Detection of Neuroendocrine Tumors: 99mTc-P829 Scintigraphy Compared with 111In-Pentetreotide Scintigraphy

The aim of this study was to evaluate the diagnostic value of a new somatostatin analog, 99m Tc-P829, compared with that of 111 In-pentetreotide. Methods: Forty-three patients (32 men, 11 women; age range, 24-78 y; mean age, 56 y) with biologically or histologically proven neuroendocrine tumors were prospectively included: 11 patients with Zollinger-Ellison syndrome, 16 patients with carcinoid tumors, and 16 patients with other types of functioning (n = 6) or nonfunctioning (n = 10) endocrine tumors. 111 In-Pentetreotide planar images (head, chest, abdomen, and pelvis) were obtained 4 and 24 h after injection of 10 μg somatostatin analog labeled with 148 ± 17 MBq 111 In, and SPECT was performed 24 h after injection. Similar 99m Tc-P829 planar images were obtained at 1, 4-6, and 24 h after injection of 50 μg peptide labeled with 991.6 ± 187.59 MBq 99m Tc. Abdominal SPECT was performed 4-6 h after injection. Results: 111 InPentetreotide detected 203 tumoral sites in 39 (91%) of 43 patients, whereas 99m Tc-P829 detected 77 sites in 28 (65%) of 43 patients (P < 0.005). In the liver, 129 sites (in 24 patients) were detected by 111 In-pentetreotide scintigraphy and 34 sites (in 10 patients) were detected by 99m Tc-P829 scintigraphy. Conclusion: In patients with endocrine tumors, the detection rate of 99m Tc-P829 scintigraphy was lower than that of 111 In-pentet-reotide scintigraphy, which appeared to be more sensitive, especially for liver metastases.