Segmentation of avascular necrosis of the femoral head using 3-D MR images.

Avascular necrosis of the femoral head (ANFH) is a common clinical disorder in the orthopedic field. Traditional approaches to study the extent of ANFH rely primarily on manual segmentation of clinical magnetic resonance images (MRI). However, manual segmentation is insufficient for quantitative evaluation and staging of ANFH. This paper presents a new computerized approach for segmentation of necrotic lesions of the femoral head. The segmentation method consists of several steps including histogram based thresholding, 3-D morphological operations, oblique data reconstruction, and 2-D ellipse fitting. The proposed technique is rapid and efficient. In addition, it is available as a Microsoft Windows free software package on the Internet. Feasibility of the method is demonstrated on the data sets of 30 patients (1500 MR images).