Contrast-Enhanced CISS/FIESTA Imaging for Increased Conspicuity of Pituitary Microadenomas in Cushing Disease.

Abstract

Background and purpose: Pituitary microadenomas can be challenging to see on MRI, particularly when they are small. The detection of microadenomas commonly relies on contrast-enhanced sequences, highlighting the adenoma that demonstrates hypoenhancement relative to the native pituitary gland on T1-weighted sequences. Detecting adenomas in patients with Cushing disease is crucial because surgery is the standard of care treatment. Accurate preoperative lesion localization is directly associated with improved outcomes. The purpose of our study was to determine the utility of contrast-enhanced CISS/FIESTA with cycling (FIESTA-C) for identifying pituitary microadenomas in patients with Cushing disease.

Materials and methods: This cross-sectional study retrospectively reviewed pituitary MR images in patients with Cushing disease who had postcontrast CISS/FIESTA-C. Images were evaluated for lesion conspicuity (well-defined margins), as well as the signal intensity (SI) of the adenoma and native pituitary gland. The normalized SI difference was calculated by subtracting the lesion SI from the pituitary SI and dividing by the pituitary SI. Patient age, sex, and diagnosis based on intraoperative findings, pathology results, and postoperative adrenal insufficiency were recorded.

Results: Seventeen patients (15 women) were included in this study. Sixteen (94%) adenomas were discrete on CISS/FIESTA-C compared with 11 (65%) on T1-weighted imaging. The mean adenoma normalized SI difference with CISS/FIESTA-C was 0.512 (SD, 0.12), relative to 0.242 (SD, 0.15) on T1-weighted imaging (P < .001).

Conclusions: In comparison with MR T1-weighted images, contrast-enhanced CISS/FIESTA-C imaging detects a higher number of pituitary microadenomas with superior conspicuity. Because up to 50% of patients with Cushing disease present without a pituitary lesion detected on MRI, postcontrast CISS/FIESTA-C may be especially valuable as an additional sequence in this population.