The Diagnostic Value Study Of DWI,DTI And MRS In Cerebral Infarction

Ischemic cerebrovascular disease, i.e. cerebral infarction, is a common disease that threatens people's health and lives. The early diagnosis and therapy of cerebral infarction has been the focus of attention in medical science. Recently, the use and development of echo plannar imaging have provided a broad space for the early identification and therapy of cerebral infarction.The paper has done a retrospective analysis of the changes of MRI, DWI, DTI, and MRS in 94 cases of cerebral infarction of different stages, and has also studied its related literature, the purpose of which is to explore the value of the new technology in accurately identifying cerebral infarction and provide evidence for clear differentiation of the different phases of cerebral infarction, guidance on clinical therapy and judgment of prognosis.Methods: The study has collected 94 cases of different-phase cerebral infarction, using SIEMENS 1.5T Avanto MR scanning system. T1WI,T2WI,Dark-fluid and DWI were scanned regularly: the slice thickness was 6mm, the slice interval was 0.6mm, the field of view was 230mm×230mm, T1WI: TR/TE=400/7.8ms, T2WI: TR/TE=3250/99ms, Dark-fluid: TR/TE=9000/109ms, TI=2500ms. Diffusion weighted imaging used echo plannar imaging, x, y, z three direction were exerted by diffusion sensitive gradient. b=0s/mm2 and b=1000s/mm2, TR/TE=2000/71ms, the slice thickness was 6mm, the slice interval was 0.6mm, the field of view was 230mm×230mm. The ADC (apparent diffusion coefficient) map was made automaticly. Magnetic resonance spectroscopy used chemical shift imaging (CSI) method: TR/TE=1500/135ms, stimulated time: 4. The density of NAA, Cho, Lac were identified, and they were compared with corresponding regions. Diffusion tensor imaging used echo plannar imaging, 12 directions were exerted by diffusion sensitive gradient, b=1000s/mm2, TR/TE=4500/80ms, stimulated time: 4. All the orginal data were collected and treated by special DTI tools, which could give FA (fractional anisotropy) map. The change of FA value were analyzed. DTT was performed and bilateral corticospinal tract (CST) were reconstructed by seed method.Results: The successful rate of identifying and localizing super-acute cerebral infarction on DWI is 100%. Conventional T2WI and Dark-fluid, however, are very unlikely to identify and localize focus of super-acute cerebral infarction. Its successful rate of identifying such focuses in 6 hours is less than 50%. The focuses of super-acute and acute cerebral infarction are displayed as obvious high signal on DWI images, and low signal on ADC maps. The changing shown on T2WI and Dark-fluid images are not as clear as those on DWI ones. As illnesses proceed, signal on ADC maps gradually rises higher and higher, and finally it changes into high ones. The changes of DWI signal are just the opposite, whose process is a bit slower than the changes shown on ADC map. The mean ADC and rADC value of super-acute, acute, sub-acute and chronical cerebral infarction have a tendency of gradual increase. The FA values of cerebral infarction focuses are all lower than those in corresponding regions. The DTT images have demonstrated 7 cases of non-obvious changes, 11 cases of attenuated and slight changes, and 16 cases of obvious destructive interruption in corticospinal tract. All 24 cases of cerebral infarction focus all have showed the obvious increase of Lac concentration, and the increasing degree in the central region of cerebral infarction focus is bigger than that in the adjacent regions. Cho/NAA has risen, too.Conclusion:1. The combination of DWI and conventional MRI could identify"responsible lesion"and differentiate the phases of the cerebral infarction.2. The value of DTI deserves affirmation, which displays the change of CST caused by cerebral infarction.3. The value of MRS deserves affirmation, which shows the metabolism of cerebral infarction focuses.4. The use of DWI, DTI, and MRS provide evidence for clear differentiation of the different phases of cerebral infarction, guidance on clinical therapy and judgment of prognosis.