Development and external validation of a dual-energy CT-biochemical score for the detection of radiolucent common bile duct stones.

Authors

Loic Demir, Romain L'Huillier, Romain Moinet, Teddy Deregnaucourt, Angelo Della Corte, Marine Julien, Pascal Rousset, Lucine Vuitton, Paul Calame

Published in

Diagnostic and interventional imaging. Aug 03, 2026. Epub Aug 03, 2026.

Abstract

The purpose of this study was to evaluate the diagnostic performance of dual-energy computed tomography (DECT) effective atomic number (Z_eff) mapping for detecting radiolucent common bile duct (CBD) stones and to develop and externally validate a simple, combined imaging-biochemical score.
This retrospective multicenter study included consecutive adults who underwent magnetic resonance cholangiopancreatography (MRCP) due to suspected choledocholithiasis after a negative conventional abdominal dual-layer DECT performed within 21 days. In the derivation cohort, Z_eff and electron-density maps were independently reviewed by two radiologists, with consensus adjudication for interreader disagreements, using MRCP as the reference standard for CBD stones. Variables associated with MRCP-confirmed stones were entered into a multivariable logistic regression to derive a simplified score (i.e., ZBG score) based on Z_eff map positivity, conjugated bilirubin or gamma-glutamyl transferase serum levels, which was then validated in an external validation cohort.
The derivation cohort included 100 patients (mean age, 65.8 ± 19.3 [standard deviation] years; 54 men), of whom 19 had radiolucent CBD stones. The validation cohort included 101 patients (mean age, 60.2 ± 19.4 [standard deviation] years; 49 men), of whom 17 had radiolucent CBD stones. Consensus Z_eff mapping yielded 63% sensitivity (95% confidence interval [CI]: 38-84), 86% specificity (95% CI: 77-93), and 82% (95% CI: 73-89) accuracy for the diagnosis of radiolucent CBD stones. Z_eff map positivity (odds ratio [OR], 18.69; 95% CI: 4.22-82.68; P < 0.001) and conjugated bilirubin ≥ 50 µmol/L and/or γ-glutamyl transferase > 500 IU/L (OR, 20.67; 95% CI: 3.39-126.09; P = 0.001) were two variables that were independently associated with CBD stones. These two variables were combined into the ZBG score, with 1 point assigned to each item. The resulting ZBG score (range: 0-2) showed an area under the curve of 0.870 (95% CI: 0.801-0.939) in the derivation cohort and 0.877 (95% CI: 0.791-0.963) in the validation cohort for the diagnosis of radiolucent CBD stones.
For patients with suspected CBD stones and negative conventional CT results, a simple score combining DECT Z_eff mapping and routine cholestatic biomarkers provides accurate risk stratification for radiolucent CBD stones.

PMID:
42547357
Bibliographic data and abstract were imported from PubMed on 04 Aug 2026.

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