To evaluate the role of computed tomography (CT) in the investigation of pulmonary nodules, a special reference phantom that enabled CT densitometric measurements independent of variations between scanners and patients was used in ten institutions. A total of 384 nodules not considered calcified by conventional methods were examined; 118 (31%) proved to be benign, and in 65 of these (55%), unsuspected calcification was demonstrated. In 28 of the 65, definite calcification could be identified on thin-section CT scans by simple inspection of the scans at narrow windows. In the remaining 37, presence of calcification could not be clearly established without comparison with the reference CT number from the calibration phantom. CT was most effective in establishing the benignancy of nodules 3 cm or less in diameter and those with discrete or smooth margins. CT rarely yields a confident diagnosis of benign disease in larger nodules and in those with irregular or spiculated borders. After review of prior spot radiographs, low kilovolt peak spot radiographs, and conventional tomograms, the authors conclude that thin-section CT aided by a reference phantom in equivocal cases should be an integral part of the diagnostic approach to the pulmonary nodule.

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Medical records and computed tomographic (CT) scans of 83 patients with upper abdominal trauma were retrospectively reviewed to determine errors in diagnosis using CT. Patients with possible pancreatic injury, small bowel perforation, or injury to an occult malignancy represented the most difficult diagnostic cases. A false-positive diagnosis of pancreatic injury occurred in seven of 77 patients (9%) and represented the most frequent error in the series. In three patients with subsequently surgically proved small bowel perforation, one duodenal and two proximal jejunal, the injuries were not correctly diagnosed on CT scans. In retrospect, positive CT findings were present in the case of duodenal rupture. Additionally, in two patients, duodenal rupture was suspected based on CT findings of extraluminal gas and fluid near the duodenum, but both cases were proved normal at surgery. The series included three patients with trauma involving unsuspected tumors in the liver, kidney, and stomach.

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