BOLD-fMRI Study Of The Motor Centre Cortex In Patients With Cerebral Tumors

Blood Oxygenation Level-Dependent functional Magnetic Resonance Imaging (BOLD-fMRI) is a new technique for neuroimaging, which expanded physiological function field of radiology beyond observing anatomic structure. In recent years, fMRI has obtained extensive advance in neuroscience, such as neurosurgery, psychology, recognition, etc.. BOLD-fMRI mainly bases on the unmatching of hemodynamic Level during brain cortex activation, and the unmatching can result in of diamagnetic deoxyhemoglobin in brain active area decrease relatively. The decrease of diamagnetic deoxyhemoglob makes the signal of T2* singal increase and it can be detected by fast MR sequence. As a visualized and noninvasive technique, fMRI has the predominant characteristics in high temporal and spatial resolutions for displaying the neuronal activities, so it is well fit for research on the pathophysiological mechanisms in patients with motor cortex space-occupying lesions.Because of various pathology of the space-occupying lesions and different state of the affected motor cortex, the clinical symptom of patients wasn't homogeneous: (1)when the space-occupying lesion was small or the motor cortex was affected slightly, the patients might had a little or without motor deficits. BOLD-fMRI technique could not only locate the affected motor cortex but research on the pathophysiology of motor cortex reorganization by analyzing the volume(V) and T value in the motor cortex activation. (2)For the hemiparetic patients with cerebral tumors, to locate the affected side sensorimotor cortex was often impossible. To our knowledge, there were few studies about pathophysiology of motor cortex reorganization in patients with space-occupying lesions and locating motor cortex in hemiparetic patients with brain tumor using fMRI. In this study, we studied the motor cortex in patients with space-occupying lesions and tumors. The details were shown as following:Part I fMRI study of the motor cortex reorganization in patientswith space-occupying lesionsObjective: To study the cortex reorganization using BOLD-fMRI and analyze its relevant pathophysiology of the patients with space-occupying lesions in motor cortex area.Methods: Twelve patients were examined using BOLD-fMRI technique at GE-signa 1.5T MRI system (nine with tumor, three with abscess; All patients with little or without motor deficit and all the myodynamia of contralateral upper limbs was no less than IV grade). A block-paradigm was applied with the contralateral and the ipsilateral fingers holding still or oppositing respectively, there were two times scan for each patient, each scan obtained tweleve blocks, each block was twenty seconds and the first block was control state. Functional data was obtained using EPI series. Data processing was carried out using SPM99. Result was analyzed with Single-subject analysis, t test was used to analyze the statistic significance(high threshold, P=0.05).Results: There were several correlative functional cortex activation in all patients. The Ml(primary motor aera) and SMA(supplementary motor aera)activation aera of each patient was observed and analyzed. Compared to the unaffected side motor cortex activation, the affected side cortex activation exhibited at least one kind of difference in all the patients, which showed:(D Functional displacement presented in ten patients but without weakening of the affected Ml (four cases in the affected Ml, four in both affected Ml and SMA, and two only in SMA) .? Activation of SMA was stronger (four patients) or weaker (two patients) when the affected contralateral fingers opposition than when the ipsilateral fingers movement. In the two patients which activation of SMA weakened, the volume of SMA activation of one patients was mostly lied in the affected side. For another patient, the SMA aera was affected.(3) Functional activation within the affected Ml was decreased(one patient), but the SMA activation of the patient was stronger when the contralateral fingers opposition.Conclusion: The result suggests that two parttens of motor cortex reorganization present in patients with space-occupying lesions situated in motor area: the affected side activation displace but exist compensation, and there is compensation between the affected Ml and SMA. FMRI can exhibit the activation of motor cortex straightly and has potential as a tool to guide the neurosurgery.Part II fMRI study of locating the affected Ml in hemipareticpatients with cerebral tumorsObjective: To study the Ml aera using the BOLD-fMRI in hemiparetic patients with brain tumors, and to analyze the feasibility of robust location of the affected side Ml using the affected ipsilateral hand motor task.Methods: Seven patients was examined using BOLD-fMRI technique at GE-signa 1.5T MRI system (the Ml aera of tumor side affected severely, the myodynamia of contralateral upper limbs less than IV grade). A block-paradigm was applied to the affected contralateral and the unimpaired ipsilateral and the both side fingers holding still or oppositing respectively, there were three times scan for each patient, each scan obtained tweleve block, each block was twenty seconds and the first block was control state.Functional data was obtained using EPI series. Data processing was carried out using SPM99. Result was analyzed with Single-subject analysis, / test was used to analyze the statistic significance(low threshold, P<0.05 ). Results: Because the tumor side Ml of each patient was affected severely, most of patients could not finish all the three motor tasks, but all patients finished the ipsilateral hand task successfully. The activation aera of affected side Ml (primary motor aera) and PM(premotor cortex) of each patient was observed and analyzed, the result showed:(D In the two tasks which included the contralateral hand (the contralateral hand task and the both side hand task), there were only one patient finshed the two tasks and two patients finshed the both side hand motor task. The affected Ml was activated in all the three patients(42.9%, n=7).(2) All patients finished the unimpaired ipsilateral hand task successfully. The activation aera of tumor side PM was found in six patients(85.7%, n=7). Then, the precentral gyrus of the tumors side can be identified by takening the PM as a functional landmark.Moreover, the precentral gyrus of the tumor side were observed in two cases(patient 2,3) of all the patients by both the task which obtained the contralateral hand and the unimpaired ipsilateral hand task. The result suggested that location of the affected side precentral gyrus with the two different methods had a rather accordance. Conclusion: The precentral gyrus on the tumors side in patients with tumor situatedin motor coetex may be located using two methods:(1) If the patients can afford to finish the contralateral hand or the both side hand task, the affected side Ml must be activated. Then, the location of precentral gyrus on the tumor side became to be an easy job , but most patients can not finish the two tasks.(2) Because of accomplishing the unaffected ipsilateral hand task easily for all patients and location the ipsilateral PM well, the precentral gyrus on the tumors side can be identified by takening the PM as a functional landmark.Especially, The second mothod make up the shortage of location the affected side precentral gyrus using the the contralateral hand or the both side hand task. The two methods can do well in location of the precentral gyrus on the tumor side. fMRI can exhibit the activation of motor cortex straightly and has potential as a tool to direct the neurosurgery. SummaryFor the patients with a little or without any motor deficits, the result suggest that there were two parttens of motor cortex reorganization. The reorganization perhaps correlate with the adaption or compensation of the motor cortex. For the hemiparetic patients with the motor cortex tumors, the precentral gyrus on the tumor side may be located using three different hand motor tasks. Meanwhile, the result suggested that fMRI can exhibit the activation of motor cortex straight and has potential as a tool to direct the neurosurgery.Being a new technique, fMRI has the above-mentioned advantage, but it also has some shortcoming. For example, it is difficult to select the adapted threshold for distinguishing whether functional cortex is activated or not in the data analysis with the general linear model. Nowadays, the result of fMRI hasn't been regarded as statistic parameter yet. For this reason, the result of this study was not analyzied with precise statistics among the samples. With the more knowledge on the pathophysiological of motor cortex diseases and with the continuous development of fMRI technique, the above-mentioned shortcoming must be get improvement. fMRI will play a more important role in the fields of the clinical application and primary study about the patients with motor cortex space-occupying lesions.