Bone Metastases in Patients with Neuroendocrine Tumor: ⁶⁸Ga-DOTA-Tyr³-Octreotide PET in Comparison to CT and Bone Scintigraphy

Abstract

Somatostatin receptor scintigraphy is an accurate imaging modality for the diagnosis of neuroendocrine tumor. Because detection of distant metastases has a major impact on treatment, early diagnosis of metastatic spread is of great importance. So far, no standard procedure has become established for the early diagnosis of bone metastases from neuroendocrine tumor. We compared the diagnostic value of CT with that of the novel somatostatin analog 68 Ga-1,4,7,10-tetraazacyclododecane-N,N9,N$,N999-tetraacetic acid-D-Phe 1 -Tyr 3 -octreotide ( 68 Ga-DOTATOC) in the detection of such metastases. Methods: Fifty-one patients (22 women and 29 men; age range, 32-87 y) with histologically verified neuroendocrine tumor were included in this study. PET scans were fused with CT scans using a vacuum fixation device. 18 F-NaF or 99m Tc-dicarboxypropane diphosphonate bone scans or clinical follow-up served as the reference standard. Results: Twelve of the 51 patients had no evidence of bone metastases on any of the available imaging modalities, and 37 patients had 68 Ga-DOTATOC PET results true-positive for bone metastases. 68 Ga-DOTATOC PET results were true-negative for 12 patients, false-positive for one, and false-negative for another, resulting in a sensitivity of 97% and a specificity of 92%. 68 Ga-DOTATOC PET detected bone metastases at a significantly higher rate than did CT (P , 0.001). Furthermore, conventional bone scans confirmed the results of somatostatin receptor PET but did not reveal additional tumors in any patients. Conclusion: 68 Ga-DOTATOC PET is a reliable, novel method for the early detection of bone metastases in patients with neuroendocrine tumor. Our results show that CT and conventional bone scintigraphy are less accurate than 68 Ga-DOTATOC PET in the primary staging or restaging of neuroendocrine tumor.

Imaging of gastroenteropancreatic neuroendocrine tumors

“…This was substantiated by Putzer et al [59] , who evaluated 51 patients with histologically proven NETs with 68Ga-DOTATOC PET/CT. Reported sensitivity and specificity were 97% and 92%, respectively, higher than CT or bone scan, and detected bone metastasis in patients at a significantly higher rate.…”

Quantitative and Qualitative Intrapatient Comparison of 68Ga-DOTATOC and 68Ga-DOTATATE: Net Uptake Rate for Accurate Quantification

“…The method demonstrates specificity and sensitivity well above 90%, exceeding that of CT and scintigraphy (2)(3)(4). The superiority of 68 Ga-labeled somatostatin analogs in terms of specificity, sensitivity, staging accuracy, detection rate, quantification, and acquisition time over 18 F-FDG (5), 18 F-3,4-dihydroxyphenylalanine (6), 123 Imetaiodobenzylguanidine (7,8), 111 In-DTPA-pentetreotide (9), 18 F-NaF, and 99m Tc-dicarboxypropanediphosphonate (10) has been demonstrated. The high impact of 68 Ga PET/CT on patient management can be illustrated by the fact that the course of treatments was changed or adjusted in 50%-60% of cases on the basis of 68 Ga PET/CT results (11)(12)(13)(14)(15).…”

Ga-68 DOTATATE PET/CT in Neuroendocrine Tumors: Initial Experience

“…It can be used in some cases of non-NET, if treatment with radiolabeled therapeutic SST analogs is considered. Ga-68 DOTA peptides imaging can be used in NET to localize primary tumors, staging, restaging, recurrence detection 4,[13][14][15][16][17][18][19][23][24][25] monitor the response to therapy, 26 to determine SSTR status to select the patients for SSTR radionuclide therapy. 26,27 In the present study, Ga-68 DOTATATE PET scan was positive in 23/39 (59%) patients referred for characterization or diagnosis, in 6/19 (31.5%) patients for localization, in 13/24 (54%) patients for detection of unknown NET primary, in 16/17 (94%) patients for staging, in 6/7 (85%) patients for recurrence assessment, 12/12 (100%) patients for response evaluation and 7/18 (38.8%) patients in restaging.…”