First Application of 7-T Magnetic Resonance Imaging in Endoscopic Endonasal Surgery of Skull Base Tumors

Abstract

Background Successful endoscopic endonasal surgery for the resection of skull base tumors is reliant on preoperative imaging to delineate pathology from the surrounding anatomy. The increased signal-to-noise ratio afforded by 7T MRI can be used to increase spatial and contrast resolution, which may lend itself to improved imaging of skull base. In this study, we apply a 7T imaging protocol to patients with skull base tumors and compare the images to clinical standard of care. Methods Images were acquired at 7T on 11 patients with skull base lesions. Two neuroradiologists evaluated clinical 1.5T, 3T, and 7T scans for detection of intracavernous cranial nerves and ICA branches. Detection rates were compared. Images were utilized for surgical planning and uploaded to a neuronavigation platform and used to guide surgery. Results Image analysis yielded improved detection rates of cranial nerves and ICA branches at 7T. 7T images were successfully incorporated into preoperative planning and intraoperative neuronavigation. Conclusion Our study represents the first application of 7T MRI to the full neurosurgical workflow for endoscopic endonasal surgery. We detected higher rates of cranial nerves and ICA branches at 7T MRI compared to 3T and 1.5 T, and found that integration of 7T into surgical planning and guidance was feasible. These results suggest a potential for 7T MRI to reduce surgical complications. Future studies comparing standardized 7T, 3T, and 1.5 T MRI protocols in a larger number of patients are warranted to determine the relative benefit of 7T MRI for endonasal endoscopic surgical efficacy.

Utility of 7 Tesla MRI for Preoperative Planning of Endoscopic Endonasal Surgery for Pituitary Adenomas

“…de Rotte et al first reported the feasibility of pituitary imaging at 7 T MRI. 9 Barrett et al, who qualitatively compared 7 T versus conventional MRI in a preliminary set of skull base patients, confirmed improved detection rates of internal carotid artery (ICA) branches and cranial nerves (CNs) at 7 T. 14 Most recently, Law et al reported results from a microadenoma in one Cushing's patient who was MRI negative at conventional field strength but visible at 7 T in a location that correlated with petrosal sampling and postoperative outcome. 15 Early reports suggesting feasibility and benefits of ultra-high field MRI over lower field techniques in pituitary pathology have been limited by small sample sizes and inability to statistically compare 7 T to lower field scans.…”

“…15 Early reports suggesting feasibility and benefits of ultra-high field MRI over lower field techniques in pituitary pathology have been limited by small sample sizes and inability to statistically compare 7 T to lower field scans. 9,14 Furthermore, the utility of 7 T MRI has not been quantitatively examined in a homogenous cohort of pituitary adenoma patients. The purpose of the present study was to acquire preoperative 7 T MRI and quantitatively compare detailed neuroradiological findings for pituitary adenomas and adjacent skull base neurovascular structures to conventionl MRI.…”

7T MRI in epilepsy patients with previously normal clinical MRI exams compared against healthy controls

“…Details of the sequences are available in Table 2 . This protocol was optimized for detection of epileptogenic foci by reference to literature [ 18 , 19 , 25 , 26 , 28 , 29 , 32 ] and in consultation with a CAQ neuroradiologist (BD) [ 37 , 38 ].…”

Emerging Use of Ultra-High-Field 7T MRI in the Study of Intracranial Vascularity: State of the Field and Future Directions

“…However, multiple authors have also conceded that susceptibility artifacts near large air-tissue interfaces and the skull base could compromise the utility of 7T in some patients. 8,10 MR imaging at 7T may also assist in identifying parenchymal areas with an increased likelihood of microscopic high-grade glioma infiltration, which is challenging at clinical field strengths and important for determining resection margins. 11 Various imaging metrics, including those based on DWI, have been used to identify white matter infiltration by gliomas that cannot be resolved at lower field strengths.…”

“…de Rotte et al 17 were the first to demonstrate the feasibility of pituitary adenoma imaging at 7T; however, their study did not report on vascular sequences. Barrett et al 10 used a semiquantitative rating system to demonstrate superior visualization of internal carotid artery branches and vasculature within skull base tumors using 7T TOF, despite higher B 0 and B 1 inhomogeneity artifacts at 7T. It does appear that TOF could benefit surgical navigation to minimize vascular injury during endoscopic pituitary surgery (Fig 1).…”