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.

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.

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.

Applications of fluid-attenuated inversion recovery sequence in patients with acute ischemic stroke / 国际脑血管病杂志

The fluid-attenuated inversion recovery (FLAIR) sequence technique is widely used in each system organ examination in clinical practice.It has an important value for the diagnosis of various diseases,especially for central nervous system examination.This article reviews the applications and related research of FLAIR technique in patients with acute ischemic stroke.

Fluid Attenuated Inversion Recovery (FLAIR) Imaging of the Normal Brain: Comparisons between Under the Conditions of 3.0 Tesla and 1.5 Tesla

OBJECTIVE: The aim of this study was to evaluate the differences in normal brain MRI findings between under 3.0 Tesla (T) and 1.5T MRI conditions with the use of the fluid attenuated inversion recovery (FLAIR) sequences. MATERIALS AND METHODS: Eleven normal adults underwent imaging with the use of the FLAIR sequences on both 1.5T and 3.0T scanners. Two neuroradiologists compared the signal intensity (SI) of the centrum semiovale (CS), pulvinar thalami (PT) and normal iron deposit structures (IDSs) on the 3.0T and 1.5T FLAIR images, and they evaluated three MRI findings qualitatively: high SI of CS; low SI of PT; low SI of IDS. We also evaluated signal-to-noise ratios (SNRs) for the CS, PT, red nucleus and cerebellar dentate nucleus on the FLAIR images. RESULTS: Based on qualitative analyses, the 3.0T FLAIR images showed all three MRI findings for all cases. Low SI for the PT in seven cases (64%), high SI of the CS in one case (9%) and low SI of the cerebellar dentate nucleus in one case (9%) were visualized only on 3.0T FLAIR images. The mean SNRs of the PT, red nucleus and dentate nucleus in patients where 3.0T FLAIR imaging was performed were significantly lower as compared with the SNRs on 1.5T FLAIR images. The SNR of the CS was not significantly different between under the two magnetic field strengths (p > 0.05). CONCLUSION: We have demonstrated that normal, high and low SIs of the CS, PT and IDS on 3.0T FLAIR images were depicted more frequently and more prominently as compared with those on 1.5T FLAIR images in normal adult brains.

Application of tailored radiofrequency (TRF) in T2-FLAIR MR imaging / 医疗卫生装备

Objective To investigate the influence of TRF on high-intensity cerebrospinal fluid artifacts in T2-FLAIR MR imaging.Methods In a GE Signa Twinspeed 1.5T system,50 cases were examined with T2-FLAIR sequences including 2 different optional imaging parameters according to the augmentation of TRF.Results TRF pulses significantly improved image quality(P

The Experimental Research of Primary Technique Parameter in Fluid Attenuated Inversion Recovery / 实用放射学杂志

Objective To study the correlation between the main parameters and the effect of repression in MR fluid attenuated inversion recovery(FLAIR).Methods 0.5 unit was used in this experiment.The protein aqua of different material appearance and concentration was prepared.FLAIR was performed using the tube imitative experimented method and with different paramters.The best scan parameters were selected by comparison each other and their relativity was analysed.Results The best technical parameters:TR=4000~5000 ms,TE=90~100 ms,TI=1800~2000 ms.Conclusion TI is the key parameter in determining the repression effect,TR and TE only determine the scans time and layer number.FLAIR's repress result is stable,and it can estimate the protein content in the protein aqua.