Hu Yi, Presenter: Nothing to Disclose

Guo Qiyong MD, PhD, Abstract Co-Author: Nothing to Disclose

Pan Shinong MD, Abstract Co-Author: Nothing to Disclose

GUO Wenli MS, Abstract Co-Author: Nothing to Disclose

He Ming, Abstract Co-Author: Nothing to Disclose

To prospectively study the artifacts reducing effect of Orthopedic Metal Artifact Reduction (O-MAR) Technique combined with the 4th generation Iterative Reconstruction Algorithm (iDose4).

All experiments received approval of the animal Ethics Committee in Shengjing hospital. Twelve femora of Japanese white rabbits with an implanted stainless steel-based plate and 3 screws underwent CT scans (128-slice scanner, Philips) before and after the orthopedic operation. CT parameters were as followed: 100 kV, 120 mAs, 1 mm slice thickness, slice interval 0.5 mm. Four groups were divided for postoperative sans: Group A：reconstructed by filtered back projection (FBP); Group B：reconstructed by iDose4 (level 4) only; Group C：reconstructed by FBP and O-MAR; Group D：reconstructed by O-MAR combined with iDose4. Quantitative evaluation included CT attenuation, signal-to-noise ratio (SNR) and standard deviation of signal (SD) using ANOVA test. Two independent readers assessed image distortion, artifacts range, clearance of intermuscular space and bony trabecule at each level of screws by using a 4-point scale. Data were analyzed using Wilcoxon signed-rank test.

①Compared to preoperative imaging, Group C and D attained more credible CT attenuations than Group A and B (92.9±25.0 HU, 93.5±24.7 HU, 62.3±10.0 HU and 62.1±9.9 HU vs 62.9±HU(preoperation), PAand PB<0.05, PC and PD>0.05)；②All SDs of four groups increased obviously after operation, but Group C and D showed relatively better imaging homogeneity ( 33.8±10.2(preoperation), 151.7±60.9, 139.3±61.5, 107.8±51.4, 93.3±51.9, all P<0.01); ③SNRs from Group A to D exhibited a trend to increase, but they were still much lower than those of preoperation ( 2.2±1.0, 2.3±1.1, 3.0±1.5 and 3.5±1.7 vs 7.1±1.2( preoperation), P<0.01). ④In the qualitative analysis, Group D showed the best with the least image distortion, the weakest artifacts and intermuscular space and bony trabecule with clear conspicuity.

O-MAR combined with iDose4 could remarkably reduce metal artifacts with more credible CT values, better imaging homogeneity (lower SD values) and higher image quality than conventional FBP reconstruction alone.

With O-MAR combined with iDose4, credible imaging with the least metal artifacts and low radiation can be obtained and thus allow accurate assessment for patients with metal fixation.

Yi, H, Qiyong, G, Shinong, P, Wenli, G, Ming, H, Evaluation of Artifacts Reducing Effect of Orthopedic Metal Artifact Reduction Technique and New Iterative Reconstruction Algorithm.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12025932.html