111In-pentetreotide scintigraphy in the detection of insulinomas: importance of SPECT imaging.

UNLABELLED

The aim of this study was to determine whether the systematic use of SPECT can increase the reported low sensitivity of somatostatin receptor scintigraphy (SRS) in detecting insulinomas.

METHODS

Fourteen patients were evaluated. After 111In-pentetreotide injection (approximately 250 MBq intravenously), abdominal SPECT images were obtained at 4 h and multiple planar images were obtained at 4 and 24 h. MRI and CT were performed within 1 mo of SRS. Sixteen tumors were histologically verified after surgery in 14 patients.

RESULTS

SPECT revealed 14 lesions in 12 patients (sensitivity, 87.5%), both planar SRS and MRI revealed 7 tumors in 7 patients (sensitivity, 43.8%), and CT revealed only 5 lesions in 4 patients (sensitivity, 31.3%). Moreover, in 4 patients SPECT was the only examination with positive findings.

CONCLUSION

SPECT at 4 h is mandatory for preoperative detection of insulinomas using SRS because the images are more sensitive than planar images and are superior to images from other conventional methods.