ORIGINAL ARTICLE   

Journal of Neurosurgical Sciences 2022 February;66(1):9-16

DOI: 10.23736/S0390-5616.19.04621-6

Copyright © 2019 EDIZIONI MINERVA MEDICA

language: English

Accuracy of computed tomography: magnetic resonance imaging image fusion using a phantom for skull base surgery

Toru HIRANO ¹ ✉, Katsuhiro ICHIKAWA ², Masahiko WANIBUCHI ³, Takeshi MIKAMI ³, Junpei SUZUKI ¹, Hiroshi NAGAHAMA ¹, Nobuhiro MIKUNI ³

¹ Division of Radiology and Nuclear Medicine, Sapporo Medical University Hospital, Sapporo, Japan; ² Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan; ³ Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan

BACKGROUND: The aim of this study is to assess the positional accuracy of image fusions of the skull base region using different magnetic resonance imaging (MRI) and computed tomography (CT) image pairs.
METHODS: An image set of 3D fast imaging employing steady-state acquisition-C (FIESTA-C) was used as the base image set. Image fusions were performed using an image set with different fields of view (FOVs): one with different matrix size, one with a different sequence of 3D spoiled gradient recalled acquisition, and one with different modality (CT), using a phantom including multi columnar objects. Position of columns at the center, and 4 and 8 cm from the center were measured. The displacements between the base image set and fused image set were measured. For slices with different z-positions, the displacement of the 8-cm column was assessed. For 20 clinical MRI cases, the distance between the dorsum sellae and the cranial nerves was measured.
RESULTS: No significant differences were found between the different FOVs or image sequences. However, with the different matrix sizes and modalities, significant displacements were observed, although they were all within 0.5 mm. Similar displacements were observed in the slices at different z-positions. All cranial nerves were located within 40 mm of the dorsum sellae.
CONCLUSIONS: The displacements following image fusion were within approximately 0.5 mm, even at 8 cm from the center. This suggests that the region where the cranial nerves are located, within 40 mm of the dorsum sellae, had no risk of positional error following image fusion.

KEY WORDS: Computed tomography; Magnetic resonance imaging; Skull base; Cranial nerves