Intraindividual comparison of ¹⁸F‐FDOPA and ⁶⁸Ga‐DOTATOC PET/CT detection rate for metastatic assessment in patients with ileal neuroendocrine tumours

Abstract

Introduction: In patients with ileal neuroendocrine tumours (ileal NETs), headto-head evaluation of diagnostic performances of 68 Ga-DOTA-peptides and 18 F-fluorodihydroxyphenylalanine (18 F-FDOPA) positron emission tomography/computed tomography (PET/CT) has been performed in only few small patients' cohorts. The aim of this retrospective study was to compare 68 Ga-DOTATOC and 18 F-FDOPA PET/CT for metastatic disease assessment in a homogeneous large series of patients with well-differentiated ileal NETs. Methods: All patients with ileal NETs who underwent both 18 F-FDOPA and 68 Ga-DOTATOC PET/CT within a 3-month period and no therapeutic change between the two studies were retrospectively included. The detection rates of both modalities were calculated using per-patient, per-region and per-lesion analyses. Results: Forty one patients with ileal NETs were evaluated. 18 F-FDOPA and 68 Ga-DOTATOC showed similar detection rates according to per-patient (97% for both) and per-region analyses (94% for 18 F-FDOPA vs 88% for 68 Ga-DOTATOC, P = .35). For a total of 605 positive lesions, 458 (76%) were detected by both modalities, 122 (20%) exclusively by 18 F-FDOPA PET/CT, and 25 (4%) by 68 Ga-DOTATOC PET/CT only. In a per-lesion analysis, 18 F-FDOPA PET/CT performed better than 68 Ga-DOTATOC PET/ CT (overall detection rates of 96% vs 80%; P < .001). 18 F-FDOPA PET/CT detected significantly more metastases than 68 Ga-DOTATOC PET/CT in the liver, peritoneum, abdominal and supra-diaphragmatic lymph nodes. Conclusion: 18 F-FDOPA PET/CT seems not inferior than 68 Ga-DOTATOC PET/ CT for the delineation of metastatic spread of ileal NETs. Therefore, according to local expertise and technical availability, 18 F-FDOPA should be considered as a valid clinical diagnostic option for exhaustive metastatic assessment in patients with ileal NETs. Obviously, 68 Ga-DOTATOC PET/CT remains mandatory for PRRT assessment. Further comparative studies are needed to determine the optimal approach in various clinical scenarios such as preoperative staging and primary tumour detection.

Head‐to‐head comparison between 18F‐DOPA PET/CT and 68Ga‐DOTA peptides PET/CT in detecting intestinal neuroendocrine tumours: A systematic review and meta‐analysis

“…By contrast, in the three most recent and largest studies, which enrolled a more homogeneous series, with 98 patients affected by well‐differentiated intestinal NETs (84% of their entire population), a good diagnostic concordance between the two different modalities was found in terms of PBA 20–22 . However, 18 F‐DOPA PET/CT detected a significantly higher number of lesions than 68 Ga‐DOTA peptides PET/CT 20–22 . Overall, the difference in sensitivity between the two imaging modalities ranged from 7% to 46% in favour of 18 F‐DOPA PET/CT, 20–22 which was able to detect up to 86% more lesions than 68 Ga‐DOTA peptides PET/CT 21 .…”

“…However, when patients with high levels of serotonin were considered, 18 F‐DOPA PET/CT had the same diagnostic performance as 68 Ga‐DOTA peptides PET/CT 18 . By contrast, in the three most recent and largest studies, which enrolled a more homogeneous series, with 98 patients affected by well‐differentiated intestinal NETs (84% of their entire population), a good diagnostic concordance between the two different modalities was found in terms of PBA 20–22 . However, 18 F‐DOPA PET/CT detected a significantly higher number of lesions than 68 Ga‐DOTA peptides PET/CT 20–22 .…”

“…Table 3 details the available data from all studies included in the present systematic review. Overall, 18 F‐DOPA PET/CT and 68 Ga‐DOTA peptides PET/CT performed well in detecting patients with intestinal NETs localisations, identifying more than 80% of true positive patients 17–22 . However, discrepancies between the two imaging modalities were observed in the three oldest studies, which enroled only 14 patients with intestinal NETs, 17–19 whose anatomical origin (i.e., foregut, midgut or hindgut) was not clearly specified 18 .…”

“…Therefore, 6 articles were finally selected and 112 intestinal NETs patients were included (Figure 1). 17‐22 …”

“…PET image analysis was performed by means of qualitative(visual) analysis and, in all but one study, additional semi‐quantitative analysis through the calculation of the maximal standardised uptake values. On visual analysis, all foci of radiotracer uptake greater than the surrounding tissue that could not be explained by physiological activity were considered to be abnormal in four studies 17,18,20,20,22 . In the remaining two studies, PET findings were defined as positive in the case of tracer uptake higher than physiological activity 19,21 .…”