Yijun Liu, Presenter: Nothing to Disclose

Renwang Pu MBBCh,FRCPC, Abstract Co-Author: Nothing to Disclose

Ying Ge MD, Abstract Co-Author: Nothing to Disclose

Ailian Liu MD, Abstract Co-Author: Nothing to Disclose

Yue Dong, Abstract Co-Author: Nothing to Disclose

Yanwei Miao MD, Abstract Co-Author: Nothing to Disclose

Huizhi Cao, Abstract Co-Author: Nothing to Disclose

To investigate in a phantom the utility of model-based iterative reconstruction (MBIR) to improve image quality and reduce radiation dose in abdominal CT.

Using a 64-detector CT scanner (Discovery CT750 HD, GE), abdominal phantom was scanned and the scan parameters were set as: section thickness, 0.625 mm; rotation speed, 0.5 sec; helical pitch, 1.375; and noise index (NI), 5-30 (5 step) HU. The projection data sets were reconstructed with FBP and MBIR. And readers were blinded to the reconstruction algorithm. The mean CT values, image noise and contrast-to-noise ratio (CNR) relative to muscle for the liver, kidney and spleen with both algorithm were assessed. We compared those results between FBP and MBIR by Wilcoxon signed-rank test and determined the highest NI by MBIR to obtain similar or better image quality to that obtained with our routine protocol (10-NI by FBP).

MBIR significantly reduced the objective noise for liver, kidney and spleen (12.3 ± 1.4, 14.2 ±2.1 and 13.5 ± 1.8 at 30-NI; 8.3 ± 0.6, 8.7 ± 0.5 and 8..6 ± 0.9 at 10-NI) compared to FBP (36.3 ± 1.4, 41.1 ± 2.9 and 39.7 ± 2.2, 87 at 30-NI; 13.7 ± 1.1, 14.2 ± 0.7 and 13.9 ± 0.8 at 10-NI) (P < 0.05 for all). MBIR also improved the subjective noise and image sharpness (2.0 ± 0.0, 2.0 ± 0.0, 3.0 ± 0.0 at 30-NI; 3.0 ± 0.0, 3.0 ± 0.0, 3.0 ± 0.0 at 10-NI) compared to FBP (1.0 ± 0.0, 1.0 ± 0.0, 1.0 ± 0.0 at 30-NI; 2.0 ± 0.0, 2.0 ± 0.0, 2.0 ± 0.0 at 10-NI) (P < 0.05 for all). Image quality was better by MBIR, even at 30-NI, than by FBP at 10-NI.

Compared to our routine protocol for abdominal CT, use of MBIR may improve image quality and still reduce radiation dose by 74%.

MBIR may dramatically improve image quality with the same radiation dose and reduce radiation dose with similar or better image quality than that of FBP in abdominal CT.

Liu, Y, Pu, R, Ge, Y, Liu, A, Dong, Y, Miao, Y, Cao, H, Improved Image Quality and Reduced Radiation Dose in Abdominal CT Using Model-based Iterative Reconstruction: Anthropological Phantom Experiment.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12037474.html