REGISTRATION OF IMAGES FROM SEQUENTIAL MR STUDIES OF THE BRAIN

For sequential studies of patients with brain tumors, the authors have designed an automated registration procedure for intra- and interexam ination alignment of magnetic resonance images. This was evaluated wit h artificially misregistered data and data from repeat studies of six healthy volunteers and six brain tumor patients. In a subset of cases, a manual procedure based on matching of neuroanatomic landmarks was a lso applied for comparison. The results showed that the technique is r obust and reproducible, giving an accuracy in the range of 1-2 mm, whi ch corresponded to the spatial resolution of the images. Subject motio n between imaging sequences within the same study was negligible, alth ough adjustments (one to two section thicknesses) were required in the z direction to correlate multisection and volume images and to allow accurate image segmentation. For alignment between sequential voluntee r and patient examinations, translations of up to 22 mm and rotations in the x, y, and z axes of up to 9 degrees were required. This alignme nt procedure may be valuable in numerous aspects of treatment planning and patient follow-up.