hospital. The introduction covers statistical evidence of the growing dependence of biliary tract surgeons on operative cholangiography. The rudiments of diagnoses of the various diseases that can be detected by operative cholangiography are presented. Pertinent clinical facts along with cholangiographic diagrams are presented under arbitrary sections: I. Stones; II. Anomalies; III. Other Diseases; IV. Techniques of Operative Visualization of the Biliary System.

Acute pancreatitis is commonly presented as a confusing and challenging diagnostic problem. This article is intended to show the increasingly important contribution radiology plays in the establishment of a correct initial diagnosis as well as in recognizing the serious complications of acute pancreatitis. A short discussion of the etiology and pathophysiology of pancreatitis is essential in understanding the mechanism of production of the X-ray findings. The most important recently published papers on this topic are reviewed together with a personal evaluation of the most significant and reliable radiographic changes. Statistical data, indications, and contraindications as well as the limitations of our radiographic procedures are discussed.