Nobuyuki Asato MD, Presenter: Nothing to Disclose

Masakatsu Tsurusaki MD, PhD, Abstract Co-Author: Nothing to Disclose

Tomoko Hyodo MD, Abstract Co-Author: Nothing to Disclose

Mitsuru Matsuki, Abstract Co-Author: Nothing to Disclose

Kazunari Ishii MD, Abstract Co-Author: Nothing to Disclose

Takamichi Murakami MD, PhD, Abstract Co-Author: Nothing to Disclose

To evaluate utility of iodine quantification using GSI (Gemstone Spectral Imaging by dual-energy CT) iodine map for staging liver fibrosis in the patients with chronic liver disease by using liver biopsy as the reference standard.

This study was approved by the institutional review board. Forty-eight patients who underwent dynamic CT scanning using dual-energy CT within 2-months before or after liver biopsy for suspicion of chronic liver disease. The fibrosis stage was assessed according to METAVIR scores (fibrosis stage 0 [F0], 5 patients; F1, 8; F2, 9; F3, 16; and F4, 10). All patients underwent non-contrast and contrast-enhanced CT of the upper abdomen with a fast kV switching single-source dual-energy (80 kVp and 140 kVp) using 64-slice MDCT. Iodine density on each dynamic phase was quantitatively measured by the iodine map and was correlated with the fibrosis stage. We determined the optimal cutoff value and diagnostic ability for discriminating each stage of fibrosis using receiver operating characteristic (ROC) curve analysis of iodine density quantifications between portal phase and equilibrium phase. The percentage of iodine that remains from portal phase to equilibrium phase was defined as the residual ratio.

The residual ratio increased with the stage of fibrosis: F0, 66.6±3.6%; F1, 67.4±3.4%; F2, 72.9±5.6%; F3, 74.9±5.5%; and F4, 83.8±4.7%. There was a statistically significant correlation between the residual ratio and fibrosis stage (Spearman's Rho; r= 0.77, p < 0.001). The mean area under the ROC curve values for discriminating liver fibrosis stages were: 0.86 for stages of F1 or greater (Cutoff value=69.9%), 0.92 for stages of F2 or greater (72.2%), 0.86 for stages of F3 or greater (72.3%), and 0.94 for stage F4 (77.0%).

Iodine quantification using the GSI iodine map is a reliable technique for staging liver fibrosis and discriminating liver fibrosis stage in patients with chronic liver disease.

Contrast enhanced dynamic CT is the most widely used modality for the patients with chronic liver disease. Iodine quantification using dual-energy CT (iodine map) could be one of the minimally-invasive options to assess fibrous stages as well as US elastography or MR elastography.

Asato, N, Tsurusaki, M, Hyodo, T, Matsuki, M, Ishii, K, Murakami, T, Noninvasive Assessment of Liver Fibrosis with Iodine Quantification Using Dual-energy CT in Chronic Liver Disease.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007854.html