Comparative Analysis of MIP & SSD Imaged in Diagnosis of intracranial Aneurysms

ABSTRACT

There is an increasing tendency to use three dimentional computed tomographic angiography(CTA) in diagnosis of intracranial aneurysm. The authors have planned to get a better CTA image through comparing of the maximum intensity projection(MIP) and shaded surface display(SSD) techniques. Eighteen patients were evaluated who had been studied with conventional cerebral angiography(CCA), CTA and received aneurysmal surgery, all together. Original spiral CT images were studied with helical CT scanner with 120ml of non-ionic contrast material, 3ml/sec injection rate, 1mm collimation and 1mm reconstruction interval. MIP and SSD images of CTA were reconstructed with diting by using a standard processing algorithm of volume rendering technique and three dimensional technique. There were 3 cases(12%) of false negatives in both MIP and SSD images among the ottal 25 cases of saccular aneurysms. There were 2 cases(8%) of false positives in SSD images that were actually negative for aneurysm in MIP and CCA. Our results have demonstrated that CTA is a quick, reliable and relatively simple diagnostic tool or screening of intracranial aneurysms, and superior to CCA in evaluating configuration, direction and its associated vascular anatomy. The MIP image was better to reveal vasospasm, calcification, neck shape and adjacent vascular anatomy. On the other hand, the SSD image showed higher false positive rate due to pseudo-saccular fusion and superior to glance over the external configuration and for planning of surgery.