Suspicious adrenal lesion detected by CT but without FDG-PET uptake. (Provided by G. Boland)

Suspicious adrenal lesion detected by CT but without FDG-PET uptake. (Provided by G. Boland)

In what is possibly the largest study in its kind, Harvard University researchers have shown that PET/CT can reliably tell whether unsuspected adrenal lesions discovered while managing oncologic patients are benign or malignant.

Incidental adrenal lesions in patients with cancer require accurate characterization because this can significantly affect staging, therapy, and prognosis. Several imaging tests are available to offer a helping hand, including contrast/noncontrast CT and MRI. None, however, has proven conclusive. A study of 38 patients found PET/CT to be sensitive and specific for the characterization of incidental adrenal lesions. The results encouraged an investigative group led by Dr. Giles W. L. Boland, an associate professor of radiology at Massachusetts General Hospital, to validate the findings in a larger cohort of patients. Between October 2004 and March 2007, Boland and colleagues evaluated 150 patients with varied malignancies, including lymphoma and lung, head and neck, and colorectal cancer. All patients underwent noncontrast PET/CT and a follow-up CT scan six months later. The researchers confirmed that PET/CT was highly effective for differentiating benign from malignant adrenal disease in this patient population. Based on a qualitative analysis, PET/CT yielded a sensitivity, specificity, accuracy, and positive and negative predictive values for characterization of benign adrenal "incidentalomas" of 100%, 97%, 98%, 87% and 100%, respectively. Boland cautioned the study had several limitations, including the retrospective nature of the sample. He called for careful consideration of many other criteria, including Hounsfield unit and standardized uptake value measurements, adrenal wash-outs, and lesion size assessments. But the findings showed a way forward, he said. "PET/CT is indeed an accurate test," Boland said.