Laboratorial Study Of Navigation Accuracy For Intraoperative Magnetic Resonance Imaging And The Surgical Application Of Integrating Functional Magnetic Resonance Imaging

Object: Navigation accuracy is the key marker for the evaluation of intraoperativemagnetic resonance imaging (iMRI) navigation. In this labortorial study, ananthropomorphic head phantom was used to investigate the accuracy of PoleStar N20iMRI and its influence factors, with the aim of providing theoretical guidance for clinicalapplication.Methods: A Peg-Board phantom was used as a model. The accuracy of PoleStar N20iMRI navigation was measured with reference to the target spatial locations, differentbody position, imaging sequences, noise, movement of the operating table and themagnet poles. The data were analyzed statistically.Results: The accuracy of PoleStar N20 iMRI was obviously related to imaging sequences,noise percentage and slice thickness. There was no relationship between the accuracy andthe target spatial location or body position or movement of operating table or magnetpoles.Conclusions: Neuronavigation accuracy of PoleStar N20 iMRI was excellent and reliablefor clinical application.Object: The purpose of this study was to obtain detailed map of white matter fiber tracts in patients with intracerebral neoplasm by using MR diffusion tensor imaging (DTI). Thelikelihood, method, and clinical application for integration of DTI and iMRI of PoleStarN20 in brain surgery involving pyramidal tracts were studied and presented.Methods: The preoperative DTI was merged into iMRI for neuronavigation by usingmanual point merge technique with non-rigid calculation in 19 patients with brain surgeryinvolving pyramidal tracts. If needed, the iMRI scan and integration of images wererepeated during the operation. The relationship between the tumors and adjacentpyramidal tracts were segmented and reconstructed for three-dimensional visualizationand navigation. The motor function of extremities were examined before and afteroperation.Results: The merge of DTI with iMRI were of success. During the operation, we got theinformation about range of tumor to be resected and adjacent pyramidal tractsdynamically. The lesions were completely resected in 12 cases (63.2%), subtotal in15.8%. Postoperative neurological status was improved or stabilized in 84.2% cases.Conclusions: The integration of DTI and iMRI can provid the three-dimensionalvisualization of lesions and pyramidal tracts. This method is feasible to raise the totalremoval rate and decrease the rate of aggravation of motor function in brain surgeryinvolving pyramidal tracts.Object: In this study, we applied the blod oxygen level dependent (BOLD) functionalmagnetic resonance imaging (fMRI) for the localization of motor cortex and linguisticcortex. The likelihood, method, and clinical application for integration of BOLD andiMRI in brain surgery involving functional cortex were studied and presented.Methods: A total of 48 patients with brain tumors adjacent to the functional cortex wererandomly divided into trial (integration navigation) or control group (non-integration navigation). In the trail group, the preoperative BOLD was merged into iMRI forneuronavigation by using manual point merge technique with non-rigid calculation. Ifneeded, the iMRI scan and integration of images were repeated during the operation. Therelationship between the tumors and adjacent functional cortex were segmented andreconstructed for three-dimensional visualization and navigation. In patients with lesionsadjacent to linguistic cortex, the awaking anaesthesia and direct cortical electricalstimulation were performed to evaluate the effectiveness of BOLD. The motor functionof extremities and linguistic function were examined before and after operation.Results: The integration of DTI with iMRI were of success in trial groups. Thesensitivity of BOLD was 72.7% and specificity was 81.8%. Lesion resection: In motorcortex cases, the lesions were completely resected in 86.7% of the trial group, and 64.7%of the control group. In linguistic cortex cases, the lesions were completely resected in83.3% of the trial group, and only 60% in the control group. Morbidity rate: In motorcortex cases, 80% of the patients in trial group did not suffer surgery-induced paralysis,while in control group this figure was only 35.3% (statistically significant). In linguisticcortex cases, 83.3% of the patients in trial group did not suffer aphasia, higher than the60% in control group.Conclusions: The integration of BOLD and iMRI can provid the three-dimensionalvisualization of lesions and functional cortex. This method is feasible to raise the totalremoval rate and decrease the rate of aggravation of motor or linguistic function in brainsurgery involving functional cortex.Object: Although neuronavigation based on integration of updated intra-operative iMRIand DTI or BOLD proved to be effective in correcting errors caused by brain shift, but DTI or BOLD images was still provided before the surgery. Brain shift will certainlycause the corresponding shift in these functional structures. Making a negative factoraffecting the accuracy of neuronavigation. In order to solve this problem, we usedmathematical models based on thin-plate splines to adjust the navigative errors of DTI orBOLD induced by brain shift.Methods: The techniques of DTI and BOLD were used to localize the pyramidal tractsand functional cortex in 19 patients with brain tumors involving pyramidal tracts inhigh-field MRI and 21 patients with tumors involving motor or linguistic cortex. In thisresearch, pre-operative iMRI and intra-operative iMRI were used respectively forpre-operative and intra-operative data fields, and non-rigid calculation based on thin-platesplines was applied for predicting the tendency of brain shift. When this calculatedtendency was integrated into DTI or BOLD images, predictive DTI or BOLD imagesafter brain shift were acquired. Then we integrated these DTI or BOLD images intointra-operative iMRI images so as to visually learn the location and relative relationshipof the brain tissue, residual tumor and pyramidal tracts or functional cortex after brainshiftResults: The imaging and integration were of success in total 40 patients. We alsosuccessfully acquired the prediction of DTI and BOLD images shift.Conclusions: The mathematical model of non-rigid calculation method based onthin-plate splines was effective in predicting the shift of DTI or BOLD images.