What imaging studies are available for evaluating adrenal pathology?
- There are three main imaging techniques for the differentiation of malignant from benign adrenal tumors: CT, magnetic resonance imaging (MRI), and positron emission tomography with fluorodeoxyglucose (FDG-PET/CT).
- CT and MRI are mainly techniques to identify benign lesions and exclude adrenal malignancy. FDG-PET/CT is mainly used for detection of malignant disease.
- Abdominal CT is the initial modality of choice.
- An adrenal protocol CT consists of thin-cut imaging through the adrenal glands first without IV contrast, and then with contrast, followed by delayed (usually 10–15 minutes) images to assess contrast washout.
- MRI is considered essentially equivalent to CT for adrenal tumors and is a reasonable, although more expensive, alternative; MRI should be considered in patients with contrast allergy and in situations where radiation exposure should be limited (pregnancy, children, patients with known germline mutations).
- MRI is recommended in patients with known or suspected metastatic pheochromocytomas.
- FDG-PET/CT standard uptake value (SUV) has been utilized to differentiate between benign and malignant adrenal lesions.
- Meta-iodo-benzyl-guanidine (MIBG) nuclear medicine scans are best utilized for recurrent, familial, or extraadrenal pheochromocytomas.