Nuclear Medicine & Radiation Therapy

Magnetic Resonance Imaging Fusion of Cranial Nerves Impaired by Skull Base Tumors: A Technical Development

Abstract

Pedro Gonçalves Pereira and Rui Manaças

Objectives: Magnetic Resonance Image Fusion is used to highlight tissue characteristics unrevealed by the individual sequences. We have applied a fusion algorithm merging isotropic sequences T2 Constructive Interference in a Steady State-CISS and contrast-enhanced (CE) T1 to obtain multiplanar (MPR) composed images (CESS) of skull base tumors and the surrounding cranial nerves (CN). We hypothesize that CESS images may complement standard Diffusion-Tensor Tractography and depict the deviated trajectories of CN impaired by space occupying lesions within the subaracnoid cisterns.
We describe the fundamentals of this technique and present the cases of several patients in which the information garnered was coincident with CN tractographies and neurosurgical results.
Methods: A retrospective and observational study of six patients (three vestibular schwannomas, two petro-clival meningiomas and one difuse epidermoid) was performed, comparing CESS with CN tractographies and intraoperative findings. Isotropic T2-CISS, pos-Gadolinium T1 images and Diffusion-Tensor (DT) tractographies were obtained preoperatively. MPR fused CESS was processed with the MR vendor’s proprietary software.
Results: All fused imaging sets resulted correctly aligned. The location of the CN on CESS was seen has a fiber of low contrast and increased thickness at the tumor margin, coincident with CN tractographies and surgical results.
Conclusion: We speculate that image fusion (CESS) complements CN tractography evaluation and aid in the operative planning.