Tomography

Vol. 3 No. 2 - June 2017

Tomography is a scientific journal for publication of articles in imaging research

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Language Mapping Using T2-Prepared BOLD Functional MRI in the Presence of Large Susceptibility Artifacts—Initial Results in Patients With Brain Tumor and Epilepsy Jun Hua 1,2 , Xinyuan Miao 1,2 , Shruti Agarwal 3 , Chetan Bettegowda 4 , Alfredo Quiñones-Hinojosa 5 , John Laterra 6 , Peter C. M. Van Zijl 1,2 , James J. Pekar 1,2 , and Jay J. Pillai 3 1 F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland; 2 Neurosection, Division of MRI Research, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; 3 Division of Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland; 4 Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland; 5 Neurological Surgery, Mayo Clinic, Jacksonville, Florida; and 6 Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland Corresponding Author: Jun Hua, PhD Johns Hopkins University School of Medicine, Department of Radiology, Kennedy Krieger Institute, F. M. Kirby Research Center for Functional Brain Imaging, 707 N Broadway, Baltimore, MD, 21205; E-mail: jhua@mri.jhu.edu Key Words: presurgical, implant, hemorrhage, dropout, distortion Abbreviations: Functional magnetic resonance imaging (fMRI), echo planar imaging (EPI), T2-prepared (T2prep), blood oxygenation level-dependent (BOLD), gradient-echo (GRE), magnetic resonance (MR), fluid attenuated inversion recovery (FLAIR), 3-dimensional (3D), echo time (TE), repetition time (TR), temporal signal-to-noise ratio (tSNR), contrast-to-noise ratio (CNR), regions of interest (ROIs), cerebrovascular reactivity (CVR) At present, presurgical functional mapping is the most prevalent clinical application of functional magnetic resonance imaging (fMRI). Signal dropouts and distortions caused by susceptibility effects in the current stan- dard echo planar imaging (EPI)-based fMRI images are well-known problems and pose a major hurdle for the application of fMRI in several brain regions, many of which are related to language mapping in presur- gical planning. Such artifacts are particularly problematic in patients with previous surgical resection cavi- ties, craniotomy hardware, hemorrhage, and vascular malformation. A recently developed T2-prepared (T2prep) fMRI approach showed negligible distortion and dropouts in the entire brain even in the presence of large susceptibility effects. Here, we present initial results comparing T2prep- and multiband EPI-fMRI scans for presurgical language mapping using a sentence completion task in patients with brain tumor and epilepsy. In all patients scanned, T2prep-fMRI showed minimal image artifacts (distortion and dropout) and greater functional sensitivity than EPI-fMRI around the lesions containing blood products and in air-filled cavi- ties. This enhanced sensitivity in T2prep-fMRI was also evidenced by the fact that functional activation during the sentence completion task was detected with T2prep-fMRI but not with EPI-fMRI in the affected areas with the same statistical threshold, whereas cerebrovascular reactivity during a breath-hold task was preserved in these same regions, implying intact neurovascular coupling in these patients. Although further investiga- tions are required to validate these findings with invasive methods such as direct cortical stimulation map- ping as the gold standard, this approach provides an alternative method for performing fMRI in brain re- gions with large susceptibility effects. INTRODUCTION Presurgical functional mapping in patients with brain tumor and epilepsy is increasingly performed in large medical centers across the United States and worldwide (1-4). In patients with brain tumor, because of the infiltrative nature of most gliomas, complete surgical tumor removal is often impossible. To accom- plish a maximal tumor resection for optimal therapeutic effect and simultaneously preserve neurological function and quality of life, a critical balance must be sought between the extent of resection and risk of postprocedural neurological deficit due to inadvertent injury to adjacent healthy functional (also known as "eloquent") brain tissue. A similar concern exists with resection of other focal brain lesions such as vascular malformations and epileptogenic lesions such as malformations of cortical devel- opment. Thus, individual-based brain mapping of critical brain functions, such as sensorimotor and language, and accurate information on hemispheric dominance are of utmost impor- tance for neurosurgeons to decide which surgical options are RESEARCH ARTICLE ABSTRACT © 2017 The Authors. Published by Grapho Publications, LLC This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). ISSN 2379-1381 http://dx.doi.org/10.18383/j.tom.2017.00006 TOMOGRAPHY.ORG | VOLUME 3 NUMBER 2 | JUNE 2017 105

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