Band-limited interpolation for maximum intensity projection images

X-ray computed tomography (CT) scanners, due to its inherent scanning geometry, provide images with nonisotropic voxels. The typical CT scanner generates axial slices with the thickness on the order of a few millimeters with sub-millimeter pixels. The multi-slice images obtained with such protocol must then be interpolated across the slices for an effective and realistic 3-D visualization of the patient anatomy. In this paper, we focus on the effects of slice interpolation for maximum intensity projection (MIP) images with the projection direction orthogonal to the saris, for instance, for the generation of coronal or sagittal views. Linear interpolations, although simple, due to the inherent noise in the data, generate MIP images with noise whose variance vary quadratically along the z-axis. As such, the MIP images will often suffer from horizontal streaking artifacts, exactly at the position of the original slices. To combat this situation we have developed a different interpolation technique based on a digital finite impulse response (FIR) filter. It is shown that this band-limited interpolation based on the FIR filter will flatten the change in the noise variance along the z-axis, the net effect being either the elimination or a reduction of the horizontal streaking artifact.