Image registration strategy of T1-weighted and FIESTA MRI sequences in trigeminal neuralgia gamma knife radiosurgery

Abstract

Background/Aims: In Gamma Knife radiosurgery, T1 MRI is most commonly used and is generally sufficient for targeting the trigeminal nerve. For patients whose trigeminal nerves are unclear on T1 MRI, FIESTA MRI supplements anatomical structure visualization and may improve trigeminal nerve delineation. The purpose of this study was to develop a registration strategy for T1 and FIESTA MRIs. Methods: We conducted a retrospective study on 54 trigeminal neuralgia patients. All patients were scanned with T1 and FIESTA MRIs. We evaluated 4 methods of registration: automatic image definition, superior-slice definition, middle-slice definition and inferior-slice definition. Target discrepancies were measured by deviations from an intracranial landmark on T1 and FIESTA MR images. Results: The overall range in registration error was 0.10-5.19 mm using superior-, 0.10-1.56 mm using middle- and 0.14-2.89 mm using inferior-slice definition. Registration error >2 mm was observed in 11% of the patients using superior-, 4% using middle- and 7% using inferior-slice FIESTA MRI definition. Conclusions: Among patients for whom FIESTA and T 1 MRI are used, registration based on middle-slice definition reduces registration error and improves targeting of the trigeminal nerve. Copyright © 2010 S. Karger AG.