Prevalence of Rathke’s Cleft and Other Incidental Pituitary Gland Findings on Contrast-Enhanced 3D Fat-Saturated T1-MPRAGE at 7 Tesla MRI

BACKGROUND AND PURPOSE: A cleft-like non-enhancing hypointensity was observed repeatedly in the pituitary gland at the adenohypophysis/neurohypophysis border on contrast-enhanced 3D-Fat-Saturated T1-MPRAGE (C+3D-FS-T₁ MPRAGE) using clinical 7T MRI. Our primary goal is to assess the prevalence of this finding. The secondary goals are to evaluate the frequency of other incidental pituitary lesions, MRI artifacts, and their effect on pituitary imaging on the C+3D-FS-T₁ MPRAGE at 7T.

MATERIALS AND METHODS: 100 patients who underwent 7T neuroimaging between 10/27/2021 and 8/10/23 were included. Each case was evaluated for cleft-like pituitary hypointensity, pituitary masses, and artifacts on C+3D-FS-T₁ MPRAGE. Follow-up exams were evaluated if present. The average prevalence for each finding was calculated, as were descriptive statistics for age and sex.

RESULTS: A cleft-like hypointensity was present in 66% of 7T MRIs. There were no significant differences between the "cleft-like present" and "cleft-like absent" groups regarding sex (P = .39) and age (P = .32). The cleft-like hypointensity was demonstrated in follow-up MRIs in 3/3 patients with 7T, 1/12 with 3T, and 1/5 with 1.5T. A mass was found in 22%, while 75% had no mass, and 3% were indeterminate. A mass was found in 18 (27%) of the "cleft-like present" and 4 (13%) of the "cleft-like absent" groups. The most common mass types were Rathke cleft cyst (RCC) in 7 (31.8%) patients, "RCC vs. entrapped CSF" in 6 (27.3%), and microadenoma in 6 (22.2%) in the "cleft-like present" group. There were no significant differences in the mass types between the "cleft-like present" and "cleft-like absent" groups (P = .23). Susceptibility and/or motion artifacts were frequent in general using C+3D-FS-T₁ MPRAGE (54%). Artifact-free scans were significantly more frequent in the "cleft-like present" group (P =.03).

CONCLUSIONS: A cleft-like non-enhancing hypointensity was frequently seen on the C+3D-FS-T1 MPRAGE at 7T MRI, which most likely represents a normal embryological Rathke's cleft remnant and cannot be seen in lower field strength MRIs. Susceptibility and motion artifacts are common in the sella. They may affect image quality, and the artifacts at 7T may lead to an underestimation of the prevalence of Rathke cleft and other incidental findings.

ABBREVIATIONS: C+3D-FS-T ₁MPRAGE = Contrast-Enhanced 3D-Fat-Saturated T₁-Magnetization Prepared Rapid Gradient Echo Imaging; RCC = Rathke's Cleft Cyst.