Gamma Knife radiosurgery with magnetic resonance/computed tomography fusion imaging for a patient unable to extend the neck

Gamma Knife radiosurgery (GKRS) is a widely accepted and precise treatment modality for brain neoplasms, and it primarily relies on accurate magnetic resonance imaging (MRI) for lesion localization.However, standard MRI techniques pose significant challenges in patients with severe cervical spine immobility.Here, we describe a case involving a 79-year-old patient with newly diagnosed lung cancer who presented with three metastatic brain lesions requiring GKRS.Because of severe neck stiffness caused by ankylosing spondylitis, the patient's head could not be adequately positioned within the MRI head coil, compromising image quality and localization precision.To address this limitation, computed tomography (CT) imaging was performed after MRI, and the magnetic resonance (MR)/ CT datasets were fused using GammaPlan software.Comparative analysis between MR-only imaging and MR/CT fusion imaging demonstrated notable improvements in lesion delineation accuracy based on the fused dataset, allowing more precise radiosurgical targeting.This case highlights the clinical utility and necessity of MR/CT fusion imaging to achieve accurate lesion targeting and treatment efficacy in patients with substantial cervical spine mobility restrictions.