| Objective: leukoaraiosis (LA) is a kind of nonspecific cerebral leukodystrophy. It causes wide damage to white matter around ventricle for many reasons. The aged people are susceptible to LA. It always occurs with other white matter diseases and the most common one is cerebrovascular disease. The incidence rate of LA would increase when there is lacunar infarction or bleeding on MR imaging. Because the signal intensity of LA is extremely similar to acute lacunar infarction near ventricle, it is very difficult to distinguish them in the aged patients. As acute lacunar infarction especially with multiple or with little symptoms may be the major dangerous factor that can cause vascular dementia in the aged. It is very significant to find acute lacunar infarction from LA in time to improve the patient's prognosis.Diffusion tensor imaging (DTI) is widely being used in clinical research in cerebral infarction. It can discover the patho-alter of the infarction focus much earlier, display the course of white matter fibers and analyse the relationship between the infarction and the fibers so as to judge the degree of the impaired cerebral infarction, trace the developing process of the cerebral infarction and predict the result of it.The aim of this research is to use DTI technology of 3.0 T MR to measure the fractional anisotropy (FA) and average diffusion coefficient (DCavg) of LA foci and the complicated acute lacunar infarction and to describe the courser of the white matter fibers to approach the diagnostic value of DTI on the discrimination of the foci of the two, so it can guide clinic and appraise the prognosis better.Method: We chose 82 LA patients with acute cerebral infarction symptom or (and) signs (or the potential patients with LA). They were examined in our hospital from May to December in 2006, including 49 male and 33 female at the age from 48 to 81 years old. The mean age of all the 82 cases was 63.6 years old. In addition we selected 30 aged volunteers without LA or without other diseases of certral nervous system. All the cases were examined by 3.0T MRI of its conventional scan and DTI scan and all the imaging data were kept. After three months the same measures were used to recheck all the cases. Then we divided all the 82 cases into 3 groups, divide the acute lacunar infarction cases of final diagnosis as Group A the identified cases of LA as Group B and the volunteers which were blank group as Group C. All the imagings were transmitted to the Advantage Workstation 4.2P and postprocessed with functool software. Anisotropic and DCavg maps were reconstruction FA values and DCavg values of LA lesions and acute lacunar infarction of the region of interests were measured and analysised by SPSS 11.5 software.Results: We found FA values and DCavg values of LA and acute lacunar infarction were sharply different from each other (P<0.0001), though they were all shown equal or hypo-signal on T1WI and hyperintensity on T2WI . FA values of Group A were 0.32±0.11, while FA values of Group B were 0.26±0.10 and Group C were 0.49±0.11of. The FA values of them had statistical significance(F=85.2,P=0.0001). We could see the disruption of white matter tracts of infarction and the distortion of white matter tracts around an infarct of Group A in FA map. We could also see the change of fibers were closely correlated with the localization of the infarction. Group A were shown hypo-signal in DCavg map, while Group B were shown hyperintensity. The DCavg values of Group B were 1.36±0.21×10–3mm2/s,while DCavg values of A group were 0.35±0.05×10–3 mm2/s and those of Group C were 0.74±0.07×10–3mm2/s. The DCavg values of Group A were obviously lower than those of Group C and the values of Group B were obviously higher than Group C'. After statistical calculation, we could draw a conclusion that the DCavg values of the three also had statistical significance(F=72.6,P=0.0001).Conclusion:1 DTI technology is a utility diagnostic technique to distinguish acute lacunar infarction from LA lesions, which were often missing on conventional MRI scan.2 3.0T DTI technology may display the hyper-acute and acute cerebral infarction more clearly than conventional MRI or CT. It can also rigorously distinguish the period when the focus of infection was. As a new diagnostic method, DTI technology should be a routine examination for cerebrovascular diseases.3 DTI sequence should be added when the patient with cerebral ischemia has been examinated by routine MRI and found LA or cerebral infarction on acute stage in doubt. DTI can find hyper-acute and acute cerebral infarction immediately in order to treat the illness in time.4 DTI technology can reflect the mini-alter of alba formation pericerebral infarction with non-invasion in vivo. It can also appraise the degree of cerebral infarction and anticipate the result. |
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