Xiaochao Guo, Presenter: Nothing to Disclose

Jian-Xing Qiu MD, Abstract Co-Author: Nothing to Disclose

Xiaoying Wang MD, Abstract Co-Author: Nothing to Disclose

Juan Hu, Abstract Co-Author: Nothing to Disclose

To evaluate the accuracy of iodine quantification in liver tissue homogenate with material decomposition algorithm by using gemstone spectral imaging (GSI).

Discovery CT750HD scanner (GE Healthcare) was used in this study. The tissue homogenate was made of fresh pig liver. A set of 10 test tubes containing liver tissue homogenate mixed with different known iodine concentrations were scanned by using GSI mode, with a collimation thickness of 0.625 mm, a rotation speed of 0.6 second, and a helical pitch of 0.983:1.  The iodine concentration of each test tube was 0(water only), 0.1, 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, 10.0 and 30.0 mg/ml, respectively. Aw4.5 workstation were used to measure the CT value (at 70keV monochromatic images) and iodine density (using "water" - "iodine" combination of basic materials) of the compounds in each test tube. The iodine concentrations were measured by using a circular region of interest that covered 80% of the test tube cross section on the iodine-based material decomposition images. Paired sample t-test was used to analysis the variance between measured and actual iodine concentrations.

The compounds increasingly attenuated X-ray with the iodine concentration increasing. The CT value (at 70keV) was 3.24 ± 2.78, 40.73 ± 14.42, 46.67 ± 16.13, 67.75 ± 13.41, 95.77 ± 27.40, 149.35 ± 21.71, 205.27 ± 22.31, 339.14 ± 34.56, 520.30 ± 41.70 and 945.53 ± 87.64 HU, respectively. The measured iodine density was -0.16 ± 0.14, 0.10 ± 0.26, 0.50 ± 0.27, 1.05 ± 0.22, 2.00 ± 0.30, 4.20 ± 0.27, 5.96 ± 0.28, 8.34 ± 0.84, 10.74 ± 0.95 and 30.40 ± 2.78 mgI/ml, respectively. The measured iodine concentration was highly consistent with actual concentration (r=0.9997, p < 0.01). There was no statistical difference between measured and actual iodine concentration (p > 0.05).  

GSI-based material decomposition provides an accurate quantitative approach to directly measure the material content. Iodine concentration can be accurately measured in liver tissue homogenate.  

Iodine is a common material in enhanced CT scan. It can be accurately measured in mixed materials with GSI, which is important for quantitative analysis of inflow contrast and blood supply of tissue.

Guo, X, Qiu, J, Wang, X, Hu, J, Quantitative Measurement of Iodine in Liver Tissue Homogenate with Material Decomposition Algorithm via Fast kVp Switching Dual Energy CT: An Experimental Study.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12029140.html