Myung Jin Chung MD, Abstract Co-Author: Patent agreement, General Electric Company Patent agreement, Samsung Electronics Co Ltd

Wan-Youk Kim, Presenter: Nothing to Disclose

Dong Ik Cha MD, Abstract Co-Author: Nothing to Disclose

Sung Mok Kim MD, Abstract Co-Author: Nothing to Disclose

Moon Chan Kim RT, Abstract Co-Author: Nothing to Disclose

Kyung Soo Lee MD, PhD, Abstract Co-Author: Nothing to Disclose

To create virtual non-contrast CT, two-material decomposition is allowed from Spectral CT based on sinogram space, instead of three-material decomposition method allowed in image space. However, various virtual non-contrast images can be made from various material decomposition (MD) methods in spectral CT. We evaluated the feasibilities of three different virtual non-contrast (VNC) images derived from single source dual energy spectral CT compared to true non-contrast (TNC) image.

This HIPAA-compliant study was approved by institutional review board and informed consent was provided from all patients. Twenty-four patients prospectively underwent non-contrast CT followed by contrast enhanced chest CT using single source fast kVp switching dual energy scan. Iodine eliminated images so called as VNC were reconstructed using two kinds of 2-material decomposition algorithms (MDW, material density-iodine/water; MDC, material density-iodine/calcium) and material suppression algorithm (MSI, iodine suppression image). Using third party workstation, semiautomatic calcium measurements were performed.

Quantified calcium scores (AJ score) from all three VNCs correlated well with that of TNC (R2 = 0.95, 0.88, and 0.88 for MDW, MDC, and MSI, respectively). However correlation coefficients were less than 0.9 (C = 0.83, 0.62, and 0.63 for MDW, MDC, and MSI, respectively). Measured calcium volumes on VNCs also correlated well with that of TNC (R2 = 0.94, 0.87, and 0.90 for MDW, MDC, and MSI, respectively), with correlation coefficients of 0.78, 0.59, and 0.63 for MDW, MDC, and MSI, respectively. Among the three VNCs, MDW correlated best with TNC.

VNC image from contrast enhanced CT using dual energy material decomposition/suppression is feasible for coronary calcium scoring. However, among various methods to make virtual noncontrast image from spectral CT, material quantifications are different depending on the decomposition methods. Furthermore, the absolute value on VNC tends to be smaller than that on TNC and should be considered with calibration.

Absolute values of calcium scoring on VNC tend to be smaller than that on TNC and should be considered with calibration.

Chung, M, Kim, W, Cha, D, Kim, S, Kim, M, Lee, K, Virtual Non-contrast CT Using Dual Energy Spectral CT: Reproducibility of Calcium Mass for Coronary Calcium Scoring.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13010917.html