Head-to-Head Comparison of ⁶⁴Cu-DOTATATE and ⁶⁸Ga-DOTATOC PET/CT: A Prospective Study of 59 Patients with Neuroendocrine Tumors

Somatostatin receptor imaging is a valuable tool in the diagnosis, follow-up, and treatment planning of neuroendocrine tumor (NET). PET-based tracers using ⁶⁸Ga as the radioisotope have in most centers replaced SPECT-based tracers as the gold standard. ⁶⁴Cu-DOTATATE is a new PET tracer that has been shown to be far superior to the SPECT tracer ¹¹¹In-diethylenetriaminepentaacetic acid-octreotide. Because of the advantages of ⁶⁴Cu over ⁶⁸Ga, we hypothesized that the tracer has a higher sensitivity than ⁶⁸Ga-based tracers. To test this hypothesis, we compared on a head-to-head basis the diagnostic performance of ⁶⁴Cu-DOTATATE with that of ⁶⁸Ga-DOTATOC in NET patients. Methods: Fifty-nine NET patients were scanned with both ⁶⁴Cu-DOTATATE and ⁶⁸Ga-DOTATOC PET/CT and compared on a head-to-head basis. Discordant lesions were verified during at least 30 mo of follow-up. Results: A total of 701 lesions were concordantly detected on both ⁶⁴Cu-DOTATATE and ⁶⁸Ga-DOTATOC PET/CT scans, whereas an additional 68 lesions were found by only one of the scans. ⁶⁴Cu-DOTATATE showed 42 lesions not found on ⁶⁸Ga-DOTATOC, of which 33 were found to be true-positive on follow-up. ⁶⁸Ga-DOTATOC showed 26 lesions not found on ⁶⁴Cu-DOTATATE, of which 7 were found to be true-positive on follow-up. False-positives were mainly lymph node lesions. Accordingly, 83% of the additional true lesions found on only one of the scans were found by ⁶⁴Cu-DOTATATE. On a patient-basis, additional true lesions were found by ⁶⁴Cu-DOTATATE and ⁶⁸Ga-DOTATOC in 13 and 3 patients, respectively. All patients with additional lesions also had concordant lesions found by both scans. Conclusion:⁶⁴Cu-DOTATATE has advantages over ⁶⁸Ga-DOTATOC in the detection of lesions in NET patients. Although patient-based sensitivity was the same for ⁶⁴Cu-DOTATATE and ⁶⁸Ga-DOTATOC in this cohort, significantly more lesions were detected by ⁶⁴Cu-DOTATATE. Furthermore, the shelf life of more than 24 h and the scanning window of at least 3 h make ⁶⁴Cu-DOTATATE favorable and easy to use in the clinical setting.