The Study Of MRI In Patients With TIA

PartⅠMRA Evaluation of Cerebral Feeding Arterial Lesion, Cerebral Blood Flow and Collateral Compensation in TIA patientsObjective:3D TOF MRA,3D CE-MRA and cine PC MRA were applied to evaluate the distribution of cerebral feeding arterial lesions,the changes of cerebral blood flow and the ability of collateral compensation of the circle of Willis in patients with TIA.Materials and Methods:MRA was performed in 75 TIA patients,106 healthy subjects and 44 cerebral infarction patients by GE 1.5T MR system.All subjects accepted the following examinations:3D TOF MRA for intracranial arteries, 3D CE-MRA for head and neck arteries,and Cine PC MRA for ICA and BA.The distribution of the arterial lesions,the degree of stenosis of cerebral feeding arteries, the development of the VA and the ocurrence of arteriosclerosis of VA,the morpha of the circle of Willis,and cerebral blood flow were analyzed.Statistical analysis was performed by SPSS11.0 software package.Differences were considered statistically significant at P less than 0.05.Results:65.3%TIA patients(49/75)had arteriosclerosis.There was no significant difference of the distribution of the arteriosclerosis between the TIA group and the stroke group(P＞0.05).The ocurrence of the severe obstructive lesions in the TIA group was lower than that in the stroke group(P=0.018).The case of the lesions only located in the arteries that before the circle of Willis in the TIA group(51.0%,25/49)was more than that in the stroke group(21.6%,8/37)(P=0.006).As far as the severe obstructive lesions that located the arteries before the circle of Willis were considered,the TIA group(21.33%,16/75)was less than the stroke group(47.73%,21/44)(P=0.003).There was no significant difference of the incidence of dysplastic VA accompanied with arteriosclerosis between ICA-TIA group(44.4%,8/18)and VA-TIA group(45.5%,5/11)(P=0.958). The cases were more common in both the ICA-TIA group and VA-TIA group than that in the healthy group(7.14%,2/28)(P=0.005;P=0.003).Dysplasia or absence of the A1 of ACA in ICA-TIA group(39.6%,19/48)was more often than that in healthy group(19.8%,21/106)(P=0.010).There was no significant difference between ICA-TIA and V-BA TIA(18.5%,5/27)(P=0.060),and between V-BA TIA and healthy group(P=0.880).The simultaneous presentation rate of ACOA and PCOA in TIA group(48%,36/75)was higher than that in stroke group(25%,11/44) (P=0.013),and no difference compared with the healthy group(49.1%,52/106) (P=0.889).There were no significant difference in both the type of the circle of Willis and the integrity of the entire and anterior and posterior circle of Willis between the TIA group and the healthy group,and between the TIA group and the stroke group(P＞0.05).The integrity of the entire and the posterior circle of Willis was higher in healthy group than that in stroke group(P=0.009;P=0.008).No significant difference of the cerebral blood flow between the TIA group(686.68±113.25 ml/m) and the healthy group(701.76±135.34 ml/m)(P=0.391).The cerebral blood flow of both the TIA group and the healthy group were higher than that of the stroke group (616.65±54.87)(P=0.002;P＜0.001).The cerebral blood flow of 16 TIA patients with the severe obstructive lesions that located the arteries before the circle of Willis (632.82±106.15 ml/m)was less than both that of the other 59 TIA patients with (701.28±111.50 ml/m)and that of the healthy controls(P=0.045;P=0.034).No significant difference between the 16 TIA patients and the 21 stroke patients with the same arterial lesions(597.37±58.85 ml/m)(P=0.377).There was no significant difference of the cerebral blood flow between the 59 TIA patients and the healthy controls(P=0.981).The cases that accompanied with lesions located the arteries after the circle of Willis in the 16 TIA patients(8/16)was less than that in the 21 stroke patients(18/21)(P=0.019).Conelusions:1.There was no significant difference of the distribution of the arteriosclerosis between the TIA group and the stroke group. The ocurrence of the severe obstructive lesions in the TIA group was lower than that in the stroke group.The case of the lesions only located in the arteries that before the circle of Willis in the TIA group was more than that in the stroke group.The case of the lesions only located in the arteries that before the circle of Willis in the TIA group was more than that in the stroke group.As far as the severe obstructive lesions that located the arteries before the circle of Willis were considered,the TIA group was less than the stroke group.2.The variation of V-BA may be one of the risk factor for TIA.The variation of A1 may be increase the predisposing factors for ICA-TIA.3. The simutaneous occurrence of ACOA and PCOA in the TIA group is higher than in the stroke group,indicating the active effect of the circle of Willis on the TIA.4. Compared with the healthy group,the cerebral blood flow in the TIA group does not obviously decrease.But the cerebral blood flow in the TIA patients with severe arterial lesions that located before the circle of Willis was decreased than the healthy controls.It provides valuable information to explore the pathogenesis of TIA.5. There may be no significant difference on the crerbral blood flow between the TIA patients and stroke patients with the same severe artrerial lesions,but the occurrence of accompanying with lesions located the arteries after the circle of Willis in TIA patients was less than that in stroke patients.It indicate that the risk of stroke is high when the patients with severe arterial lesions that located the arteries before the circle of Willis accompanied with arterial lesions that located the arteries after the circle of Willis.6.It is meaningful to exactly and fully recognize and analyze the disease,and take effective measure to prevent the further progress that the various MRA techniques are applied to evaluate the cerebral blood flow,the feeding arterial lesions and collateral circulation of patients with TIA. PartⅡApplications of MR Diffusion Imaging,MR Perfusion Imaging and MR Spectrum in patients with Transient Ischemic AttackObjective:To explore the examination of DWI combined with PWI and MRS would substantiate the diagnosis of brain ischemia in the patients with transient neurologic symptoms and to explore the application to TIA.Material and Methods: Thirty-four TIA patients were consecutively chosen.The examinations were performed as follow:axial DWI,T2WI,MRS,3D TOF MRA,PWI,3D CE-MRA. Positive DWI:the presence of hyperintensity on DWI.Positive PWI:the presence of abnormal perfusion.To analyze the characters of the DWI lesions.To compare the age,gender,duration of symptom,delay between onset of symptoms and MRI,risk factor,clinical syndrome,the presence of intracranial severe arterial lesion,the type and the integrity of the circle of Willis between the patients with positive DWI/PWI and the patients with negative DWI/PWI.MRS:To select the noninfarcted centrum semiovale in the symptomatic side and the corresponding region of the contralateral side as the volume of interest.To compare the ratios of NAA/Cho,NAA/Cr and Cho/Cr between the symptomatic side and the corresponding side.Statistical analysis was performed by SPSS 11.0 software package.Differences were considered statistically significant at P less than 0.05.Result:61.76%patients with TIA demonstrated positive DWI lesions.Mean duration of symptoms was 2.45±3.51h. Lesions were solitary in 9 patients and multiple in 12 patients.The number of the lesions was 40.Anterior circulation was affected in 18 patients,posterior circulation was affected in one and anterior and posterior in two.Thirty-two lesions located in anterior circulation and eight lesions located in posterior circulation.Sixteen lesions located in the watershed region.Twenty lesions located cortical and subcortical region,and twenty lesions located in the deep region.Mean lesion volume was 8.09±4.51cm~3.Mean ADC lesion ratio was 0.85±0.27.There were significant differences between patients with positive DWI and the patients with negative DWI in terms of the presence of aphasia and motor deficit(p=0.006;p=0.038).There were no significant differences between patients with positive DWI and the patients with negative DWI in terms of age,gender,sensory disturbances,perioral numbness,the duration of symptom,delay between onset of symptoms and MRI,some risk factors(hypertension,diabetes mellitus,coronary heart disease,hyperlipidemia and history of smoking),the presence of intracranial severe arterial lesion,the type and the integrity of the circle of Willis.PWI demonstrated abnormal in 47.06%patients. Mean duration of syndroms was 2.55±3.86h.The perfusion delay on the MTT map was found in 14 patients.The abnormal perfusion on the CBV map was found in 10 patients.Six patients showed the increase of CBV(6 positive DWI).Four patients showed the decrease of CBV(3 positive DWI).Intracranial arterial severe obstructive lesions in the patients with positive PWI(62.5%)was more common than that in the patients with negative PWI(16.7%)(p=0.012).There were no significant differences between patients with positive PWI and the patients with negative PWI in terms of age,gender,aphasia,motor deficit,sensory disturbances and perioral numbness,the duration of symptom,delay between onset of symptoms and MRI,some risk factors(hypertension,diabetes mellitus,coronary heart disease and hyperlipidemia), and the type and the integrity of the circle of Willis.None of the type of the circle of Willis,the integrity of the entire circle of Willis and the anterior circle of Willis and the posterior circle of Willis were significantly different among the patients with positive DWI/PWI and negative DWI/PWI.The peak of Lac was seen in the five patients.NAA/Cho in the symptoms side(1.57±0.44)was obviously decreased than that in the contralateral side(1.79±0.44)(P=0.043).NAA/Cr in the symptoms side (1.71±0.07)was obviously decreased than that in the contralateral side(1.93±0.39) (P=0.026);Cho/Cr in the symptoms side(1.23±0.15)was obviously increased than that in the contralateral side(1.15±0.15)(P=0.024).The NAA/choline,NAA/creatine, and choline/creatine ratios of patients with positive DWI/PWI did not differ significantly from patients with negative DWI/PWI for either the symptomatic side or the contralateral side.Conelusion:1.61.76%TIA patients(21/34)have ischemic lesions on DWI.The volume of the lesions are small.Most of the lesions locate in the watershed region.The ADC ratio is moderately decreased.The lesions on DWI may accompany with or without abnormal perfusion.Motor deficit and aphasia may be the predictors of the ischemic lesion of DWI.The duration of symdromes and the delay between onset of symptoms and MRI do not always have the association with the ischemic lesion of DWI.2.47.1%TIA patients(16/34)have perfusion abnormalities evident on MRI despite having complete resolution of neurological symptoms.Any intracranial arterial severe obstructive lesion maybe the predict factor of perfusion abnormality in the patients with TIA.Aphasia may be the predictors of the abnormal PWI.The presence of perfusion abnormality may accompany with or without high intensity on DWI.3.None of the type of the circle of Willis,the integrity of the entire circle of Willis and the anterior circle of Willis and the posterior circle of Willis were significantly different among the patients with positive DWI/PWI and negative DWI/PWI.4.The peak of Lac was seen in some patients with TIA.NAA/Cho and NAA/Cr in the symptoms side were obviously decreased than that in the contralateral side;Cho/Cr in the symptoms side was obviously increased than that in the contralateral side.5.The application of DWI and PWI help to discover the ischemic lesions and abnormal perfusion.It is important to instruct effective treatment and prevent further stroke.MRS may discover the region of abnormal metabolism even ahead of the change of morphology.The one-shop imaging examination methods for patients with TIA:DWI/PWI→T2WI→MRS→3D TOF MRA→3D CE MRA.