Abstract: Objective To propose a new method for automatic segmentation of manually determined knee articular cartilage
into 9 subregions for T2 measurement. Methods The middle line and normal line were automatically obtained based on the
outline of articular cartilage manually drawn by experienced radiologists. The region of articular cartilage was then
equidistantly divided into 3 layers along the direction of the normal line, and each layer was further equidistantly divided into
3 segments along the direction of the middle line. Finally the mean T2 value of each subregion was calculated. Bland-Altman
analysis was used to evaluate the agreement between the proposed and manual subregion segmentation methods. Results The
95% limits of agreement of manual and automatic methods ranged from -3.04 to 3.20 ms, demonstrating a narrow 95% limits of
agreement (less than half of the minimum average). The coefficient of variation between the manual and proposed subregion
methods was 4.04%. Conclusion The proposed subregion segmentation method shows a good agreement with the manual
segmentation method and minimizes potential subjectivity of the manual method.