COMBINED AND 3-DIMENSIONAL RENDERED MULTIMODAL DATA FOR PLANNING CRANIAL BASE SURGERY - A PROSPECTIVE EVALUATION

MAGNETIC RESONANCE (MR), X-RAY computed tomography (CT), and angiograp hic images best depict soft tissue, bone, and blood vessels respective ly. No one on its own is sufficient in the preoperative assessment of cranial base lesions. We have developed and evaluated a computational technique for the three-dimensional (3D) combination and display of mu ltimodality images for planning cranial base surgery. This evaluation was prospective and performed in such a way that the results could be quantified. Eight patients (three acoustic neuromas, four subfrontal a nd suprasellar meningiomas, and one petrous apex meningioma) underwent MR, CT, and MR angiographic investigations. These images were registe red with anatomical landmarks rather than an external frame. Two techn iques were used to display the resulting combined images: multiple sli ces in which bone from CT was overlaid on soft tissue from registered MR and pseudo-3D-rendered movie sequences showing bone from CT, lesion s and optic nerves from MR, and blood vessels from MR angiography. The advantages of the combined displays compared with those of convention al methods of viewing were assessed prospectively by the operating sur geon and by an independent surgeon, and the results were compared with operative findings. The preoperative assessment showed a significant improvement (P < 0.05, sign test) in the depiction of both individual structures (lesion and bone from overlaid slices and lesion and vascul ature from 3D-rendered displays) and structural relationships (tumor-b one relationships from overlaid slices and of tumor-vasculature relati onships from 3D-rendered displays). The operative findings indicated t hat a more accurate interpretation of this information was possible fr om the combined images.