A prospective head-to-head comparison of 68Ga-NOTA-3P-TATE-RGD and 68Ga-DOTATATE in patients with gastroenteropancreatic neuroendocrine tumours

Purpose The aim of this study was to compare Ga-68-NOTA-3P-TATE-RGD, a dual somatostatin receptor 2- and integrin alpha(v)beta(3)-targeting tracer, to Ga-68-DOTATATE in a single group of patients with gastroenteropancreatic (GEP)-neuroendocrine tumours (NETs). Methods Thirty-five patients with histologically confirmed GEP-NETs (5 grade 1, 28 grade 2, and 2 grade 3 tumours) were prospectively enrolled with informed consent. The primary tumour mainly originated from the pancreas and rectum. All patients were scanned with both Ga-68-NOTA-3P-TATE-RGD PET/CT and Ga-68-DOTATATE PET/CT within a week and compared on a head-to-head basis. Sixteen patients also had conventional F-18-FDG PET/CT. Images were evaluated semi-quantitatively using maximum standardized uptake values (SUVmax) of tumour and tumour-to-background ratio. Results All patients had at least one positive lesion on each of the two scans. A total of 1190 and 1106 lesions were detected on Ga-68-NOTA-3P-TATE-RGD images and Ga-68-DOTATATE images, respectively (P = 0.152). Ga-68-NOTA-3P-TATE-RGD PET/CT revealed significantly more lesions in the liver than Ga-68-DOTATATE PET/CT (634 vs. 532, P = 0.021). Both tracers produced comparable results for detecting primary tumours (20 vs. 20, P = 1.000), lymph node metastases (101 vs. 102, P = 0.655), and bone metastases (381 vs. 398, P = 0.244). The tumour SUVmax in 12 patients was significantly higher for Ga-68-NOTA-3P-TATE-RGD than for Ga-68-DOTATATE (27.2 +/- 13.6 vs. 19.5 +/- 10.0, P < 0.001); among them, 9 had F-18-FDG PET/CT and all were found to be FDG-positive. The remaining 23 patients had significantly higher Ga-68-DOTATATE uptake than Ga-68-NOTA-3P-TATE-RGD uptake (22.3 +/- 16.4 vs. 11.9 +/- 7.5, P < 0.001); among them, 7 had F-18-FDG PET/CT and 6 were FDG-negative. Generally, Ga-68-DOTATATE demonstrated higher tumour SUVmax than Ga-68-NOTA-3P-TATE-RGD (20.8 +/- 16.0 vs. 14.2 +/- 8.9, P < 0.001), including primary tumours, liver lesions, lymph node lesions, and bone lesions. However, the tumour-to-background ratio of liver lesions was significantly higher when using Ga-68-NOTA-3P-TATE-RGD compared with that when using Ga-68-DOTATATE (8.4 +/- 5.5 vs. 4.7 +/- 3.7, P < 0.001). Conclusion Ga-68-NOTA-3P-TATE-RGD performed better than Ga-68-DOTATATE in detection of liver metastases with a higher tumour-to-background ratio. Moreover, Ga-68-NOTA-3P-TATE-RGD tended to demonstrate higher uptake over Ga-68-DOTATATE in FDG-avid NETs.

Automated summary

The study demonstrates that Ga-68-NOTA-3P-TATE-RGD performed better in detecting liver metastases and tended to show higher uptake in FDG-avid NETs compared to Ga-68-DOTATATE.