Investigating the Effects of Motion Streaks on pQCT-Derived Leg Muscle Density and Its Association With Fractures  Adrian C.H. Chan, Jonathan D. Adachi, Alexandra Papaioannou, Andy Kin On Wong  Journal of Clinical Densitometry  Volume 21, Issue 1, Pages 130-139 (January 2018) DOI: 10.1016/j.jocd.2016.12.001 Copyright © 2016 Terms and Conditions

Fig. 1 Illustration of motion artifact from pQCT muscle scans. Note the level to which motion streaks transect the muscle region when motion is more severe. Journal of Clinical Densitometry 2018 21, 130-139DOI: (10.1016/j.jocd.2016.12.001) Copyright © 2016 Terms and Conditions

Fig. 2 Automated threshold-based segmentation for positive movement from muscle. (A) Figure showing both positive and negative motion streaks running through the body of the muscle. (B) Figure showing positive motion streaks and cortical bone segmentation generated from CORTBD analysis with threshold of 110 mg/cm3. (C) Figure with just cortical bone segmented excluding any motion streaks generated using CORTBD analysis with threshold of 710 mg/cm3. Positive motion streaks were isolated by subtracting cortical bone (C) from bone plus positive motion streaks (B). Journal of Clinical Densitometry 2018 21, 130-139DOI: (10.1016/j.jocd.2016.12.001) Copyright © 2016 Terms and Conditions

Fig. 3 Example of the watershed pools used to segment motion streaks from muscle. Larger pools (left column) approximated motion streak area, whereas smaller pools (middle column) were used to further refine its boundaries. Final segmentation result is shown in the right column. A comparison of the image before (top row) and after (bottom row) segmentation is displayed. Red indicates muscle area, and green as motion streak. Total MCSA includes both green and red regions. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.) Journal of Clinical Densitometry 2018 21, 130-139DOI: (10.1016/j.jocd.2016.12.001) Copyright © 2016 Terms and Conditions

Fig. 4 Automated threshold-based segmentation for negative movement from the muscle tissue. (A) Figure showing both positive and negative motion streaks running through the body of the muscle. (B) Illustration of negative movement alone without bone but including marrow, as generated from CALCBD analysis with inner and outer thresholds of 40 mg/cm3, contour mode 31, peel mode 2, and F03F05F05 filter applied. (C) Figure of cortical bone with marrow, determined using CORTBD with an outer threshold of 710 mg/cm3, separation mode 4, and inner threshold of −101 mg/cm3. (D) Figure of cortical bone without marrow, determined using CORTBD with an outer threshold of 710 mg/cm3, separation mode 4, inner threshold 40 mg/cm3, and filter F03F05F05. Marrow from figure B was removed by subtracting bone plus marrow in figure C, but adding back bone using figure D. The final result yields negative motion streaks alone. Journal of Clinical Densitometry 2018 21, 130-139DOI: (10.1016/j.jocd.2016.12.001) Copyright © 2016 Terms and Conditions

Fig. 5 Bland-Altman analysis comparing the difference between muscle densities (MD) measured before (MDUC) vs after (MDC) excluding motion streaks measured using the semi-automated method (A) and the fully automated method (B). Upper and lower dashed lines indicate 95% limits of agreement. Solid thick line indicates the mean of differences between MDUC and MDC. Plotted points are darker shades as motion grade is higher. Journal of Clinical Densitometry 2018 21, 130-139DOI: (10.1016/j.jocd.2016.12.001) Copyright © 2016 Terms and Conditions