64Cu-TETA-Octreotide as a PET Imaging Agent for Patients with Neuroendocrine Tumors

[摘要] 64Cu (half-life, 12.7 h; β+, 0.653 MeV [17.4%]; β−, 0.579 MeV [39%]) has shown potential as a radioisotope for PET imaging and radiotherapy. 111In-diethylenetriaminepentaacetic acid (DTPA)-d-Phe1-octreotide (OC) was developed for imaging somatostatin-receptor–positive tumors using conventional scintigraphy. With the advantages of PET over conventional scintigraphy, an agent for PET imaging of these tumors is desirable. Here, we show that 64Cu-TETA-OC (where TETA is 1,4,8,11-tetraazacyclotetradecane-N,N′,N′′,N′′′-tetraacetic acid) and PET can be used to detect somatostatin-receptor–positive tumors in humans. Methods: Eight patients with a history of neuroendocrine tumors (five patients with carcinoid tumors and three patients with islet cell tumors) were imaged by conventional scintigraphy with 111In-DTPA-OC (204–233 MBq [5.5–6.3 mCi]) and by PET imaging with 64Cu-TETA-OC (111 MBq [3 mCi]). Blood and urine samples were collected for pharmacokinetic analysis. PET images were collected at times ranging from 0 to 36 h after injection, and the absorbed doses to normal organs were determined. Results: In six of the eight patients, cancerous lesions were visible by both 111In-DTPA-OC SPECT and 64Cu-TETA-OC PET. In one patient, 111In-DTPA-OC showed mild uptake in a lung lesion that was not detected by 64Cu-TETA-OC PET. In one patient, no tumors were detected by either agent; however, pathologic follow-up indicated that the patient had no tumors. In two patients whose tumors were visualized with 111In-DTPA-OC and 64Cu-TETA-OC, 64Cu-TETA-OC and PET showed more lesions than 111In-DTPA-OC. Pharmacokinetic studies showed that 64Cu-TETA-OC was rapidly cleared from the blood and that 59.2% ± 17.6% of the injected dose was excreted in the urine. Absorbed dose measurements indicated that the bladder wall was the dose-limiting organ. Conclusion: The high rate of lesion detection, sensitivity, and favorable dosimetry and pharmacokinetics of 64Cu-TETA-OC indicate that it is a promising radiopharmaceutical for PET imaging of patients with neuroendocrine tumors.

[学科分类] 医学（综合）

[关键词] ⁶⁴Cu;octreotide;PET;¹¹¹In