3D Fluid-attenuated Inversion Recovery Sequence Research Articles

Selective otolithic dysfunction in patients presenting with acute spontaneous vertigo: consideration based on MRI.

Acute unilateral peripheral vestibulopathy or vestibular neuritis (AUPV/VN) manifests as acute onset vertigo, often accompanied by nausea, vomiting, and moderate gait instability. It is suspected when vestibular hypofunction is documented on video-head impulse (video-HITs) and caloric tests in the presence of contralesionally beating horizontal-torsional nystagmus. Herein, we report patients presenting with acute vestibular syndrome (AVS) showing selective otolithic dysfunction in the presence of normal caloric and video-HITs and abnormal enhancement of the peripheral vestibular structures on MRI. We retrospectively reviewed the medical records of patients presenting with AVS between September 2019 and April 2024 at a tertiary referral hospital in South Korea. All patients underwent extensive neurotologic evaluation, including cervical and ocular vestibular-evoked myogenic potentials (cVEMP and oVEMP, respectively), subjective visual vertical, video-oculography, video-HITs, caloric tests, and audiometry. Patients also underwent MRI according to a standard protocol for the inner ear and internal acoustic canal with an additional 3D-fluid attenuated inversion recovery sequence acquired 4 h after intravenous gadolinium injection. We identified four patients with selective otolith dysfunction. Video-HITs and caloric test results were normal in all patients, except one with a canal paresis on the opposite side of otolithic dysfunction. Patients usually showed abnormal oVEMP (n = 3) and cVEMP (n = 2) or subjective visual vertical (n = 3). Gadolinium enhancements were found in the vestibule (n = 3), inferior (n = 2) or superior (n = 1) vestibular nerves on dedicated inner ear MRI. Selective otolithic dysfunction can present with AVS, which can be easily overlooked. A thorough neurotologic evaluation and MRI dedicated to the inner ear can help detect selective otolithic dysfunction, expanding the clinical spectrum of AVS.

Sensitivity of Magnetic Resonance Imaging in Detection of Choroidal Metastases

Introduction: The objective of this study was to determine the sensitivity of brain magnetic resonance imaging (MRI) in the detection of choroidal metastasis (CM) from systemic primary cancers. Methods: A retrospective chart review identified patients with clinically confirmed CM seen on the Oncology Service (Byers Eye Institute) between January 2018 and March 2022. Patients had an MRI brain and/or orbits performed within 3 months of CM diagnosis. Evaluation of CM detection by MRI was then divided into two parts: an initial “standard read,” where determination of CM detection was based solely on the original radiology report, to reflect real-world performance, and a subsequent “dedicated read,” for which a board-certified neuroradiologist, blinded to the laterality and location of the CM, reevaluated the studies to provide an objective “gold standard” interpretation regarding the radiographic detection of CM. Results: The study included 42 eyes of 40 patients with confirmed CM. On standard read, MRI detection of CM occurred in 21 of 42 eyes (50%), with no significant difference between MRI brain and orbit protocols (p = 0.249). Features associated with improved detection were increased tumor basal diameter (p < 0.001) and ultrasonographic tumor thickness (p = 0.003). On dedicated read, MRI detection of CM improved to 26 of 33 eyes (76%; limited to eyes with full complement of pre- and post-gadolinium sequences). Post-gadolinium 3D fluid-attenuated inversion recovery (FLAIR) sequence with fat suppression was the most sensitive (88%) for CM detection. 42% and 58% of lesions were visualized using conventional pre-gadolinium T1- and T2-weighted imaging, respectively. Conclusions: MRI sensitivity to detect CM improved from 50% to 76% with focused reinterpretation. Increased utilization of the post-gadolinium 3D FLAIR sequence and increased ocular scrutiny in cancer patients undergoing brain imaging may facilitate earlier diagnosis of CM.

Diagnostic value of contrast-enhanced 3D FLAIR sequence in acute optic neuritis.

Contrast-enhanced fluid-attenuated inversion recovery (FLAIR) sequence of the brain has the potential for detecting optic nerve abnormality. This study aimed to compare the diagnostic value of whole-brain contrast-enhanced three-dimensional FLAIR with fat suppression (CE 3D FLAIR FS) sequence in detecting acute optic neuritis to dedicated orbit MRI and clinical diagnosis. Twenty-two patients with acute optic neuritis who underwent whole-brain CE-3D-FLAIR FS and dedicated orbit MRI were retrospectively included. The hypersignal FLAIR of the optic nerve on whole-brain CE-3D-FLAIR FS, enhancement, and hypersignal T2W on orbit images were assessed. The optic nerve to frontal white matter signal intensity ratio on CE-FLAIR FS was calculated as maximum signal intensity ratio (SIR) and mean SIR. Twenty-six hypersignals of optic nerves were found on CE-FLAIR FS from 30 pathologic nerves. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of CE FLAIR FS brain and dedicated orbital images for diagnosing acute optic neuritis were 77%, 93%, 96%, 65%, and 82% and 83%, 93%, 96%, 72%, and 86%, respectively. Optic nerve to frontal white matter SIR of the affected optic nerves was higher than that of normal optic nerves. Using a cutoff maximum SIR of 1.24 and cutoff mean SIR of 1.16, the sensitivity, specificity, PPV, NPV, and accuracy were 93%, 86%, 93%, 80%, and 89% and 93%, 86%, 93%, 86%, and 91%, respectively. The hypersignal of the optic nerve on whole-brain CE 3D FLAIR FS sequence has qualitative and quantitative diagnostic potential in patients with acute optic neuritis.

Delayed post-contrast MRI in the assessment of Meniere’s disease—initial South Australian experience

Background: The underlying pathology of Meniere’s disease (MD) has long been attributed to endolymphatic hydrops (EH), until recently only detectable on post-mortem studies. In this retrospective cross-sectional study, we utilised heavily T2 weighted post-contrast 3D FLAIR (fluid attenuated inversion recovery) sequences at 3T MRI (magnetic resonance imaging) for detection and grading of EH in patients with clinically suspected MD.

3D FLAIR Cochlear Abnormality Does Not Predict on Sudden Sensorineural Hearing Loss Prognosis: A Retrospective Cohort Study

Background and Objectives Previous studies reported abnormalities in MRI as a poor prognostic indicator of sudden sensorineural hearing loss (SSNHL). Since abnormalities in three-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) are strongly correlated with the initial hearing function, the prognostic value of the 3D FLAIR images should be carefully evaluated to avoid collinearity. We aimed to evaluate abnormalities on the 3D FLAIR images as an independent prognostic factor in the matched SSNHL groups.Subjects and Method We retrospectively reviewed medical records of 179 patients with SSNHL who underwent temporal MRI, including the 3D FLAIR sequence, between January 2015 and December 2019. Patients were divided based on the presence of cochlear abnormalities on the 3D FLAIR images. Hearing prognosis was evaluated with and without matching for initial hearing and treatment interval.Results The groups were similar in sex (p=0.091), age (p=0.925), treatment interval (p= 0.216), and MRI interval (p=0.828). Notably, patients with cochlear abnormalities on the 3D FLAIR images showed distinctly more severe hearing loss (p&lt;0.001) at the initial pure tone average (PTA) assessment and poorer outcomes (p&lt;0.001) compared to those without abnormality. After matching for initial hearing and treatment interval, the hearing outcome, measured by PTA, was similar between the groups (p=0.681).Conclusion Cochlear signal abnormality in 3D FLAIR MRI was associated with poor initial hearing. However, it did not affect hearing recovery outcomes when the groups were matched.

Magnetic resonance imaging in dogs with neuroangiostrongyliasis (rat lungworm disease).

The magnetic resonance imaging (MRI) appearance of the brain and spinal cord in humans with neuroangiostrongyliasis (NA) due to Angiostrongylus cantonensis infection has been well reported. Equivalent studies in animals are lacking. This case series describes clinical and MRI findings in 11 dogs with presumptively or definitively diagnosed NA. MRI of the brain and/or spinal cord was performed using high-field (1.5 T) or low-field (0.25 T) scanners using various combinations of transverse, sagittal, dorsal and three-dimensional (3D) T1-weighted (T1W), transverse, sagittal and dorsal T2-weighted (T2W), T2W fluid-attenuated inversion recovery (FLAIR) and T2*-weighted (T2*W) gradient echo (GRE), dorsal T2W short tau inversion recovery (STIR) and post-gadolinium transverse, sagittal, dorsal and 3D T1W and transverse T2W FLAIR sequences. In 4/6 cases where the brain was imaged, changes consistent with diffuse meningoencephalitis were observed. Evidence of meningeal involvement was evident even when not clinically apparent. The spinal cord was imaged in 9 dogs, with evidence of meningitis and myelitis detected in regions consistent with the observed neuroanatomical localization. Pathognomonic changes of neural larva migrans, as described in some human patients with NA, were not detected. NA should be considered in the differential diagnosis of dogs with MRI evidence of focal or diffuse meningitis, myelitis and/or encephalitis, especially in areas where A. cantonensis is endemic. If not precluded by imaging findings suggestive of brain herniation, cerebrospinal fluid (CSF) collection for cytology, fluid analysis, real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) testing should be considered mandatory in such cases after the MRI studies.

Improving the image quality of 3D FLAIR with a spiral MRI technique.

Fluid-attenuated inversion recovery (FLAIR) nulls the CSF signal and is widely used in neuro MRI exams. A 3D scan can provide high SNR, contiguous coverage, and reduced sensitivity to through-plane CSF flow. In this work, a 3D spiral FLAIR technique is proposed to improve the image quality of conventional 3D Cartesian FLAIR. The 3D spiral FLAIR sequence incorporated a spiral-in/out readout to preserve higher scan efficiency and eliminate off resonance-induced artifacts observed with a commonly implemented spiral-out readout, a compensation approach to minimize phase errors due to the concomitant fields accompanying the spiral gradient, and an adapted variable flip angle scheme to preserve scan efficiency and maintain a long and stable echo train. 3D Cartesian and spiral FLAIR (~6 min each) were acquired on a 3 Tesla scanner from 6 subjects (age range: 31-64 years; mean: 39.5). Two neuroradiologists rated the images in a blinded fashion on a 5-point scale. The noise performance was assessed quantitatively. Compared to 3D Cartesian FLAIR, 3D spiral FLAIR exhibits greater reduction of artifacts from CSF, especially anterior to the brain stem (rated better in 4 cases), artifacts attributed to blood/flow in the deep brain (better or much better in all 6 cases), and superior overall image quality (much better in 5 cases) despite residual susceptibility artifacts near the nasal cavity. Quantitative assessment demonstrates ~1.5× higher average SNR than Cartesian data. 3D spiral FLAIR achieves higher SNR, reduced CSF, and blood/flow artifacts, providing an alternative to 3D Cartesian FLAIR for neurological exams.

Audiovestibular Phenotypes and Advanced Magnetic Resonance Imaging Features of Cochlin Gene Mutation Carriers

Objective: To describe clinical and imaging findings in a group of patients affected by nonsyndromic deafness A9 (DFNA9), using advanced magnetic resonance imaging (MRI) with 3-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) sequence. Method: A retrospective case review was conducted in a tertiary referral center in Italy. Four sequential adult DFNA9-affected patients, who had undergone MRI at our Department between January 2017 and June 2018, were enrolled (male = 2, female = 2; median age: 65.6 years; 8 diseased ears analyzed). Three patients were relatives; the fourth was unrelated. The main outcome measures – age, sex, records of audiological and vestibular testing, genetic assessment, MRI findings – were analyzed. Results: All subjects suffered from bilateral progressive sensorineural hearing loss, more severely at the high frequencies and with a typical clinical pattern of bilateral chronic degenerative cochleovestibular deficit. Aural fullness was reported at the onset of the disease. All patients revealed a pathogenic heterozygous mutation in the Limulus factor C, Coch-5b2 and Lgl1 domain of cochlin. None of the patients showed a significant vestibular and cochlear endolymphatic hydrops at MRI, while high bilateral contrast enhancement on 4-h delayed postcontrast 3D FLAIR sequence was observed in all ears. Conclusions: Increased perilymph enhancement on 4-h delayed postcontrast 3D FLAIR sequence is the common imaging feature of DFNA9 ears, suggesting that blood-labyrinthine barrier breakdown may play the main role in the pathophysiology of this disease. Significant hydrops has been excluded by MRI. This finding might be clinically useful in differentiating DFNA9 disease from other pathologies with similar clinical findings like Ménière’s disease.

To Compare Diagnostic Ability of Contrast-Enhanced Three-Dimensional T1-SPACE with Three-Dimensional Fluid-Attenuated Inversion Recovery and Three-Dimensional T1-Magnetization Prepared Rapid Gradient Echo Magnetic Resonance Sequences in Patients of Meningitis.

Aims:The aim of this study is to compare postcontrast three-dimensional (3D) T1-Sampling perfection with application-optimized contrasts by using different flip angle evolutions, 3D fluid-attenuated inversion recovery (FLAIR), and 3D T1-magnetization prepared rapid gradient echo (MPRAGE) sequences in patients of meningitis.Settings and Design:A hospital-based cross-sectional study done in the Department of Radiodiagnosis, IGMC Shimla for a period of 1 year from June 1, 2016, to May 30, 2017.Subjects and Methods:A total of 30 patients suspected of meningitis underwent magnetic resonance imaging evaluation with postcontrast 3D T1-MPRAGE, 3D T1-SPACE, and 3D FLAIR sequences. The abnormal leptomeningeal enhancement was noted by two radiologists together on these sequences and scores were given to the abnormal leptomeningeal enhancement.Statistical Analysis Used:The sensitivity of 3D T1-SPACE, 3D T1-MPRAGE, and 3D FLAIR was calculated and compared. The level of agreement between these sequences was assessed by kappa coefficient. P < 0.05 was taken as statistically significant.Results:3D T1-SPACE shows superiority in meningeal enhancement along basal cisterns, Sylvian fissure and along cerebral convexities. It is also found to be better in delineating parenchymal lesions. 3D FLAIR failed to demonstrate enhancement along cerebral convexities however found to be better than 3D T1-MPRAGE in delineating enhancement along basal cisterns and Sylvian fissures. 3D T1-MPRAGE has shown subtle enhancement in basal cisterns, Sylvian fissure and along cerebral convexities. 3D T1-SPACE, 3D FLAIR, and 3D T1-MPRAGE has sensitivity of 91.67%, 66.67%, and 54.17%, respectively.Conclusion:Postcontrast 3D T1-SPACE sequence is an excellent tool than postcontrast 3D T1-MPRAGE and 3D FLAIR sequences in the evaluation of meningeal enhancement and depiction of additional lesions in brain parenchyma.

Comparing longitudinal brain atrophy measurement techniques in a real-world multiple sclerosis clinical practice cohort: towards clinical integration?

Background:Whole brain atrophy (WBA) estimates in multiple sclerosis (MS) correlate more robustly with clinical disability than traditional, lesion-based metrics. We compare Structural Image Evaluation using Normalisation of Atrophy (SIENA) with the icobrain longitudinal pipeline (icobrain long), for assessment of longitudinal WBA in MS patients.Methods:Magnetic resonance imaging (MRI) scan pairs [1.05 (±0.15) year separation] from 102 MS patients were acquired on the same 3T scanner. Three-dimensional (3D) T1-weighted and two-dimensional (2D)/3D fluid-attenuated inversion-recovery sequences were analysed. Percentage brain volume change (PBVC) measurements were calculated using SIENA and icobrain long. Statistical correlation, agreement and consistency between methods was evaluated; MRI brain volumetric and clinical data were compared. The proportion of the cohort with annualized brain volume loss (aBVL) rates ⩾ 0.4%, ⩾0.8% and ⩾0.94% were calculated. No evidence of disease activity (NEDA) 3 and NEDA 4 were also determined.Results:Mean annualized PBVC was −0.59 (±0.65)% and −0.64 (±0.73)% as measured by icobrain long and SIENA. icobrain long and SIENA-measured annualized PBVC correlated strongly, r = 0.805 (p < 0.001), and the agreement [intraclass correlation coefficient (ICC) 0.800] and consistency (ICC 0.801) were excellent. Weak correlations were found between MRI metrics and Expanded Disability Status Scale scores. Over half the cohort had aBVL ⩾ 0.4%, approximately a third ⩾0.8%, and aBVL was ⩾0.94% in 28.43% and 23.53% using SIENA and icobrain long, respectively. NEDA 3 was achieved in 35.29%, and NEDA 4 in 15.69% and 16.67% of the cohort, using SIENA and icobrain long to derive PBVC, respectively.Discussion:icobrain long quantified longitudinal WBA with a strong level of statistical agreement and consistency compared to SIENA in this real-world MS population. Utility of WBA measures in individuals remains challenging, but show promise as biomarkers of neurodegeneration in MS clinical practice. Optimization of MRI analysis algorithms/techniques are needed to allow reliable use in individuals. Increased levels of automation will enable more rapid clinical translation.

Comparing lesion detection of infratentorial multiple sclerosis lesions between T2-weighted spin-echo, 2D-FLAIR, and 3D-FLAIR sequences

PurposeInfratentorial lesions in patients with multiple sclerosis are associated with long-term disability. Two-dimensional fluid-attenuated inversion recovery demonstrates poor infratentorial lesion detection when compared to T2-weighted spin echo. Evidence of improved detection with 3D fluid-attenuated inversion recovery has been conflicting. This study compares the infratentorial lesion detection performance, observer performance, and signal and contrast properties between T2-weighted spin echo, 2D, and 3D fluid-attenuated inversion recovery. MethodsTwo board-certified radiologists independently reviewed and counted infratentorial lesions from 85 brain MRIs in patients with clinically definite multiple sclerosis and concurrent 3D, 2D fluid-attenuated inversion recovery, and T2-weighted spin echo sequences. Contrast-to-noise and signal-to-noise ratios were measured for 25 MRIs. Wilcoxon signed-rank test was used for pairwise comparisons of the combined average infratentorial lesion count, contrast-to-noise, and signal-to-noise ratios, and was adjusted for three pairwise comparisons using Bonferroni correction. A corrected p value < 0.05 was considered statistically significant. ResultsThe number of lesions on 3D fluid-attenuated inversion recovery was significantly higher than those on 2D (p < 0.001) and T2-weighted spin echo (p < 0.001). Results of contrast-to-noise and signal-to-noise ratios were overall mixed and predominantly not concordant with lesion count findings, with T2-weighted spin echo demonstrating the highest signal-to-noise ratios and contrast-to-noise ratio of lesion compared with white matter but the lowest contrast-to-noise ratio of lesion compared with gray matter. ConclusionThe 3D fluid-attenuated inversion recovery sequence addresses the disadvantage of poor infratentorial lesion detection on 2D, while still maintaining the advantage over T2-weighted spin echo in the detection of lesions adjacent to the cerebrospinal fluid.

Efficiency of Double Inversion Recovery (DIR) Sequence in the Evaluation of Supratentorial Cortical Lesions in Multiple Sclerosis

The aim of this study is to investigate if the three–dimensional (3D) double inversion recovery (DIR) sequence is superior compared to the 3D fluid–attenuated inversion–recovery (FLAIR) sequence in detecting intracortical, mixed, juxtacortical (JX), and deep grey matter (GM) lesions in multiple sclerosis (MS) patients. The correlation between intracortical lesion load and disability status was also investigated. Magnetic resonance imaging examinations of 24 patients (9 males, 15 females; mean age 34.4±12.0 (16-69) were retrospectively evaluated from our database. Lesions were counted and classified according to anatomic regions as intracortical, mixed, JX, and deep GM on the 3D DIR and FLAIR sequences. The incidence of lesions on the two sequences were identified and compared. The relationship between the number of lesions and type of MS, patient age, gender, duration of the disease, disability, the mean number of attacks per year and Expanded Disability Status Scale (EDSS) score was also investigated. More lesions were detected by the DIR sequence compared to the FLAIR sequence in all regions except for thalamus (11/12). The lesion detection superiority of DIR was statistically significant for intracortical lesions (p<0.001) and GM lesions (intracortical +mixed) (p<0.001). Lesion load of the JX area in the DIR sequence decreased as the disease duration (r=-0.444; p=0.030) and age (r=-0.473; p=0.020) increased. JX lesion load in the DIR sequence decreased as the number of attacks increased (r=-0.602; p=0.002). More mixed lesion load on the DIR sequence were found in cerebral atrophy group than in no cerebral atrophy group (p=0.026). EDSS score increased as the disease duration and number of attacks increased (p=0.003, p<0.001). There was no correlation between lesion location and EDSS score. The DIR sequence is superior to the FLAIR sequence in the detection of intracortical and GM lesions. Also, the mixed lesion load on the DIR sequence is correlated with cerebral atrophy.

Comparison of Double Inversion Recovery and FLAIR Sequences in Diagnosing Multiple Sclerosis Infratentorial Plaques

Fluid–Attenuated Inversion Recovery (FLAIR) is the most commonly used sequence in routine practice for MS. Recent studies employ alternative sequences such as Double Inversion Recovery (DIR) in addition to conventional MRI techniques. In this study we compared these two sequences for their sensitivity in detecting infratentorial lesions in MS. A total of 24 patients with 3D DIR and 3D FLAIR sequences were included in this study. Plaques were classified according to their localization such as brainstem and cerebellar plaques. The relationship between number of infratentorial plaques and age, gender, MS type, disease duration, average annual number of attacks, cerebellar atrophy existence and EDSS score was also analyzed. DIR sequence detected higher number of lesions compared to FLAIR sequence in brainstem (59 vs 45 plaque in 24 cases) and cerebellum (50 vs 25 plaque in 24 cases). In detecting cerebellar lesions, superiority of DIR sequence compared to FLAIR sequence was statistically significant (p=0.049). Patients with longer disease duration had less cerebellar lesion load in FLAIR sequence at a statistically significant rate. Patients with longer disease duration and higher number of attacks had higher EDSS scores. There was no relationship between brainstem plaques number of cerebellum plaques and EDSS score. Comparing groups with and without cerebellar atrophy, cerebellar atrophy was also more frequent in patients with higher level of cerebellar lesion load in DIR sequence (p=0.028). Our findings suggest that DIR sequence is superior to FLAIR sequence in detecting cerebellar lesions. Cerebellar lesion load detected in DIR sequence was correlated to cerebellar atrophy. For this reason, especially during early period of disease, DIR sequence may be more useful than FLAIR sequence in distinguishing definite MS from clinical isolated syndromes and also for determining atrophy risk.

Reduced scan time three-dimensional FLAIR using modulated inversion and repetition time.

The purpose of this study is to design and evaluate a new reduced scan time three-dimensional (3D) FLuid Attenuated Inversion Recovery (FLAIR) sequence. The 3D FLAIR sequence was modified so that the repetition time was modulated in a predetermined smooth manner (3D mFLAIR). Inversion times were adjusted accordingly to maintain cerebrospinal fluid (CSF) suppression. Simulations were performed to determine SNR for gray matter (GM), white matter (WM), and CSF. Fourteen volunteers were imaged using the modified and product sequence. SNR measurements were performed in GM, WM, and CSF. Mean value and the 95% confidence interval ([CI]) were assessed. Scan time for the 3D FLAIR and 3D mFLAIR sequences was measured. There was no statistically significant difference in the SNR measured in GM (P value = 0.5; mean SNR = 42.8 [CI]: 38.2-45.5 versus 42.2 [CI]: 38.3-46.1 for 3D FLAIR and 3D mFLAIR, respectively) and WM (P value = 0.25; mean SNR = 32.1 [CI]: 30.3-33.8 versus 32.9 [CI]: 31.1-34.7). Scan time reduction greater than 30% was achieved for the given parameter set with the 3D mFLAIR sequence. Scan time for 3D FLAIR can be effectively reduced by modulating repetition and inversion time in a predetermined manner while maintaining the SNR and CNR of a constant TR sequence.

Optimization of Magnetization-Prepared 3-Dimensional Fluid Attenuated Inversion Recovery Imaging for Lesion Detection at 7 T

The aim of this study was to optimize the 3-dimensional (3D) fluid attenuated inversion recovery (FLAIR) pulse sequence for isotropic high-spatial-resolution imaging of white matter (WM) and cortical lesions at 7 T. We added a magnetization-prepared (MP) FLAIR module to a Cube 3D fast spin echo sequence and optimized the refocusing flip angle train using extended phase graph simulations, taking into account image contrast, specific absorption rate (SAR), and signal-to-noise ratio (SNR) as well as T1/T2 values of the different species of interest (WM, grey matter, lesions) at 7 T. We also effected improved preparation homogeneity at 7 T by redesigning the refocusing pulse used in the MP segments. Two sets of refocusing flip angle trains-(a) an SNR-optimal and (b) a contrast-optimal set-were derived and used to scan 7 patients with Alzheimer disease/cognitive impairment and 7 patients with multiple sclerosis. Conventional constant refocusing flip MP-FLAIR images were also acquired for comparison. Lesion SNR, contrast, and lesion count were compared between the 2 optimized and the standard FLAIR sequences. Whole brain coverage with 0.8 mm isotropic spatial resolution in ∼5-minute scan times was achieved using the optimized 3D FLAIR sequences at clinically acceptable SAR levels. The SNR efficiency of the SNR-optimal sequence was significantly better than that of conventional constant refocusing flip MP-FLAIR sequence, whereas the scan time was reduced more than 2-fold (∼5 vs >10 minutes). The contrast efficiency of the contrast-optimal sequence was comparable with that of the constant refocusing flip sequence. Lesion load ascertained by lesion counting was not significantly different among the sequences. Magnetization-prepared FLAIR-Cube with refocusing flip angle trains optimized for SNR and contrast can be used to characterize WM and cortical lesions at 7 T with 0.8 mm isotropic resolution in short scan times and without SAR penalty.

Fluid-attenuated inversion recovery vascular hyperintensities are not visible using 3D CUBE FLAIR sequence

Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH), initially described on 2D FLAIR images, are a useful imaging marker in patients with acute ischaemic stroke. We aimed to compare the sensitivity of the 3D CUBE FLAIR sequence with 2D FLAIR for the detection of FVH. Forty-seven consecutive patients admitted for a suspected stroke were explored by 2D and 3D CUBE FLAIR MR sequences at 1.5 and 3 T. Three blinded readers assessed FVH defined as hyperintensities within cerebral arteries. Location of FVH, acute brain infarct and arterial stenosis were also assessed. 2D images were compared with 3D images for the detection of FVH. Agreement between readers was assessed. Of the 47 patients, 21 FVHs were observed on 2D FLAIR images of 15 patients (11 with acute brain infarct and 11 with an arterial stenosis). No FVH was visualised on 3D CUBE FLAIR images for either proximal or distal locations. Agreement between readers was excellent. FVHs are not visible using 3D CUBE FLAIR images. This study suggests that, in suspected acute ischaemic stroke, the assessment of FVH should only be performed on conventional 2D FLAIR images. • Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH) are of neuroradiological importance. • FVHs are useful imaging markers in patients with an acute ischaemic stroke. • FVHs are not visible using 3D CUBE FLAIR images. • Assessment of FVH should be performed on conventional 2D FLAIR images.

3D FLAIRED: 3D fluid attenuated inversion recovery for enhanced detection of lesions in multiple sclerosis

Contrast optimization of a three-dimensional (3D) Fluid-attenuated inversion recovery (FLAIR) sequence is examined in the context of multiple sclerosis. In order to develop 3D FLAIR for enhanced detection of lesions, an iterative approach based on theoretical considerations was used. The 3D FLAIR sequence was systematically acquired with incremental parameter changes on a single subject with multiple sclerosis in a 3-T MRI scanner. Region of interest analysis was performed on the images, and the best estimate of the optimal acquisition parameters was established. This process was iterated on subsequent patients with multiple sclerosis until only marginal gains in quality were obtained. Three-dimensional FLAIR for enhanced detection produced increased lesion detection and identification in the supratentorial and infratentorial regions when compared with default GE 3D FLAIR and two-dimensional FLAIR sequences. Lesion border delineation was enhanced as evidenced by better lesion and white matter contrast ratios, demonstrating that the approach is a viable method for improved lesion detection.

Three-Dimensional Fluid Attenuated Inversion Recovery Imaging With Isotropic Resolution and Nonselective Adiabatic Inversion Provides Improved Three-Dimensional Visualization and Cerebrospinal Fluid Suppression Compared to Two-Dimensional Flair at 3 Tesla

In this investigation, we compare two-dimensional (2D) fluid-attenuated inversion recovery (FLAIR) imaging of the brain to an isotropic three-dimensional (3D) FLAIR technique that uses a modulated refocusing flip angle echo train and parallel imaging with 2D acceleration. Two-dimensional and 3D FLAIR sequences were obtained in 16 patients. All examinations were performed on a 3 Tesla (T) magnetic resonance (MR) system. Flow artifacts within the subarachnoid space and ventricles were scored using a 4-point scale. For 2D and 3D FLAIR, the signal-to-noise ratios and contrast-to-noise ratios were calculated. Compared to 2D FLAIR, the 3D FLAIR images were less degraded by flow artifacts in the subarachnoid space and ventricle (P < 0.03) based on the qualitative imaging scores. Signal-to-noise ratios and contrast-to-noise ratios were higher for 3D FLAIR (P < 0.02) for all variables when compared with 2D FLAIR sequence. The acquisition time for whole brain isotropic fast spin echo 3D FLAIR can be dramatically reduced by using an extended echo train with flip angle modulation and parallel imaging. The adiabatic, nonselective inversion pulse encompasses the entire volume and provides uniform suppression of the cerebrospinal fluid signal eliminating cerebrospinal fluid pulsation artifacts. Other advantages include reformatting in any desired plane, volume measurements, displays of surface anatomy, and coregistration.

Intracortical Lesions in Multiple Sclerosis: Improved Detection with 3D Double Inversion-Recovery MR Imaging

To prospectively compare the depiction of intracortical lesions by using multislab three-dimensional (3D) double inversion-recovery (DIR), multislab 3D fluid-attenuated inversion-recovery (FLAIR), and T2-weighted spin-echo (SE) magnetic resonance (MR) imaging in patients with multiple sclerosis. Local ethics review board approval and informed consent were obtained. Conventional T2-weighted SE and multislab 3D FLAIR and DIR images were acquired in 10 patients with multiple sclerosis (five women, five men) and 11 age-matched healthy control subjects (seven women, four men). Mean age was 40 years (range, 25-54 years) in patients and 34 years (range, 24-55 years) in control subjects. Lesions were classified according to seven anatomic regions: intracortical, mixed white matter-gray matter, juxtacortical, deep gray matter, periventricular white matter, deep white matter, and infratentorial lesions. The numbers of lesions per category were compared between techniques (Dunnett-corrected analysis of variance). Gain or loss (with 95% confidence intervals [CIs]) of numbers of lesions detected at 3D DIR imaging was calculated in comparison with those detected at T2-weighted SE and 3D FLAIR imaging. Total number of lesions did not differ between 3D DIR and 3D FLAIR sequences, but the 3D DIR sequence showed a gain of 21% (95% CI: 4%, 41%) in comparison with the T2-weighted SE sequence. Because of high gray matter-white matter contrast, DIR images depicted more intracortical lesions (80 lesions in 10 patients) than both SE (10 lesions) and FLAIR (31 lesions) images; gains with DIR were 538% (95% CI: 191%, 1297%) and 152% (95% CI: 15%, 453%) compared with SE and FLAIR, respectively. Only four intracortical lesions were detected in control subjects. Also, DIR imaging enabled a better definition of mixed white matter-gray matter lesions because of greater contrast between the lesion and its surroundings. MR imaging with 3D DIR enables increased intracortical lesion detection in the multiple sclerosis brain, as well as improved distinction between juxtacortical and white matter-gray matter lesions.