J.S. Suri (USA), K. Liu (PRC), S. Singh (UK), and S. Laxminarayan (USA)
Magnetic Resonance Angiography (MRA), Black Blood Angiography (BBA), Pre-filtering, Median, Directional, Scale-Space, Ellipsoidal, Vessels, Arteries, Veins, Quan tification, Stenosis, MIP
Pre-filtering is a critical step in 3-D segmentation of the blood vessel and its display. This paper presents a scale space approach for filtering the black blood angiographic volumes and its implementation issues. The raw MR an giographic volume is first converted to isotropic volume followed by 3-D higher order separable Gaussian deriva tive convolution with known scales to generate edge vol ume. The edge volume is then run by the directional pro cessor at each voxel where the eigenvalues of the 3-D el lipsoid are computed. The vessel score per voxel is then estimated based on these three eigenvalues which suppress the non-vasculature and background structures yielding the filtered volume. The filtered volume is ray-cast to gener ate the maximum intensity projection images for display. The performance of the system is evaluated by computing the mean, variance, SNR and CNR images. The system is run over 20 patient studies from different parts of the body such as: brain, abdomen, kidney and knee/ankle. The computer program takes around 150 seconds of processing time per study for a study for a data size of ½¾¢ ½¾¢½w hich includes the complete performance evaluation. We also compare our strategy with the recently published MR filtering algorithms by Alexander et al. ’s [1] and Sun et al. ’s [2].
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