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Computed tomography (CT) has proven to be invaluable in the diagnosis of craniocerebral injuries. Acute epidural hematomas have been described as having a characteristic appearance on CT of a lenticular shaped area of blood density most commonly situated over the cerebral convexity. This case demonstrates an acute epidural hematoma that is essentially isodense with brain tissue.
Computed tomography (CT) was the only modality to identify a lesion causing hemoptysis in a patient with a cavity due to coccidioidomycosis. It is suggested that CT be considered as the initial study for evaluation of hemoptysis following a negative plain chest film examination.
Computed tomography of the lungs is usually performed in the supine position. The prone position may add important information by countering the effects of gravity on pulmonary vascularity. In addition, better expansion of the posterior lung fields may be achieved in the prone position than possible when the patient lies supine. Three cases are presented in which the prone scan provided significant additional diagnostic information affecting interpretation.
Computed tomography (CT) has the potential of providing a precise quantification of trabecular bone. A special purpose low dose CT system for applications at peripheral measuring sites has been developed. With this system, the quantification of trabecular bone can be achieved with a reproducibility on the order of 0.3%. It has been used successfully in pilot studies of immobilization osteoporosis in children and adults on a week by week basis. Currently, the method is being used in a preliminary investigation of bone loss in women in an attempt to differentiate normal changes from changes due to postmenopausal osteoporosis. Results obtained so far indicate that intervals of 3 months are adequate for following the natural course of osteoporosis or its response to therapy on an individual basis.
Computed tomography (CT) has enabled noninvasive evaluation of coronary bypass graft patency. Thirty-three patients operated on with 75 venous coronary bypass grafts were studied in the early postoperative period. Scans were taken with geometric magnification with a field of view of 16 or 24 cm, which gave a high spatial resolution. In 12 patients, complementary angiography was performed, which demonstrated occlusion of six of the grafts. Blind review of the CT examinations demonstrated 67 out of 70 patent grafts (96%).
Computed tomography (CT) performed on two patients with abdominal pain showed irregular, segmental thickening of the submucosa of the colon that proved to be due to ischemic colitis. In one case, CT showed narrowing of the lumen of the right colon by a polypoidal mass that was clearly the CT analog of thumbprinting. In the second case, CT was used as an alternative to barium studies to monitor the course of the patient. It is concluded that CT can be useful in the diagnosis and management of colonic ischemia.
Computed tomography can show hemiatrophy of the tongue and the floor of the mouth. The normal neuroanatomy of this region with regard to its motor supply is reviewed. In theory six variants of motor nerve lesions with hemiatrophy can be encountered, three of which are illustrated in this report. Knowledge of the muscular anatomy and the motor nerve supply to the tongue and floor of the mouth is helpful when evaluating lesions of the base of the skull with CT. This is particularly true for the lesions involving the trigeminal and hypoglossal nerves.
Computed tomography of the liver was performed on two patients with subacute hepatitis. The CT findings included the presence of multiple regenerative nodules in the atrophied liver, shown by decreased CT attenuation. Complications due to hepatitis, such as massive ascites and splenomegaly, were also observed. The CT observations during the course of the disease suggested that the hepatic necrosis had been repaired by hypertrophy of regenerating nodules, not by an increase in the number of nodules, which ultimately gave rise to postnecrotic cirrhosis. Scintigraphy confirmed atrophy and repair of the liver. Thus, CT and scintigraphy were considered to be useful for the diagnosis of extensive hepatic necrosis and for evaluating the process of liver repair.
Computed tomography (CT) scans were examined for 89 selected patients in an attempt to establish normal values at various ages for longitudinal and transverse diameters of the brain, the greatest distance between the right and left sides of the anterior horn of the lateral ventricle, the width of the lateral ventricles in the region of the caudate nuclei, and the greatest width of the third ventricle. The patients' ages ranged from less than one year to over 40 years. These measurements and their ratios to one another are reported. The cerebral longitudinal fissure, Sylvian fissure and subarachnoid space were evident to some degree below the age of two years, especially below the age of one year, and again above the age of 40 years. The cortical sulcus was occasionally found to have a width of less than 1.9mm below the age of one year and above the age of 40 years.
Computed tomography (CT) was used to quantify components of the thigh in young (n = 13) and elderly (n = 11) men. Cross-sectional areas (CSA) of the total limb, total muscle plus bone, quadriceps compartment, hamstring compartment and bone were measured at each of five scan sites along the length of the thigh. Non-muscle tissue (NMT) areas within the muscle compartments were measured using changes in density based on Hounsfield units. Skin plus subcutaneous fat areas and quadriceps and hamstring lean muscle areas were calculated by subtraction. Geometric formulae were used to calculate related volumes for each thigh component. Volumes were also predicted from regression equations employing thigh length and component CSA from single mid-limb CT scans. The results showed that while total thigh CSA was not different in elderly men, they had significantly smaller total muscle plus bone (13.0%), and quadriceps (26.4%), and hamstring (17.9%) muscle areas. The elderly men also had significantly greater CSA for skin plus subcutaneous fat (37.6%), and for NMT in the quadriceps (59.4%) and hamstring (127.3%) muscle compartments. These results suggest that comparisons of relative leg muscle strength between young and elderly men may be misleading due to the decrease in actual muscle tissue associated with ageing. Appropriate quantification of muscle size and CSA must be carried out before such comparisons can be meaningful.
Computed tomography (CT) can yield quantitative imaging data from detailed maps of linear attenuation coefficients within tissue. The attenuation characteristics of skeletal muscle and adipose tissue can be quantified in vivo to provide information about the composition of skeletal muscle and the distribution of adipose tissue within muscle. Several studies have taken advantage of this utility to quantify skeletal muscle composition and fatty infiltration of muscle, in particular to quantify the attenuation characteristics of muscle as a marker of its lipid content. In this manner we found that the mean muscle attenuation of skeletal muscle reflects an increase in its fat content in obesity, and that this regional body composition parameter is strongly related to insulin-resistant glucose metabolism. In addition, muscle composition and adipose tissue distribution within muscle may be altered with clinical weight-loss interventions. CT may also provide important information about the changes in muscle mass and composition with aging and disease, which may, in turn, affect the muscle's function. In summary, CT can provide important quantitative data on the composition of muscle, and the distribution of adipose tissue within it, and this may be important in examining the relationships among skeletal muscle metabolism, lipid accumulation within muscle, and muscle function.
Computed tomography (CT) provides a noninvasive technique with high resolution cross-sectional tomographic images which allow volume measurements of an object, independent of its geometric configuration. A phantom of known volume with controllable periodic motion was used to validate the CT method of volume determination. A good correlation (P less than 0.05) was achieved. Missing angle reconstruction algorithms for gating were applied to estimate left ventricular volumes and ejection fraction in an experimental animal, and the results compared with a standard angiographic method. Left ventricular volumes correlated poorly, whereas the ejection fraction obtained correlated well (r = 0.9). The discrepancies may be attributed in part to the CT method in which difficulties were recognized in defining the left ventricular borders at the base of the heart and partial volume effect, and in part to inaccuracies in the standard angiographic method. Once validated, this method has been applied to the animal model in the form of a pilot study.
Computed tomography (CT) provides an extraordinarily effective means of diagnosing intracranial hemorrhages. Normal blood has a relatively high x-ray attenuation in the circulation and following extravasation, permitting the discrimination by CT of many pathologically enlarged vascular spaces containing circulating blood and/or blood clot (such as arteriovenous malformations and large aneurysms) in addition to recent hemorrhages, from continguous anatomical structures. To promote further understanding of the factors contributing to the attenuation of blood in normal and abnormal states. the attenuations of various preparations of whole blood and blood fractions were investigated in further detail.
Computed tomography of the neck will demonstrate the thyroid gland particularly well after contrast enhancement. Lucent nodules within the thyroid can be demonstrated, but the attenuation numbers are not reliable enough to distinguish cystic from solid lesions with current techniques because of partial volume effects and motion artifacts.
Computed tomography has revolutionized the diagnosis of ophthalmologic and neuro-ophthalmologic disease. High resolution CT with thin-section techniques has made available the depiction of finer anatomic orbital detail and permits radiologic detection of more subtle lesions than was previously available. The display of normal-sized superior ophthalmic veins by CT is further evidence of the resolving power of the currently available machines. A segment of the superior ophthalmic vein was identified in 18 of 64 orbits examined by CT. Virtually the entire superior ophthalmic vein was identified in three orbits.
Computed tomography (CT) accurately localized juvenile angiofibromata in 3 patients. The expanded pterygopalatine fossa and canal were visualized by CT in all three cases. Because of the hemorrhagic tendency of these tumors, a noninvasive modality such as CT is especially valuable in planning therapy.
Computed tomography was performed on 5 children with posterior fossa cystic abnormalities. On an axial tomogram, an enlarged cisterna magna could not be distinguished from a Dandy-Walker variant, nor could an encysted fourth ventricle be distinguished from a subarachnoid cyst. Supplementary air encephalography or sagittal reconstruction of tomograms is necessary to define posterior fossa cysts accurately.
Computed tomography can aid in the distinction of calculi from both tumors and clots in the urinary tract. Its availability, simplicity of interpretation, and noninvasiveness establish it as an important diagnostic modality in selected cases when calculus is in the differential diagnosis of upper urinary tract filling defects.