Slice profile characteristics of MPR images in multi-slice CT

Abstract:  Few studies have investigated the detailed imaging characteristics of multiplanar reconstruction (MPR) images, which have come to be used in imaging diagnosis. The purpose of this study was to evaluate the slice profile characteristics of MPR images. The slice profile of a coronal image was measured by the bead method. Moreover, it assumed that the slice profile of an MPR image became a convolution of the square profile corresponding to the nominal slice thickness and line spread function (LSF) of an axial image, and the simulation was performed. The nominal slice thicknesses of the original axial image and coronal image were 1.0 mm, 2.0 mm, and 3.0 mm. Three reconstruction kernels (B20, B30, and B40) of the original axial image were used. The results of measurement revealed that the full width at half maximum (FWHM) values were 1.7 mm for reconstruction kernel B20 and 1.3 mm for reconstruction kernel B40 in the case of a nominal slice thickness of 1.0 mm. The simulated and measured modulation transfer factors (MTF) were in close agreement. Then the slice profile of the coronal (sagittal) MPR image forms by the convolution of a LSF of the y- (x-) direction and the square profile with a nominal MPR slice width, and is affected by the reconstruction kernel.