Dual-energy CT with iodine quantification in distinguishing between bland and neoplastic portal vein thrombosis in patients with hepatocellular carcinoma

Aim: To investigate the diagnostic accuracy of dual-energy multidetector computed tomography (MDCT) with iodine quantification compared to conventional enhancement measurements in distinguishing bland from neoplastic portal vein thrombosis in patients with hepatocellular carcinoma.

Material and methods: Thirty-four patients (26 men, eight women; mean age, 62 years) with hepatocellular carcinoma and portal vein thrombosis underwent contrast-enhanced dual-energy MDCT during the late hepatic arterial phase for the assessment of portal thrombosis (bland, n=21; neoplastic, n=13). Datasets were analysed separately by two different readers. Interobserver correlation and variability were calculated and compared with the Bland-Altman method. Diagnostic accuracy of conventional enhancement measurements and iodine quantification was calculated by setting either histopathology (n=7) or a reference standard based on MDCT imaging criteria and thrombus evolutionary characteristics compared to a previous MDCT examination (n=27). For iodine quantification threshold determination receiver operating characteristic (ROC) curves were drawn. p-Values <0.05 were considered significant.

Results: For conventional enhancement measurements and iodine quantification interobserver correlation was 98% and 96%. Enhancement measurement resulted in a sensitivity of 92.3%, specificity of 85.7%, positive predictive value (PPV) of 80%, and negative predictive value (NPV) of 94.7%. An iodine concentration of 0.9 mg/ml optimised discrimination between neoplastic and bland thrombi (area under the ROC [AUC] 0.993) resulting in a sensitivity of 100%, specificity of 95.2%, PPV of 92.9%, and NPV of 100%. The overall diagnostic accuracy of iodine quantification (97%) was significantly better than conventional enhancement measurements (88.2%; p<0.001).

Conclusion: Compared to conventional enhancement measurements, iodine quantification improves the characterisation of portal vein thrombi during the late hepatic arterial phase in patients with hepatocellular carcinoma.