The Effect of Metallic Dental Restorations and Implants in Causing Patient Discomfort and Artefacts During Magnetic Resonance Imaging of the Head and Neck

Context: Patients with metallic dental objects in their oral cavity are often associated with discomfort or artefacts during magnetic resonance imaging (MRI) of the head and neck. Aim: This study was conducted to evaluate the effects of metallic dental objects in causing patient discomfort and artefacts during MRI of the head and neck region. Design: This is an observational study including 538 participants from various specialized MRI centres in Kozhikode. Methods and Material: MRI records of 538 participants who underwent head and neck MRI as a part of their medical treatment were collected. With the help of questionnaire and clinical examination, the type of metallic dental object in the patient’s oral cavity was identified. After examining the MRI images, four categories of artefacts were established. In MRI brain, artefacts in three different sequences were also studied. Statistical Analysis Used: The significance of the difference between proportions was analysed by the Chi?square test. Results: Artefacts were found in 65 cases with metallic dental objects but none of the participants had experienced any kind of discomfort. The artefact formation significantly depended on the type of metallic dental restoration in the patient’s oral cavity. Orthodontic braces and titanium bone plate created severe artefacts in head and neck MRI making interpretation almost impossible. In the MRI brain, diffusion?weighted imaging is most sensitive to artefact followed by fluid?attenuated inversion recovery. Conclusions: Artefacts were found in 65 cases with metallic dental restorations but none of the participants had experienced any kind of discomfort.

Fluid?attenuated inversion recovery diffusion?weighted imaging (DWI) for evaluating chemotherapy response in patients with acute leukemia: Comparison with conventional DWI

Background: At present, the diagnosis and efficacy evaluation of acute leukemia (AL) are assessed by bone marrow aspiration, which is invasive and subject to sampling errors. Therefore, there is a pressing need to develop a noninvasive and accurate imaging method to evaluate bone marrow changes in patients with AL. This study aimed to compare the apparent diffusion coefficient (ADC) values obtained from fluid?attenuated inversion recovery diffusion?weighted imaging (FLAIR?DWI) and conventional DWI in the lumbar bone marrow of patients with AL and to investigate their performance for evaluating response to induction chemotherapy. Methods: A total of 28 patients with newly diagnosed AL and 25 patients with AL after induction chemotherapy underwent MRI scans at 1.5 Tesla using a conventional DWI and a FLAIR?DWI sequence on sagittal planes covering the lumbar bone marrow. Further, the ADC values from these two sequences, denoted as ADCCON and ADCFLAIR, were measured on multiple vertebrae. The percentage of leukemia cells in bone marrow was recorded, and bone marrow aspiration was performed on treated patients to determine complete remission (CR) and nonremission (NR). Results: ADCFLAIR [(0.453 ± 0.103) × 10?3 mm2/s] was significantly lower than ADCCON [(0.486 ± 0.096) × 10?3 mm2/s] in the 28 untreated patients (t = 3.051, P = 0.005). In the 25 treated patients, ADCFLAIR and ADCCON values [(0.566 ± 0.239) × 10?3 mm2/s] and [(0.716 ± 0.235) × 10?3 mm2/s], respectively, were higher compared with the untreated patients. The ADCCON values showed a nonsignificant difference between the CR (n = 18) and NR (n = 7) groups (t = 1.409, P = 0.305). However, the ADCFLAIR values exhibited statistically significant difference (t = 2.542, P = 0.018) between the two groups. In a receiver operator characteristic (ROC) analysis, the area under the curve (AUC) using ADCFLAIR (0.770) was larger than that of ADCCON (0.611) in distinguishing the CR and NR patients following the chemotherapy. Conclusion: Although both ADCCON and ADCFLAIR are sensitive to tissue changes induced by chemotherapy, FLAIR?DWI outperformed conventional DWI in separating AL patients with CR from NR after chemotherapy. A possible mechanism is that FLAIR?DWI suppresses signals from free water, making the ADC measurement more sensitive to structural changes in the bone marrow

Tissue Window versus Time Window? A Review of Patients Receiving Extended Hours Thrombolysis Guided By DWI-FLAIR Mismatch : Case Series

@#Introduction: Intravenous thrombolysis (IVT) is the gold standard for the treatment of patients with acute ischemic stroke (AIS) presenting within four and a half hours of onset. However, development of new thrombolytic agents and advanced imaging has led to extended time for thrombolysis based on advanced imaging. Here we describe four patients who presented in the extended hours; that benefitted from thrombolysis. Case series: We advocate magnetic resonance imaging (MRI) for AIS, that includes diffusion weighted imaging (DWI), apparent diffusion coefficient (ADC), fluid attenuated inversion recovery (FLAIR), susceptibility weighted imaging (SWI), and magnetic resonance angiography (MRA). We included four patients who were more than 18 years old, with National Institute of Health Stroke Scale (NIHSS) of six or more, presenting between four and a half to nine hours after stroke onset with no contraindications for intravenous thrombolysis. The imaging criteria used to determine eligibility for IVT is evidence of DWI-FLAIR mismatch on MRI. If FLAIR detects no signal change in the area of stroke on DWI, it is then termed DWIFLAIR mismatch, or FLAIR-negative – indicating high probability that the brain tissue is still viable, and that patients are good candidates for IVT. Conclusion: For patients with AIS who present within nine hours, DWI-FLAIR mismatch serves as an excellent surrogate marker of salvageable brain tissue, allowing a greater proportion of patients benefiting from this life-saving therapy. Our experience also shows that with careful patient selection, treatment with IVT can safely be given without an increased risk of bleeding or mortality.

Prediction of the onset time of acute stroke by deep learning based on DWI and FLAIR / 中华放射学杂志

Objective:To evaluate the effect of deep learning based on DWI and fluid attenuated inversion recovery (FLAIR) to construct a prediction model of the onset time in acute stroke.Methods:A total of 324 cases of acute stroke with clear onset time, from January 2017 to May 2020 in Nanjing First Hospital, were retrospectively enrolled and analyzed. The patients were divided into a training set of 226 patients and a test set of 98 patients according to the complete randomization method using a 7∶3 ratio, and the patients were divided into ≤ 4.5 h and >4.5 h according to symptom onset time in each group. The acute infarction areas on DWI and the corresponding high signal area on FLAIR were manually outlined by physician. Using the InceptionV3 model as the basic model for image features extraction, the deep learning prediction model based on single sequence (DWI, FLAIR) and multi sequences (DWI+FLAIR) were established and verified. Then the area under curve (AUC), accuracy of human readings, single sequence model and multi sequence model in predicting the acute stroke onset time from imaging were compared.Results:DWI-FLAIR mismatch was found in 94 cases (94/207) of patients with symptom onset time from imaging ≤ 4.5 h, while in 28 cases (28/117) of patients with symptom onset time from imaging >4.5 h. ROC analysis showed that the AUC of DWI-FLAIR mismatch in predicting acute stroke onset time from imaging was 0.607, and the accuracy was 60.2%. The prediction model of deep learning based on single sequence showed that the AUC of FLAIR was 0.761 and the accuracy was 71.4%; the AUC of DWI was 0.836 and the accuracy was 81.6%. The AUC of predicting stroke onset time based on the multi-sequence (DWI+FLAIR) deep learning model was 0.852, which was significantly better than that of manual identification ( Z = 0.617, P = 0.002), FLAIR sequence deep learning model ( Z = 2.133, P = 0.006) and DWI sequence deep learning model ( Z = 1.846, P = 0.012). Conclusion:The deep learning model based on DWI and FLAIR is superior to human readings in predicting acute stroke onset time from imaging, which could provide guidance for intravenous thrombolytic therapy for acute stroke patients with unknown onset time.

Comparison of Flair MRI to Contrast Enhanced T1W MRI in Selected Intracranial Pathologies for a Patient Population in North Kerala, India,

Fluid Attenuated Inversion Recovery (FLAIR) MRI of brain is sensitive in detecting parenchymal lesions, extra axial lesions such as meningoencephalitis, and leptomeningeal tumoural disease. We wanted to compare gadolinium enhanced T2W FLAIR with PC-T1W (post contrast T1 weighted) MRI sequence in detection and evaluation of meningeal and parenchymal lesions. We also wanted to compare gadolinium enhanced T1W FLAIR with PC-T1W MRI sequence in detection and evaluation of meningeal and parenchymal lesions.METHODS65 patients with clinical diagnosis of cerebral meningitis or intracranial tumoural disease were scanned on 1.5 T 16 channel MRI scanner. A standard brain protocol was used, followed by PC-T1W and post contrast FLAIR, with PC-T1W MR preceding post contrast FLAIR. Images were assessed independently by 2 radiologists who marked the technique they thought had made the meningeal and parenchymal disease more conspicuous. In case of disagreement the radiologists made a consensus determination.RESULTSPC-T2 FLAIR showed better enhancement in 100% of the intra axial lesions compared to PC-T1W images. However, PC-T1 FLAIR showed better enhancement than PC-T1W images in only 81% of the same. PC-T2 FLAIR showed better enhancement in 100% of the extra-axial lesions compared to PC-T1W images. However, PC-T1 FLAIR showed less enhancement in all the extra axial lesions.CONCLUSIONSContrast enhanced T2 FLAIR MRI showed better enhancement of parenchymal and meningeal lesions. PC-T2 FLAIR detected more number of lesions when compared to PC-T1W, aided better delineation of extra-axial mass lesions due to superior enhancement, and had a better demarcated dural tail. Post-contrast T2 FLAIR images should be included in routine protocol for contrast MRI brain study.

Pitfall in the detection of acute lesions of transient ischemic attack with fluid-inversion prepared diffusion weighted imaging / 中华核医学与分子影像杂志

Objective To explore the limits of fluid-inversion prepared diffusion weighted imaging (FLIPD) in detection of acute cerebral ischemic lesions.Methods From January 2012 to March 2014,forty-nine patients (33 males,16 females,age (55.6± 12.3) years) clinically diagnosed as transient ischemic attack (TIA) were included.Patients underwent brain MRI (conventional diffusion weighted imaging (DWI) and FLIPD) within 3 d after the onset of TIA.The detection ability of MRI with the two sequences was compared,and the relative signal intensity (rSI) and apparent diffusion coefficient (ADC) of acute ischemic lesions based on two sequences were compared.Kappa test and two-sample t test were used to analyze the data.Results A total of 87 acute ischemic lesions were detected in 21 patients by conventional DWI,and 54 were detected in 19 patients by FLIPD (Kappa=0.916,P＜0.05).The rSI of ischemic lesions on FLIPD was significantly lower than that on conventional DWI (1.37±0.22 vs 1.57±0.26;t=6.647,P＜0.001).The ADC value of ischemic lesions on FLIPD was slightly lower than that on conventional DWI:(0.54 ±0.10) ×10-3 mm2/s vs (0.57±0.13)×10-3 mm2/s (t=2.120,P＜0.05).The missed lesions on FLIPD were located in the white matter (n =18),cerebellum and brainstem (n =8),and the cortex (n =7).Conclusions A slight diffuse abnormality may be missed on FLIPD,so this method is not suitable for the detection of acute ischemic lesions.FLIPD technology still needs improvement.

Relationship between white matter hyperintensities and hyperintense vessel sign on fluid-attenuated inversion recvery magnetic resonance imaging in older adults / 中华老年医学杂志

Objective To investigate the correlation between white matter hyperintensities (WMH)and hyperintense vessel sign (HVS) on fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging(MRI)in old adults and to explore the risk factors and pathogeneses of WMH.Methods We retrospectively collected imaging and clinical data of patients who had received both head and neck CTA and brain MRI within one month at our hospital from 2013 to 2016.The Fazekas visual scale was used to evaluate periventricular white matter hyperintensity(PWMH)and deep white matter hyperintensity(DWMH)in each brain hemisphere.According to the presence or absence of HVS in a cerebra[hemisphere,patients were assigned into an HVS-positive group or an HVS-negative group.Clinical data,PWMH,and DWMH differences were compared between the two groups.Results A total of 271 patients(542 cerebral hemispheres)were included in this study.HVS-positive imaging occurred in 79(14.6％)cerebral hemispheres and negative imaging was observed in 463 (85.4％) cerebral hemispheres.There was a significant difference between the HVS-positive and negative groups in the ipsilateral CIA stenosis(x2 =126.840,P＜0.01).The incidence of ipsilateral severe carotid artery stenosis in the HVS-positive group was 62.0％ (49/79),which was significantly higher than 9.9％ (46/463)in the HVS-negative group.The incidence of moderate-severe DWMH was 65.8％(52/79) in the HVS-positive group,which was higher than 34.8％ (161/463)in the negative group(x2 =34.962,P ＜20.01).Nevertheless,the incidences of moderate-severe PWMH in the two groups were 65.8％ (52/79) and 55.5％ (257/463),respectively,without a significant difference between them (x2 =6.944,P =0.074).After adjusting for age,gender,ipsilateral ICA stenosis,hypertension,diabetes,etc.multivariate analysis suggested that HVS-positive imaging was still an independent risk factor for DWMH(OR =2.653,95％CI:1.489-4.726,P =0.001).Conclusions HVS-positive imaging is an independent risk factor for DWMH in the elderly,but no clear correlation with PWMH is found.It suggests that hypoperfusion is a possible mechanism for the development of DWMH in the elderly.

Correlation analysis of quantitative measurement of fluid-attenuated inversion recovery sequence and onset time of acute ischemic stroke / 中国脑血管病杂志

Objective To investigate the relationship between the ratio of signal intensity of fluid-attenuated inversion recovery (FLAIR)sequence lesion side／contralateral side and the onset time of acute ischemic stroke. Methods Forty-three consecutive patients with acute ischemic stroke admitted to the Department of Neurology,Dongguan Hospital of Traditional Chinese Medicine from November 2016 to January 2018 were enrolled retrospectively. They were all first onset and were diagnosed by MRI,and the onset time was 0. 5 to 6. 0 h. According to the time window of effective rescue of the penumbra,43 patients were divided into a ≤4. 5 h group (n＝19)and a ＞4. 5-6. 0 h group (n＝24). The signal intensity values of FLAIR, diffusion-weighted imaging,signal intensity of apparent diffusion coefficient sequence on the lesion side and contralateral brain tissue in the two groups of patients were measured respectively,and the relative signal intensity (RSI)was calculated and compared between the two groups. Taking RSI as the dependent variable and onset time as the independent variable,a general linear regression analysis was performed. Results (1)In FLAIR sequence,the signal intensity value and RSI value of patients in the≤4. 5 h group were lower than those in the ＞4. 5-6. 0 h group. There were significant differences between the 2 groups (disease side signal intensity value:531 ± 109 vs. 681 ± 306,t ＝2. 04;RSI value:1. 19 ± 0. 13 vs. 1. 45 ± 0. 18,t＝5. 29,all P＜0. 05). There was no significant difference in the signal intensity values on the contralateral sides between the two groups (P＞0. 05). (2)In diffusion weighted imaging and apparent diffusion coefficient sequence,there were no significant differences in the signal intensity value and RSI value on the disease side and the contralateral side between the the≤4. 5 hours group and the ＞4. 5-6. 0 h group (all P＞0. 05). (3)In the FLAIR sequence,with the prolongation of the time of the disease,RSI gradually increased,and was positively correlated (r＝0. 756,P＜0. 01). Conclusions The quantitative measurement of the disease side／contralateral side of FLAIR sequence might reflect the onset time of acute ischemic stroke. Its RSI value increased with the prolonged onset time.

Fluid-attenuated inversion recovery vascular hyperintensity: Correlation with other radiologic findings in acute ischemic stroke with middle cerebral artery occlusion

Objective: To assess fluid-attenuated inversion recovery (FLAIR) vascular hyper-intensity (FVH) and explore its relationship with CT perfusion (CTP) penumbral/infarct core mismatch ratio and diffusion weighted imaging (DWI) final infarct volume in acute ischemic stroke (AIS) patients with middle cerebral artery occlusion (MCAO). Methods: The CTP and MRI images of 38 AIS patients with MCAO were reviewed. The FVH score (longitudinal direction) [FVH score (L)] and FVH score (transverse direction) [FVH score (T)] were quantified on the FLAIR images. The FVH score (L) (range, 0-16) was based on a rostrocaudal extension of FVH and the FVH score (T) (range, 0-3) was based on FVH supply of the occluded MCA territory. The mismatch ratio was calculated from the ratio of the [mean transit time - cerebral blood volume (CBV)] lesion/CBV lesion on the CTP images. The DWI infarct volume was measured on the DWI images. Results: The mismatch ratio was larger for the group of FVH score (L)=7~8 than those of FVH score (L)=5~6 and FVH score (L)=3~4 (p=0.03), whereas the DWI infarct volume was smaller (p=0.04). Similarly, the mismatch ratio of FVH score (T)=2~3 group was larger than FVH score (T)=1 group (p=0.01), whereas the DWI infarct volume was smaller (p=0.02). Both FVH score (L) and FVH score (T) correlated positively with mismatch ratio (P=0.02, P=0.001, respectively), but negatively with DWI infarct volume (P=0.03, P=0.004, respectively). Conclusions: Higher FVH score is associated with larger mismatch ratio and smaller DWI infarct volume in AIS patients with MCAO. FLAIR vascular hyperintensity may represent collateral arterial circulation, and may play a role in protecting the ischemic penumbra.

Comparison of T2 FLAIR and GRE-T2* WI in detection of traumatic extra-axial hemorrhage / 实用放射学杂志

Objective To explore the value of fluid-attenuated inversion recovery (FLAIR)sequence and gradient echo T2 ?weighted image (GRE-T2 ? WI)in diagnosis of acute traumatic extra-axial hemorrhage.Methods 50 patients who were diagnosed as acute traumatic extra-axial hemorrhage by plain CT underwent FLAIR and GRE-T2 ? WI in acute stage.The diagnosis consistency (Kappa ),detection rate of subarachnoid hemorrhage(SAH),epidural hemorrhage(EDH)and subdural hemorrhage(SDH)were compared.The detection rates of SAH in 8 locations among FLAIR,GRE-T2 ? WI and combination of two sequences were analyzed by Chi-square test.Results 48 patients were enrolled in the study.The diagnosis consistency of SAH between FLAIR and GRE-T2 ? WI was high (k =1.0).The detection rate of SAH was 100% for both FLAIR and GRE-T2 ? WI.Comparing with GRE-T2 ? WI and combi-nation of two sequences,FLAIR tended to misdiagnose SAH in perimesencephalic cistern (P <0.05).The diagnosis consistency of EDH between FLAIR and GRE-T2 ? WI was high (k =1.0).3 patients with EDH were all detected by FLAIR and GRE-T2 ? WI. The diagnosis consistency of SDH between FLAIR and GRE-T2 ? WI was high (k =0.943).The detection rate of 12 patients with SDH was 100% in FLAIR,and 1 patient with SDH was missed by GRE-T2 ? WI.Conclusion The detection rate of acute traumatic extra-axial hemorrhage is high for both FLAIR and GRE-T2 ? WI.Combination of two sequences can improve the accuracy of acute traumatic extra-axial hemorrhage in clinic.

Research of correlation between MRI fluid-attenuated inversion recovery hyperintense vessel sign and prognosis in acute middle cerebral artery infarction / 重庆医学

Objective To investigate the significance of MRI T2 fluid-attenuated inversion recovery hyperintense vessel sign (FLAIR HVS)in clinical prognosis evaluation of the patients with acute middle cerebral artery irnfarction.Methods The data in 57 inpatients with acute middle cerebral artery infarction in our hospital from Aug.2013 to Aug.2015 were retrospectively analyzed.All cases were performed the intact MRI examination(ineluding FLAIR,DWI and MRA)and CTA.The infarct volume with DWI,national institute of health stroke scale(NIHSS)score and modified Rankin Scale(mRS)score on 30 d after discharge were performed the comparative analysis.Results Fifty-seven cases of middle cerebral artery occlusion were divided into the distal HVSgroup and non-distal HVS group(8 cases in proximal HVS group,21 cases in HVS negative group).The infarction volume of DWI sequence,NIHSS scores at admissiom and discharge and mRS score on 30 d after discharge in the distal HVS group were superior to those in the non-distal HVS group(P＜0.05).Conclusion MRI-T2 FLAIR sequence HVS has certain reference value in the prognosis evaluation in the patients with middle cerebral artery occlusion.

Assessment of Diffusion-Weighted Imaging-FLAIR Mismatch: Comparison between Conventional FLAIR versus Shorter-Repetition-Time FLAIR at 3T

PURPOSE: Fluid-attenuated inversion recovery (FLAIR) imaging can be obtained faster with shorter repletion time (TR), but it gets noisier. We hypothesized that shorter-TR FLAIR obtained at 3 tesla (3T) with a 32-channel coil may be comparable to conventional FLAIR. The aim of this study was to compare the diagnostic value between conventional FLAIR (TR = 9000 ms, FLAIR9000) and shorter-TR FLAIR (TR = 6000 ms, FLAIR6000) at 3T in terms of diffusion-weighted imaging-FLAIR mismatch. MATERIALS AND METHODS: We recruited 184 patients with acute ischemic stroke (28 patients 0.05). Interobserver agreement was excellent for both DWI-FLAIR9000 and DWI-FLAIR6000 (k = 0.904 and 0.883, respectively). Between the two FLAIR imaging sets, there was no significant difference of signal intensity ratio (mean, standard deviation; 1.25 ± 0.20; 1.24 ± 0.20, respectively) (P > 0.05). CONCLUSION: For the determination of mismatch or match between DWI and FLAIR imaging, there is no significant difference between FLAIR9000 and FLAIR6000 at 3T with a 32-channel coil.

Importance of Contrast-Enhanced Fluid-Attenuated Inversion Recovery Magnetic Resonance Imaging in Various Intracranial Pathologic Conditions

Intracranial lesions may show contrast enhancement through various mechanisms that are closely associated with the disease process. The preferred magnetic resonance sequence in contrast imaging is T1-weighted imaging (T1WI) at most institutions. However, lesion enhancement is occasionally inconspicuous on T1WI. Although fluid-attenuated inversion recovery (FLAIR) sequences are commonly considered as T2-weighted imaging with dark cerebrospinal fluid, they also show mild T1-weighted contrast, which is responsible for the contrast enhancement. For several years, FLAIR imaging has been successfully incorporated as a routine sequence at our institution for contrast-enhanced (CE) brain imaging in detecting various intracranial diseases. In this pictorial essay, we describe and illustrate the diagnostic importance of CE-FLAIR imaging in various intracranial pathologic conditions.

Application of Magnetic Resonance Imaging Fluid- attenuated Inversion Recovery Vascular Hyperintensities in Transient Ischemic Attack / 中国康复理论与实践

@#Objective To investigate the application of magnetic resonance imaging (MRI) fluid-attenuated inversion recovery vascular hyperintensities (FVH) for the diagnosis of transient ischemic attack (TIA). Methods Consecutive 218 inpatients for TIA from May 2011 to July 2013 were reviewed with gender, age, cardiovascular risk factors, TIA or a history of stroke, TIA duration, and calculate the ABCD2 scores. All patients accepted MRI and MRA within 24 hours of symptom onset. FVH positive patients would follow up MRI and MRA within 7 days. All the patients were followed up in 90 days. Results FVH was identified in 45 patients (21%), 15 cases of them was found diffusion weighted imaging (DWI) hyperintensities on the same sides. The prevalence of atrial fibrillation (AF, P<0.001), DWI positive (P= 0.010) and arterial occlusive lesions (AOL, P=0.003) were more in the FVH positive patients than in the negative ones, while the duration of symptoms was shorter (P=0.010). Multivariate Logistic regression analysis showed that AF (OR=7.17, 95% CI: 2.71-18.4), AOL (OR=4.93, 95% CI: 3.53-12.6) and hemiplegic (OR=2.84, 95% CI: 1.21-7.42) independently associated with FVH. 7 days after the onset, FVH was not found in 15 patients (65%, transient FVH), in whom the prevalence of AF was more (P=0.020), and AOL was less (P<0.001). A total of 197 patients (90%) were successfully followed up. In the FVH-positive patients, 5 cases developed into recurrent TIA and 6 into ischemic stroke (IS), focused on the the same sides of FVH; while the FVH-negative patients, 2 cases developed into recurrent TIA and 5 into IS. COX proportional hazard analysis showed that FVH (HR=3.64, 95% CI: 1.08-12.6) and AOL (HR=3.82, 95% CI: 1.07-15.8) independently associated with the recurrence of TIA or IS. Conclusion FVH can be helpful for the diagnosis of TIA and predictions for recurrent TIA or IS after a TIA.

Clinical Significance and Related Factors of Fluid-Attenuated Inversion Recovery Vascular Hyperintensi- ties in Transient Ischemic Attack / 中国神经精神疾病杂志

Objective To investigate clinical significance and related factors of fluid-attenuated inversion recov?ery vascular hyperintensities (FVH) in transient ischemic attack (TIA) of carotid system. Method Data including general information and TIA risk factors was continuously collected from 142 patients with carotid system TIA from the depart?ment of neurology of Sheng jing Hospital affiliated China Medical University from January 2012 to February 2014.All pa?tients completed brain MRI including FLAIR and diffusion-weighted imaging (DWI)and MRA examinations within 72 hours after TIA. All patients were followed up for one month. Risk factors and FVH situations were analyzed based on clinical manifestations and DWI results. Result There were 87 male cases (61.27%)and FVH positive 57 cases (40.14%) among 142 cases with carotid system TIA (mean age 63.2±11.5). Logistic regression analysis revealed that the large intra?cranial carotid artery stenosis≥50%(OR=2.44,95%CI:1.09~5.49, P=0.03) and prior history of ischemic stroke (OR=3.88,95%CI:1.04~14.5, P=0.04) were independently associated with positive FVH. At one month followed-up, 40 cas?es (28.17%) of 142 patients progressed to acute cerebral infarction. Vulnerable plaque number in the contralateral carot?id artery (P=0.018), contralateral intracranial large vessel stenosis in MRA≥50%(P=0.007) and contralateral FVH oc?currence rate (P=0.001) were significantly higher in cerebral infarction group than in non-cerebral infarction group. Con?clusion FVH is common in carotid TIA patients, which is associated with intracranial carotid artery stenosis ischemic and previous history of ischemic stroke. Vulnerable plaque number of contralateral carotid artery, contralateral intracranial large vessel stenosis≥50%and the rate of occurrence of contralateral FVH may be associated with short-term progress leading TIA to acute infarction.

Hyperintensity of Subarachnoid Space on FLAIR Images Caused by Supplemental Oxygen

A hyperintensity in the subarachnoid space on fluid-attenuated inversion-recovery (FLAIR) images is often caused by diseases such as subarachnoid hemorrhage or meningitis. Oxygen has a known paramagnetic effect and also causes signal changes in the subarachnoid space on FLAIR images. These changes usually develop when the inspired air contains a high oxygen fraction. Here we present a patient with a hyperintensity in the subarachnoid space on FLAIR images whose inspired air contained only a low oxygen fraction.

Application of Magnetic Resonance Imaging Fluid-attenuated Inversion Recovery Vascular Hyperintensities in Transient Ischemic Attack / 中国康复理论与实践

Objective To investigate the application of magnetic resonance imaging (MRI) fluid-attenuated inversion recovery vascular hyperintensities (FVH) for the diagnosis of transient ischemic attack (TIA). Methods Consecutive 218 inpatients for TIA from May 2011 to July 2013 were reviewed with gender, age, cardiovascular risk factors, TIA or a history of stroke, TIA duration, and calculate the ABCD2 scores. All patients accepted MRI and MRA within 24 hours of symptom onset. FVH positive patients would follow up MRI and MRA with-in 7 days. All the patients were followed up in 90 days. Results FVH was identified in 45 patients (21%), 15 cases of them was found diffu-sion weighted imaging (DWI) hyperintensities on the same sides. The prevalence of atrial fibrillation (AF, P<0.001), DWI positive (P=0.010) and arterial occlusive lesions (AOL, P=0.003) were more in the FVH positive patients than in the negative ones, while the duration of symptoms was shorter (P=0.010). Multivariate Logistic regression analysis showed that AF (OR=7.17, 95%CI:2.71-18.4), AOL (OR=4.93, 95%CI:3.53-12.6) and hemiplegic (OR=2.84, 95%CI:1.21-7.42) independently associated with FVH. 7 days after the onset, FVH was not found in 15 patients (65%, transient FVH), in whom the prevalence of AF was more (P=0.020), and AOL was less (P<0.001). A total of 197 patients (90%) were successfully followed up. In the FVH-positive patients, 5 cases developed into recurrent TIA and 6 into ischemic stroke (IS), focused on the the same sides of FVH;while the FVH-negative patients, 2 cases developed into recurrent TIA and 5 into IS. COX pro-portional hazard analysis showed that FVH (HR=3.64, 95%CI:1.08-12.6) and AOL (HR=3.82, 95%CI:1.07-15.8) independently associat-ed with the recurrence of TIA or IS. Conclusion FVH can be helpful for the diagnosis of TIA and predictions for recurrent TIA or IS after a TIA.

Study of optimization of FLAIR pulse sequence for image quality / 实用放射学杂志

Objective To explore the effect on image quality and scanning time by changing parameters and using different scan-ning technique for the clinical application of axial FLAIR pulse sequence.Methods Seven different sets of parameters of T2-FLAIR Pulse Sequences were performed on thirty patients at a 3.0 T MR scanner.Group A was scanned with a routine sequence for refer-ence.Group B,reducing the matrix to 128.Group C,increasing the turbo factor parameter to 24.Group D,setting the contatena-tion to 1.Group E setting the Accel.factor PE to 4.Group F,using a BLADE-FLAIR sequence.Group G,using a HASTE-FLAIR sequence.The SNRs of all images were statistically analyzed by ANOVA among 7 sequences.The image quality of all images was statistically analyzed by Kruskal-Wallis test among 7 sequences.Results The SNR of seven groups of images were 54.69 ±8.12, 1 57.57±25.61,44.56±7.37,38.48 ± 9.32,44.1 9 ±8.79,45.60 ± 6.92,105.20 ± 18.25,respectively(F = 266.368,P =0.000). The scores of image quality were 3.87±0.09,2.50±0.12,3.72±0.1 6,3.10±0.10,1.88±0.10,3.92±0.07,2.08±0.10,re-spectively and the differences among groups were statistically significant(χ2 =1 93.361,P =0.000).Conclusion Suitable turto factor and BLADE technique can be the best option for FLAIR sequence in the head.HASTE-FLAIR sequence can act as the secondary op-tion for the uncooperative patients.

T1-weighted FLAIR MR Imaging for the Evaluation of Enhancing Brain Tumors: Comparison with Spin Echo Imaging

PURPOSE: Spin-echo (SE) technique is most commonly used pulse sequence for T1-weighted MR imaging. T1-weighted fluid-attenuated inversion recovery (T1FLAIR) is a relatively new pulse sequence and it provides higher tissue contrast between the gray matter (GM) and white matter (WM) of the brain than T1-weighted SE (T1SE) sequence. However, there has been controversy for the evaluation of enhancing brain tumors with T1FLAIR compared to T1SE. The purpose of this study was to compare T1FLAIR and T1SE sequences for the evaluation of enhancing intracranial tumors. MATERIALS AND METHODS: Fifty-two patients with enhancing brain tumors were evaluated with contrast-enhanced (CE) T1SE and T1FLAIR imaging. Eight quantitative criteria were calculated: lesion-to-WM contrast ratio (CR) and contrast-to-noise ratio (CNR), lesion-to-GM CR and CNR, lesion-to-CSF CR and CNR, and WM-to-GM CR and CNR. For qualitative evaluation, two radiologists assessed lesion conspicuity on CE T1SE and T1FLAIR sequences with three-scale: 1, T1SE superior; 2, sequence equal; T1FLAIR superior. RESULTS: Seventy-nine tumors (31 primaries, 48 metastases) were assessed. For quantitative measurement, the T1FLAIR lesion-to-GM, lesion-to-CSF, WM-to-GM CR and CNR values were comparable and statistically superior to those of the T1SE images (p < 0.001 in all). However, lesion-to-WM CR and CNR were similar on both two sequences without statistically significant difference (p = 0.661, 0.662, respectively). For qualitative evaluation, both radiologists assessed that T1FLAIR images were superior to T1SE images for the evaluation of lesion conspicuity. CONCLUSION: For the evaluation of enhancing intracranial tumors, T1FLAIR sequence was superior or comparable to T1SE sequence.

Hyperintense Vessel Sign on T2-FLAIR on Patients with Carotid Endarterectomy / 中国医学影像学杂志

Purpose To evaluate the correlation between T2-FLAIR hyperintense vessel sign (HVS) and the stenotic degree of internal carotid artery (ICA) and assess the HVS changes after the carotid endarterectomy (CEA). Materials and Methods Fifty-one patients with CEA were retrospectively enrolled. The stenosis of the bilateral ICA were as:≥90%, and<90%. The distribution of HVS locations was classified as three regions:sylvian fissure, sulci of temporo-occipital lobe and other areas. The presence and the location of HVS were counted. The extrension of HVS on T2-FLAIR were graded as:I:the presence of HVS was<1/3 of the MCA territory, II:the presence of HVS was≥1/3 of the MCA territory.χ2-test was performed for correlation between HVS and ICA stenosis. The difference of HVS and stenosis of ICA and their effects on CEA was accessed. Results HVS was significantly higher in the ICA stenosis more than 90%group than in the less than 90% group (χ2=23.584, P<0.001). The frequencies of HVS were 12, 34 and 15 in sylvian fissure, sulci of temporo-occipital lobe and other area, respectively. The proportion of grade II HVS was higher in the ≥ 90% group than in the<90% group (χ2=8.395, P<0.05). After CEA, HVS on 29 affected hemispheres were showed to be disappeared (n=24) or remained (n=5) in the treated side. Conclusion The presence and the grade of HVS were correlated with the stenotic degree of ICA. In the patients with ICA stenosis, HVS was most frequently found in the sulci of temporal lobe and occipital lobe, and seldom found in sylvian fissure. HVS disappeared after CEA indicating that HVS can be considered as a marker for CEA treatment.