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The purpose was to assess the difference of collaterals in symptomatic versus asymptomatic patients with unilateral middle cerebral artery (MCA) stenosis by comparing cerebral blood flow (CBF) at two post labeling delays (PLD) using three-dimensional pseudo-continuous arterial spin labeling (3D pCASL). Eighty-one patients (49 symptomatic and 32 asymptomatic) with unilateral MCA stenosis ≥50% who underwent pCASL with two PLDs were included. Mean CBF and CBF subtraction images between two PLDs of MCA territories were compared in symptomatic and asymptomatic groups, respectively. Compared with the asymptomatic group, patients with symptomatic MCA stenosis had significantly lower CBF in the MCA territory of stenotic side at each PLD. The CBF of stenotic territory showed greater increase than that of normal side from PLD 1.5 to 2.5 s. The CBF of asymptomatic MCA territory increased similarly with that of symptomatic MCA territory from PLD of 1.5 to 2.5 s in stenotic side, while symptomatic patients experienced significantly slower antegrade flow. On CBF subtraction images, asymptomatic patients showed larger volume of differences between PLD of 1.5 and 2.5 s compared with those of symptomatic patients ( p = 0.037). The results suggest that more robust collateral perfusion on two-delay 3D pCASL is present in asymptomatic patients compared with symptomatic patients.

Background and purposeMulti-delay arterial spin-labeling (ASL) perfusion imaging has been used as a promising modality to evaluate cerebral perfusion. Our aim was to assess the association of leptomeningeal collateral perfusion scores based on ASL parameters with outcome of endovascular treatment in patients with acute ischemic stroke (AIS) in the middle cerebral artery (MCA) territory.Materials and methodsASL data at 4 post-labeling delay (PLD) times (PLD = 1.5, 2, 2.5, 3 s) were acquired during routine clinical magnetic resonance examination on AIS patients prior to endovascular treatment. A 3-point scale of leptomeningeal collateral perfusion grade on 10 anatomic regions was determined based on arterial transit times (ATT), cerebral blood flow (CBF), and arterial cerebral blood volume (CBV), estimated by the multi-delay ASL protocol. Based on a 90-day modified Rankin Scale (mRS), the patients were dichotomized to moderate/good (mRS 0-3) and poor outcome (mRS 4-6) and the regional collateral flow scores were compared.ResultsFifty-five AIS patients with unilateral MCA stroke (mean 73.95±14.82 years) including 23 males were enrolled. Compared with poor outcome patients, patients with moderate to good outcomes had a significantly higher leptomeningeal collateral perfusion scores on CBV (3.01±2.11 vs. 1.82±1.51, p=0.024) but no differences on scores on CBF (2.31±1.61 vs. 1.66±1.32, p=0.231) and ATT (2.67±2.33 vs. 3.42±3.37, p=0.593).ConclusionsHigher leptomeningeal collateral perfusion scores on CBV images by ASL may be a specific marker of clinical outcome after endovascular treatment in patients with acute MCA ischemic stroke. Further study with larger sample size is warranted.

Aims: To examine whether functional connectivity (FC) of the occipital gyrus differs between patients with Parkinson's disease (PD) motor subtypes and healthy controls (HCs). Methods: We enrolled 30 PD patients exhibiting tremor dominance (TD), 43 PD patients with postural instability and gait disturbance (PIGD), and 42 HCs. The occipital gyrus was partitioned into six areas of interest, as seed points, via the Anatomical Automatic Labeling template to compare the FC of the three groups and analyze the relationship of FC with clinical scales. Results: Compared with the PIGD group, the TD group showed increased FC between the left superior occipital gyrus (SOG.L) and right median cingulate and paracingulate gyri (DCG.R)/right paracentral lobule/bilateral inferior parietal, but supramarginal and angular gyri; the left middle occipital gyrus (MOG.L) and left posterior cingulate gyrus (PCG.L); the MOG.R and SOG.L/right calcarine fissure and surrounding cortex/DCG.R/PCG.L/right cuneus; the left inferior occipital gyrus (IOG.L) and right caudate nucleus; and the IOG.R and PCG.L. Conclusion: Differentiated FC between the occipital gyrus and other brain areas within the PD motor subtypes, which may serve as neural markers to distinguish between patients with TD and PIGD PD. [ABSTRACT FROM AUTHOR]

Background and purposeThree-dimensional pseudocontinuous arterial spin labeling with multiple postlabeling delays has been used to assess cerebral blood flow (CBF). We used this modality to estimate antegrade and collateral flow in patients with unilateral middle cerebral artery stenosis.MethodsConsecutive patients with unilateral middle cerebral artery 50% to 99% stenosis at 2 centers underwent pseudocontinuous arterial spin labeling with a postlabeling delays of 1.5 and 2.5 s. Mean CBF of bilateral middle cerebral artery territory at the postlabeling delays 1.5 and 2.5 s was measured. Early-arriving flow proportion was defined as (CBF 1.5 s at lesion side/CBF 2.5 s at normal side)×100%. Late-arriving retrograde flow proportion was defined as ([CBF 2.5 s-CBF 1.5 s] at lesion side-[CBF 2.5 s-CBF 1.5 s] at normal side)/CBF 2.5 s at normal side×100%. Antegrade and collateral scales were evaluated in patients with conventional angiography. Spearman correlation coefficients were calculated between early-arriving flow and late-arriving retrograde flow proportions on arterial spin labeling and antegrade and collateral scales on conventional angiography, respectively.ResultsForty-one patients (46.0±12.0 years) were enrolled. The mean early-arriving flow proportion was 78.3±14.9%. The mean late-arriving retrograde flow proportion was 16.1±10.2%. In 21 patients with conventional angiography, Spearman correlation coefficient was 0.53 (95% confidence interval, 0.11-0.79) between antegrade grade and early-arriving flow proportion (P=0.01) and 0.81 (95% confidence interval, 0.56-0.92) between collateral grade and late-arriving retrograde flow proportion (P

Background: Ultra‐high field 7T MRI can provide excellent tissue contrast and anatomical details, but is often cost prohibitive, and is not widely accessible in clinical practice. Purpose: To generate synthetic 7T images from widely acquired 3T images with deep learning and to evaluate the feasibility of this approach for brain imaging. Study Type: Prospective. Population: 33 healthy volunteers and 89 patients with brain diseases, divided into training, and evaluation datasets in the ratio 4:1. Sequence and Field Strength: T1‐weighted nonenhanced or contrast‐enhanced magnetization‐prepared rapid acquisition gradient‐echo sequence at both 3T and 7T. Assessment: A generative adversarial network (SynGAN) was developed to produce synthetic 7T images from 3T images as input. SynGAN training and evaluation were performed separately for nonenhanced and contrast‐enhanced paired acquisitions. Qualitative image quality of acquired 3T and 7T images and of synthesized 7T images was evaluated by three radiologists in terms of overall image quality, artifacts, sharpness, contrast, and visualization of vessel using 5‐point Likert scales. Statistical Tests: Wilcoxon signed rank tests to compare synthetic 7T images with acquired 7T and 3T images and intraclass correlation coefficients to evaluate interobserver variability. P < 0.05 was considered significant. Results: Of the 122 paired 3T and 7T MRI scans, 66 were acquired without contrast agent and 56 with contrast agent. The average time to generate synthetic images was ~11.4 msec per slice (2.95 sec per participant). The synthetic 7T images achieved significantly improved tissue contrast and sharpness in comparison to 3T images in both nonenhanced and contrast‐enhanced subgroups. Meanwhile, there was no significant difference between acquired 7T and synthetic 7T images in terms of all the evaluation criteria for both nonenhanced and contrast‐enhanced subgroups (P ≥ 0.180). Data Conclusion: The deep learning model has potential to generate synthetic 7T images with similar image quality to acquired 7T images. Level of Evidence: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Background: Global brain health has gained increasing attention recently. Imaging markers of brain frailty have been related to functional outcomes in previous studies on anterior circulation; however, little data are available on imaging markers and posterior circulation. Purpose: To investigate the impact of brain frailty on functional outcomes in patients with acute perforating artery infarction (PAI) of the posterior circulation. Study Type: Prospective. Population: One hundred patients (60.78 ± 9.51 years, 72% men) with acute posterior circulation PAI (determined by diffusion‐weighted magnetic resonance imaging (MRI)/time‐of‐flight MR angiography). Field Strength/Sequence: T1‐ and T2‐weighted fast spin echo, T2‐weighted fluid‐attenuated inversion recovery, diffusion‐weighted echo planar, gradient echo (susceptibility‐weight imaging), and 3D time‐of‐flight MR angiography sequences at 3.0 T. Assessment: Periventricular and deep white matter hyperintensities (WMH), enlarged perivascular spaces (EPVS) in the basal ganglia and centrum semiovale area, lacunes, cerebral microbleeds (CMB), and total brain frailty score by calculating the above imaging characters were rated visually by three radiologists with 9, 10, and 11 years of experience and one neuroradiologist with 12. Infarction volume was assessed using baseline diffusion‐weighted imaging (DWI) data obtained within 24 hours of symptom onset. A modified Rankin Scale (mRS) score >1 on day 90 defined an adverse functional outcome. Associations between the imaging markers of brain frailty and functional outcomes were assessed. Statistical Tests: Fisher's exact test, Mann–Whitney U test, and multivariable binary logistic regression. A P value <0.05 was considered statistically significant. Results: Adverse prognoses (mRS > 1) were observed in 34 (34%) patients. Infarction volume, periventricular WMH, deep WMH, basal ganglia EPVS, CMB, and the brain frailty score were significantly associated with adverse functional outcomes. An increased brain frailty score was significantly associated with unfavorable mRS score on day 90 (odds ratio 1.773, 95% confidence interval 1.237–2.541). Data Conclusion: Advanced MRI imaging markers of brain frailty, individually or combined as a total brain frailty score, were associated with worse functional outcomes after acute posterior circulation PAI. Level of Evidence: 3 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

Background: Glioma genotypes are of importance for clinical decision‐making. This data can only be acquired through histopathological analysis based on resection or biopsy. Consequently, there is a need for alternative biomarkers that noninvasively provide reliable information for preoperatively identifying molecular characteristics. Purpose: To investigate apparent diffusion coefficient (ADC) as imaging biomarker for preoperatively identifying glioma genotypes based on the 2021 World Health Organization (WHO) classification of central nervous system (CNS) tumors. Study Type: Retrospective. Subjects: One hundred and fifty‐nine patients (47.6 ± 14.4 years) diagnosed with WHO grade 2–4 glioma including 93 males and 66 females. Field Strength/Sequence: A 3 T/spin echo echo planner imaging. Assessment: The ADC measurements were assessed by two neuroradiologists (both with 6 years of experience). Three different lowest portions inside the tumors without overlap were manually drawn on the ADC maps as regions of interest (ROIs). The mean ADC value of the three ROIs was defined as the minimum ADC value (ADCmin). An ROI was placed in the contralateral normal appearing white matter (NAWM) to obtain the ADC value (ADCNAWM). The ADCmin to ADCNAWM ratio (ADCratio) was calculated. Genetics results were retrospectively recorded from pathologic and genetic test reports. Statistical Tests: Two‐sample independent t‐tests, receiver operating characteristic curve analysis, and intraclass correlation coefficient analysis were used. Statistical significance was set at P < 0.05. Results: Isocitrate dehydrogenase (IDH)‐mutated glioma showed higher ADCmin and ADCratio than IDH wild‐type glioma. Among IDH‐mutated glioma, higher ADCmin and ADCratio were found in 1p19q intact glioma than in 1p19q codeletion glioma. ADC parameters enabled differentiation of IDH mutation status with area under the curve (AUC) of 0.84 and 0.86. Data Conclusion: ADC has potential discriminative value for IDH mutation and 1p19q codeletion status. Evidence Level: 3. Technical Efficacy: Stage 2. [ABSTRACT FROM AUTHOR]

Background: Arterial spin labeling (ASL) has shown potential for the assessment of penumbral tissue in patients with acute ischemic stroke (AIS). The postlabeling delay (PLD) parameter is sensitive to arterial transit delays and influences cerebral blood flow measurements. Purpose: To assess the impact of ASL acquisition at different PLDs for penumbral tissue quantification and to compare their performance regarding assisting patient selection for endovascular treatment with dynamic susceptibility contrast MRI (DSC‐MRI) as the reference method. Study Type: Retrospective. Population: A total of 53 patients (59.98 ± 12.60 years, 32% women) with AIS caused by internal carotid or middle cerebral artery occlusion. Field Strength/Sequence: A 3‐T, three‐dimensional pseudo‐continuous ASL with fast‐spin echo readout. Assessment: Hypoperfusion volume was measured using DSC‐MRI and ASL with PLDs of 1.500 msec and 2.500 msec, respectively. Eligibility for endovascular treatment was retrospectively determined according to the imaging criteria of the Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke trial (DEFUSE 3). Statistical Tests: Kruskal–Wallis tests, Bland–Altman plots, Cohen's kappa, and receiver operating characteristic analyses were used. The threshold for statistical significance was set at P ˂ 0.05. Results: Hypoperfusion volume for ASL with a PLD of 1.500 msec was significantly larger than that for DSC‐MRI, while the hypoperfusion volume for a PLD of 2.500 msec was not significantly different from that of DSC‐MRI (P = 0.435). Bland–Altman plots showed that the mean volumetric error between the hypoperfusion volume measured by DSC‐MRI and ASL with PLDs of 1.500/2.500 msec was −107.0 mL vs. 4.49 mL. Cohen's kappa was 0.679 vs. 0.773 for DSC‐MRI and ASL, respectively, with a PLD of 1.500/2.500 msec. The sensitivity and specificity for ASL with a PLD of 1.500/2.500 msec in identifying patients eligible for treatment were 89.74% vs. 97.44% and 92.86% vs. 64.29%, respectively. Data Conclusion: In AIS, PLDs for ASL acquisition may have a considerable impact on the quantification of the hypoperfusion volume. Evidence Level: 3 Technical Efficacy: Stage 2 [ABSTRACT FROM AUTHOR]

Aim: This study aimed to evaluate the diagnostic value of ultrahigh‐field magnetic resonance imaging (MRI) for brain tumors in clinical practice. Methods: Thirty patients with brain tumors underwent 7‐ and 3‐T MRI. The performance and diagnostic confidence of 7‐ and 3‐T MRI in the visualization of tumor details such as internal structure and feeding artery were evaluated by radiologists. Contrast‐enhanced region performance and tumor detail diagnostic confidence score (DCS) were calculated and compared between 7 and 3T using Wilcoxon rank sum test. Results: In 19 with obvious enhancement and 11 cases without obvious enhancement, 7‐ and 3‐T MRI showed similar performance. The tumors' internal structure and feeding artery were more clearly depicted by 7‐T MRI (62.2% and 54.4%, respectively) than by 3‐T MRI (2.2% and 6.7%, respectively). Furthermore, the mean DCSs of both internal structure and feeding artery were higher at 7T than at 3T (internal structure: 16.29 ± 9.67 vs. −5.79 ± 4.12, p = 0.028; feeding artery: 21.96 ± 6.93 vs. 4.46 ± 7.07, p = 0.028). The DCS was more significantly improved in the senior radiologist group. Conclusion: Better visualization of brain tumor details and higher tumor detail diagnostic confidence can be obtained with 7‐T MRI. [ABSTRACT FROM AUTHOR]

Background: Precise diagnosis and early appropriate treatment are of importance to reduce neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) morbidity. Distinguishing NMOSD from MS based on clinical manifestations and neuroimaging remains challenging.Purpose: To investigate radiomic signatures as potential imaging biomarkers for distinguishing NMOSD from MS, and to develop and validate a diagnostic radiomic-signature-based nomogram for individualized disease discrimination.Study Type: Retrospective, cross-sectional study.Subjects: Seventy-seven NMOSD patients and 73 MS patients.Field Strength/sequence: 3T/T2 -weighted imaging.Assessment: Eighty-eight patients and 62 patients were respectively enrolled in the primary and validation cohorts. Quantitative radiomic features were automatically extracted from lesioned regions on T2 -weighted imaging. A least absolute shrinkage and selection operator analysis was used to reduce the dimensionality of features. Finally, we constructed a radiomic nomogram for disease discrimination.Statistical Tests: Features were compared using the Mann-Whitney U-test with a nonnormal distribution. We depicted the nomogram on the basis of the results of the logistic regression using the rms package in R. The Hmisc package was used to investigate the performance of the nomogram via Harrell's C-index.Results: A total of 273 quantitative radiomic features were extracted from lesions. A multivariable analysis selected 11 radiomic features and five clinical features to be included in the model. The radiomic signature (P < 0.001 for both the primary and validation cohorts) showed good potential for building a classification model for disease discrimination. The area under the receiver operating characteristic curve was 0.9880 for the training cohort and 0.9363 for the validation cohort. The nomogram exhibited good discrimination, a concordance index of 0.9363, and good calibration in the primary cohort. The nomogram showed similar discrimination, concordance (0.9940), and calibration in the validation cohort.Data Conclusion: The diagnostic radiomic-signature-based nomogram has potential utility for individualized disease discrimination of NMOSD from MS in clinical practice.Level Of Evidence: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1113-1121. [ABSTRACT FROM AUTHOR]

An increasing number of evidence suggests that bidirectional communication between the cardiovascular system and the central nervous system (CNS), known as the heart-brain interaction, is crucial in understanding the impact of coronary artery disease (CAD) on brain health. The multifactorial role of CAD in the brain involves processes such as inflammation, oxidative stress, neuronal activity, neuroendocrine imbalances, and reduced cerebral perfusion, leading to various cerebral abnormalities. The mechanisms underlying the relationship between CAD and brain injury are complex and involve parallel pathways in the CNS, endocrine system, and immune system. Although the exact mechanisms remain partially understood, neuroimaging techniques offer valuable insights into subtle cerebral abnormalities in CAD patients. Neuroimaging techniques, including assessment of neural function, brain metabolism, white matter microstructure, and brain volume, provide information on the evolving nature of CAD-related cerebral abnormalities over time. This review provides an overview of the pathophysiological mechanisms of CAD in the heart-brain interaction and summarizes recent neuroimaging studies utilizing multiparametric techniques to investigate brain abnormalities associated with CAD. The application of advanced neuroimaging, particularly functional, diffusion, and perfusion advanced techniques, offers high resolution, multiparametric capabilities, and high contrast, thereby allowing for the early detection of changes in brain structure and function, facilitating further exploration of the intricate relationship between CAD and brain health. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3., (© 2024 International Society for Magnetic Resonance in Medicine.)