Comparison of neuroendocrine tumor detection and characterization using DOTATOC-PET in correlation with contrast enhanced CT and delayed contrast enhanced MRI

PurposeWe evaluated the rate of successful characterization of gastroenteropancreatic neuroendocrine tumors (NETs) present with an increased somatostatin receptor, comparing CE-CT with CE-MRI, each in correlation with DOTATOC-PET.Methods and materials8 patients with GEP-NET were imaged using CE-MRI (Gd-EOB-DTPA), CE-CT (Imeron 400) and DOTATOC-PET. Contrast-enhancement of normal liver-tissue and metastasis was quantified with ROI-technique. Tumor delineation was assessed with visual-score in blind-read-analysis by two experienced radiologists.ResultsOut of 40 liver metastases in patients with NETs, all were detected by CE-MRI and the lesion extent could be adequately assessed, whereas CT failed to detect 20% of all metastases. The blind-read-score of CT in arterial and portal phase was median −0.65 and −1.4, respectively, and 2.7 for delayed-MRI. The quantitative ROI-analysis presented an improved contrast-enhancement-ratio with a median of 1.2, 1.6 and 3.3 for CE-CT arterial, portal-phase and delayed-MRI respectively.ConclusionLate CE-MRI was superior to CE-CT in providing additionally morphologic characterization and exact lesion extension of hepatic metastases from neuroendocrine tumor detected with DOTATOC-PET. Therefore, late enhanced Gd-EOB-DTPA-MRI seems to be the adequate imaging modality for combination with DOTATOC-PET to provide complementary (macroscopic and molecular) tumor characterization in hepatic metastasized NETs.