Applications Of Resting-state FMRI In Brain Functional Cortex Localization And Brain Plasticity

Part ⅠPreliminary application of resting-state functional magnetic resonance imaging in preoperative localizing language cortex for glioma patientsObjectives To introduce the application of resting-state functional magnetic resonance imaging (R-fMRI) in preoperative localizing language area for glioma patients.Methods 12 patients with gliomas involved in the language area underwent R-fMRI and language functional magnetic resonance imaging (L-fMRI). Site-by-site comparisons between R-fMRI/L-fMRI and DCS were performed to calculate sensitivity and specificity of R-fMRI and L-fMRI with DCS as a gold standard.Results 12 patients performed R-fMRI successfully meanwhile 10 patients accomplished acquisition of L-fMRI because another two patients were unable to cooperate well with the language task during scanning. For language area localization, the sensitivity and specificity of R-fMRI were 47.7% and 95.3%. The sensitivity and specificity of L-fMRI were 34.3% and 88.1%. The area under ROC curve of R-fMRI is 0.69 and that of L-fMRI is 0.61. The sensitivity and specificity of combined R-fMRI and L-fMRI were 60% and 83.5%, the area under ROC curve is 0.73.Conclusions R-fMRI may be utilized as one of valuable tools, to some extent, to localize the language area before glioma surgery and the sensitivity of it should be improved. Combined R-fMRI and L-fMRI could help localizing language area more accurately.Part IILocalizing hand motor area using resting-state fMRI:validated with direct cortical stimulationObjectives Resting-state functional magnetic resonance imaging (R-fMRI) is a promising tool in clinical applications, especially for potential neurosurgery pre-surgical mapping. This study aimed to investigate sensitivity and specificity of R-fMRI in localization of hand motor area in brain tumor patients, validated with direct cortical stimulation (DCS). In addition, we compared this technique to motor Blood-oxygenation-level-dependent (BOLD) fMRI (M-fMRI).Methods R-fMRI and M-fMRI were acquired from 17 brain tumor patients. Cortex sites of hand motor area were recorded by DCS. Site-by-site comparisons between R-fMRI/M-fMRI and DCS were performed to calculate sensitivity and specificity of R-fMRI and M-fMRI with DCS as a gold standard. The performance of R-fMRI and M-fMRI was compared statistically.Results A total of 609 cortex sites were tested with DCS and compared with findings of R-fMRI in 17 patients. For hand motor area localization, the sensitivity and specificity of R-fMRI were 90.91% and 89.41%. Given that two subjects cannot comply with M-fMRI,520 DCS sites were compared with findings of M-fMRI in 15 patients. The sensitivity and specificity of M-fMRI were 78.57% and 84.76%. For these 15 patients who performed both R-MRI and M-fMRI, there is no statistical difference of sensitivity or specificity between these two methods (p=0.3198 and p= 0.1431 respectively). The area under ROC curve of R-fMRI is 0.89 and that of M-fMRI is 0.82.Conclusions Both sensitivity and specificity of R-fMRI are high in localizing hand motor area, and even equivalent or slightly higher compared with M-fMRI. Given its convenience for patients, R-fMRI is a promising tool to substitute M-fMRI in pre-surgical mapping.Part ⅢMapping sensorimotor area using intraoperative resting-state functional MRI in brain tumor surgery:initial experienceObjectives This study aimed to introduce our initial experience of intraoperative Resting-state fMRI(R-fMRI) in real-time mapping sensorimotor area during brain tumor surgery.Methods Preoperative and intraoperative R-fMRI were acquired from 30 brain tumor patients. Functional connectivity was used to show motor cortex. Different correlated factors were analyzed for better quality of imaging. Direct cortical stimulation (DCS) was utilized to find whether there is immediate reorganization following tumor resection and to find whether the intraoperative R-fMRI is accurate in showing motor cortex.Results Preoperative and intraoperative R-fMRI were successfully acquired from 30 brain tumor patients.21 cases of intraoperative R-fMRI showed satisfying image quality, which correlated not with the anesthesia method, but with whether the tumor cavity was filled with normal saline before scanning. In 4 cases,19 positive motor cortex sites were found by DCS before and after tumor resection and no brain reorganization was shown. For real-time motor area localization, the sensitivity and specificity of intraoperative R-fMRI were 61.7% and 93.7%. The area under ROC curve of R-fMRI is 0.78.Conclusions R-fMRI was a promising tool in real-time mapping motor cortex during tumor surgery. This technique should be improved and evaluated for the clinic use in the further studies.Part ⅣSensorimotor cortical changes assessed with resting-state fMRI following total brachial plexus root avulsionObjective Peripheral nerve injury can induce immediate and long-standing remodeling of brain cortex, which will affect efficacy after nerve repair. This study studied changes of corresponding cortical representations in patients with brachial plexus injuries.Methods Resting-state functional magnetic resonance imaging (R-fMRI) was acquired for 13 adult patients with total brachial plexus root avulsion, three of whom underwent second scans seven or eight months later. The time of examination ranged from one to 16 months after injuries. Nine healthy adults were enrolled as control. Seed-based functional connectivity was performed for all subjects.Results For nine patients whose first fMRI was performed from one to four months after brachial plexus injuries, images showed that their cortical maps of sensorimotor areas corresponding to hand and arm in the hemisphere contralateral to the injured side had much weaker correlation with the supplementary motor area (SMA) than those ipsilateral to the injured side, while symmetrical maps of bilateral cortical sensorimotor areas corresponding to hand and arm were observed in other four cases with fMRI tested from seven to 16 months after injuries. For three of the nine patients with asymmetrical cortical representations, second scans indicated symmetric results or even stronger correlation with SMA in the cerebral cortex contralateral to the injured side.Conclusions Total brachial plexus root avulsion makes cortical representations of the brachial plexus undergo a change from inactive to active state, which implies that peripheral deafferentation after brachial plexus injuries will induce corresponding cortical representations to be occupied by adjacent non-deafferented cortical territories.