Robust presurgical functional MRI at 7 T using response consistency

Abstract

Functional MRI is valuable in presurgical planning due to its non‐invasive nature, repeatability, and broad availability. Using ultra‐high field MRI increases the specificity and sensitivity, increasing the localization reliability and reducing scan time. Ideally, fMRI analysis for this application should identify unreliable runs and work even if the patient deviates from the prescribed task timing or if there are changes to the hemodynamic response due to pathology. In this study, a model‐free analysis method—UNBIASED—based on the consistency of fMRI responses over runs was applied, to ultra‐high field fMRI localizations of the hand area. Ten patients with brain tumors and epilepsy underwent 7 Tesla fMRI with multiple runs of a hand motor task in a block design. FMRI data were analyzed with the proposed approach (UNBIASED) and the conventional General Linear Model (GLM) approach. UNBIASED correctly identified and excluded fMRI runs that contained little or no activation. Generally, less motion artifact contamination was present in UNBIASED than in GLM results. Some cortical regions were identified as activated in UNBIASED but not GLM results. These were confirmed to show reproducible delayed or transient activation, which was time‐locked to the task. UNBIASED is a robust approach to generating activation maps without the need for assumptions about response timing or shape. In presurgical planning, UNBIASED can complement model‐based methods to aid surgeons in making prudent choices about optimal surgical access and resection margins for each patient, even if the hemodynamic response is modified by pathology. Hum Brain Mapp 38:3163–3174, 2017. © 2017 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Association between tissue hypoxia, perfusion restrictions, and microvascular architecture alterations with lesion-induced impairment of neurovascular coupling

“…55 , 56 Further studies demonstrated the usefulness and reliability of 7 tesla BOLD fMRI for presurgical planning. 57 , 58 Therefore, future studies are highly warranted to replicate our findings on a larger scale including CVR mapping and high-field or ultra-high-field BOLD fMRI. The model for calculation of OEF has also several limitations.…”

7 T and beyond: toward a synergy between fMRI-based presurgical mapping at ultrahigh magnetic fields, AI, and robotic neurosurgery

“…In the next decade, magnetic field strengths are expected to go even higher than 7 T to reach 10 T or even 20 T [ 128 , 129 ]. This growing interest in UHF is already promoting the development of novel analysis methods to detect atypical brain activations [ 130 ]), to generate reliable patient-specific fMRI maps in cases with altered hemodynamic responses [ 131 ] or with huge head motion artefacts [ 132 ]. Thanks to the increase in BOLD sensitivity at UHF, presurgical mapping with fMRI at 1-mm isotropic resolution offers high BOLD sensitivity, accurate spatial mapping, and manageable data size.…”

7 Tesla and Beyond

“…[298][299][300][301][302] Thus far, however, UHF f MRI has been less extensively evaluated for clinical application, for example, for presurgical planning. 303,304…”

“…In addition to the main applications of UHF fMRI to study neuronal activity at high spatial resolution, further promising areas of research are focused on fMRI of the cortical layers and columns 298–302 . Thus far, however, UHF fMRI has been less extensively evaluated for clinical application, for example, for presurgical planning 303,304 …”