The importance of MRI quality and reader’s experience for detecting an adenoma in Cushing’s disease

In Cushing's disease (CD), detection of an adenoma by MRI is challenging. The aim of this study is to compare real-life MRI in the initial diagnostic workup of CD with high-quality MRI performed in a tertiary center for pituitary diseases.We retrospectively analyzed 139 patients with CD who underwent primary transsphenoidal surgery (TSS) in our department and had both an MRI conducted at a different institution (external MRI; extMRI) and an MRI conducted at our institution (internal MRI; intMRI). Preoperative interpretation of MRI was performed independently by an external radiologist (extRAD), an internal neuroradiologist (intRAD) and a pituitary surgeon (SURG). Intraoperative detection of an adenoma and endocrinological remission provided proof of the true adenoma localization in 105 patients.Interpretation of extMRI by extRAD and SURG was concordant in only 64% (89/139) of cases, while 74.1% (103/139) concordance was observed for interpretation of intMRI by intRAD and SURG. Based on extMRI, the true localization of the adenoma was correctly predicted in only 46.7% of the patients by extRAD and in 65.7% by SURG. In contrast, the sensitivity to correctly identify the adenoma on intMRI was 80.0% for intRAD and 94.3% for SURG.Both the quality of MRI and the reader's experience are paramount for detection of microadenomas in CD. Every effort should be made to perform high-quality initial MRI according to current standards and to ensure rating by an expert in pituitary imaging.