Conspicuity and characterization of pre-selected hypodense hepatic lesions in pancreatic cancer patients: limited clinical value of dual-energy portal phase CT

Abstract

Abstract Purpose To assess the impact of 50-keV virtual monoenergetic images (VMIs) and iodine metrics on conspicuity and characterization of hypodense hepatic lesions in pancreatic ductal adenocarcinoma (PDAC) patients undergoing dual-energy portal phase CT. Methods Consecutive patients with hypodense hepatic lesions who underwent dual-energy portal phase CT between January and December 2025 were retrospectively identified. Lesions were pre-selected by a resident. Two radiologists independently evaluated blended and 50-keV VMIs for lesion conspicuity and confidence for metastasis using 5-point Likert scales. Contrast-to-noise ratio (CNR) and iodine metrics were calculated. Subjective scores and CNRs were compared using the Wilcoxon test. Diagnostic performance for characterization was assessed using histopathology and/or imaging as the reference standard. Iodine metrics were compared using non-parametric tests. Subgroup analyses included lesions ≤ 10 mm and those in steatotic livers. Results 181 lesions in 86 patients were included (58% metastases). Interobserver agreement was good/very good, except for diagnostic confidence in steatotic livers (k = 0.58/0.48). No differences were found between image sets in subjective conspicuity, diagnostic confidence, or characterization performance. Metastases had higher CNR on 50-keV VMIs than on blended images in the overall cohort (9.9 ± 5.7 vs. 8.5 ± 5.3, p < 0.001) and for lesions ≤ 10 mm (9.5 ± 5.1 vs. 8 ± 4, p = 0.003), but not in steatotic livers. Iodine metrics were higher in metastases than in cysts, with substantial overlap with non-cystic benign lesions. Conclusion 50-keV VMIs improve objective conspicuity but not subjective conspicuity, diagnostic confidence, or characterization performance. Iodine metrics provide complementary information but cannot distinguish metastases from non-cystic benign lesions.