Tomokatsu Tsukamoto RT, Presenter: Nothing to Disclose

Takashi Takahata RT, Abstract Co-Author: Nothing to Disclose

Keisuke Nishihara MD, Abstract Co-Author: Nothing to Disclose

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

Hiroki Mori MD, Abstract Co-Author: Nothing to Disclose

Katsuhide Ito MD, Abstract Co-Author: Nothing to Disclose

Yue Dong, Abstract Co-Author: Nothing to Disclose

On fast kVp-switching single-source dual-energy (ssDE) CT scan (gemstone spectral imaging: GSI), automatic exposure control (AEC) remains unavailable. For GSI clinical applications, it is important to compare DOSE between GSI scans and conventional helical scans. The purpose of this paper is to analyze DOSE and image quality with GSI scan mode by comparing it to conventional helical scan mode in body CT.

For consecutive 111 patients (72 men; mean age, 63.1 ± 12.1 years; mean body mass index (BMI>23.0), 25.7 ± 2.3) undergoing contrast-enhanced upper abdomen CT (0.984 pitch) with a ssDECT scanner (Discovery CT750 HD, GE). The study includes non-contrast CT scans at 120 kVp (an effective energy≅ 66 keV) with AEC (Auto mA; noise index, 10.0 HU at 5-mm thickness; 0.6 sec; 0.984pitch) with ASiR: 0% (FBP), 30% and 50% to reconstruct polychromatic (POLY) images and post-contrast CT during the portal phase with GSI using Max AEC mA table to reconstruct MONO (66keV) images.

CTDIvol values between MONO mode and POLY mode were 15.8 ± 4.1 and 14.7 ± 4.4 mGy. The MONO mode increases DOSE only 7.6% comparison with POLY mode, but the result does not have statistical significantly (P > 0.05). The SD values (image quality) within different mode (MONO-66keV, POLY-ASiR 0, 30 and 50%) for the gall bladder, muscular and liver were (18.8 ± 2.7 HU, 21.8 ± 2.1 HU, 17.8 ± 1.9 HU and 15.2 ± 2.0 HU), (21.7 ± 3.6 HU, 23.7 ± 2.9 HU, 19.8 ± 2.7 HU and 17.3 ± 2.7 HU), and (23.1 ± 3.5 HU, 27.1± 2.8 HU, 21.9± 2.2 HU and 18.6 ± 2.0 HU), respectively. The average image noise (SD) variation with MONO-66keV mode compared with POLY-ASiR mode (0% FBP, 30% and 50%) for the gall bladder, muscular and liver were (-13.8%, 5.4% and 23.5%), (-8.7%, 9.4% and 25.0%), and (-15.0%, 5.1% and 23.9%), respectively. MOMO mode have significant difference at each POLY mode (P<0.05), the image quality with MONO mode (66keV) were significantly higher than FBP, close than ASIR30%, poor than ASiR50% in POLY-120kVp mode.

From this study, we can conclude that GSI scan mode at MONO-66keV without automatic exposure control has similar DOSE level and similar image quality level with normal helical (120kVp) scan mode at POLY-30%ASiR with automatic exposure control.

In this study, we have demonstrated that GSI images represented at MONO-66keV can achieve similar DOSE level and similar image quality as conventional helical (120kVp) scan.

Tsukamoto, T, Takahata, T, Nishihara, K, Mesaki, K, Mori, H, Ito, K, Dong, Y, CT Scan DOSE and Image Quality Analysis with Different Scan Mode (Spectral Imaging Mode and Conventional Helical Mode) on Fast kVp-Switching Single-Source Dual-Energy Scan in 111 Abdomen Cases.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009030.html