| Objective:To investigate and summarize the experiences of visulization of the pyramidal tract(PT) by diffusion tensor imaging (DTI)based fiber tracking(FT) in brain surgery. Methods:In the first part, the reproducibility of reconstruction of the PT by DTI based FT was confirmed. In this study, the PTs at the normal sides were reconstructed in 20 patients. FA threshold was set as 0.1. There were two methods to put regions of interest (ROI). The location of the first ROI was different in the two methods. The first ROI was put underneath of the precentral gyrus in the first method and at brain stem in the second method. Each PT was reconstructed three times. The reproducibility was assessed byκvalue, which was calculated according to the correspondence of the reconstructed PT at different times. The correspondence of the two methods was also assessed. In the second part, the experiences of cerebral tumor surgeries assisted by the pyramidal tract navigation were summarized in 74 patients. The factors which influnced the preservation of the PT were investigated. In the third part, intraoperative situation of the PTs and outcomes of surgeries were studied in the patients whose preoperative tractographies of the PT were directly adjacent to the tumors. The data of 41 patients whose tractographies of the PT were directly adjacent to the tumors was prospectively collected. The distances between intraoperative tractographies of the PT and the resection cavities were measured after tumor removal. Preoperative and postoperative muscle strength grades(MSG) and tumors'World Health Organization (WHO) grading were also recorded and statistically analyzed. Results:In the first part, the reproducibility of the two methods was good with theκvalue equal to 0.74±0.042 and 0.77±0.07 respectively. There was not significant difference between theκvalue of the two methods(p> 0.01). The two methods were not correspondent and theκvalue was just 0.47±0.08. The volumes of the PTs reconstructed by the two methods were 11.89±2.07 cm3 and 7.02±1.76cm3 respectively. There was significant difference between them(p< 0.01). The shape of the PTs reconstructed by using the first method were more close to the actual shape. In the second part, patients'motor deficits improved in 7(9.4%) patients after surgery,did not change in 45(60.8%) patients, aggravated in 14(18.9%) patients and developed hemiplegia in 5(6.7%) patients. Twelve patients'motor deficits aggravated after surgery in the 36 patients whose distances between the PT and the tumor were smaller than 5mm. Only three patients had new motor deficits in the 12 patients whose distances ranged 5 to 10mm. None had acquired motor deficits in the 26 patients whose distances were greater than 10mm. Maximum shifting of the PT ranged from-16.2mm to+17.2mm.In the third part, twelve patients'intraoperative tractographies of the PT were still at the borders of tumor cavities after tumor removal in the 41 patients whose tractographies of the PT were directly adjacent to the tumors. The patients whose distances between intraoperative tractographies of the PT and the tumor cavities were greater than 5mm did not have acquired motor deficits after surgery. The distances between intraoperative tractographies of the PT and the tumor cavities were significantly correlated with preoperative MSG and postoperative changes of MSG. Conclusions:The first method was prefered in the reconstruction of the PT. The reproducibility of this method was sufficient for clinical requirment. The pyramidal tract navigation can decrease the occurance of severe motor deficits. The distance between the PT and tumor as well as irregular shifting of the PT can affect the preservation of the PT. Though the PT is directly adjacent to the tumor preoperatively, it might shift away from the tumor cavity after tumor removal. If the distance between surgical operation and the tractography of the PT is less than 5mm, the PT might be damaged and neurological deficits in motor function coule be induced. |
PDF Full Text Request