Differential diagnosis of hepatic cancerous nodules and cirrhosis nodules by spectral CT imaging: a feasibility study.

Background: It is difficult to distinguish atypical cancerous nodule from cirrhosis nodule. Purpose: To investigate the value of spectral computed tomography (CT) imaging parameters in differentiating hepatic cancerous nodules from cirrhosis nodules. Material and Methods: Forty-six patients with hepatic nodules underwent contrast-enhanced CT scans in spectral mode. Monochromatic CT images and iodine/water-based material-decomposition images were synthesized. CT values were measured at 70 keV monochromatic images and the difference of CT value in the arterial phase (AP) and delayed phase (DP) (△CT1); AP and portal venous phase (PP) (△CT2) were calculated. Normalized to the iodine concentration in the aorta (NIC), lesion to normal liver parenchyma iodine concentration ratio (LNR) was calculated. Slope of the spectral HU curve (λHU) was obtained. Intraclass correlation coefficient (ICC) was used for consistency test. Receiver operating characteristic (ROC) curves were also generated. Results: There were 23 hepatic cancerous nodules and 23 cirrhosis nodules. All gemstone spectral imaging (GSI) parameters had significantly larger value in cancerous nodules than in cirrhosis nodules, except NIC in DP. The LNR in AP had the largest area under the curve (AUC) of 0.96, indicating its highest ability to differentiate hepatic cancerous nodules from cirrhosis nodules. Using 1.99 as a threshold value for LNR in AP we could obtain sensitivity of 95.65% and specificity of 91.30%. Conclusion: We have demonstrated in this feasibility study that spectral CT imaging provides multiple quantitative parameters which may be used to help differentiating hepatic cancerous nodules from cirrhosis nodules. [ABSTRACT FROM AUTHOR]