The Study Of The Value Of Diffusion Tensor Imaging In Acute Cerebral Infarction

Objective: Acute cerebral infarction is a baneful common disease. So coming to diagnosis early and prognosis rationally play an important role in acute cerebral infarction. Magnetic resonance diffusion tensor imaging (DTI) based on conventional magnetic resonance imaging(MRI) and diffusion weighted imaging(DWI) is the water diffusion imaging technique devel- oped in rencent years. Diffusion tensor tractography(DTT),a new noninvasive technique, can help estimate the structural connectivity of the briar. Analyzing the characteristics of MRI,DWI and DTI in 45 patients with acute cerebral infarction in different phases, measuring the values of fractional anistro- phy(FA),apparent diffusion coefficient(ADC) in different regions of interests(ROI) and performing bilateral corticospinal tract(CST) to explore the values of DTI in acute cerebral infarction.Methods: Forty-five patients (mean age 62.33±12.57 years, range 42 to 87years old; male 34, female 11) presenting within 7days of the onset were studied. All the patients have neuro- logical impairment in some degree. According to the visiting time, hyper acute phase(<12h)n=7,acute phase(12²4h)n=18, subacute phase(>24h⁷d)n=20. Patients with primary cerebral hemorrhage assessed by computed tomography(CT) were exclu- ded from the study. Conventional MRI (anteroposterior axes T1WI T2WI, abscissa axis T1WI T2WI),DWI and DTI were performed on a Siemens Avanto 1.5T using a standard. The values of FA and ADC were measured in the infarcted regions, corresponding contralateral regions, and the central and peripheral parts in lesions. CST performed by DTT showed disrupted whose myodnamia was not or not completely recovered. The injured degree of CST in grade 1 was complete, grade 2 was complete but compression shift, grade 3 was break. All the patients were measured according to National Institutes of Health Stroke Scale(NIHSS) when on admission and two months after the onset. The statistics were made by SPSS 13.0, and P<0.05 is considered to have statistical difference. The difference between measurement data was decided by compared t-test, the difference between numeration data was assessed byχ² test, and the correlation analysis was taken by spearman correlation.Results:1 The comparison of the positive result between DWI and MRI(T2WI)All of the 45 patients'are right handedness. All the lesions can be seen on DWI sequence, the positive rate of DWI in infarction detection was 100%. At the same time,only 40 patients were detected through T2WI and the positive rate was 88.89%. The other 5 patients who's lesions were not undetected were in hyperacute phase. The contrastion showed that the posi- tive rate of DWI was higher than conventional MRI (χ²=5.00, P<0.05).2 The variation of the FA and ADC in different phases in infarctionADC of lesions were significant in hyperacute and acute phase(P<0.01). FA of lesions were significant in acute and subacute phase(P<0.01).3 The variation of the FA and ADC between the central and peripheral parts in lesionsDifference of FA between central and peripheral parts of lesions were significant in acute phase(P<0.01). Difference of ADC between central and peripheral parts of lesions were significant in hyperacute and acute phase(P<0.05).4 The relationship between the value of FA and prognosisAll the patients' NIHSS score was average 5.57±2.56(rage 1 to 17) when on admission and was average 2.33±2.47(rage 0 to 12) two months after the onset. The decreasing percentage of FA value in infarctions has significant positive correlation with NIHSS₍₁₎(r=0.500,P<0.05), and has no correlation with NIHS S₍₂₎.5 The condition of CSTThe CST was created in each patient,and there were 22 cases of grade 1,13 cases of grade 2,10cases of grade 3.Injured degree of CST has significant positive correlation with NIHSS₍₂₎ (r=0.812, P<0.05). Conclusion:1 DWI,DTI are more sensible than conventional MRI in the diagnosis of hyperacute phase in cerebral infarction.2 There is characteristic discipline in charges of FA and ADC in different phases of stroke and it is useful for staging.3 DTT has important value to detect the ischemic penum- bra.4 The larger the decreasing percentage of FA is, the more serious the clinical manifestation is. It can be considered as an objective index of prognosis.5 Observing the condition of CST in patients with acute cerebral infarction and analyzing the relationship between the impairment of CST and lesions can prognosis early and object- ively.