This is a prospective study which aims to validate a new diagnostic approach in the tissue characterization of adrenal tumors indeterminate on conventional imaging. For this purpose, it is not necessary to have a control group since the diagnostic accuracy in a well defined subset of patients.

Visit 0 : Enrollment, eligibility. Visit 1 : FDG-PET. Visit 2 : Postoperative visit. Visit 3 : 6 months post-PET. Visit 4 : 12 months post-PET.

Primary objective The primary objective is to assess the diagnostic accuracy of FDG-PET, particularly the SUVmax tumor/liver ratio, in the diagnosis of indeterminate adrenal tumors on conventional imaging.

Secondary objectives

• To assess the diagnostic accuracy of the tumor SUVmax, and SUVmax of the tumor/mean SUV of the liver.
• To evaluate the relationship between SUVmax tumor/liver ratio and Weiss score.
• To evaluate the impact of the use of FDG-PET on the treatment options.
• To evaluate the economic impact of FDG-PET in the management of indeterminate adrenal tumors (ancillary study).

Inclusion Criteria:

• Adult ≥ 18 yrs, male or female;
• Indeterminate adrenal tumor (6.3.1.). The CT must include the calculation of SD and contrast washout and should have been performed within the 30 days before the inclusion visit (visit 0) ;
• Patient insured with public health care system ;
• Patient who accept to participate to the study and to sign the consent document form.

Exclusion Criteria:

• Technical inability to perform FDG-PET.
• Patient's death before final diagnosis.