Impact of [11C]-Methionine PET/MRI in the Detection of Pituitary Adenomas Secreting ACTH and Causing Cushing's Disease

Cushing's disease is characterized by the existence of a benign pituitary tumor developed from corticotropic cells responsible for excessive ACTH secretion. This results in hypercorticism causing high morbidity and mortality and severely impairing quality of life. The etiological diagnosis is based on Magnetic Resonance Imaging (MRI). However, pituitary MRI revealed a pituitary tumor in only 60% of patients. The diagnostic procedure is complicated by the existence of extra pituitary tumors responsible for ACTH ectopic secretion. This rare etiology imposes, in the absence of typical pituitary image, the realization of catheterization of the lower petrosal sinuses. Treatment of Cushing's disease is based on transsphenoidal surgical management, even in the absence of a formal MRI image, if pituitary origin is confirmed by the catheterization. Although pituitary surgery without identified target is part of French recommendations, this surgery is associated with a high risk of failure and morbidity. Optimization of the management of patients' with Cushing's disease thus requires the improvement of the diagnostic methods. Hypothesis of our study is that \[11C\] MET MRI-PET may be performed as a first-line MRI for suspected Cushing's disease and may limit indications for catheterization of lower petrosal sinuses. Its localizing value should also make it possible to improve the surgical results with a better identification of the adenoma