A new scheme for automatic 2D detection of spheric and aspheric femoral heads: A case study on coronal MR images of bilateral hip joints of patients with Legg-Calve-Perthes disease. (July 2019) - Memiş, Abbas
Highlights: A new two-level scheme which is based on the Circular Hough Transform (CHT) and Integro-differential Operator (IDO) is proposed to detect the spheric and aspheric femoral heads in magnetic resonance (MR) images. A case study on the coronal MR sections of the patients with Legg-Calve-Perthes Disease (LCPD) was performed. Performance evaluations and experimental results observed on healthy and pathological hip joints in 24 coronal MR image sections belong to 13 patients. 0.8978 mean Dice Similarity Coefficient (DSC) on healthy femoral heads and 0.8529 mean DSC on pathological femoral heads were observed. Proposed approach may be used in detection of the other anatomical structures that have a circular shape in medical images provided by various medical imaging modalities in multiple planes. Abstract: Background and objective: In orthopaedics, hip joint and circular structure of the femoral head can be distorted by a wide variety of hip joint disorders. Hence, automatic detection and segmentation of the femoral head is an important issue in the studies of computerized hip joint segmentation, quantification and assessment. In the proposed study, we need to detect the center coordinates and radius of spheric and aspheric femoral heads automatically in bilateral hip magnetic resonance (MR) images using a new scheme. Methods: This paper presents a new two-level scheme based on the Circular Hough Transform (CHT) and Integro-differential Operator (IDO) to detect the spheric and aspheric femoral heads in MR images in 2D. Initially, MR slices are divided vertically into two equal halves to automatically separate the hip joints and Canny's edge detection method is performed on each of the halves to obtain edge images. Then, healthy and pathological femoral heads are detected by performing the CHT over edge images in the first stage of proposed scheme. In the second stage, femoral head circle detected with CHT is fine tuned by performing Daugman's IDO. Results: Performance evaluations of the proposed femoral head detection scheme were carried out on healthy and pathological hip joints in 24 coronal MR image sections belong to 13 patients with Legg-Calve-Perthes Disease (LCPD). In performance evaluations on 24 healthy and 24 pathological hip joints, Root Mean Square Error (RMSE) and Dice Similarity Coefficient (DSC) values were measured for automatically detected femoral heads. We observed 1.96 mm. (std. 1.21 mm.) mean RMSE for center coordinates, 1.45 mm. (std. 1.39 mm) mean RMSE for radii, 0.8978 (std. 0.0733) mean DSC on healthy femoral heads and 3.56 mm. (std. 3.19 mm.) mean RMSE for center coordinates, 1.56 mm. (std. 1.33 mm.) mean RMSE for radii, 0.8529 (std. 0.0927) mean DSC on pathological femoral heads. Conclusions: Proposed femoral head detection scheme has promising results for the detection and the segmentation of the spheric and aspheric femoral heads and also has a potential to be used in detection of the other anatomical structures having a circular shape.