Gd-DTPA-enhanced MR imaging of pituitary adenomas.

Eleven previously nonoperated patients with suspected pituitary microadenomas were scanned on a 1.5-T GE system before and after administration of IV gadolinium-DTPA (0.1 mmol/kg). Six patients had Cushing disease, four had hyperprolactinemia, and one had acromegaly. Surgical confirmation was available in all cases, and these findings were correlated with results of CT and venous sampling, when available. The normal pituitary gland, infundibulum, and cavernous sinuses enhance immediately after the administration of gadolinium-DTPA, allowing contrast between the enhancing normal glandular tissue and low-intensity microadenomas. Contrast-enhanced MR detected a lesion not seen on the unenhanced images in two patients with Cushing disease and in one patient with hyperprolactinemia. Tumor delineation was improved with gadolinium administration in two additional cases. In six patients, administration of gadolinium did not significantly alter the precontrast interpretation. Adenomas were found at surgery in all 11 patients. The tumor was correctly localized on MR in four of the six patients with Cushing disease, resulting in an accuracy of 66.7%. In another patient, although a focal lesion was detected on MR, location of the adenoma at surgery was discrepant with the MR findings and was therefore considered a false-positive study. In the single false-negative examination, both pre- and postcontrast MR failed to detect a surgically confirmed microadenoma suspected on both contrast-enhanced CT and venous sampling. Correct localization of the adenoma was achieved in all of the five non-Cushing patients, yielding an accuracy of 100%. Immediate T1-weighted coronal scans were most useful in detecting intrasellar disease. Delayed scans obtained 30 min after injection did not improve the differentiation of pituitary gland from microadenoma.(ABSTRACT TRUNCATED AT 250 WORDS)