Yong Eun Chung MD, PhD, Presenter: Nothing to Disclose

Hye-Jeong Lee MD, Abstract Co-Author: Nothing to Disclose

Myeong-Jin Kim MD, PhD, Abstract Co-Author: Nothing to Disclose

To investigate the feasibility of dual energy CT (DECT) for iodine contrast media reduction in the diagnosis of hypervascular and hypovascular focal liver lesions.

A VX2 tumor was implanted in two different segments of the liver in 13 rabbits. After 2-4 weeks, two phase contrast enhanced CT scans including the late arterial phase (LAP) and hepatic venous phase (HVP) were performed three times with 24 hour intervals. Contrast media of 1 ml/kg was injected via the ear vein during a 7 second period, with three different concentrations of iodine, i.e. 300 (I300), 150 (I150) and 75 mgI/mL (I75). The mean HU and standard deviation (SD) was measured in the liver, the hypervascular portion of the VX2 tumor which represented hypervascular tumors, and the central necrotic area of the VX2 tumor, which represented hypovascular tumors in 140 kVp images with I300 as a reference standard. The mean HU and SD were also measured in monochromatic images (between 40keV and 140 keV with 10 keV intervals) at the same locations with I150 and I75. Contrast-to-noise ratio (CNR) for hypervascular lesions in LAP and hypovascular lesions in HVP were calculated and the ratio of CNR (CNRratio) between monochromatic image sets with I150 and I75 and the reference standard was calculated.

A total of 23 VX2 tumors in 25 rabbits were evaluated. For hypervascular lesions, CNRratio was higher than 1 in 40 keV (1.23), 50 keV (1.28) and 60 keV (1.17) images with I150, whereas CNRratio wasn’t higher than 1 in any keV images with I75. In terms of hypovascular lesions, CNRratio was higher in 40 keV (2.19), 50 keV (1.55) and 60 keV (1.16) with I150, and 50 keV (1.12), 60 keV (1.24) and 70 keV (1.14) with I75.

With dual energy CT, the total amount of iodine contrast media might be halved in the diagnosis of hypervascular liver lesions and reduced to one fourth in the diagnosis of hypovascular liver lesions, while preserving CNRs of the focal liver lesion.

In patients with impaired renal function, the total amount of iodine contrast media can be reduced by using DECT without deteriorating diagnostic performance for focal liver lesions.

Chung, Y, Lee, H, Kim, M, Feasibility of Dual-energy CT for Iodine Contrast Media Reduction: An Animal Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009704.html