Diagnostic accuracy of preoperative CT scanning of pituitary somatotroph adenomas.

Between 1980 and 1986, 58 patients (23 women and 35 men) had coronal CT scans of the sella turcica for suspected growth hormone-secreting adenoma and underwent transsphenoidal exploration. The CT examinations were performed with a fourth-generation EMI scanner (CT 7070), and reports of the preoperative CT were compared with the findings at transsphenoidal exploration. The same neurosurgeon performed all the operations. In three patients arthritic changes in the neck caused difficulties in positioning, which made it impossible to obtain adequate coronal CT scans. These nondiagnostic examinations are excluded from the statistical calculations. In all 55 patients with scans that were able to be evaluated, distinct adenomas were found at surgery. Among these were 39 macroadenomas (diameter larger than 10 mm) and 16 microadenomas. Three macroadenomas and two microadenomas caused combined hypersecretion of growth hormone and prolactin. All macroadenomas were localized correctly on the preoperative CT scans (sensitivity 100%), but in two cases there was a discrepancy in size of more than 5 mm compared with the operative findings. Preoperative CT scans correctly localized 13 of 16 microadenomas, for a sensitivity rate of 81.2%. Two patients with negative scans and one patient in whom the adenoma was found in a location other than that reported on the preoperative CT scan were considered to have negative scans for the purpose of statistical calculations. If both correct localization and size estimation within 2 mm of that found at surgery are considered, the accuracy rate was 90.9% for the entire group of patients, 94.9% for those with macroadenomas, and 81.2% for microadenomas.