¹⁸F-FDG PET/MRI for non-invasive risk stratification of Intraductal Papillary Neoplasms of the Bile Duct (IPNB).

Abstract

To evaluate the value of hybrid ¹⁸F-FDG PET/MRI in assessing the biological aggressiveness of intraductal papillary neoplasms of the bile duct (IPNBs). This retrospective study included patients with pathologically confirmed IPNB who underwent ¹⁸F-FDG PET/MRI. Imaging features analyzed included ¹⁸F-FDG uptake, enhancement, diffusion restriction, duct walls infiltration, lesion size, SUVmax and lesion-to-liver SUVmax ratio. Final lesion classification was based on a composite reference standard integrating pathology with imaging follow-up, to account for potential biopsy sampling error. Spearman's correlation assessed associations between SUV parameters and histological grade. Group comparisons used the Mann-Whitney U test and Fisher's exact test. ROC analysis evaluated SUV parameters in diagnosing IPNBs with associated invasive adenocarcinoma. Eight patients (5 M, 3 F; median age: 65.5) with 10 lesions were included: five IPNBs with associated invasive adenocarcinoma, four dysplastic, and one non-dysplastic lesion. SUVmax and lesion-to-liver SUVmax ratio positively correlated with histological grade (ρ = 0.784, p = 0.007 and ρ = 0.844, p = 0.002, respectively). SUVmax ratio was higher in IPNBs with associated invasive adenocarcinoma versus both non-adenocarcinoma (p = 0.016) and dysplastic lesions (p = 0.032). Lesion SUVmax was higher in IPNBs with associated invasive adenocarcinoma only versus non-adenocarcinoma (p = 0.032) without reaching significance against dysplastic lesions (p = 0.063). ROC analysis yielded AUC values of 0.90-0.96 (95% CI 0.674-1.000) for SUV parameters. Cut-offs of 8.04 for SUVmax and 3.00 for SUVmax ratio achieved 80% sensitivity and 100% specificity. Hybrid ¹⁸F-FDG PET/MRI shows promising potential for preoperative assessment and risk stratification of IPNBs, warranting validation in larger prospective studies. • Preoperative differentiation between dysplastic and IPNBs with invasive adenocarcinoma remains challenging, yet critical for surgical planning and prognosis. • ¹⁸F-FDG PET/MRI SUV parameters correlate with histological grade, with the lesion-to-liver SUVmax ratio showing the strongest and most robust association. • ¹⁸F-FDG PET/MRI may support non-invasive risk stratification of IPNBs, potentially overcoming the limitations associated with biopsy sampling.