| Objective: To study the clinical value on diffusion-weighted imaging(DWI) in patients with transient ischemic attack(TIA) by investigating the risk factors associated with abnormal DWI,the different imaging findings with high b-values and the correlation of ADC values & ABCD2 scores. It was very important to avoid the progression of cerebral infarction, reduce the morbidity and mortality through early prevention, early detection, early diagnosis and early treatment in patients with TIA.Methods: 44 patients with TIA from the 2nd hospital of hebei medical university were selected according to the diagnostic standard of the fourth national cofference of cerebral vascular disease. All patients underwent the same imaging examination within three days after the symptom onset that included conventional MRI(c MRI) with varied T1-flair, T2-FSE and T2-flair sequences,magnetic resonance angiography(MRA),and DWI with different b-values(b=1000,b=2000,b=3000).The other auxiliary examinations were also achieved that included blood routine, urine routine, stool routine, blood biochemistry, coagulation,blood homocysteine(HCY),electrocardiogram and cervical duplex ultrasonography.ABCD2 scores were also recorded.The clinical information were collected from every cases that include age, gender, professional,vascular risk factors(such as high blood pressure, diabetes, coronary heart disease,TIA or cerebral infarction history, high HCY, neck vascular patches), clinical symptoms(such as motor deficits, aphasia,sensory disturbance, etc), duration of symptoms, as well as attack times.All patients were divided into positive DWI group and negative DWI group according to DWI(b=1000) results. The clinical related risk factors in DWI abnormalities were evaluated; The differences in DWI with different b-values(b=1000, b= 2000 and b=3000) about lesion conspicuity, lesion extent and image artifact were observed;The lesion volume, apparent diffusion coefficient(ADC) values were quantitative analyzed on the DWI images; The correlation of ADC values and ABCD2 scores were also analyzed.Results:1 Basic clinical informationThere were no significant differences in age and gender distribution between the positive DWI group and negative DWI group(P>0.05),clinical risk factors that include high blood pressure, intracranial atherosclerosis,high HCY,ABCD2 scores,motor deficits,aphasia,attack times,duration of symptoms had significant differences between the two groups(P<0.05),while other factors that include smoking,drinking,TIA or cerebral infarction history, neck vascular patches,sensory disturbance and diplopia also had no significant differences between the two groups(P>0.05).2 The related risk factors in DWI abnormalitiesThe multi-factors logistic regression analysis showed that TIA patients with long duration of symptoms(OR:3.74), more attack times(OR:2.68), motor deficits(OR:6.92) and aphasia(OR:4.85) were significantly correlated with DWI abnormalities(P<0.05).3 The imaging changes of TIA patientsA total of 15(34.1 %) patients revealed ischemic acute lesions on c MRI, while 25(56.8 %) patients were positive on DWI with standard b-value(b= 1000),it showed significant differences(P<0.05). DWI was more sensitive to show related brain lesion than c MRI and it had the superiority to identify the acute ischemia and chronic ischemia.DWI with high b-value did not increase the sensitivity for the detection of related brain lesion in TIA patients.but in some cases, responsibility lesions were founded in more slices.Qualitative analysis showd that lesions were more conspicuous in all TIA patients.The lesion size were larger in 12 cases, similar in 9 cases because of the too small infarction or lacunar infarction. But excessively increased b-value affected the quality of the image.The image artifacts resulted in hyperintensive area,which was very difficult to distinguish from the restricted diffusion area after acute infarction. With the b-value increased, The qualitative analysis showed that the mean lesion volume increased 0.167cm3(IQR:0.153cm3) at b=1000 second/mm2,0.250cm3(IQR:0.199cm3)at b=2000 second/mm2, 0.336cm3(IQR:0.246cm3) at b=3000 second/mm2,(P<0.05),while the ADC-value decreased 0.547×10-3 second/mm2(IQR: 0.1810-3 second/mm2) at b=1000, 0.489×10-3 second/mm2(IQR: 0.125×10-3 second/mm2)at b=2000, 0.43×10-3 second/mm2(IQR: 0.112×10-3 second/mm2) at b=3000,(P<0.05).4 The correlation of ADC values and ABCD2 scoresThe correlation coefficient between the ADC values and ABCD2 scores were 0.461, 0.400, 0.508 in different b-values(b=1000,b=2000 and b=3000) respectively, All were positive correlation with significant differences(P<0.05).The total ADC value and total ABCD2 score correlation coefficient was 0.371(P<0.05). All of these showed that ADC values and ABCD2 scores were positively correlated, with the increase of ABCD2 scores, ADC values were also increased.Conclusions:1 DWI is much sensitive to show the related brain lesion of TIA than c MRI and it has the superiority to identify the acute ischemia or chronic ischemia.2 TIA patients with long duration of symptoms, more attack times, motor deficits and aphasia are significantly correlated with DWI abnormalities.3 Using higher b-value on DWI can be beneficial in evaluating the real related brain lesion volume and may still be beneficial in detecting the subtle tiny lesions,but the excessively increase of the b-value will reduce the quality of the image.DWI with b=2000 second/mm2 not only has the superiority than the other b-values for detection of patients with TIA,but also can help us to take more active strategies to avoid the progression of cerebral infarction.4 ADC values and ABCD2 scores are positively correlated, with the increase of ABCD2 scores, ADC values are also increased. |
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