Pheochromocytomas: detection with 11C hydroxyephedrine PET.

PURPOSE

To evaluate the accuracy of carbon 11 (11C) hydroxyephedrine (HED) positron emission tomography (PET) in the detection of pheochromocytomas.

MATERIALS AND METHODS

Nineteen patients (12 women, seven men; mean age, 53 years) suspected of having pheochromocytoma were evaluated. Patients had enlarged adrenal glands at computed tomography and either increased urinary catecholamine levels (n = 18) or normal biochemistry (n = 1). Dynamic PET examination in the adrenal region was performed after injection of 800 MBq 11C HED. PET data were analyzed visually and semiquantitatively. Time-activity curves were generated for different organs. PET results were validated with histologic evaluation (n = 16) or clinical follow-up (n = 3). The diagnostic value of HED PET was evaluated by calculating the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy.

RESULTS

In 12 patients, 13 pheochromocytomas were verified at surgery and histologic evaluation. All but one of the pheochromocytomas were detected with HED PET, which demonstrated elevated uptake. The rest of the patients (n = 7) did not have pheochromocytomas. In these patients, HED PET did not show any abnormal uptake in the suspicious tumors (confirmed at surgery in four patients and at clinical follow-up in three). Mean standardized uptake value of the tumors was 21.4 (range, 11.1-40.9). The time-activity curves for pheochromocytomas showed early uptake after injection, and the activity increased with the time of examination. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of HED PET in the detection of pheochromocytomas were 92% (12 of 13), 100% (seven of seven), 100% (12 of 12), 87.5% (seven of eight), and 95% (19 of 20), respectively.

CONCLUSION

HED PET is useful in the detection of pheochromocytomas, providing a high level of accuracy.