BACKGROUND AND PURPOSE: Intravenous administration of indocyanine green (ICG) has been approved in brain surgeries for decades, yet concerns about neurotoxicity prevent its direct administration into the cerebrospinal fl...BACKGROUND AND PURPOSE: Intravenous administration of indocyanine green (ICG) has been approved in brain surgeries for decades, yet concerns about neurotoxicity prevent its direct administration into the cerebrospinal fluid (CSF). Armed with prior animal studies demonstrating the feasibility of using ICG microdosing into the CSF, we sought to evaluate its nonclinical safety profile and obtain surrogate measures in adults prior to its use in human neonates. METHODS: Evaluation of ICG toxicity was conducted in mixed primary CNS cell cultures and in an extended safety study of juvenile rat pups deploying intraventricular injections of saline (as control) or ICG. Analysis of animal behavior included Novel Object Place Recognition Test and rotarod behavioral tests. Immunohistochemical analysis of tumor necrosis factor-alpha (TNF-α), oxidative deoxyribonucleic acid damage, microglial activation, and neuronal density was performed on collected brains. We measured ICG levels (before and after intravenous administration) in collected CSF from external ventricular drain catheters of 10 brain-injured adults. RESULTS: TNF-α and lactate dehydrogenase assay for cytotoxicity showed transient elevations after 1 h of incubation with 1291 µM ICG, but none at or below 322 µM ICG, even after 24 h of incubation. Behavioral tests and immunohistochemical analyses showed no differences between ICG-administered animals and controls. Intraventricular concentrations of ICG in collected human CSF ranged between 0.17 and 7.93 µM, with no adverse events associated with intravenous administration. CONCLUSIONS: With intraventricular microdosing of 100 µg ICG, maximal ICG concentrations in neonatal CSF range from 1.3 to 6 5 µM. CNS cell culture, rat safety studies, and surrogate measures in adults evidence the safety of microdosing ICG directly into the CSF.
BACKGROUND AND PURPOSE: In neurosurgery, functional MRI is crucial for preoperative planning to obtain the cortical cortex map of language areas. This preliminary work involved analyzing the functional MRIs of 20 oncolog...BACKGROUND AND PURPOSE: In neurosurgery, functional MRI is crucial for preoperative planning to obtain the cortical cortex map of language areas. This preliminary work involved analyzing the functional MRIs of 20 oncological patients. Our question is if resting-state functional MRI (rs-fMRI) can replace standard task-based functional MRI (tb-fMRI) in routine clinical applications. The aim of this challenge is to determine if rs-fMRI is as effective as tb-fMRI and to develop a systematic approach for the extraction of a cortical language map. METHODS: We started by analyzing our rs-fMRI images and validated the correct mapping of language regions using an independent components analysis approach; then, we used the analysis of connectivity networks to compare the two techniques. RESULTS: The regions identified in rs-fMRI align with established medical knowledge; a comparison of rs-fMRI and tb-fMRI reveals that the four language regions-Broca's and Wernicke's areas in both hemispheres-exhibit activation in both techniques; furthermore, we highlighted that rs-fMRI reveals more comprehensive details about functional connectivity in contrast to tb-fMRI. CONCLUSIONS: rs-MRI and tb-MRI provide similar levels of efficacy in revealing the functional areas of the brain for preoperative mapping when a lesion lies in areas related to language; thus, both techniques can be utilized for this goal. Based on this, we developed an rs-fMRI processing pipeline for clinical usage and applied it to a patient outside the study.
BACKGROUND AND PURPOSE: This study aims to assess the potential of ultrashort echo time imaging-based magnetization transfer ratio (UTE-MTR) in detecting demyelination in mice with mild traumatic brain injury (mTBI) caus...BACKGROUND AND PURPOSE: This study aims to assess the potential of ultrashort echo time imaging-based magnetization transfer ratio (UTE-MTR) in detecting demyelination in mice with mild traumatic brain injury (mTBI) caused by an open-field low-intensity blast (LIB) injury model. METHODS: This study included 30 male C57BL/6 mice, approximately 8 weeks old, sourced from Jackson Laboratories in Bar Harbor, ME, and conducted under institutional guidelines. The mice were divided into the mTBI group (n = 15) and the sham control group (n = 15). All animal experiments followed the approved protocols for the Care and Use of Laboratory Animals and Animal Research. The mTBI group underwent the open-field LIB injury. Behavioral tests were conducted to assess motor activity and anxiety-like responses. UTE-MT imaging was performed using a 3 Tesla Bruker system to measure UTE-MTR from two UTE-MT datasets with saturation powers of 1500° and 500°, and two frequency offsets of 2 and 50 kHz, respectively. Luxol fast blue (LFB) staining was performed to evaluate myelin content. The mean UTE-MTR values for regions of interest centered at the medial section of the corpus callosum were computed. The behavioral tests, LFB myelin staining, and UTE-MTR values were compared between the two groups using the independent t-test. p values <0.05 were considered significant. RESULTS: The mTBI mice demonstrated decreased motor activity and increased anxiety-like response over sham controls. The mTBI mice also showed significantly lower UTE-MTR values (0.399±0.007 vs. 0.393±0.005; p<0.05) and reduced LFB myelin staining (0.848±0.324 vs. 1.145±0.260; p = 0.048) over sham controls. CONCLUSION: The significantly lower UTE-MTR values in the corpus callosum of mTBI mice are consistent with reduced LFB myelin staining, indicating that UTE-MTR can detect myelin loss and associated alterations in motor and anxiety domains post-LIB exposure.
BACKGROUND AND PURPOSE: Real-time phase-contrast (RT-PC) flow MRI can be used to determine quantitative flow parameters throughout the vessel lumen of extracranial, brain-supplying arteries. Its potential value in the di...BACKGROUND AND PURPOSE: Real-time phase-contrast (RT-PC) flow MRI can be used to determine quantitative flow parameters throughout the vessel lumen of extracranial, brain-supplying arteries. Its potential value in the diagnostic workup of patients with carotid artery stenosis has not been evaluated. METHODS: RT-PC flow MRI was performed in 10 patients with carotid stenosis in comparison to conventional neurovascular ultrasound (nvUS). Peak systolic velocity, end-diastolic velocity, mean flow velocity, and flow volumes have been evaluated by RT-PC flow MRI. Measurements have been performed at standardized sites along the common, internal, and external carotid arteries on both sides and at the maximum of the carotid stenosis. RESULTS: Blood flow velocities were significantly lower with RT-PC flow MRI compared to nvUS and not consistently correlated between both methods. Within the maximum of the carotid stenosis, RT-PC flow MRI showed implausible flow velocity reductions compared to nvUS. In contrast, the flow volumes determined by RT-PC flow MRI-with exception of the stenosis maximum-were comparable with nvUS and significantly correlated in the prestenotic common carotid artery. CONCLUSION: RT-PC flow MRI does not appear to be suitable for quantifying blood flow velocities and volumes in the patients with carotid stenosis compared to nvUS. Apart from the lower temporal resolution of RT-PC MRI, the lack of correlation of blood flow velocities might be ascribed to the prevalence of nonlaminar flow within and behind the stenosis, which violates a general prerequisite for valid flow velocity measurements by PC MRI.
BACKGROUND AND PURPOSE: Primary trigeminal neuralgia (PTN) is a prevalent chronic pain disorder whose pathogenesis is not solely confined to the trigeminal system. Although substantial progress has been made in understan...BACKGROUND AND PURPOSE: Primary trigeminal neuralgia (PTN) is a prevalent chronic pain disorder whose pathogenesis is not solely confined to the trigeminal system. Although substantial progress has been made in understanding the underlying mechanisms, comprehensive and consistent data concerning the involvement of the hippocampal formation in this process are lacking. The aim of this study was to evaluate structural changes in hippocampal subfields in patients with PTN. METHODS: Fifty-nine individuals who were diagnosed with PTN and 28 healthy controls matched for age and sex underwent high-resolution 3 Tesla MRI. HippUnfold software was used for the segmentation of hippocampal subfields and the extraction of features. Covariance analyses were performed to analyze changes in the volume, thickness, and gyrification index of different subfields in patients with PTN compared to controls. Furthermore, the relationships between MR morphometry data and the severity of nerve root compression, as well as the intensity and duration of pain, were examined in patients with PTN. RESULTS: Our analysis demonstrated a decrease in the volume of the right cornu ammonis subfield 1 (CA1)-CA3 and left CA2 hippocampal subfields in patients with PTN compared to healthy controls (adjusted p < 0.05 for all comparisons). No statistically significant associations were found between hippocampal MR morphometry data and clinical metrics. CONCLUSIONS: Our results suggest the existence of bilateral structural abnormalities in the hippocampal subfields in individuals with PTN, which could contribute to the development and progression of this condition.
BACKGROUND AND PURPOSE: The primary objective was to compare diffusion tensor imaging (DTI) scalar parameters of peripheral nerves between subjects with type 2 diabetes mellitus (T2DM) and those without diabetes. Seconda...BACKGROUND AND PURPOSE: The primary objective was to compare diffusion tensor imaging (DTI) scalar parameters of peripheral nerves between subjects with type 2 diabetes mellitus (T2DM) and those without diabetes. Secondarily, we aimed to correlate DTI scalar parameters with nerve morphometric properties. METHODS: Median, tibial, and sural nerves were harvested from 34 male cadavers (17 T2DM, 17 nondiabetic). Each nerve was divided into three segments. The initial segment was scanned using 9.4 Tesla MRI system (three-dimensional pulsed-gradient spin-echo sequence). DTI scalars were calculated from region-average diffusion-weighted signals. Second segment was optically cleared, acquired with optical projection tomography (OPT), and analyzed for morphometrical properties. Toluidine-stained sections were prepared from last segment, and axon- and myelin-related properties were evaluated. RESULTS: DTI scalar parameters of median and tibial nerves were comparable between the groups, while sural nerves of T2DM exhibited on average 41% higher mean diffusivity (MD) (p = 0.03), 38% higher radial diffusivity (RD) (p = 0.03), and 27% lower fractional anisotropy (FA) (p = 0.005). Significant differences in toluidine-evaluated parameters of sural nerves were observed between the groups, with a positive correlation between FA with fiber density (p = 0.0001) and with myelin proportion (p < 0.0001) and an inverse correlation between RD and myelin proportion (p = 0.003). OPT-measured morphometric properties did not correlate with DTI scalar parameters. CONCLUSIONS: High-field DTI shows promise as an imaging technique for detecting axonal and myelin-related changes in small sural nerves ex vivo. The reduced fiber density and decreased myelin content, which can be observed in T2DM, likely contribute to observed FA reduction and increased MD/RD.
BACKGROUND AND PURPOSE: Structural MRI (sMRI) is used in monitoring multiple sclerosis (MS) but lacks sensitivity in detecting clinically relevant damage to normal-appearing white matter (NAWM), that is, pre-lesional tis...BACKGROUND AND PURPOSE: Structural MRI (sMRI) is used in monitoring multiple sclerosis (MS) but lacks sensitivity in detecting clinically relevant damage to normal-appearing white matter (NAWM), that is, pre-lesional tissue, and specificity for identifying the underlying substrate of injury. In this longitudinal study, we identified pre-lesional tissue in MS patients and investigated its microstructure by modeling diffusion-weighted imaging (DWI) data using diffusion tensor imaging and neurite orientation dispersion and density imaging (NODDI). METHODS: We enrolled 18 patients with relapsing-remitting MS (10 females, 31.92 ± 8.09 years, disease duration 0.91 ± 1.81 years) and 18 healthy controls (10 females, 31.89 ± 8.15 years). Participants underwent two sMRI and DWI sessions (baseline and follow-up) with the same protocols. Average apparent diffusion coefficient (ADC), fractional anisotropy (FA), orientation dispersion index (ODI), and neurite density index (NDI) were estimated in data-driven regions of interest: nonpersistent lesional tissue (lesional tissue at baseline, resolved at follow-up), lesions that only existed at follow-up (pre-lesional tissue at baseline, lesions at follow-up), persistent lesional tissue (lesions at baseline and follow-up), and NAWM. RESULTS: Compared to NAWM, pre-lesional tissue showed lower ODI, and resolved lesional tissue showed higher FA and ADC and lower ODI and NDI. Over time, persistent lesional tissue showed a decrease in FA and ODI and an increase in NDI. Compared to nonpersistent lesional tissue, persistent lesional tissue showed higher ADC and lower NDI. CONCLUSIONS: DWI and, more particularly, NODDI, can reveal the unique microstructure of persistent, resolved, and pre-lesional tissue in MS.
BACKGROUND AND PURPOSE: This study presents automated atlas-based magnetization transfer (MT) measurements of the typically developing pediatric cervical spinal cord (SC). We report normative MT ratio (MTR) values from t...BACKGROUND AND PURPOSE: This study presents automated atlas-based magnetization transfer (MT) measurements of the typically developing pediatric cervical spinal cord (SC). We report normative MT ratio (MTR) values from the whole cervical cord white matter (WM) and WM tracts, examining variations with age, sex, height, and weight. METHODS: MT scans of 33 healthy females (mean age = 12.8) and 22 males (mean age = 13.09) were acquired from the cervical SC (C2-C7) using a 3.0 T MRI. Data were processed using the SC Toolbox, segmented, and registered to the PAM50 template. Affine and non-rigid transformations co-registered the PAM50 WM atlas to subject-specific space. MTRs were measured for the specific WM tracts (left and right dorsal fasciculus gracilis, dorsal fasciculus cuneatus, and lateral corticospinal tracts [LCST]) and the whole WM. Descriptive statistics, correlation analysis, and unpaired t-tests (p < 0.05) assessed relationships with age, height, weight, and sex. RESULTS: Normative MTR measurements were obtained from all regions. The coefficients of variation were low to moderate. No significant differences (p > 0.05) were found across all the cervical levels. However, significant sex differences were observed in whole WM (p = 0.04) and LCST (p = 0.03). MTR values correlated positively with age, with significant correlations at C5 (r = 0.3, p false discovery rate = 0.04). A decreasing trend in MTR values across levels was found for whole WM (r = -0.2, p < 0.001). CONCLUSIONS: This study provides an understanding of MTR values in pediatric cervical SC and their variations by sex, age, height, and weight, providing a baseline for comparisons in pediatric SC diseases.
BACKGROUND AND PURPOSE: Accurate and consistent lesion segmentation from magnetic resonance imaging is required for longitudinal multiple sclerosis (MS) data analysis. In this work, we propose two new transfer learning-b...BACKGROUND AND PURPOSE: Accurate and consistent lesion segmentation from magnetic resonance imaging is required for longitudinal multiple sclerosis (MS) data analysis. In this work, we propose two new transfer learning-based pipelines to improve segmentation performance for subjects in longitudinal MS datasets. METHOD: In general, transfer learning is used to improve deep learning model performance for the unseen dataset by fine-tuning a pretrained model with a limited number of labeled scans from the unseen dataset. The proposed methodologies fine-tune the deep learning model for each subject using the first scan and improve segmentation performance for later scans for the same subject. We also investigated the statistical benefits of the proposed methodology by modeling lesion volume over time between progressors according to confirmed disability progression and nonprogressors for a large in-house dataset (937 MS patients, 3210 scans) using a linear mixed effect (LME) model. RESULTS: The results show statistically significant improvement for the proposed methodology compared with the traditional transfer learning method using Dice (improvement: 2%), sensitivity (6%), and average volumetric difference (16%), as well as visual analysis for public and in-house datasets. The LME result showed that the proposed subject-wise transfer learning method had increased statistical power for the measurement of longitudinal lesion volume. CONCLUSION: The proposed method improved lesion segmentation performance and can reduce manual effort to correct the automatic segmentations for final data analysis in longitudinal studies.
Reynolds AS, Suh J, Hasan A
… +6 more, Upadhyaya P, Rajajee V, Hirzallah MI, Greer DM, Sarwal A, American Society of Neuroimaging Brain Death Task force
BACKGROUND AND PURPOSE: Ancillary testing is essential for diagnosing brain death/death by neurologic criteria (BD/DNC) when clinical determination (neurologic exam and apnea testing) cannot be fully or safely performed....BACKGROUND AND PURPOSE: Ancillary testing is essential for diagnosing brain death/death by neurologic criteria (BD/DNC) when clinical determination (neurologic exam and apnea testing) cannot be fully or safely performed. Transcranial Doppler ultrasound (TCD) has been recommended as an ancillary test; however, the technical descriptions have been heterogeneous. We aimed to consolidate the technical considerations related to the use of TCD as an ancillary test in the evaluation of BD/DNC. METHODS: We performed a scoping review of the available literature from inception to December 2024. Articles describing TCD as an ancillary test for BD/DNC were included using appropriate Medical Subject Headings terms. The focus was on technical details and clinimetric properties of TCD (e.g., signal quality, frequency, gate, probe location, etc.). Technical categories were curated as full-text reviews were completed. RESULTS: We reviewed 181 articles to extract technical descriptions of TCD under several categories. Image acquisition was divided into machine-related factors (59 studies, four questions), exam-related aspects (82 studies, 13 questions), and patient anatomical factors (19 studies, three questions). Image interpretation concerns were addressed in 50 studies (three questions). Patient-related clinical factors affecting TCD utility were addressed in 44 studies (seven questions). Legislative priorities were discussed in 19 studies; in 13 studies, authors commented on their recommendations for research priorities. CONCLUSION: We found significant inconsistencies and a lack of technical details described in the literature. Next steps include a national survey of current TCD protocols for BD/DNC evaluation, and an expert consensus guidelines report on the technical use of TCD as an ancillary test.
Martínez García B, Chico García JL, Pérez Gil D
… +12 more, Garay Albízuri P, Llanes Ferrer A, García Alcántara G, Cabañas Engenios G, Matute Lozano MC, De Felipe Mimbrera A, Vera Lechuga R, Cruz Culebras A, Carrión Sánchez I, Fernández-Golfín C, Masjuan J, García Madrona S
BACKGROUND AND PURPOSE: Right-to-left shunt (RLS), usually related to a patent foramen ovale (PFO), is an important cause of cryptogenic stroke (CS) in young patients. Transcranial Doppler (TCD) with an agitated saline b...BACKGROUND AND PURPOSE: Right-to-left shunt (RLS), usually related to a patent foramen ovale (PFO), is an important cause of cryptogenic stroke (CS) in young patients. Transcranial Doppler (TCD) with an agitated saline bubble study is a highly sensitive modality for RLS diagnosis using a transtemporal approach (TTD). However, a minority of patients have insufficient temporal bone windows. We aimed to evaluate the accuracy of transforaminal TCD (TFD) for RLS diagnosis. METHODS: We included patients with CS or transient ischemic attack who were tested in the standard protocol for RLS between March 2022 and February 2023. We evaluated the concordance of RLS grades between TFD and transesophageal echocardiogram (TEE) using the weighted kappa index. We also compared TTD and TFD approaches. RESULTS: Forty patients were included (66.7% men; median age 49 years). Medium or large RLS were found in 28 patients (70%) with TTD and in 27 patients with TFD (67.5%). Through TEE, 19 (82.6%) medium or large PFO were confirmed, and a high agreement rate of 0.684 (p = 0.0003) was observed for grading RLS. Moreover, the agreement rate of RLS grade between TTD and TFD was 0.73 (p < 0.0001). CONCLUSION: TFD is a valid approach for RLS diagnosis, with substantial concordance with TEE in grading RLS. Our study found a good grade of agreement between TFD and TEE. Therefore, the value of TCD goes beyond quantifying RLS and could assist in identifying the patients with the largest RLS, who would gain the greatest benefit from PFO closure.
BACKGROUND AND PURPOSE: This study investigated the neural mechanisms underlying Parkinson's disease (PD) subtypes-tremor dominant (TD) and postural instability gait difficulty (PIGD)-by analyzing regional homogeneity (R...BACKGROUND AND PURPOSE: This study investigated the neural mechanisms underlying Parkinson's disease (PD) subtypes-tremor dominant (TD) and postural instability gait difficulty (PIGD)-by analyzing regional homogeneity (ReHo) values from resting-state functional MRI. METHODS: Fifty-nine PD patients (29 TD patients, 30 PIGD patients) and 30 healthy controls (HCs) were enrolled. ReHo values were analyzed via analysis of variance and a two-sample t-test, with age and sex as covariates. Correlations between ReHo values and clinical motor symptoms were also examined. RESULTS: Distinct ReHo patterns were observed in patients with the PD subtypes and HCs. TD patients presented decreased ReHo in the cerebellar-thalamic-cortical circuit, whereas PIGD patients presented lower ReHo in the striatum and supplementary motor area (SMA). TD patients had higher ReHo in the bilateral dorsolateral superior frontal gyrus and SMA but lower ReHo in the bilateral medial orbital part of the superior frontal gyrus and other regions on the left than PIGD patients. Specific brain area ReHo values were correlated with tremor scores, PIGD scores, and rigidity scores. CONCLUSION: Different motor subtypes of PD patients and HCs showed distinct ReHo patterns. ReHo correlation with clinical traits suggests its value as a biomarker for subtype-specific diagnostic strategies.
BACKGROUND AND PURPOSE: Silent brain infarcts (SBIs), which manifest as dot-like lesions on diffusion-weighted imaging (DWI) after endovascular procedures, are associated with an increased risk of stroke, dementia, and c...BACKGROUND AND PURPOSE: Silent brain infarcts (SBIs), which manifest as dot-like lesions on diffusion-weighted imaging (DWI) after endovascular procedures, are associated with an increased risk of stroke, dementia, and cognitive decline. We aimed to identify the factors associated with SBIs following middle cerebral artery (MCA) stenting or balloon angioplasty. METHODS: We retrospectively reviewed patients who underwent MCA stenting or balloon angioplasty, including those with symptomatic, atherosclerotic MCA stenosis of ≥50%. DWI scans were conducted before and after the procedure, and newly detected DWI lesions were classified as SBIs. We investigated the factors associated with the development of SBIs, and for patients with SBIs, we conducted a detailed analysis based on lesion location (cortex and perforator territory vs. cortex only vs. perforator territory only). RESULTS: Among 120 patients, 64 (53.3%) exhibited SBIs postprocedure. Factors significantly associated with SBIs included smaller stenosis diameter (odd ratio [95% confidence interval] = 0.03 [0.002-0.35], p = 0.006), longer stenosis length (1.24 [1.02-1.51], p = 0.033), higher MCA tortuosity (1.20 [1.07-1.34], p = 0.002), and diffuse involvement of MCA stenosis (3.99 [1.17-13.62], p = 0.027). Among the patients who exhibited SBIs, D-dimer (p = 0.002), C-reactive protein (p = 0.026), and hemoglobin A1c (p = 0.025) differed according to detailed mechanism. CONCLUSIONS: Stenosis diameter, stenosis length, and MCA tortuosity were significantly associated with the development of SBIs following MCA stenting.
Intracranial pressure (ICP) monitoring is a cornerstone of neurocritical care in managing severe brain injury. However, current invasive ICP monitoring methods carry significant risks, including infection and intracrania...Intracranial pressure (ICP) monitoring is a cornerstone of neurocritical care in managing severe brain injury. However, current invasive ICP monitoring methods carry significant risks, including infection and intracranial hemorrhage, and are contraindicated in certain clinical situations. Additionally, these methods are not universally available. Optic nerve sheath diameter (ONSD) measurement presents a promising noninvasive alternative for ICP monitoring, though its clinical adoption has been limited due to its operator dependence and inconsistencies in imaging acquisition and measurement techniques. Automating both ONSD image acquisition and measurement could enhance accuracy and reliability, thereby improving its utility as a noninvasive ICP estimation tool. A range of image analysis and machine learning (ML) techniques have been applied to address these challenges. In this paper, we provide a narrative review of the current literature on ONSD automation, examining the strengths and limitations of classical image analysis and ML models in improving ONSD-based ICP assessment.
BACKGROUND AND PURPOSE: The central vein sign (CVS) is a diagnostic imaging biomarker for multiple sclerosis (MS). FLAIR* is a combined MRI contrast that provides high conspicuity for CVS at 3 Tesla (3T), enabling its se...BACKGROUND AND PURPOSE: The central vein sign (CVS) is a diagnostic imaging biomarker for multiple sclerosis (MS). FLAIR* is a combined MRI contrast that provides high conspicuity for CVS at 3 Tesla (3T), enabling its sensitive and accurate detection in clinical settings. This study evaluated whether CVS conspicuity of 3T FLAIR* is reliable across imaging sites and MRI vendors and whether gadolinium (Gd) contrast increases CVS conspicuity. METHODS: A cross-sectional, multicenter study recruited adults referred for possible diagnosis of MS at 10 sites. FLAIR* contrast was generated using high-resolution T2*-weighted (acquired pre- and post-injection of Gd) and T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) brain images at 3T from two MRI vendors. Lesions and veins were segmented to compute lesion-to-vein contrast-to-noise ratio (CNR), a quantitative measure of CVS conspicuity. CNR measures for pre- and post-Gd FLAIR* were compared across sites and vendors. RESULTS: Eighty-seven participants from nine sites were included in the analysis. There was no significant difference in mean CNR between sites for pre-Gd (p-value = 0.07) or post-Gd (p-value = 0.27) FLAIR*. There were also no significant differences between vendors for pre-Gd (p-value = 0.10) or post-Gd (p-value = 0.31) FLAIR*. Patient-level pairwise differences in CNR between pre-Gd and post-Gd FLAIR* revealed a significant increase for post-Gd FLAIR* (p-value < 0.001). CONCLUSIONS: CVS conspicuity on 3T FLAIR* is consistent across imaging sites and MRI vendors. Moreover, Gd-based contrast agent significantly improved CVS conspicuity on 3T FLAIR*. These findings support the implementation of FLAIR* in clinical settings for MS.
Mei J, Salim HA, Lakhani DA
… +24 more, Balar A, Vagal V, Koneru M, Wolman D, Xu R, Urrutia V, Marsh EB, Pulli B, Hoseinyazdi M, Luna L, Deng F, Hyson NZ, Bahouth M, Dmytriw AA, Guenego A, Albers GW, Lu H, Nael K, Hillis AE, Llinas R, Wintermark M, Faizy TD, Heit JJ, Yedavalli V
BACKGROUND AND PURPOSE: Prolonged length of stay (LOS) following a stroke is associated with unfavorable clinical outcomes. Factors predicting LOS in medium vessel occlusion (MeVO), impacting up to 40% of acute ischemic...BACKGROUND AND PURPOSE: Prolonged length of stay (LOS) following a stroke is associated with unfavorable clinical outcomes. Factors predicting LOS in medium vessel occlusion (MeVO), impacting up to 40% of acute ischemic stroke (AIS) cases, remain underexplored. This study aims to investigate the predictors of LOS in AIS-MeVO. METHODS: We conducted a retrospective analysis of prospectively maintained stroke databases, comprising AIS cases with MeVO in the anterior circulation, assessed by adequate CT perfusion (CTP). Baseline and clinical data were obtained from electronic health records. Alberta Stroke Program Early CT Scores (ASPECTS) were calculated from non-contrast head CT. The perfusion mismatch volume (time to maximum > 6 s minus relative cerebral blood flow <30%) volume was reported from CTP. Multiple regression was employed to examine the relationship between baseline parameters and hospital LOS. RESULTS: A total of 133 patients (median age 71 [interquartile range 63-80] years, 59.4% females) were included in the study cohort. The perfusion mismatch volume significantly positively correlated with LOS (r = 0.264, p = 0.004). After adjusting for age, sex, hypertension, diabetes, prior stroke or transient ischemic attack, admission NIHSS, ASPECTS, Tan score, intravenous thrombolysis, mechanical thrombectomy (MT), and hemorrhagic transformation, a larger mismatch volume remained independently associated with longer hospital stays (β = 0.209, 95% confidence interval [CI] 0.006-0.412, p = 0.045). Additional significant determinants of longer hospital stay included admission NIHSS (β = 0.250, 95% CI: 0.060-0.440, p = 0.010) and MT (β = 0.208, 95% CI: 0.006-0.410, p = 0.044). Among patients who underwent MT (n = 83), multiple regression analysis incorporating both perfusion mismatch volume and admission NIHSS revealed that perfusion mismatch volume remained independently associated with LOS (β = 0.248, 95% CI: 0.019-0.471, p = 0.033), while admission NIHSS did not retain significance (β = 0.208, 95% CI: 0.019-0.433, p = 0.071). CONCLUSIONS: In our cohort of AIS patients with MeVO in the anterior circulation, and particularly in those who underwent MT, the perfusion mismatch volume serves as an independent predictor of LOS. These findings offer critical valuable insights in clinical assessments and decision-making protocols of MT in AIS-MeVO.
BACKGROUND AND PURPOSE: MRI is crucial for multiple sclerosis (MS), but the relative value of portable ultra-low field MRI (pULF-MRI), a technology that holds promise for extending access to MRI, is unknown. We assessed...BACKGROUND AND PURPOSE: MRI is crucial for multiple sclerosis (MS), but the relative value of portable ultra-low field MRI (pULF-MRI), a technology that holds promise for extending access to MRI, is unknown. We assessed white matter lesion (WML) detection on pULF-MRI compared to high-field MRI (HF-MRI), focusing on blinded assessments, assessor self-training, and multiplanar acquisitions. METHODS: Fifty-five adults with MS underwent pULF-MRI following their HF-MRI. Two neuroradiologists independently assessed pULF-MRI images in an evaluation process, including initial assessment blinded to HF-MRI, self-training with reference to HF-MRI and evaluation of 20 cases with additional T2-fluid-attenuated inversion recovery in an additional plane. A third rater conducted cross-referenced analysis with HF-MRI data to determine true-positive lesions, false-positive areas, and case-level sensitivity and positive predictive value. RESULTS: The mean age of participants was 50 years (standard deviation: 11; 74% women). Initially, Rater 2 marked more false-positive areas than Rater 1 (p = 0.003). After self-training, both raters embraced a conservative approach, with Rater 2 marking fewer false-positive areas (p = 0.01). Both raters maintained 100% case-level sensitivity and positive predictive value for detecting at least one WML, particularly in periventricular areas. Multiplanar acquisitions reduced both false-positive areas and true-positive lesions. True-positive lesions and false-positive areas had similar contrast-to-noise ratios in the juxtacortical region (p = 0.73) but not in periventricular, deep parenchymal regions (p = 0.004, p = 0.01). CONCLUSION: With adequate training, radiological interpretation of pULF-MRI has high sensitivity and positive predictive value for MS lesions but should be approached conservatively. These results suggest utility for patient triage, potentially reducing diagnostic delay, and screening high-risk individuals.
Salim HA, Lakhani DA, Balar AB
… +22 more, Mei J, Luna L, Shahriari M, Hyson NZ, Deng F, Dmytriw AA, Guenego A, Urrutia VC, Marsh EB, Lu H, Xu R, Leigh R, Shah G, Wen S, Albers GW, Hillis AE, Llinas R, Nael K, Wintermark M, Heit JJ, Faizy TD, Yedavalli VS
BACKGROUND AND PURPOSE: Prolonged venous transit (PVT), derived from computed tomography perfusion (CTP) time-to-maximum (T) maps, reflects compromised venous outflow (VO) in acute ischemic stroke due to large vessel occ...BACKGROUND AND PURPOSE: Prolonged venous transit (PVT), derived from computed tomography perfusion (CTP) time-to-maximum (T) maps, reflects compromised venous outflow (VO) in acute ischemic stroke due to large vessel occlusion (AIS-LVO). Poor VO is associated with worse clinical outcomes, but pre-treatment markers predictive of PVT are not well described. METHODS: We conducted a retrospective analysis of 189 patients with anterior circulation AIS-LVO who underwent baseline CT evaluation, including non-contrast CT, CT angiography, and CTP. PVT was assessed on T maps; PVT+ was defined as T ≥ 10 s within the posterior superior sagittal sinus or torcula. Baseline clinical data were collected. Multivariable logistic regression identified independent associations between pre-treatment markers and PVT. RESULTS: PVT+ was identified in 65 patients (34%). In multivariable analysis, higher admission National Institutes of Health Stroke Scale (NIHSS) scores (adjusted odds ratio [aOR], 1.05 per point; 95% confidence interval [CI], 1.01-1.11; P = 0.028) and male sex (aOR, 1.98; 95% CI, 1.03-3.89; P = 0.043) were independently associated with PVT+. CONCLUSIONS: Higher admission NIHSS scores and male sex are independently associated with PVT in anterior circulation AIS-LVO, suggesting that readily available clinical markers may help identify patients with poor VO profiles.
BACKGROUND AND PURPOSE: This study aims to investigate the longitudinal changes in translocator protein (TSPO) following stroke in different brain regions and potential associations with chronic brain infarction. METHODS...BACKGROUND AND PURPOSE: This study aims to investigate the longitudinal changes in translocator protein (TSPO) following stroke in different brain regions and potential associations with chronic brain infarction. METHODS: Twelve patients underwent SPECT using the TSPO tracer 6-Chloro-2-(4'-123I-Iodophenyl)-3-(N,N-Diethyl)-Imidazo[1,2-a]Pyridine-3-Acetamide, as well as structural MRI, at 10, 41, and 128 days (median) after ischemic infarction in the middle cerebral artery. TSPO expression was measured in lesional (MRI lesion and SPECT lesion), connected (pons and ipsilesional thalamus), and nonconnected (ipsilesional cerebellum and contralesional occipital cortex) regions. Correlations were explored between the volume of chronic infarction and TSPO expression in nonconnected regions of interest (ROIs) at 128 days RESULTS: Throughout the study period, TSPO levels decreased by 24%-33% in lesional ROIs, while levels increased in connected ROIs by 35%-69% and in nonconnected ROIs by 53%-77%. At 128 days poststroke, TSPO expression in ipsilesional cerebellum positively correlated with chronic infarction volume (p = 0.002, r = 0.72). CONCLUSIONS: This study expands the current knowledge of spatial and temporal TSPO expression in humans by quantifying TSPO changes in lesional, connected, and nonconnected brain regions at three time points after cerebral infarction as well as correlating late-stage TSPO upregulation and chronic infarction volume.