The majority of lesions were adrenal adenomas, myelolipomas, and cysts [6]. SUVs are typically greater for metastatic disease [21]. However, mild activity can be seen in benign adenomas (typically less than background liver), thus potentially leading to false-positive interpretations. Studies have predominantly evaluated FDG-PET or PET/CT in the oncologic population. However, Tessonnier et al [44] used FDG-PET/CT to evaluate 41 adrenal tumors in 37 patients who had no history of malignancy, and all tumors were without diagnostically benign features on CT or MRI. In this small series, a tumor/liver SUVmax ratio >1.8, yielded 100% sensitivity and specificity for malignancy. In addition, it is recognized that FDG-PET is less sensitive and specific for lesions <10 mm [25]. In one study, 2 of 5 lesions that proved to be false-negative for malignancy on PET were <10 mm [26]. 11C-metomidate has been found to localize in adrenocortical tumors and is useful for determining whether a tumor is of adrenocortical origin. However, it cannot distinguish between benign and malignant tumors [64,65]. Image-Guided Biopsy Adrenal Gland For lesions >2 cm and <4 cm and no history of malignancy, there is no primary evidence supporting the use of biopsy for initial evaluation [27-30]. Adrenal Mass Evaluation malignancy. Benign incidentalomas in all three groups had a mean measurement of 2.1 cm, and malignancies had a mean measurement of 9.3 cm [48]. Fine-needle aspiration alone cannot reliably be used to differentiate adrenocortical carcinoma from adrenal adenoma. In addition, the sensitivity of needle biopsy for adrenocortical carcinoma is low. In one study, the sensitivity of needle biopsy for detecting adrenocortical carcinoma was reported as 50% [48]. Another study reports the maximal sensitivity as 70% [49]. In addition, percutaneous biopsy of adrenal lesions is not without risk.
Adrenal Mass Evaluation. The majority of lesions were adrenal adenomas, myelolipomas, and cysts [6]. SUVs are typically greater for metastatic disease [21]. However, mild activity can be seen in benign adenomas (typically less than background liver), thus potentially leading to false-positive interpretations. Studies have predominantly evaluated FDG-PET or PET/CT in the oncologic population. However, Tessonnier et al [44] used FDG-PET/CT to evaluate 41 adrenal tumors in 37 patients who had no history of malignancy, and all tumors were without diagnostically benign features on CT or MRI. In this small series, a tumor/liver SUVmax ratio >1.8, yielded 100% sensitivity and specificity for malignancy. In addition, it is recognized that FDG-PET is less sensitive and specific for lesions <10 mm [25]. In one study, 2 of 5 lesions that proved to be false-negative for malignancy on PET were <10 mm [26]. 11C-metomidate has been found to localize in adrenocortical tumors and is useful for determining whether a tumor is of adrenocortical origin. However, it cannot distinguish between benign and malignant tumors [64,65]. Image-Guided Biopsy Adrenal Gland For lesions >2 cm and <4 cm and no history of malignancy, there is no primary evidence supporting the use of biopsy for initial evaluation [27-30]. Adrenal Mass Evaluation malignancy. Benign incidentalomas in all three groups had a mean measurement of 2.1 cm, and malignancies had a mean measurement of 9.3 cm [48]. Fine-needle aspiration alone cannot reliably be used to differentiate adrenocortical carcinoma from adrenal adenoma. In addition, the sensitivity of needle biopsy for adrenocortical carcinoma is low. In one study, the sensitivity of needle biopsy for detecting adrenocortical carcinoma was reported as 50% [48]. Another study reports the maximal sensitivity as 70% [49]. In addition, percutaneous biopsy of adrenal lesions is not without risk.