Title : Recent advances in brain imaging
Abstract:
Introduction: Brain surgery may benefit from functional MRI (fMRI) that can detect changes in cerebral blood flow and oxygen utilization caused by tissue activation. Therefore, the patient needs to perform certain tasks in the scanner while fMRI is acquired. However, task-based fMRI (tb-fMRI) is time consuming and some patients can barely perform the tasks. As an alternative, resting state fMRI (rs-fMRI) can be utilized to demonstrate various brain networks within <10min acquisition time. This study attempts to compare tb-fMR and rs-fMRI in epilepsy patients towards a possibility of replacing tb-fMRI with rs-fMRI in situations where patients are non-cooperative or time is short.
Methods: The study included 19 subjects (8M/11F) aged between 17-61 years (mean 36.68 ± 11.82) suffering from variations of epilepsy (details in Tab. 1) that successfully completed tb- and rs-fMRI during a single session on a 3T scanner (Verio, Siemens, Germany). Acquisition of tb-fMRI 120 volumes of EPI was performed with TR/TE of 2000/20ms, FOV 220mm, 4mm slice thickness, in a block design for five language tasks (antonym generation, word generation, reading and comprehension, rhyming and picture naming). During rs-fMRI 200 volumes of EPI images with identical parameters were acquired. T1-weighted 3D MPRAGE was acquired for anatomical reference with TR/TE 2200/2.55ms, TI 900ms, FOV 240mm and flip angle of 8°. All data were retrospectively processed using commercially available fMRI planning software (Elements BOLD MRI mapping, Brainlab, Germany; CE-market, FDA clearance pending), which allows automated post-processing, such as denoising, and interactive tools to analyze tb- and rs-fMRI data.
Results: Results from tb-fMRI analysis yielded plausible results in almost all the subjects and which were concordant with the interactive seed based ROI from rs-fMRI, except for two subjects (ID 04,05). As an example, Wernicke’s area showed significant differences between tb- and rs-fMRI in patient 05 (Fig.1; tb-fMRI in yellow, rs-fMRI in pink). Overall, the quality of rs-fMRI results matches well with tb-fMRI and therefore can be considered as an alternative option for functional preoperative mapping, especially in cases where patients are non-cooperative or time is short.
