Development and external validation of a dual-energy CT-biochemical score for the detection of radiolucent common bile duct stones - 04/08/26
Highlights |
• | Dual-energy CT Z eff maps may help detect radiolucent common bile duct stones. |
• | Z eff map positivity and cholestatic biomarkers were the two independent predictors of radiolucent common bile duct stones. |
• | A score combining Z eff positivity, conjugated bilirubin ≥ 50 µmol/L, and/or gamma-glutamyl transferase > 500 IU/L ( i.e ., ZBG score) shows robust performance in both derivation and external validation cohorts for the diagnosis of radiolucent common bile duct stone. |
• | A ZBG score of zero identifies a very low-risk subgroup, whereas higher scores identifies patients with a high probability of common bile duct stone. |
• | The ZBG score may help rationalize magnetic resonance cholangiopancreatography referrals in patients with suspected radiolucent common bile duct stones. |
Abstract |
Purpose |
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.
Materials and methods |
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.
Results |
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.
Conclusion |
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.
Le texte complet de cet article est disponible en PDF.Keywords : Cholangiopancreatography, Choledocholithiasis, Dual-energy computed tomography, Effective atomic number, Magnetic resonance imaging, Tomography, X-ray computed
Abbreviation : AUC, CBD, CI, CT, DECT, ERCP, GGT, MRCP, OR, ROC, Z eff
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