Automatic reregistration for correction of localized misregistration artifacts in digital subtraction angiography of the head and neck.

A new automatic computer program, to remove misregistration artifacts secondary to motions such as rotation, contraction and relaxation of the body, has been developed. This program is called automatic reregistration and consists of determination of distortion vectors of corresponding segments of the mask and live images by detection of the peak value of two-dimensional cross correlation, followed by obtaining distortion vectors of other pixels through interpolation. Shift of the coordinate of the distorted live image is subtracted. Clinical evaluation of this new program, in comparison with already developed remasking and manual reregistration, have proved that some misregistration artifacts, uncorrectable by the latter two methods, have been removed to some extent. The new program has proven to be clinically useful.