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Background and Purpose: Traumatic brain injury (TBI) is a major source of health loss and disability worldwide. Accurate and timely diagnosis of TBI is critical for appropriate treatment and management of the condition. Neuroimaging plays a crucial role in the diagnosis and characterization of TBI. Computed tomography (CT) is the first-line diagnostic imaging modality typically utilized in patients with suspected acute mild, moderate and severe TBI. Radiology reports play a crucial role in the diagnostic process, providing critical information about the location and extent of brain injury, as well as factors that could prevent secondary injury. However, the complexity and variability of radiology reports can make it challenging for healthcare providers to extract the necessary information for diagnosis and treatment planning., Methods/results/conclusion: In this article, we report the efforts of an international group of TBI imaging experts to develop a clinical radiology report template for CT scans obtained in patients suspected of TBI and consisting of fourteen different subdivisions (CT technique, mechanism of injury or clinical history, presence of scalp injuries, fractures, potential vascular injuries, potential injuries involving the extra-axial spaces, brain parenchymal injuries, potential injuries involving the cerebrospinal fluid spaces and the ventricular system, mass effect, secondary injuries, prior or coexisting pathology)., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Magnetic resonance imaging (MRI) has emerged as a promising technique for non-invasive medical imaging. The primary challenge in MRI is the trade-off between image visual quality and acquisition time. Current MRI image denoising algorithms employ global thresholding to denoise the whole image, which leads to inadequate denoising or image distortion. This study introduces a novel pixel-wise (localized) thresholding approach of singular vectors, obtained from singular value decomposition, to denoise magnetic resonance (MR) images. The pixel-wise thresholding of singular vectors is performed using separate singular values as thresholds at each pixel, which is advantageous given the spatial noise variation throughout the image. The method presented is validated on MR images of a standard phantom approved by the magnetic resonance accreditation program (MRAP). The denoised images display superior visual quality and recover minute structural information otherwise suppressed in the noisy image. The increase in peak-signal-to-noise-ratio (PSNR) and contrast-to-noise-ratio (CNR) values of ≥ 18% and ≥ 200% of the denoised images, respectively, imply efficient noise removal and visual quality enhancement. The structural similarity index (SSIM) of ≥ 0.95 for denoised images indicates that the crucial structural information is recovered through the presented method. A comparison with the standard filtering methods widely used for MRI denoising establishes the superior performance of the presented method. The presented pixel-wise denoising technique reduces the scan time by 2-3 times and has the potential to be integrated into any MRI system to obtain faster and better quality images.

Objective: Minimally invasive endoscope-assisted approaches to the anterior skull base offer an alternative to traditional open craniotomies. Given the restrictive operative corridor, appropriate case selection is critical for success. In this paper, the authors present the results of three different minimal access approaches to meningiomas of the anterior and middle fossae and examine the differences in the target areas considered appropriate for each approach, as well as the outcomes, to determine whether the surgical goals were achieved., Methods: A consecutive series of the endoscopic endonasal approach (EEA), supraorbital approach (SOA), or transorbital approach (TOA) for newly diagnosed meningiomas of the anterior and middle fossa skull base between 2007 and 2022 were examined. Probabilistic heat maps were created to display the distribution of tumor volumes for each approach. Gross-total resection (GTR), extent of resection, visual and olfactory outcomes, and postoperative complications were assessed., Results: Of 525 patients who had meningioma resection, 88 (16.7%) were included in this study. EEA was performed for planum sphenoidale and tuberculum sellae meningiomas (n = 44), SOA for olfactory groove and anterior clinoid meningiomas (n = 36), and TOA for spheno-orbital and middle fossa meningiomas (n = 8). The largest tumors were treated using SOA (mean volume 28 ± 29 cm3), followed by TOA (mean volume 10 ± 10 cm3) and EEA (mean volume 9 ± 8 cm3) (p = 0.024). Most cases (91%) were WHO grade I. GTR was achieved in 84% of patients (n = 74), which was similar to the rates for EEA (84%) and SOA (92%), but lower than that for TOA (50%) (p = 0.002), the latter attributable to spheno-orbital (GTR: 33%) not middle fossa (GTR: 100%) tumors. There were 7 (8%) CSF leaks: 5 (11%) from EEA, 1 (3%) from SOA, and 1 (13%) from TOA (p = 0.326). All resolved with lumbar drainage except for 1 EEA leak that required a reoperation., Conclusions: Minimally invasive approaches for anterior and middle fossa skull base meningiomas require careful case selection. GTR rates are equally high for all approaches except for spheno-orbital meningiomas, where alleviation of proptosis and not GTR is the primary goal of surgery. New anosmia was most common after EEA.

Objective: The aim of this study was to determine if the distinction between planum sphenoidale (PS) and tuberculum sellae (TS) meningiomas is clinically meaningful and impacts the results of the endoscopic endonasal approach (EEA)., Methods: A consecutive series of patients who were 18 years of age or older and underwent EEA for newly diagnosed grade I PS meningiomas (PSMs) and TS meningiomas (TSMs) between October 2007 and May 2021 were included. The PS and TS were distinguished by drawing a line passing through the center of the TS and perpendicular to the PS on postcontrast T1-weighted MRI. Probabilistic heatmaps were created to display the actual distribution of tumor volumes. Tumor volume, extent of resection (EOR), visual outcome, and complications were assessed., Results: The 47 tumors were distributed in a smooth continuum. Using an arbitrary definition, 24 (51%) were PSMs and 23 (49%) were TSMs. The mean volume of PSMs was 5.6 cm3 compared with 4.5 cm3 for TSMs. Canal invasion was present in 87.5% of PSMs and 52% of TSMs. GTR was achieved in 38 (84%) of 45 cases in which it was the goal, slightly less frequently for PSMs (78%) compared with TSMs (91%), although the difference was not significant. Th mean EOR was 99% ± 2% for PSMs and 98% ± 11% for TSMs. Neither the suprasellar notch angle nor the percentage of tumor above the PS impacted the rate of GTR. After a median follow-up of 28.5 months (range 0.1-131 months), there were 2 (5%) recurrences after GTR (n = 38) both of which occurred in patients with PSMs. Forty-two (89%) patients presented with preoperative impaired vision. Postoperative vision was stable or improved in 96% of patients with PSMs and 91% of patients with TSMs. CSF leakage occurred in 4 (16.6%) patients with a PSM, which resolved with only lumbar drainage, and in 1 (4.3%) patient with a TSM, which required reoperation., Conclusions: PSM and TSMs arise in a smooth distribution, making the distinction arbitrary. Those classified as PSMs were larger and more likely to invade the optic canals. Surgical outcome for both locations was similar, slightly favoring TSMs. The arbitrary distinction between PSMs and TSMs is less useful at predicting outcome than the lateral extent of the tumor, regardless of the site of origin.

The visual system is known to be vital for cognition and perception in the feline and canine and much behavioral research for these species has used visual stimuli and focused on visual perception. There has been extensive investigations into the visual pathway in cats and dogs via histological and neurobiological methods, however to date, only one study has mapped the canine optic pathway in vivo. Advanced imaging methods such as diffusion MRI (DTI) have been routinely used in human research to study the visual system in vivo. This study applied DTI imaging methods to assess and characterize the optic pathway of feline and canine subjects in vivo. The optic nerve (ON), optic tract (OT), and optic radiation (OR) were successfully delineated for each species and the average volume and FA for each tract is reported. The application of DTI to map the optic pathway for canine and feline subjects provides a healthy baseline for comparison in future studies., (© 2021 American College of Veterinary Ophthalmologists.)

Repeated mild Traumatic Brain Injury (TBI) is a risk factor for Chronic Traumatic Encephalopathy (CTE), characterized pathologically by neurofibrillary tau deposition in the depths of brain sulci and surrounding blood vessels. The mechanism by which TBI leads to CTE remains unknown but has been posited to relate to axonal shear injury leading to release and possibly deposition of tau at the time of injury. As part of an IRB-approved study designed to learn how processes occurring acutely after TBI may predict later proteinopathy and neurodegeneration, we performed tau PET using 18F-MK6240 and MRI within 14 days of complicated mild TBI in three subjects. PET radiotracer accumulation was apparent in regions of traumatic hemorrhage in all subjects, with prominent intraparenchymal PET signal in one young subject with a history of repeated sports-related concussions. These results are consistent with off-target tracer binding to blood products as well as possible on-target binding to chronically and/or acutely-deposited neurofibrillary tau. Both explanations are highly relevant to applying tau PET to understanding TBI and CTE. Additional study is needed to assess the potential utility of tau PET in understanding how processes occurring acutely after TBI, such as release and deposition of tau and blood from damaged axons and blood vessels, may relate to development CTE years later., Competing Interests: Conflict of interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Background and Purpose: Cerebral adrenoleukodystrophy is a devastating neurological disorder caused by mutations in the ABCD1 gene. Our aim was to model and compare the growth of early cerebral lesions from longitudinal MRIs obtained in presymptomatic patients with progressive and arrested cerebral adrenoleukodystrophy using quantitative MR imaging-based lesion volumetry., Materials and Methods: We retrospectively quantified and modeled the longitudinal growth of early cerebral lesions from 174 MRIs obtained from 36 presymptomatic male patients with cerebral adrenoleukodystrophy. Lesions were manually segmented using subject-specific lesion-intensity thresholding. Volumes were calculated and plotted across time. Lesion velocity and acceleration were calculated between sequentially paired and triplet MRIs, respectively. Linear mixed-effects models were used to assess differences in growth parameters between progressive and arrested phenotypes., Results: The median patient age was 7.4 years (range, 3.9-37.0 years). Early-stage cerebral disease progression was inversely correlated with age (ρ = -0.6631, P < .001), early lesions can grow while appearing radiographically stable, lesions undergo sustained acceleration in progressive cerebral adrenoleukodystrophy (β = 0.10 mL/month 2 [95% CI, 0.05-0.14 mL/month 2 ], P < .001), and growth trajectories diverge between phenotypes in the presymptomatic time period., Conclusions: Measuring the volumetric changes in newly developing cerebral lesions across time can distinguish cerebral adrenoleukodystrophy phenotypes before symptom onset. When factored into the overall clinical presentation of a patient with a new brain lesion, quantitative MR imaging-based lesion volumetry may aid in the accurate prediction of patients eligible for therapy., (© 2021 by American Journal of Neuroradiology.)

White matter dysfunction and degeneration have been a topic of great interest in healthy and pathological aging. While ex vivo studies have investigated age-related changes in canines, little in vivo canine aging research exists. Quantitative diffusion MRI such as diffusion tensor imaging (DTI) has demonstrated aging and neurodegenerative white matter changes in humans. However, this method has not been applied and adapted in vivo to canine populations. This study aimed to test the hypothesis that white matter diffusion changes frequently reported in human aging are also found in aged canines. The study used Tract Based Spatial Statistics (TBSS) and a region of interest (ROI) approach to investigate age related changes in fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AxD) and radial diffusivity (RD). The results show that, compared to younger animals, aged canines have significant decreases in FA in parietal and temporal regions as well as the corpus callosum and fornix. Additionally, AxD decreases were observed in parietal, frontal, and midbrain regions. Similarly, an age- related increase in RD was observed in the right parietal lobe while MD decreases were found in the midbrain. These findings suggest that canine samples show commonalities with human brain aging as both exhibit similar white matter diffusion tensor changes with increasing age., (Copyright © 2021. Published by Elsevier Inc.)

Traumatic brain injury (TBI) is a major cause of morbidity and mortality in children; survivors experience long-term cognitive and motor deficits. To date, studies predicting outcome following pediatric TBI have primarily focused on acute behavioral responses and proxy measures of injury severity; unsurprisingly, these measures explain very little of the variance following heterogenous injury. In adults, certain acute imaging biomarkers help predict cognitive and motor recovery following moderate to severe TBI. This multi-center, retrospective study, characterizes the day-of-injury computed tomographic (CT) reports of pediatric, adolescent, and young adult patients (2 months to 21 years old) who received inpatient rehabilitation services for TBI ( n  = 247). The study also determines the prognostic utility of CT findings for cognitive and motor outcomes assessed by the Pediatric Functional Independence Measure, converted to age-appropriate developmental functional quotient (DFQ), at discharge from rehabilitation. Subdural hematomas (66%), contusions (63%), and subarachnoid hemorrhages (59%) were the most common lesions; the majority of subjects had less severe Rotterdam CT scores (88%, ≤ 3). After controlling for age, gender, mechanism of injury, length of acute hospital stay, and admission DFQ in multivariate regression analyses, the highest Rotterdam score (β = -25.2, p  < 0.01) and complete cisternal effacement (β = -19.4, p  < 0.05) were associated with lower motor DFQ, and intraventricular hemorrhage was associated with lower motor (β = -3.7, p  < 0.05) and cognitive DFQ (β = -4.9, p  < 0.05). These results suggest that direct detection of intracranial injury provides valuable information to aid in prediction of recovery after pediatric TBI, and needs to be accounted for in future studies of prognosis and intervention.

Head trauma is a frequent indication for cranial imaging in children. The majority of accidental pediatric head trauma is minor and sustained without intracranial injury. Well-validated pediatric-specific clinical decision guidelines should be used to identify very low-risk children who can safely forgo imaging. In those who require acute imaging, CT is considered the first-line imaging modality for suspected intracranial injury because of the short duration of the examination and its high sensitivity for acute hemorrhage. MRI can accurately detect traumatic complications, but often necessitates sedation in children, owing to the examination length and motion sensitivity, which limits rapid assessment. There is a paucity of literature regarding vascular injuries in pediatric blunt head trauma and imaging is typically guided by clinical suspicion. Advanced imaging techniques have the potential to identify changes that are not seen by standard imaging, but data are currently insufficient to support routine clinical use. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment., (Copyright © 2020 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

While the diagnosis of traumatic brain injury (TBI) is a clinical decision, neuroimaging remains vital for guiding management on the basis of identification of intracranial pathologic conditions. CT is the mainstay of imaging of acute TBI for both initial triage and follow-up, as it is fast and accurate in detecting both primary and secondary injuries that require neurosurgical intervention. MRI is more sensitive for the detection of certain intracranial injuries (eg, axonal injuries) and blood products 24-48 hours after injury, but it has limitations (eg, speed, accessibility, sensitivity to motion, and cost). The evidence primarily supports the use of MRI when CT findings are normal and there are persistent unexplained neurologic findings or at subacute and chronic periods. Radiologists should understand the role and optimal imaging modality to use, in addition to patterns of primary brain injury and their influence on the risk of developing secondary brain injuries related to herniation. © RSNA, 2019 See discussion on this article by Mathur and Nicolaou.

Objective: Statistical challenges exist when using diffusion tensor imaging (DTI) to assess traumatic axonal injury (TAI) in individual concussed athletes. The authors examined active professional American football players over a 6-year time period to study potential TAI after concussion and assess optimal methods to analyze DTI at the individual level., Methods: Active American professional football players recruited prospectively were assessed with DTI, conventional MRI, and standard clinical workup. Subjects underwent an optional preseason baseline scan and were asked to undergo a scan within 5 days of concussion during gameplay. DTI from 25 age- and sex-matched controls were obtained. Both semiautomated region-of-interest analysis and fully automated tract-based spatial statistics (TBSS) were used to examine DTI at individual and group levels. Statistical differences were assessed comparing individual DTI data to baseline imaging versus a normative database. Group-level comparisons were also performed to determine if longer exposure to professional-level play or prior concussion cause white matter microstructural integrity changes., Results: Forty-nine active professional football players were recruited into the study. Of the 49 players, 7 were assessed at baseline during the preseason and after acute concussion. An additional 18 players were assessed after acute concussion only. An additional 24 players had only preseason baseline assessments. The results suggest DTI is more sensitive to suspected TAI than conventional MRI, given that 4 players demonstrated decreased fractional anisotropy (FA) in multiple tracts despite normal conventional MRI. Furthermore, the data suggest individual assessment of DTI data using baseline premorbid imaging is more sensitive than typical methods of comparing data to a normative control group. Among all subjects with baseline data, 1 reduced FA tract (± 2.5 standard deviations) was found using the typical normative database reference versus 10 statistically significant (p < 0.05) reduced FA tracts when referencing internal control baseline data. All group-level comparisons were statistically insignificant (p > 0.05)., Conclusions: Baseline premorbid DTI data for individual DTI analysis provides increased statistical sensitivity. Specificity using baseline imaging also increases because numerous potential etiologies for reduced FA may exist prior to a concussion. These data suggest that there is a high potential for false-positive and false-negative assessment of DTI data using typical methods of comparing an individual to normative groups given the variability of FA values in the normal population.

Objective: The authors tested the feasibility of magnetic resonance-guided focused ultrasound (MRgFUS) ablation of mesial temporal lobe epilepsy (MTLE) seizure circuits. Up to one-third of patients with mesial temporal sclerosis (MTS) suffer from medically refractory epilepsy requiring surgery. Because current options such as open resection, laser ablation, and Gamma Knife radiosurgery pose potential risks, such as infection, hemorrhage, and ionizing radiation, and because they often produce visual or neuropsychological deficits, the authors developed a noninvasive MRgFUS ablation strategy for mesial temporal disconnection to mitigate these risks., Methods: The authors retrospectively reviewed 3-T MRI scans obtained with diffusion tensor imaging (DTI). The study group included 10 patients with essential tremor (ET) who underwent pretreatment CT and MRI prior to MRgFUS, and 2 patients with MTS who underwent MRI. Fiber tracking of the fornix-fimbria pathway and inferior optic radiations was performed, ablation sites mimicking targets of open posterior hippocampal disconnection were modeled, and theoretical MRgFUS surgical plans were devised. Distances between the targets and optic radiations were measured, helmet angulations were prescribed, and the numbers of available MRgFUS array elements were calculated., Results: Tractograms of fornix-fimbria and optic radiations were generated in all ET and MTS patients successfully. Of the 10 patients with both the CT and MRI data necessary for the analysis, 8 patients had adequate elements available to target the ablation site. A margin (mean 8.5 mm, range 6.5-9.8 mm) of separation was maintained between the target lesion and optic radiations., Conclusions: MRgFUS offers a noninvasive option for seizure tract disruption. DTI identifies fornix-fimbria and optic radiations to localize optimal ablation targets and critical surrounding structures, minimizing risk of postoperative visual field deficits. This theoretical modeling study provides the necessary groundwork for future clinical trials to apply this novel neurosurgical technique to patients with refractory MTLE and surgical contraindications, multiple prior surgeries, or other factors favoring noninvasive treatment.

Mild traumatic brain injury (mTBI) affects about 42 million people worldwide. It is often associated with headache, cognitive deficits, and balance difficulties but rarely shows any abnormalities on conventional computed tomography (CT) or magnetic resonance imaging (MRI). Although in most mTBI patients the symptoms resolve within 3 months, 10-15% of patients continue to exhibit symptoms beyond a year. Also, it is known that there exists a vulnerable period post-injury, when a second injury may exacerbate clinical prognosis. Identifying this vulnerable period may be critical for patient outcome, but very little is known about the neural underpinnings of mTBI and its recovery. In this work, we used advanced functional neuroimaging to study longitudinal changes in functional organization of the brain during the 3-month recovery period post-mTBI. Fractional amplitude of low frequency fluctuations (fALFF) measured from resting state functional MRI (rs-fMRI) was found to be associated with symptom severity score (SSS, r = -0.28, p = 0.002). Decreased fALFF was observed in specific functional networks for patients with higher SSS, and fALFF returned to higher values when the patient recovered (lower SSS). In addition, functional connectivity of the same networks was found to be associated with concurrent SSS, and connectivity immediately after injury (<10 days) was capable of predicting SSS at a later time-point (3 weeks to 3 months, p < 0.05). Specific networks including motor, default-mode, and visual networks were found to be associated with SSS (p < 0.001), and connectivity between these networks predicted 3-month clinical outcome (motor and visual: p < 0.001, default-mode: p < 0.006). Our results suggest that functional connectivity in these networks comprise potential biomarkers for predicting mTBI recovery profiles and clinical outcome.

Purpose: Diffusion tensor imaging (DTI) and quantitative susceptibility mapping (QSM) have been proposed as methods to aid in the diagnosis of amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS), both diseases affecting upper motor neurons. We test the performance of DTI and QSM alone and in combination to distinguish patients with diseases affecting upper motor neurons (ALS/PLS) from patients with other motor symptom-predominant neurologic disorders., Methods: 3.0 Tesla MRI with DTI and QSM in patients referred to a subspecialty neurology clinic for evaluation of motor symptom-predominant neurologic disorders were retrospectively reviewed. Corticospinal tract fractional anisotropy and maximum motor cortex susceptibility were measured. Subjects were categorized by diagnosis and imaging metrics were compared between groups using Student's t-tests. Receiver operating characteristic curves were generated for imaging metrics alone and in combination., Results: MRI scans for 43 patients with ALS or PLS and 15 patients with motor symptom predominant, non-upper motor neuron disease (mimics) were reviewed. Fractional anisotropy was lower (0.57 vs. 0.60, p < 0.01) and maximum motor cortex magnetic susceptibility higher (64.4 vs. 52.7, p = 0.01) in patients with ALS/PLS compared to mimics. There was no significant difference in area under the curve for these metrics alone (0.73, 0.63; p > 0.05) or in combination (0.75; p > 0.05)., Conclusion: We found significant differences in DTI and QSM metrics in patients with diseases affecting upper motor neurons (ALS/PLS) compared to mimics, but no significant difference in the performance of these metrics in diagnosing ALS/PLS compared to mimics., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Background: Uncertainty continues to surround mild traumatic brain injury (mTBI) diagnosis, symptoms, prognosis, and outcome due in part to a lack of objective biomarkers of injury and recovery. As mTBI gains recognition as a serious public health epidemic, there is need to identify risk factors, diagnostic tools, and imaging biomarkers to help guide diagnosis and management. Methods: One hundred and eleven patients (15-50 years old) were enrolled acutely after mTBI and followed with up to four standardized serial assessments over 3 months. Each encounter included a clinical exam, neuropsychological assessment, and magnetic resonance imaging (MRI). Chi-square and linear mixed models were used to assess changes over time and determine potential biomarkers of mTBI severity and outcome. Results: The symptoms most frequently endorsed after mTBI were headache (91%), not feeling right (89%), fatigue (86%), and feeling slowed down (84%). Of the 104 mTBI patients with a processed MRI scan, 28 (27%) subjects had white matter changes which were deemed unrelated to age, and 26 of these findings were deemed unrelated to acute trauma. Of the neuropsychological assessments tested, 5- and 6-Digit Backward Recall, the modified Balance Error Scoring System (BESS), and Immediate 5-Word Recall significantly improved longitudinally in mTBI subjects and differentiated between mTBI subjects and controls. Female sex was found to increase symptom severity scores (SSS) at every time point. Age ≥ 25 years was correlated with increased SSS. Subjects aged ≥ 25 also did not improve longitudinally on 5-Digit Backward Recall, Immediate 5-Word Recall, or Single-Leg Stance of the BESS, whereas subjects < 25 years improved significantly. Patients who reported personal history of depression, anxiety, or other psychiatric disorder had higher SSS at each time point. Conclusions: The results of this study show that 5- and 6-Digit Backward Recall, the modified BESS, and Immediate 5-Word Recall should be considered useful in demonstrating cognitive and vestibular improvement during the mTBI recovery process. Clinicians should take female sex, older age, and history of psychiatric disorder into account when managing mTBI patients. Further study is necessary to determine the true prevalence of white matter changes in people with mTBI.

Both the size and location of injury in the brain influences the type and severity of cognitive or sensorimotor dysfunction. However, even with advances in MR imaging and analysis, the correspondence between lesion location and clinical deficit remains poorly understood. Here, structural and diffusion images from 14 healthy subjects are used to create spatially unbiased white matter connectivity importance maps that quantify the amount of disruption to the overall brain network that would be incurred if that region were compromised. Some regions in the white matter that were identified as highly important by such maps have been implicated in strategic infarct dementia and linked to various attention tasks in previous studies. Validation of the maps is performed by investigating the correlations of the importance maps' predicted cognitive deficits in a group of 15 traumatic brain injury patients with their cognitive test scores measuring attention and memory. While no correlation was found between amount of white matter injury and cognitive test scores, significant correlations (r>0.68, p<0.006) were found when including location information contained in the importance maps. These tools could be used by physicians to improve surgical planning, diagnosis, and assessment of disease severity in a variety of pathologies like multiple sclerosis, trauma, and stroke., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Mild traumatic brain injury (mTBI) remains a challenge to accurately assess with conventional neuroimaging. Recent research holds out the promise that diffusion tensor imaging (DTI) can be used to predict recovery in mTBI patients. Unlike computed tomography or conventional magnetic resonance imaging, DTI is sensitive to microstructural axonal injury, the neuropathology that is thought to be most responsible for the persistent cognitive and behavioral impairments that often occur after mTBI. Through the use of newer DTI analysis techniques such as automated region of interest analysis, tract-based voxel-wise analysis, and quantitative tractography, researchers have shown that frontal and temporal association white matter pathways are most frequently damaged in mTBI and that the microstructural integrity of these tracts correlates with behavioral and cognitive measures. Future longitudinal DTI studies are needed to elucidate how symptoms and the microstructural pathology evolve over time. Moving forward, large-scale investigations will ascertain whether DTI can serve as a predictive imaging biomarker for long-term neurocognitive deficits after mTBI that would be of value for triaging patients to clinical trials of experimental cognitive enhancement therapies and rehabilitation methods, as well as for monitoring their response to these interventions.

Our goal was to determine whether performance variability during predictive visual tracking can provide a screening measure for mild traumatic brain injury (mTBI). Seventeen subjects with chronic postconcussive syndrome and 9 healthy control subjects were included in this study. Eye movements were recorded with video-oculography as the subject visually tracked a target that moved through a circular trajectory. We compared the variability of gaze positional errors relative to the target with the microstructural integrity of white matter tracts as measured by the fractional anisotropy (FA) parameter of diffusion tensor imaging. Gaze error variability was significantly correlated with the mean FA values of the right anterior corona radiata (ACR) and the left superior cerebellar peduncle, tracts that support spatial processing and sustenance of attention, and the genu of the corpus callosum. Because the ACR and the genu are among the most frequently damaged white matter tracts in mTBI, the correlations imply that gaze error variability during visual tracking may provide a useful screening tool for mTBI. Gaze error variability was also significantly correlated with attention and working memory measures in neurocognitive testing; thus, measurement of visual tracking performance is promising as a fast and practical screening tool for mTBI.

Memory and attentional control impairments are the two most common forms of dysfunction following mild traumatic brain injury (TBI) and lead to significant morbidity in patients, yet these functions are thought to be supported by different brain networks. This 3 T magnetic resonance diffusion tensor imaging (DTI) study investigates whether microstructural integrity of white matter, as measured by fractional anisotropy (FA) within a small set of individually localized regions of interest (ROIs), is associated with these cognitive domains in normal adults and adults with mild TBI. Results in a sample of 23 normal controls reveal a significant correlation between attentional control and FA within a ROI in the left hemisphere anterior corona radiata. Furthermore, the controls demonstrate a correlation between memory performance and FA in a ROI placed in the uncinate fasciculus. Next, to examine whether these relationships are found in the pathological ranges of attention, memory and microstructural white matter integrity associated with mild TBI, these analyses were applied to a group of 43 mild TBI patients. Results, which generally demonstrated a wider range of attention, memory and FA scores, replicated the correlation between attentional control and FA in left hemisphere anterior corona radiata, as well as the correlation between memory performance and FA in the uncinate fasciculus. These two sets of brain-behaviour relationships were highly specific, as shown by a lack of correlation between attention and uncinate fasciculus FA and the lack of correlation between memory performance and anterior corona radiata FA. Furthermore, a 'correlational double dissociation' was demonstrated to exist between two distinct frontal structures independently associated with attention and memory, respectively, via a series of multiple regression analyses in both normal controls and adults with mild TBI. The results of the multiple regression analyses provide direct evidence that tract-specific variation in microstructural white matter integrity among normal controls and among mild TBI patients can account for much of the variation in performance in specific cognitive domains. More generally, such findings suggest that diffusion anisotropy measurement can be used as a quantitative biomarker for neurocognitive function and dysfunction.

The role of gray matter function and structure in mathematical cognition has been well researched. Comparatively little is known about white matter microstructures associated with mathematical abilities. Diffusion tensor imaging data from 13 children (7-9 years) and two measures of their mathematical competence were collected. Relationships between children's mathematical competence and fractional anisotropy were found in two left hemisphere white matter regions. Although the superior corona radiata was found to be associated with both numerical operations and mathematical reasoning, the inferior longitudinal fasciculus was correlated with numerical operations specifically. These findings suggest a role for microstructure in left white matter tracts for the development of mathematical skills. Moreover, the findings point to the involvement of different white matter tracts for numerical operations and mathematical reasoning.

Background and Purpose: Diffusion tensor imaging (DTI) may be a useful index of microstructural changes implicated in diffuse axonal injury (DAI) linked to persistent postconcussive symptoms, especially in mild traumatic brain injury (TBI), for which conventional MR imaging techniques may lack sensitivity. We hypothesized that for mild TBI, DTI measures of DAI would correlate with impairments in reaction time, whereas the number of focal lesions on conventional 3T MR imaging would not., Materials and Methods: Thirty-four adult patients with mild TBI with persistent symptoms were assessed for DAI by quantifying traumatic microhemorrhages detected on a conventional set of T2*-weighted gradient-echo images and by DTI measures of fractional anisotropy (FA) within a set of a priori regions of interest. FA values 2.5 SDs below the region average, based on a group of 26 healthy control adults, were coded as exhibiting DAI., Results: DTI measures revealed several predominant regions of damage including the anterior corona radiata (41% of the patients), uncinate fasciculus (29%), genu of the corpus callosum (21%), inferior longitudinal fasciculus (21%), and cingulum bundle (18%). The number of damaged white matter structures as quantified by DTI was significantly correlated with mean reaction time on a simple cognitive task (r = 0.49, P = .012). In contradistinction, the number of traumatic microhemorrhages was uncorrelated with reaction time (r = -0.08, P = .71)., Conclusion: Microstructural white matter lesions detected by DTI correlate with persistent cognitive deficits in mild TBI, even in populations in which conventional measures do not. DTI measures may thus contribute additional diagnostic information related to DAI.

Reproducible Objective Quantification Scheme (ROQS) is a novel method for regional white matter measurements of diffusion tensor imaging (DTI) parameters that overcomes the limitations of previous approaches for analyzing large cohorts of subjects reliably. ROQS is a semi-automated technique that exploits the fiber orientation information from the diffusion tensor in conjunction with a binary masking and chain-linking algorithm to segment anatomically distinct white matter tracts for subsequent quantitative analysis of DTI parameters such as fractional anisotropy and apparent diffusion coefficient. When applied to 3-T whole-brain DTI of normal adult volunteers, ROQS is shown to segment the corpus callosum much faster than manual region of interest (ROI) delineation, and with better reproducibility and accuracy.

Diffusion tensor imaging (DTI) was used to investigate the association between variation in white matter microstructure and individual differences in reading skill within children. Unlike previous DTI studies of reading, our sample examined children in both the average reading range as well as several children in the performance range of reading disability (RD). Results replicate previous findings of a strong correlation between fractional anisotropy (FA) values in a left temporo-parietal white matter region and standardized reading scores of typically developing children. Furthermore, FA values in this same region accounted for differences between children scoring in the average range and children scoring in the RD range, suggesting that the role of white matter tract microstructure is best characterized as an extreme range on a continuum of typical variation. Furthermore, significant correlations between working memory and frontal white matter tract regions were present in this same population, yet were demonstrated to be independent of the relationships found between reading and more posterior regions. Results form a "correlational double dissociation" that demonstrates domain specificity in the influence of white matter tract structures to individual differences in cognitive performance.