¹⁸F-Fluorodihydroxyphenylalanine PET/CT at the Forefront for Initial and/or Pre-surgical Evaluation of Small Intestine Neuroendocrine Tumors

Abstract

To compare the respective value of ⁶⁸Ga-DOTATOC and ¹⁸F-DOPA PET/CT for initial staging or pre-surgical work-up of patients with small intestine neuroendocrine tumors (SiNET). Methods: This is a retrospective, multicenter, non-interventional investigation involving 53 non-operated SiNET patients who underwent both ⁶⁸Ga-DOTATOC and ¹⁸F-DOPA PET/CT within a 6-months interval without therapeutic intervention or change between the two PET/CT studies. Detection rate (DR %) was calculated according to per-region and per-lesion analyses. Sensitivity for primary tumor detection was assessed in 37 operated patients taking surgical results (76 SiNET) as diagnostic gold standard. Results: Each of ⁶⁸Ga-DOTATOC PET/CT and ¹⁸F-DOPA PET/CT individually identified at least one primary SiNET in 92% (34/37) of the patients. Tumor intestinal multifocality was confirmed by histology in 8 patients. ⁶⁸Ga-DOTATOC and ¹⁸F-DOPA PET/CT were concordant positive for tumor multifocality in 5, discordant positive in 2, and concordant negative in 1 case. DR % for subdiaphragmatic nodal metastases on per-region-based analysis was 91 % and 98 % for ⁶⁸Ga-DOTATOC and ¹⁸F-DOPA PET/CT, respectively (P = 0.18). ¹⁸F-DOPA PET/CT detected a higher number of abnormal subdiaphragmatic nodes (P = 0.009). Regarding mesenteric nodes only, ¹⁸F-DOPA PET/CT detected more positive regions (P = 0.005) and nodal lesions (P = 0.003) than ⁶⁸Ga-DOTATOC PET/CT, including nodes located at the origin of mesenteric vessels. For detection of distant metastases, ⁶⁸Ga-DOTATOC and ¹⁸F-DOPA PET/CT performed equally on a per-region-based analysis. As compared to ⁶⁸Ga-DOTATOC, ¹⁸F-DOPA PET/CT detected more hepatic (p<0.001), peritoneal (p<0.001), and lung metastases (p<0.001). Conclusion: ¹⁸F-DOPA PET/CT detects more lesions than ⁶⁸Ga-DOTATOC PET/CT in studied patients. Their respective role should be discussed in terms of disease staging and treatment selection.