A median filter for 3D FAST spin echo black blood images of cerebral vessels

High-resolution black-blood MRA images of intracranial vascular anatomy can be obtained using 3D fast spin-echo techniques, Although these images demo nstrate excellent contrast between vessels and surrounding soft tissues, th e dark signal from air and bone can obscure the desired vascular informatio n when a minimum intensity projection image is created. In this paper, we d escribe an image processing technique based upon a median filter that is ef fective for detecting narrow vessel-like structures, Minimum intensity proj ection images of the filtered MRA volume can be obtained in any orientation without prior segmentation of the skull or surrounding air spaces. The fil ter is very effective for detecting and visualizing small vessels, but is m uch less effective for detecting vessels and vascular pathology larger than the filter detection width. The filtering technique is demonstrated on bla ck-blood MRA images from a volunteer study. (C) 2000 Wiley-Liss, Inc.