BACKGROUND: Three-dimensional diffusion tensor tract (DTT) is the newest imaging to describe the structure of white matter fiber in three-dimensions, it has great significance in dividing the concrete anatomic site of gray and white matter lesions, displaying the correlation with fibrous band and judging clinical prognosis, which is incomparable by other imagings. OBJECTIVE: To observe the conditions of corticospinal tract (CST) in acute cerebral ischemic stroke patients, and analyze the relationship between motor function and the severity of CST injury. DESIGN: A case-control observation. SETTING: Department of Medical Imaging, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA. PARTICIPANTS: Fifteen patients with acute cerebral infarction were selected from Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA from February to December in 2005. They all suffered from acute attack and motor disorder of hemiplegic limbs to different extent, and were conformed by CT or MRI. There were 9 males and 6 females, aging 16-87 years old, the median age was 51.7 years, and all were right handed. Fifteen right-handed normal subjects, who were matched by age and sex with the patients in the cerebral infarction group, were selected from the relatives of patients and physicians of the Imaging Department as the control group. All the subjects were informed and agreed with the study. METHODS: The patients with acute cerebral infarction and subjects in the control group received MR diffusion tensor imaging (DTI) with GE 1.5 T nuclear magnetic resonance system, fiber tracking with the software of dTV-Ⅱ. Fractional anisotropy (FA) maps and three-dimensional tractography of bilateral CST of all patients were created. Displacement, continuity and destroy of fibrous bands were observed. At the same time, muscle strength of ipsilateral hand of patients with cerebral infarction was measured with Brunnstrom standard. The correlation between the severity of CST injury and the muscle strength of ipsilateral hand was analyzed with spearman correlation analysis. MAIN OUTCOME MEASURES: ① FA values in the infarcted sites and those in the contralateral corresponding sites of patients with cerebral infarction; ② CST manifestations in the patients with cerebral infarction and the control group. RESULTS: All the 30 testees were involved in the analysis of results. ① The FA values in infarcted sites of white matter were significantly lower than those in the contralateral ones (t =4.570,P < 0.001). ② In the control group, bilateral CST were reconstructed, they originated from precentral gyrus, went downwards to internal capsule, and extended to pontine and medulla oblongata, each fiber had good uniformity in continuous form. In the patients with cerebral infarction, the forms of contralateral CST were consistent with those in the control group with good continuity. Due to the involvement by the infarcted site to different extents, the ipsilateral CST manifested as continuous interruption and loss of uniformity in anatomic structure and form. The CST involvements were divided into three grades: integrated CST for grade 1 (n =2); integrated CST but compressed or displaced for grade 2 (n =5); interrupted CST for grade 3 (n =8). ③ The severity of CST injury was obviously correlated with the muscle strength of the ipsilateral hand (r =0.888, P < 0.05). CONCLUSION: ① CST is injured to different extents in patients with acute cerebral infarction, and the severity of injury is associated with muscle strength. It is indicated that it can be used to judge the prognosis of rehabilitative treatment. ②DTT can directly display the status of pyramidal tract more three-dimensionally. BACKGROUND: Three-dimensional diffusion tensor tract (DTT) is the newest imaging to describe the structure of white matter fiber in three-dimensions, it has great significance in dividing the concrete anatomic site of gray and white matter lesions, displaying the correlation with fibrous band and judging clinical prognosis, which is incomparable by other imagings. OBJECTIVE: To observe the conditions of corticospinal tract (CST) in acute cerebral ischemic stroke patients, and analyze the relationship between motor function and severity of CST injury. -control observation. SETTING: Department of Medical Imaging, Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA. PARTICIPANTS: Fifteen patients with acute cerebral infarction were selected from Fuzhou General Hospital of Nanjing Military Area Command of Chinese PLA from February to December in 2005. They all suffered from acute attack and motor disorder of hemiplegic limbs to different extent, and we reconformed by CT or MRI. There were 9 males and 6 females, aging 16-87 years old, the median age was 51.7 years, and all were right handed. Fifteen right-handed normal subjects, who were matched by age and sex with the patients in the cerebral infarction group, were selected from the relatives of patients and physicians of the Imaging Department as the control group. All the subjects were informed and agreed with the study. METHODS: The patients with acute cerebral infarction and subjects in the control group received MR diffusion tensor imaging (DTI) with GE 1.5 T nuclear magnetic resonance system, fiber tracking with the software of dTV-II. Fractional anisotropy (FA) maps and three-dimensional tractography of bilateral CST of all patients were created. Displacement, continuity and destroy of pipelines were observed. At the same time, muscle strength of ipsilateral hand of patients with cerebral infarction was measured with Brunnstrom standard. The correlation between the sever ity of CST injury and the muscle strength of ipsilateral hand was analyzed with spearman correlation analysis. MAIN OUTCOME MEASURES: ① FA values ​​in the infarcted sites and those in the contralateral corresponding sites of patients with cerebral infarction; ② CST manifestations in the patients with cerebral infarction and the control group. RESULTS: All the 30 testees were involved in the analysis of results. ① The FA values ​​in infarcted sites of white matter were significantly lower than those in the contralateral ones (t = 4.570, P <0.001). ② In the control group, bilateral CST were reconstructed, they originated from precentral gyrus, went downwards to internal capsule, and extended to pontine and medulla oblongata, each fiber had good uniformity in continuous form. In the patients with cerebral infarction, the forms of contralateral CST were consistent with those in the control group with good continuity. Due to the involvement by the infarcted site to different extents, the i CST implanted as divided in three grades: integrated CST for grade 1 (n = 2); integrated CST but compressed or displaced for grade 2 (n = 5) ; CST for grade 3 was interrupted (n = 8). ③ The severity of CST injury was corrected as the muscle strength of the ipsilateral hand (r = 0.888, P <0.05). CONCLUSION: ① CST was injured to different extents in patients with acute cerebral infarction, and the severity of injury is associated with muscle strength. It is indicated that it can be used to judge the prognosis of rehabilitative treatment.