Thickness measurement of femoral cartilage on hip joint in MRI

A novel method, which is based on the zero-crossing points combined with Gaussian filter, is developed to estimate the cartilage thickness of hip joint automatically in magnetic resonance imaging (MRI). A 2D mathematical model for simulating human hip joint femoral cartilage distribution is founded. Based on the model, a point spread function (PSF) is applied to simulate the MR imaging process, and then the one-dimensional profile of MR intensity values along the normal direction of the sheet structure can be performed. The simulation experiment demonstrates that the thickness of sheet structure can be accurately measured by using the zero-crossing method, where the thickness of sheet structure is defined as the distance between zero-crossing points of the Gaussian second derivatives along the normal direction. Plastic sheet simulation and the vivo experiment verify the validity of the method.