Quantitative imaging of congenital hyperinsulinism with 18F-L-Fluoro-DOPA PET

Abstract

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Objectives: Accurate localization of pancreatic focal disease in infants with congenital hyperinsulinism (HI) is critical as surgery is potentially curative. We have previously reported that qualititative analysis of 18Fluorine-DOPA (FDOPA) PET is a valid noninvasive modality to discern focal from diffuse disease. Pancreatic distribution of FDOPA remains to be fully investigated. In this communication, we analyzed the FDOPA images of HI patients by measuring FDOPA uptake quantitatively. Methods: Forty-four (24 M, 20 F, 5±4 months)patients clinically diagnosed with HI, unresponsive to medical therapy, underwent a FDOPA PET study after appropriate sedation. Five 10-minute PET images of the abdominal region were obtained in a brain dedicated camera (G-PET)immediately after the intravenous injection of 2.96-5.92MBq/kg. of FDOPA. Regions of interest (ROI) were drawn in the head, body, and tail of the pancreas in an axial mid-abdominal slice. Additional ROIs were drawn in the liver and lung. Counts per area were generated in each ROI and ratios between pancreatic areas and between pancreas and lung were used for analysis. Reconstructed PET images were co-registered with those of a post-contrast CT scan. Surgery was performed no sooner than 12-18 hours following the PET scan. Results: By pathology, 22 patients had focal disease, and 22 diffuse. Focal lesions in the head of the pancreas showed a higher uptake ratio when compared to other unaffected areas than lesions in the body or tail. (2.63±0.31 vs 2.16±0.35 vs 1.36±0.27, respectively; P<0.05) On lesion/lung ratios, focal body lesions had the highest value, compared to head (7.1±0.7 vs 5.2±0.43, P<0.05) or tail (7.1±0.7 vs 3.61±0.28, P <0.03). Ratios between diffuse pancreatic regions were similar: (1.27±0.25 vs 1.06±0.26 vs 1.61±0.39, P=NS for head/body, body/tail, head/tail, respectively). Overall, ratios for focal lesions were higher than the ones for diffuse disease (2.05±0.36 vs 1.31±0.27, P<0.05). Conclusions: Quantitative analysis of the FDOPA uptake may prove to be a valuable method for characterizing focal and diffuse lesions and can be used as complementary mean to the qualitative analysis schemes in patients with HI.