7T MRI for Cushing's Disease: A Single Institutional Experience and Literature Review.

BACKGROUND AND PURPOSE:Cushing disease is typically caused by a pituitary adenoma that frequently is small and challenging to detect on conventional MRI. High field strength 7T MRI can leverage increased signal-to-noise and contrast-to-noise ratios compared to lower-field strength MRI to help identify small pituitary lesions. We aim to describe our institutional experience with 7T MRI in patients with Cushing disease and perform a review of the literature. MATERIALS AND METHODS:A retrospective analysis of 7T MRI findings in patients with pathology proven cases of Cushing disease from a single institution, followed by a review of the literature on 7T MRI for Cushing disease. RESULTS:Our institutional experience identified Cushing adenomas in 10/13 (76.9%) patients on 7T, however only 5/13 (38.5%) lesions were discrete. Overall, the imaging protocols used were heterogeneous in terms of contrast dose as well as type of post-contrast T1-weighted sequences (Dynamic, 2D vs 3D, and type of 3D sequence). From our institutional data, specific post-gadolinium T1-weighted sequences were helpful in identifying a surgical lesion as follows: Dynamic Contrast Enhanced 2/7 (28.6%), 2D FSE 4/8 (50%), 3D SPACE 5/6 (83.3%), and 3D MPRAGE 8/11 (72.7%). The literature review identified Cushing adenomas in 31/33 (93.9%) patients on 7T. CONCLUSIONS:7T MRI for pituitary lesion localization in Cushing disease is a new technique with imaging protocols that varied widely. Further comparative research is needed to identify the optimal imaging technique as well as to assess the benefit of 7T over lower-field strength MRI. ABBREVIATIONS:MRI = Magnetic Resonance Imaging, CT = Computed Tomography, 7T = 7 Tesla, DCE = Dynamic Contrast Enhanced.