Acute effects of increased intravascular volume and hypoxia on the pulmonary circulation: assessment with high-resolution CT.

High-resolution computed tomography (HRCT) was used to evaluate acute morphologic changes in the circulation of anesthetized miniature pigs (a) after volume loading and (b) after induction of hypoxia. Before and after each challenge, serial HRCT scans were obtained at a constant position in the caudal lobes of the lung. Scans were digitized and analyzed to determine the extent of changes in the cross-sectional area of vessels greater than 300 microns in diameter. Parenchymal background attenuation in anterior, middle, and posterior lung regions was used to assess volume changes in vessels less than 300 microns in diameter. Volume loading increased cross-sectional area by 25.2% +/- 4.3 in arteries and by 37.8% +/- 6.1 in veins and caused a gravity-dependent increase in parenchymal attenuation. Hypoxia decreased parenchymal attenuation, which was consistent with constriction of vessels smaller than 300 microns. Larger arteries and veins reacted heterogeneously. Vascular dilation during volume loading was predominantly passive, and hypoxia increased vascular tone throughout the circulation. HRCT represents a new in vivo approach to investigate vascular responses to various stimuli.     

Vascular abnormalities following radio- and chemotherapy of hepatic neoplasms: CT angiographic findings

Four patients (three with hepatocellular carcinoma and one with colorectal carcinoma metastatic to the liver) previously treated with chemotherapy or radiotherapy or both in an attempt to reduce tumor bulk prior to surgical resection were examined by CT angiography (CTA). Areas of abnormal enhancement and irregular vessels simulating tumor involvement proved to be free of neoplasm at surgery. Perfusion abnormalities and vascular irregularity on CTA following radiotherapy or chemotherapy should not be automatically considered as neoplastic. Tissue confirmation in such cases should be obtained to rule out treatment related hepatic parenchymal changes.     

Aging of the diaphragm: a CT study

To determine the normal morphologic evolution of the diaphragm with aging and to correlate age-related changes with other indicators of physical condition--such as skeletal muscle status, obesity, presence of pulmonary emphysema, and presence of esophageal hiatus hernia--a systematic morphometric and morphologic evaluation of computed tomographic studies of 120 patients from the 3d to 8th decades of life was undertaken. Diaphragm muscle thickness did not change significantly with increasing age. Diaphragmatic defects and pseudotumors, nonexistent in the 3d and 4th decades, increased in number and severity to affect 56% of the patients in the 7th and 8th decades. Neither the status of the skeletal muscle nor the presence of obesity correlated with age or with the presence of diaphragmatic defects. Eighty-four percent of the patients with emphysematous changes demonstrated diaphragmatic defects; thus, a strong association with emphysema was observed. If emphysematous patients are excluded, defects were more common in women. The esophageal hiatus width was found to increase with age.     

Primary adrenocortical carcinoma: CT evaluation with clinical correlation

Clinical histories and CT findings were reviewed in 38 patients with primary adrenocortical carcinomas. The primary tumors exhibited central areas of low attenuation representing tumor necrosis (n = 26), irregular contrast enhancement (n = 16), detectable calcification (n = 9), and a thin, capsulelike rim surrounding the tumor (n = 7). Tumors metastasized to liver (n = 9), lung (n = 5), and lymph nodes (n = 5). In eight of nine cases of liver metastasis the primary tumor arose in the left adrenal gland. Evidence of endocrinopathy was present in each of nine patients with lesions 6 cm or less in diameter, but in only two of seven adults with lesions exceeding 15 cm in diameter. We conclude that, contrary to established concepts, adrenocortical carcinoma may present as a smooth, homogeneous, functioning mass 6 cm or less in diameter on CT.     

Marfan syndrome: evaluation with MR imaging versus CT

Twenty-five patients with Marfan syndrome underwent computed tomography (CT) and magnetic resonance (MR) imaging. MR images were interpreted in blinded fashion and then the results were compared with findings from CT scans. MR imaging was found to be equivalent to CT in the depiction of aortic, dural, and hip abnormalities in patients who had not undergone surgery. MR imaging was superior to CT in evaluation of postoperative patients because the artifact produced by Bjork-Shiley or St. Jude valves precludes adequate evaluation of the aortic root on CT scans, while producing only a small inferior field distortion, a "pseudo-ventricular septal defect," on MR images. The absence of radiation exposure is another significant advantage for the relatively young Marfan syndrome population, who require serial studies. MR imaging is the modality of choice for evaluation and follow-up of patients with Marfan syndrome and offers an appropriate means of screening their kindred.