Purpose: Recent data have indicated that ⁶⁸Ga-DOTA-NOC positron emission tomography/X-ray computed tomography (PET/CT) may yield improved images in a shorter acquisition protocol than ¹¹¹In-DTPA-octreotide (OctreoScan®, OCT). Therefore, we performed a prospective comparison of ⁶⁸Ga-DOTA-NOC and OCT for the detection of neuroendocrine tumors (NETs).
Methods: Nineteen patients (eight carcinoid, nine pancreatic NETs, and two NE carcinoma of unknown origin) with previous positive OCT scans underwent ⁶⁸Ga-DOTA-NOC PET/CT and OCT single-photon emission computed tomography imaging for staging or follow-up. Findings were compared by region and verified with conventional imaging.
Results: All images of both modalities demonstrated focal uptake, often at multiple sites. ⁶⁸Ga-DOTA-NOC images were clearer than OCT images, facilitating interpretation. Similar foci were identified with both modalities in 41 regions, with additional foci on ⁶⁸Ga-DOTA-NOC in 21 and on OCT in 15 regions. CT, magnetic resonance imaging, or ultrasound confirmed the concordant findings in 31 of 41 regions and findings seen with ⁶⁸Ga-DOTA-NOC only in 15 of 21 regions. Findings seen with OCT only were less clear and were only confirmed in 4 of 15 regions. ⁶⁸Ga-DOTA-NOC had impact on staging in four patients and on management in three patients.
Conclusions: Although ⁶⁸Ga-DOTA-NOC and OCT images were similar, in this study, ⁶⁸Ga-DOTA-NOC demonstrated more true positive tumor foci and was better tolerated by patients. This direct comparison supports replacement of OCT with ⁶⁸Ga-DOTA-NOC-PET/CT in the evaluation of NETs.