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BACKGROUND: The dynamics of blood clot (combination of Hb [hemoglobin], fibrin, and a higher concentration of aggregated red blood cells) formation within the hematoma of an intracerebral hemorrhage is not well understood. A quantitative neuroimaging method of localized coagulated blood volume/distribution within the hematoma might improve clinical decision-making. METHODS: The deoxyhemoglobin of aggregated red blood cells within extravasated blood exhibits a higher magnetic susceptibility due to unpaired heme iron electrons. We propose that coagulated blood, with higher aggregated red blood cell content, will exhibit (1) a higher positive susceptibility than noncoagulated blood and (2) increase in fibrin polymerization-restricted localized diffusion, which can be measured noninvasively using quantitative susceptibility mapping and diffusion tensor imaging. In this serial magnetic resonance imaging study, we enrolled 24 patients with acute intracerebral hemorrhage between October 2021 to May 2022 at a stroke center. Patients were 30 to 70 years of age and had a hematoma volume >15 cm3 and National Institutes of Health Stroke Scale score >1. The patients underwent imaging 3×: within 12 to 24 (T1), 36 to 48 (T2), and 60 to 72 (T3) hours of last seen well on a 3T magnetic resonance imaging system. Three-dimensional anatomic, multigradient echo and 2-dimensional diffusion tensor images were obtained. Hematoma and edema volumes were calculated, and the distribution of coagulation was measured by dynamic changes in the susceptibilities and fractional anisotropy within the hematoma. RESULTS: Using a coagulated blood phantom, we demonstrated a linear relationship between the percentage coagulation and susceptibility (R2=0.91) with a positive red blood cell stain of the clot. The quantitative susceptibility maps showed a significant increase in hematoma susceptibility (T1, 0.29±0.04 parts per millions; T2, 0.36±0.04 parts per millions; T3, 0.45±0.04 parts per millions; P<0.0001). A concomitant increase in fractional anisotropy was also observed with time (T1, 0.40±0.02; T2, 0.45±0.02; T3, 0.47±0.02; P<0.05). CONCLUSIONS: This quantitative neuroimaging study of coagulation within the hematoma has the potential to improve patient management, such as safe resumption of anticoagulants, the need for reversal agents, the administration of alteplase to resolve the clot, and the need for surgery.
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Acidente Vascular Cerebral Hemorrágico , Acidente Vascular Cerebral , Humanos , Acidente Vascular Cerebral Hemorrágico/complicações , Imagem de Tensor de Difusão , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/complicações , Hemorragia Cerebral/complicações , Imageamento por Ressonância Magnética/métodos , Hematoma/complicações , Coagulação Sanguínea , Hemoglobinas , FibrinaRESUMO
BACKGROUND: We developed a noninvasive biomarker to quantify the rate of ventricular blood clearance in patients with intracerebral hemorrhage and extension to the ventricles-intraventricular hemorrhage. METHODS: We performed magnetic resonance imaging in 26 patients at 1, 14, 28, and 42 days of onset and measured their hematoma volume (HV), ventricular blood volume (VBV), and two diffusion metrics: fractional anisotropy (FA), and mean diffusivity (MD). The ipasilesional ventricular cerebral spinal fluid's FA and MD were associated with VBV and stroke severity scores (National Institute of Health Stroke Scale [NIHSS]). A subcohort of 14 patients were treated with external ventricular drain (EVD). A generalized linear mixed model was applied for statistical analysis. RESULTS: At day 1, the average HVs and NIHSS scores were 14.6 ± 16.7 cm3 and 16 ± 8, respectively. A daily rate of 2.1% and 1.3% blood clearance/resolution were recorded in HV and VBV, respectively. Ipsilesional ventricular FA (vFA) and ventricular MD (vMD) were simultaneously decreased (vFA = 1.3% per day, posterior probability [PP] > 99%) and increased (vMD = 1.5% per day, PP > 99%), respectively. Patients with EVD exhibited a faster decline in vFA (1.5% vs. 1.1% per day) and an increase in vMD (1.8% vs. 1.5% per day) as compared with patients without EVD. Temporal change in vMD was associated with VBV; a 1.00-cm3 increase in VBV resulted in a 5.2% decrease in vMD (PP < 99%). VBV was strongly associated with NIHSS score (PP = 97-99%). A larger cerebral spinal fluid drained volume was associated with a greater decrease (PP = 83.4%) in vFA, whereas a smaller volume exhibited a greater increase (PP = 94.8%) in vMD. CONCLUSIONS: In conclusion, vFA and vMD may serve as biomarkers for VBV status.
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OBJECTIVE: To identify specific white matter tracts (WMTs) whose disruption is associated with the severity of neurogenic lower urinary tract dysfunction (NLUTD) in two independent cohorts of women with multiple sclerosis (MS) and NLUTD. METHODS: Cohort 1 consisted of twenty-eight women with MS and NLUTD. The validation cohort consisted of 10 women with MS and NLUTD. Eleven healthy women served as controls. Participants of both MS cohorts had the same inclusion and exclusion criteria. Both MS cohorts and the healthy controls underwent the same clinical assessment and functional MRI (fMRI) protocol, except that the validation MS cohort underwent 7-Tesla fMRI scan. Fifteen WMTs (six coursing to relevant brainstem areas) involved in bladder control were a priori regions of interest (ROI). Spearman's correlation test was performed between each the Fractional Anisotropy (FA) and mean diffusivity (MD) of each WMT and the clinical parameters. RESULTS: Overall, we found a very high degree of overlap (100% of a priori ROI) in the tracts identified by our correlation analysis as having the greatest contribution to NLUTD symptoms in MS women. The right inferior cerebellar peduncle, left posterior limb of internal capsule, and left superior cerebellar peduncle displayed significant associations to the greatest number of clinical parameters. CONCLUSIONS: Our correlation analysis supports the role of specific WMT disruptions in the contribution of symptoms in women with MS and NLUTD, as confirmed in two independent MS cohorts.
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Esclerose Múltipla , Substância Branca , Humanos , Feminino , Substância Branca/diagnóstico por imagem , Esclerose Múltipla/complicações , Esclerose Múltipla/diagnóstico por imagem , Bexiga Urinária/diagnóstico por imagem , Imagem de Tensor de Difusão/métodos , Imageamento por Ressonância MagnéticaRESUMO
The Papez circuit, first proposed by James Papez in 1937, is a circuit believed to control memory and emotions, composed of the cingulate cortex, entorhinal cortex, parahippocampal gyrus, hippocampus, hypothalamus, and thalamus. Pursuant to James Papez, Paul Yakovlev and Paul MacLean incorporated the prefrontal/orbitofrontal cortex, septum, amygdalae, and anterior temporal lobes into the limbic system. Over the past few years, diffusion-weighted tractography techniques revealed additional limbic fiber connectivity, which incorporates multiple circuits to the already known complex limbic network. In the current review, we aimed to comprehensively summarize the anatomy of the limbic system and elaborate on the anatomical connectivity of the limbic circuits based on the published literature as an update to the original Papez circuit.
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Giro do Cíngulo , Sistema Límbico , Humanos , Sistema Límbico/diagnóstico por imagem , Tonsila do Cerebelo , Tálamo , Hipocampo , Vias NeuraisRESUMO
BACKGROUND: Optic disc edema develops in most astronauts during long-duration spaceflight. It is hypothesized to result from weightlessness-induced venous congestion of the head and neck and is an unresolved health risk of space travel. PURPOSE: Determine if short-term application of lower body negative pressure (LBNP) could reduce internal jugular vein (IJV) expansion associated with the supine posture without negatively impacting cerebral perfusion or causing IJV flow stasis. STUDY TYPE: Prospective. SUBJECTS: Nine healthy volunteers (six women). FIELD STRENGTH/SEQUENCE: 3T/cine two-dimensional phase-contrast gradient echo; pseudo-continuous arterial spin labeling single-shot gradient echo echo-planar. ASSESSMENT: The study was performed with two sequential conditions in randomized order: supine posture and supine posture with 25 mmHg LBNP (LBNP25 ). LBNP was achieved by enclosing the lower extremities in a semi-airtight acrylic chamber connected to a vacuum. Heart rate, bulk cerebrovasculature flow, IJV cross-sectional area, fractional IJV outflow relative to arterial inflow, and cerebral perfusion were assessed in each condition. STATISTICAL TESTS: Paired t-tests were used to compare measurement means across conditions. Significance was defined as P < 0.05. RESULTS: LBNP25 significantly increased heart rate from 64 ± 9 to 71 ± 8 beats per minute and significantly decreased IJV cross-sectional area, IJV outflow fraction, cerebral arterial flow rate, and cerebral arterial stroke volume from 1.28 ± 0.64 to 0.56 ± 0.31 cm2 , 0.75 ± 0.20 to 0.66 ± 0.28, 780 ± 154 to 708 ± 137 mL/min and 12.2 ± 2.8 to 9.7 ± 1.7 mL/cycle, respectively. During LBNP25 , there was no significant change in gray or white matter cerebral perfusion (P = 0.26 and P = 0.24 respectively) and IJV absolute mean peak flow velocity remained ≥4 cm/sec in all subjects. DATA CONCLUSION: Short-term application of LBNP25 reduced IJV expansion without decreasing cerebral perfusion or inducing IJV flow stasis. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1.
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Voo Espacial , Ausência de Peso , Circulação Cerebrovascular/fisiologia , Feminino , Humanos , Veias Jugulares/fisiologia , Pressão Negativa da Região Corporal Inferior , Imageamento por Ressonância Magnética/métodos , Estudos Prospectivos , Voo Espacial/métodosRESUMO
BACKGROUND: Bipolar disorder (BD) is a severe psychiatric disorder associated with structural and functional brain abnormalities, some of which have been found in unaffected relatives as well. In this study, we examined the potential role of decreased fractional anisotropy (FA) as a BD endophenotype, in adolescents at high risk for BD. METHODS: We included 15 offspring of patients with BD, 16 pediatric BD patients, and 16 matched controls. Diffusion weighted scans were obtained on a 3T scanner using an echo-planar sequence. Scans were segmented using FreeSurfer. RESULTS: Our results showed significantly decreased FA in six brain areas of offspring group; left superior temporal gyrus (LSTG; P < .0001), left transverse temporal gyrus (LTTG; P = .002), left banks of the superior temporal sulcus (LBSTS; P = .002), left anterior cingulum (LAC; P = .003), right temporal pole (RTP; P = .004) and left frontal pole (LFP; P = .017). On analysis, LSTG, LAC, and RTP demonstrated a potential to be an endophenotype when comparing all three groups. FA values in three regions, LBSTS, LTTG, and LFP were increased only in controls. CONCLUSION: Our findings point at decreased FA as a possible endophenotype for BD, as they were found in children of patients with BD. Most of these areas were previously found to have morphological and functional changes in adult and pediatric BD, and are thought to play important roles in affected domains of functioning. Prospective follow up studies should be performed to detect reliability of decreased FA as an endophenotype and effects of treatment on FA.
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Transtorno Bipolar , Adulto , Adolescente , Humanos , Criança , Anisotropia , Transtorno Bipolar/diagnóstico , Endofenótipos , Imagem de Tensor de Difusão/métodos , Estudos Prospectivos , Reprodutibilidade dos TestesRESUMO
Tract-based spatial statistics (TBSS) of diffusion tensor imaging (DTI) studies have consistently shown diminished white matter (WM) integrity for individuals with cocaine use disorder (CUD). The present study used seed-based d mapping (SDM) to determine the extent to which a systematic difference in the WM integrity of cocaine users may exist (as compared with that of healthy controls). Articles from 2006 (when TBSS was first developed) to present were reviewed, with eight selected for inclusion. Meta-analysis found lower fractional anisotropy (FA) in the genu of the corpus callosum for cocaine users, with a small-to-moderate peak effect size (Hedge's g = -0.331). Sensitivity analyses mostly supported the robustness of the obtained difference. Differences detected at exploratory thresholds for significance suggested insult to WM integrity extending beyond the corpus callosum. The present results compliment a previous region-of-interest (ROI)-based meta-analysis of DTI studies in individuals with CUD. These findings have significant implications for the potential role of neuroprotective agents in the treatment of CUD and merit additional iteration as more studies accrue in the literature.
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Transtornos Relacionados ao Uso de Cocaína/patologia , Substância Branca/patologia , Anisotropia , Transtornos Relacionados ao Uso de Cocaína/diagnóstico por imagem , Corpo Caloso/patologia , Imagem de Tensor de Difusão , Humanos , Substância Branca/diagnóstico por imagemRESUMO
Background and Purpose- Stroke is the leading cause of disability in United States, and aphasia is a common sequela after a left hemisphere stroke. Functional imaging and brain stimulation studies show that right hemisphere structures are detrimental to aphasia recovery but evidence from diffusion tensor imaging is lacking. We investigated the role of homologous language pathways in naming recovery after left hemispheric stroke. Methods- Patients with aphasia after a left hemispheric stroke underwent naming assessment using the Boston Naming Test and diffusion tensor imaging at the acute and chronic time points. We analyzed diffusion tensor imaging of right arcuate fasciculus and frontal aslant tracts. We used Wilcoxon rank-sum test to evaluate structural lateralization patterns and partial Spearman correlation/multivariate generalized linear model to determine the role of right arcuate fasciculus and frontal aslant tracts in naming recovery after controlling for confounders. Results were corrected for multiple comparisons. Results- On average, the structural integrity of left language pathways deteriorated more than their right homologs, such that there was rightward lateralization in the chronic stage. Regression/correlation analyses showed that greater preservation of tract integrity of right arcuate fasciculus was associated with poorer naming recovery. Conclusions- Our study provides preliminary evidence that preservation of right homologs of language pathways is associated with poor recovery of naming after a left hemispheric stroke, consistent with previous evidence that maintaining greater reliance on left hemisphere structures is associated with better language recovery.
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Afasia , Cérebro , Imagem de Tensor de Difusão , Idioma , Acidente Vascular Cerebral , Adulto , Idoso , Idoso de 80 Anos ou mais , Afasia/diagnóstico por imagem , Afasia/fisiopatologia , Cérebro/diagnóstico por imagem , Cérebro/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/fisiopatologiaRESUMO
Background Astronauts on long-duration spaceflight missions may develop changes in ocular structure and function, which can persist for years after the return to normal gravity. Chronic exposure to elevated intracranial pressure during spaceflight is hypothesized to be a contributing factor, however, the etiologic causes remain unknown. Purpose To investigate the intracranial effects of microgravity by measuring combined changes in intracranial volumetric parameters, pituitary morphologic structure, and aqueductal cerebrospinal fluid (CSF) hydrodynamics relative to spaceflight and to establish a comprehensive model of recovery after return to Earth. Materials and Methods This prospective longitudinal MRI study enrolled astronauts with planned long-duration spaceflight. Measures were conducted before spaceflight followed by 1, 30, 90, 180, and 360 days after landing. Intracranial volumetry and aqueductal CSF hydrodynamics (CSF peak-to-peak velocity amplitude and aqueductal stroke volume) were quantified for each phase. Qualitative and quantitative changes in pre- to postflight (day 1) pituitary morphologic structure were determined. Statistical analysis included separate mixed-effects models per dependent variable with repeated observations over time. Results Eleven astronauts (mean age, 45 years ± 5 [standard deviation]; 10 men) showed increased mean volumes in the brain (28 mL; P < .001), white matter (26 mL; P < .001), mean lateral ventricles (2.2 mL; P < .001), and mean summated brain and CSF (33 mL; P < .001) at postflight day 1 with corresponding increases in mean aqueductal stroke volume (14.6 µL; P = .045) and mean CSF peak-to-peak velocity magnitude (2.2 cm/sec; P = .01). Summated mean brain and CSF volumes remained increased at 360 days after spaceflight (28 mL; P < .001). Qualitatively, six of 11 (55%) astronauts developed or showed exacerbated pituitary dome depression compared with baseline. Average midline pituitary height decreased from 5.9 to 5.3 mm (P < .001). Conclusion Long-duration spaceflight was associated with increased pituitary deformation, augmented aqueductal cerebrospinal fluid (CSF) hydrodynamics, and expansion of summated brain and CSF volumes. Summated brain and CSF volumetric expansion persisted up to 1 year into recovery, suggesting permanent alteration. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Lev in this issue.
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Astronautas , Encéfalo/diagnóstico por imagem , Pressão do Líquido Cefalorraquidiano/fisiologia , Pressão Intracraniana/fisiologia , Imageamento por Ressonância Magnética , Voo Espacial , Simulação de Ausência de Peso , Adulto , Aqueduto do Mesencéfalo/diagnóstico por imagem , Feminino , Seguimentos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Hipófise/diagnóstico por imagem , Estudos ProspectivosRESUMO
Cellular therapy is a promising investigational modality to enhance poststroke recovery. We conducted a single-arm, phase I clinical trial to determine the safety and feasibility of intravenous (IV) administration of autologous bone marrow mononuclear cells (MNCs) after acute ischemic stroke (AIS). Patients with moderate severity of AIS underwent bone marrow harvest followed by IV reinfusion of MNCs within 24-72 hours of onset. A target dose of 10 million cells per kilogram was chosen based on preclinical data. Patients were followed up daily during hospitalization and at 1, 3, 6, 12, and 24 months for incidence of adverse events using laboratory, clinical (12 months), and radiological (24 months) parameters. The trial was powered to detect severe adverse events (SAEs) with incidences of at least 10% and planned to enroll 30 patients. Primary outcomes were study-related SAEs and the proportion of patients successfully completing study intervention. A propensity score-based matched control group was used for the estimation of effect size (ES) for day-90 modified Rankin score (mRS). There were no study-related SAEs and, based on a futility analysis, enrolment was stopped after 25 patients. All patients successfully completed study intervention and most received the target dose. Secondary analysis estimated the ES to be a reduction of 1 point (95% confidence interval: 0.33-1.67) in median day-90 mRS for treated patients as compared with the matched control group. Bone marrow harvest and infusion of MNCs is safe and feasible in patients with AIS. The estimated ES is helpful in designing future randomized controlled trials. Stem Cells 2019;37:1481-1491.
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Células da Medula Óssea/citologia , Transplante de Medula Óssea/efeitos adversos , Isquemia Encefálica/terapia , Leucócitos Mononucleares/citologia , Acidente Vascular Cerebral/terapia , Administração Intravenosa , Idoso , Células da Medula Óssea/fisiologia , Transplante de Medula Óssea/métodos , Isquemia Encefálica/diagnóstico por imagem , Imagem de Tensor de Difusão , Estudos de Viabilidade , Feminino , Humanos , Leucócitos Mononucleares/fisiologia , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/diagnóstico por imagem , Resultado do TratamentoRESUMO
Although the thalamus is not considered primarily as a limbic structure, abundant evidence indicates the essential role of the thalamus as a modulator of limbic functions indirectly through the amygdala. The amygdala is a central component of the limbic system and serves an essential role in modulating the core processes including the memory, decision-making, and emotional reactions. The amygdalothalamic pathway is the largest direct amygdalo-diencephalic connection in the primates including the human brain. Given the crucial role of the amygdalothalamic tract (ATT) in memory function and diencephalic amnesia in stroke patients, diffusion tensor imaging may be helpful in better visualizing the surgical anatomy of this pathway noninvasively. To date, few diffusion-weighted studies have focused on the amygdala, yet the fine neuronal connection of the amygdala and thalamus known as the ATT has yet to be elucidated. This study aimed to investigate the utility of high spatial resolution diffusion tensor tractography for mapping the trajectory of the ATT in the human brain. We studied 15 healthy right-handed human subjects (12 men and 3 women with age range of 24-37 years old). Using a high-resolution diffusion tensor tractography technique, for the first time, we were able to reconstruct and measure the trajectory of the ATT. We further revealed the close relationship of the ATT with the temporopontine tract and the fornix bilaterally in 15 healthy adult human brains.
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Tonsila do Cerebelo/anatomia & histologia , Processamento de Imagem Assistida por Computador/métodos , Sistema Límbico/anatomia & histologia , Tálamo/anatomia & histologia , Adulto , Tonsila do Cerebelo/diagnóstico por imagem , Imagem de Tensor de Difusão , Feminino , Humanos , Imageamento Tridimensional , Sistema Límbico/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Masculino , Vias Neurais/anatomia & histologia , Tálamo/diagnóstico por imagem , Substância Branca/anatomia & histologia , Substância Branca/diagnóstico por imagemAssuntos
Isquemia Encefálica , AVC Isquêmico , Acidente Vascular Cerebral , Humanos , Espectroscopia de Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/métodos , Imageamento Tridimensional/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Isquemia Encefálica/diagnóstico por imagemRESUMO
Diagnosis, clinical management and research of psychiatric disorders remain subjective - largely guided by historically developed categories which may not effectively capture underlying pathophysiological mechanisms of dysfunction. Here, we report a novel approach of identifying and validating distinct and biologically meaningful clinical phenotypes of bipolar disorders using both unsupervised and supervised machine learning techniques. First, neurocognitive data were analyzed using an unsupervised machine learning approach and two distinct clinical phenotypes identified namely; phenotype I and phenotype II. Second, diffusion weighted imaging scans were pre-processed using the tract-based spatial statistics (TBSS) method and 'skeletonized' white matter fractional anisotropy (FA) and mean diffusivity (MD) maps extracted. The 'skeletonized' white matter FA and MD maps were entered into the Elastic Net machine learning algorithm to distinguish individual subjects' phenotypic labels (e.g. phenotype I vs. phenotype II). This calculation was performed to ascertain whether the identified clinical phenotypes were biologically distinct. Original neurocognitive measurements distinguished individual subjects' phenotypic labels with 94% accuracy (sensitivity=92%, specificity=97%). TBSS derived FA and MD measurements predicted individual subjects' phenotypic labels with 76% and 65% accuracy respectively. In addition, individual subjects belonging to phenotypes I and II were distinguished from healthy controls with 57% and 92% accuracy respectively. Neurocognitive task variables identified as most relevant in distinguishing phenotypic labels included; Affective Go/No-Go (AGN), Cambridge Gambling Task (CGT) coupled with inferior fronto-occipital fasciculus and callosal white matter pathways. These results suggest that there may exist two biologically distinct clinical phenotypes in bipolar disorders which can be identified from healthy controls with high accuracy and at an individual subject level. We suggest a strong clinical utility of the proposed approach in defining and validating biologically meaningful and less heterogeneous clinical sub-phenotypes of major psychiatric disorders.
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Transtorno Bipolar/diagnóstico , Imagem de Difusão por Ressonância Magnética/métodos , Aprendizado de Máquina , Neuroimagem/métodos , Substância Branca/diagnóstico por imagem , Adulto , Transtorno Bipolar/diagnóstico por imagem , Transtorno Bipolar/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Sensibilidade e EspecificidadeRESUMO
PURPOSE: To improve the conspicuity of white matter lesions (WMLs) in multiple sclerosis (MS) using patient-specific optimization of single-slab 3D fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI). MATERIALS AND METHODS: Sixteen MS patients were enrolled in a prospective 3.0T MRI study. FLAIR inversion time and echo time were automatically optimized for each patient during the same scan session based on measurements of the relative proton density and relaxation times of the brain tissues. The optimization criterion was to maximize the contrast between gray matter (GM) and white matter (WM), while suppressing cerebrospinal fluid. This criterion also helps increase the contrast between WMLs and WM. The performance of the patient-specific 3D FLAIR protocol relative to the fixed-parameter protocol was assessed both qualitatively and quantitatively. RESULTS: Patient-specific optimization achieved a statistically significant 41% increase in the GM-WM contrast ratio (P < 0.05) and 32% increase in the WML-WM contrast ratio (P < 0.01) compared with fixed-parameter FLAIR. The increase in WML-WM contrast ratio correlated strongly with echo time (P < 10-11 ). Two experienced neuroradiologists indicated substantially higher lesion conspicuity on the patient-specific FLAIR images over conventional FLAIR in 3-4 cases (intrarater correlation coefficient ICC = 0.72). In no case was the image quality of patient-specific FLAIR considered inferior to conventional FLAIR by any of the raters (ICC = 0.32). CONCLUSION: Changes in proton density and relaxation times render fixed-parameter FLAIR suboptimal in terms of lesion contrast. Patient-specific optimization of 3D FLAIR increases lesion conspicuity without scan time penalty, and has potential to enhance the detection of subtle and small lesions in MS. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:557-564.
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Imageamento Tridimensional , Imageamento por Ressonância Magnética , Esclerose Múltipla/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Adulto , Encéfalo/diagnóstico por imagem , Líquido Cefalorraquidiano , Meios de Contraste/química , Feminino , Substância Cinzenta/diagnóstico por imagem , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos TestesRESUMO
BACKGROUND: Cognitive impairment (CI) cannot be diagnosed by magnetic resonance imaging (MRI). Functional magnetic resonance imaging (fMRI) paradigms, such as the immediate/delayed memory task (I/DMT), detect varying degrees of working memory (WM). Preliminary findings using I/DMT showed differences in blood oxygenation level dependent (BOLD) activation between impaired (MSCI, n = 12) and non-impaired (MSNI, n = 9) multiple sclerosis (MS) patients. OBJECTIVES: The aim of the study was to confirm CI detection based on I/DMT BOLD activation in a larger cohort of MS patients. The role of T2 lesion volume (LV) and Expanded Disability Status Scale (EDSS) in magnitude of BOLD signal was also sought. METHODS: A total of 50 patients (EDSS mean ( m) = 3.2, disease duration (DD) m = 12 years, and age m = 40 years) underwent the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS) and I/DMT. Working memory activation (WMa) represents BOLD signal during DMT minus signal during IMT. CI was based on MACFIMS. RESULTS: A total of 10 MSNI, 30 MSCI, and 4 borderline patients were included in the analyses. Analysis of variance (ANOVA) showed MSNI had significantly greater WMa than MSCI, in the left prefrontal cortex and left supplementary motor area ( p = 0.032). Regression analysis showed significant inverse correlations between WMa and T2 LV/EDSS in similar areas ( p = 0.005, 0.004, respectively). CONCLUSION: I/DMT-based BOLD activation detects CI in MS. Larger studies are needed to confirm these findings.
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Mapeamento Encefálico/métodos , Disfunção Cognitiva/diagnóstico , Memória de Curto Prazo/fisiologia , Córtex Motor/fisiopatologia , Esclerose Múltipla Crônica Progressiva/fisiopatologia , Esclerose Múltipla Recidivante-Remitente/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Adulto , Disfunção Cognitiva/diagnóstico por imagem , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/fisiopatologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Córtex Motor/diagnóstico por imagem , Esclerose Múltipla Crônica Progressiva/complicações , Esclerose Múltipla Recidivante-Remitente/complicações , Córtex Pré-Frontal/diagnóstico por imagem , Adulto JovemRESUMO
PURPOSE: Postacquisition combination of three-dimensional T2-weighted (T2w) and fluid-attenuated inversion recovery (FLAIR) images can improve the visualization of brain lesions in multiple sclerosis (MS). However, an optimal way to combine these images has not been described so far. The main objective of this study is to investigate an optimal combination of T2w and FLAIR to improve the conspicuity of MS lesions. MATERIALS AND METHODS: We determined the parameters for a generalized multiplicative image combination which maximize the contrast-to-noise ratio (CNR) between lesions and normal-appearing brain tissue through simulations and verified experimentally. MRI data from 11 MS patients acquired at 3 Tesla were retrospectively analyzed using the proposed approach and compared with conventional FLAIR, and to images obtained by direct multiplication of T2w and FLAIR (FLAIR2 ). Image quality was assessed by region-of-interest analysis. In addition, to evaluate the degree of cerebrospinal fluid (CSF) suppression, CSF-to-gray matter (CSF/GM) ratio was calculated. Reduction in global image contrast was assessed by computing the reduction in the contrast of mid-level intensity values. RESULTS: An optimal combination was found to be the third order expression: FLAIR3 = FLAIR1.55 × T2w1.45 . Compared with FLAIR, the lesion CNR was significantly increased by 1.9× (P < 0.005) and 2.5× (P < 0.001) using FLAIR2 and FLAIR3 , respectively. CSF/GM ratio was increased by 1.7× in FLAIR2 (P < 0.001) compared with FLAIR, while it was reduced to 0.7× on FLAIR3 (P < 0.05). The mid-intensity contrast was preserved on FLAIR2 (P = 0.2), and decreased by 29% on FLAIR3 (P < 0.001). CONCLUSION: These results show that the optimized combination of FLAIR and T2w can improve MS lesion conspicuity. J. Magn. Reson. Imaging 2016;44:1293-1300.
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Encéfalo/diagnóstico por imagem , Imagem de Tensor de Difusão/métodos , Aumento da Imagem/métodos , Imagem Multimodal/métodos , Esclerose Múltipla/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Encéfalo/patologia , Feminino , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla/patologia , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Substância Branca/patologiaRESUMO
BACKGROUND: Major psychiatric disorders are increasingly being conceptualized as 'neurodevelopmental', because they are associated with aberrant brain maturation. Several studies have hypothesized that a brain maturation index integrating patterns of neuroanatomical measurements may reliably identify individual subjects deviating from a normative neurodevelopmental trajectory. However, while recent studies have shown great promise in developing accurate brain maturation indices using neuroimaging data and multivariate machine learning techniques, this approach has not been validated using a large sample of longitudinal data from children and adolescents. METHODS: T1-weighted scans from 303 healthy subjects aged 4.88 to 18.35years were acquired from the National Institute of Health (NIH) pediatric repository (http://www.pediatricmri.nih.gov). Out of the 303 subjects, 115 subjects were re-scanned after 2years. The least absolute shrinkage and selection operator algorithm (LASSO) was 'trained' to integrate neuroanatomical changes across chronological age and predict each individual's brain maturity. The resulting brain maturation index was developed using first-visit scans only, and was validated using second-visit scans. RESULTS: We report a high correlation between the first-visit chronological age and brain maturation index (r=0.82, mean absolute error or MAE=1.69years), and a high correlation between the second-visit chronological age and brain maturation index (r=0.83, MAE=1.71years). The brain maturation index captured neuroanatomical volume changes between the first and second visits with an MAE of 0.27years. CONCLUSIONS: The brain maturation index developed in this study accurately predicted individual subjects' brain maturation longitudinally. Due to its strong clinical potentials in identifying individuals with an abnormal brain maturation trajectory, the brain maturation index may allow timely clinical interventions for individuals at risk for psychiatric disorders.
Assuntos
Encéfalo/anatomia & histologia , Encéfalo/crescimento & desenvolvimento , Indicadores Básicos de Saúde , Aprendizado de Máquina , Imageamento por Ressonância Magnética/métodos , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Estudos Longitudinais , MasculinoRESUMO
A comprehensive analysis of the effect of lesion in-painting on the estimation of cortical thickness using magnetic resonance imaging was performed on a large cohort of 918 relapsing-remitting multiple sclerosis patients who participated in a phase III multicenter clinical trial. An automatic lesion in-painting algorithm was developed and implemented. Cortical thickness was measured using the FreeSurfer pipeline with and without in-painting. The effect of in-painting was evaluated using FreeSurfer's paired analysis pipeline. Multivariate regression analysis was also performed with field strength and lesion load as additional factors. Overall, the estimated cortical thickness was different with in-painting than without. The effect of in-painting was observed to be region dependent, more significant in the left hemisphere compared to the right, was more prominent at 1.5 T relative to 3 T, and was greater at higher lesion volumes. Our results show that even for data acquired at 1.5 T in patients with high lesion load, the mean cortical thickness difference with and without in-painting is â¼2%. Based on these results, it appears that in-painting has only a small effect on the estimated regional and global cortical thickness. Hum Brain Mapp 36:3749-3760, 2015. © 2015 Wiley Periodicals, Inc.
Assuntos
Córtex Cerebral/patologia , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Esclerose Múltipla/patologia , Adolescente , Adulto , Algoritmos , Estudos de Coortes , Método Duplo-Cego , Campos Eletromagnéticos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Esclerose Múltipla Recidivante-Remitente/patologia , Análise Multivariada , Adulto JovemRESUMO
PURPOSE: To quantify the change in cerebral spinal fluid (CSF) production rate and maximum systolic velocity in astronauts before and after exposure to microgravity and identify any physiologic trend and/or risk factor related to intracranial hypertension. MATERIALS AND METHODS: Following Institutional Review Board (IRB) approval, with waiver of informed consent, a retrospective review of 27 astronauts imaged at 3T was done. Qualitative analysis was performed on T2 -weighted axial images through the orbits for degree of flattening of the posterior globe according to the following grades: 0 = none, 1 = mild, 2 = moderate, and 3 = severe. One grade level change postflight was considered significant for exposure to intracranial hypertension. CSF production rate and maximum systolic velocity was calculated from cine phase-contrast magnetic resonance imaging and compared to seven healthy controls. RESULTS: Fourteen astronauts were studied. The preflight CSF production rate in astronauts was similar to controls (P = 0.83). Six astronauts with significant posterior globe flattening demonstrated a 70% increase in CSF production rate postflight compared to baseline (P = 0.01). There was a significant increase in CSF maximum systolic velocity in the subgroup without posterior globe flattening (P = 0.01). CONCLUSION: The increased postflight CSF production rate in astronauts with positive flattening is compatible with the hypothesis of microgravity-induced intracranial hypertension inferring downregulation in CSF production in microgravity that is upregulated upon return to normal gravity. Increased postflight CSF maximum systolic velocity in astronauts with negative flattening suggests increased craniospinal compliance and a potential negative risk factor to microgravity-induced intracranial hypertension.
Assuntos
Astronautas , Líquido Cefalorraquidiano/fisiologia , Hipertensão Intracraniana/etiologia , Hipertensão Intracraniana/patologia , Imageamento por Ressonância Magnética/métodos , Ausência de Peso/efeitos adversos , Biomarcadores/líquido cefalorraquidiano , Líquido Cefalorraquidiano/citologia , Método Duplo-Cego , Humanos , Hidrodinâmica , Hipertensão Intracraniana/líquido cefalorraquidiano , Pressão Intracraniana , Masculino , Pessoa de Meia-IdadeRESUMO
Although reduced working memory brain activation has been reported in several brain regions of cocaine-dependent subjects compared with controls, very little is known about whether there is altered connectivity of working memory pathways in cocaine dependence. This study addresses this issue by using functional magnetic resonance imaging-based stochastic dynamic causal modeling (DCM) analysis to study the effective connectivity of 19 cocaine-dependent subjects and 14 healthy controls while performing a working memory task. Stochastic DCM is an advanced method that has recently been implemented in SPM8 that can obtain improved estimates, relative to deterministic DCM, of hidden neuronal causes before convolution with the hemodynamic response. Thus, stochastic DCM may be less influenced by the confounding effects of variations in blood oxygen level-dependent response caused by disease or drugs. Based on the significant regional activation common to both groups and consistent with previous working memory activation studies, seven regions of interest were chosen as nodes for DCM analyses. Bayesian family level inference, Bayesian model selection analyses, and Bayesian model averaging (BMA) were conducted. BMA showed that the cocaine-dependent subjects had large differences compared with the control subjects in the strengths of prefrontal-striatal modulatory (B matrix) DCM parameters. These findings are consistent with altered cortical-striatal networks that may be related to reduced dopamine function in cocaine dependence. As far as we are aware, this is the first between-group DCM study using stochastic methodology.