Al¹⁸F-NOTA-octreotide: first comparison with ⁶⁸Ga-DOTATATE in a neuroendocrine tumour patient

Excerpt

⁶⁸Ga-DOTA-peptide (⁶⁸Ga-DOTATATE/-TOC/-NOC) PET is the current standard for somatostatin receptor imaging in neuroendocrine tumour (NET) patients, but suffers from practical, regulatory and economical barriers associated with ⁶⁸Ge/⁶⁸Ga-generators [1, 2]. A promising alternative, Al¹⁸F-1,4,7-triazacyclononane-1,4,7-triacetate-octreotide (Al¹⁸F-NOTA-octreotide; Al¹⁸F-OC), produced using the Al¹⁸F-method, combines the advantages of a chelator-based radiolabelling method with the imaging and logistical advantages of fluorine-18, such as higher production yield, longer half-life allowing for centralised production and distribution, and improved spatial resolution due to the shorter positron range of fluorine-18 [3]. We present images of the first patient in our prospective clinical study (NCT03883776), a 53-year-old male, diagnosed with diffuse metastases of a rectal NET. A whole-body PET was performed 2 h after injection of 374 MBq (4 MBq/kg) Al¹⁸F-OC. The patient’s previous routine clinical ⁶⁸Ga-DOTATATE PET (199 MBq injected activity, acquisition 30 min post-injection) was performed 5 weeks earlier. Scans were acquired on the same integrated Siemens Biograph 40 Truepoint PET/CT system (both 4 min per bed position). Maximum-intensity projection images with both tracers are comparable, showing diffuse liver metastases and several bone and lymph node metastases. The hottest lesion was in the liver with an SUV_max of 50.9 and tumour-to-background ratio (TBR) of 9.9 using Al¹⁸F-OC, compared to 57.3 and 8.9 with ⁶⁸Ga-DOTATATE, respectively. The hottest bone lesion had an SUV_max of 27.5 and TBR of 24.5 with Al¹⁸F-OC versus 22.0 and 21.0 with ⁶⁸Ga-DOTATATE. Multiple smaller lesions show improved contrast on Al¹⁸F-OC. There was no evidence of in vivo defluorination. Our observation is concordant with the first patient experience with Al¹⁸F-OC, where high tumour uptake and TBR were reported [4]. …