Diffusion Tensor Imaging Findings Research Articles

Correlation Between DTI Findings and Volume of Corpus Callosum in Children with AUTISM.

Autism Spectrum Disorder (ASD) is a complex developmental disorder in which neurological basis is largely unknown. The Corpus Callosum (CC) is the main commissure that connects the cerebral hemispheres. Previous evidence suggests the involvement of the CC in the pathophysiology of autism. The aim of our study is to assess whether there were any changes in Corpus Callosum (CC) area and volume and to reveal the relationship between Diffusion Tensor Imaging (DTI) features in genu and splenium of corpus callosum in children with ASD. Eighteen patient and 15 controls were recruited. The volumetric sagittal TI images were used to provide measurements of midsagittal corpus callosum surface area while FA, MD, RD, and ADC values were extracted from genu and splenium of corpus callosum after which the correlation in the area and volume in ASD children was examined. CC area and volume in children with ASD were decreased than controls. FA values obtained from the genu and splenum of CC were significantly lower and RD values were significantly higher. A positive correlation was observed between the FA of the genu and splenium and area and volume of the CC. There was a negative correlation between ADC, MD and RD of CC and area and volume measurements. The conclusions in the interrelations of morphometric and DTI data may demonstrate a likelihood of damages in the axons and cortical neurons. The results showed that there existed microstructural damages from the DTI findings. Furthermore, the decrease in FA could be a representation of the reduction in the myelination in nerve pathways, impaired integrity, reduced axonal density, and organization. Indeed, the changes in volumetric and microstructural of CC could be useful in evaluating underlying pathophysiology in children with autism.

Multiple sclerosis and depressive manifestations: can diffusion tensor MR imaging help in the detection of microstructural white matter changes?

BackgroundMultiple sclerosis is one of the commonest causes of neurological disability in middle-aged and young adults. Depression in MS patients can compromise cognitive functions, lead to suicide attempts, impair relationships and reduce compliance with disease-modifying treatments. The aim of this study was to investigate and compare the microstructural changes in the white matter tracts of the limbic system in MS patients with and those without depressive manifestations using a diffusion tensor imaging (DTI) technique.MethodsThis study included 40 patients who were divided into three groups. Group 1 comprised of 20 patients with relapsing-remitting MS with depressive symptoms and group 2 comprised 10 MS patients without symptoms of depression. The third group is a control group that included 10 age-matched healthy individuals. All patients underwent conventional MRI examinations and DTI to compare the fractional anisotropy (FA) values in the white matter tracts of the limbic system.ResultsWe compared the DTI findings in MS patients with and those without depressive symptoms. It was found that patients with depression and MS exhibited a significant reduction in the FA values of the cingulum (P < 0.0111 on the right and P < 0.0142 on the left), uncinate fasciculus (P < 0.0001 on the right and P < 0.0076 on the left) and the fornix (P < 0.0001 on both sides). No significant difference was found between the FA values of the anterior thalamic radiations in both groups.ConclusionPatients with depression and MS showed more pronounced microstructural damage in the major white matter connections of the limbic pathway, namely, the uncinate fasciculus, cingulum and fornix. These changes can be detected by DTI as decreased FA values in depressed MS patients compared to those in non-depressed patients.

Pre- and Post-therapy Assessment of Clinical Outcomes and White Matter Integrity in Autism Spectrum Disorder: Pilot Study.

Objective: This pilot study aims to identify white matter (WM) tract abnormalities in Autism Spectrum Disorders (ASD) toddlers and pre-schoolers by Diffusion Tensor Imaging (DTI), and to correlate imaging findings with clinical improvement after early interventional and Applied Behavior Analysis (ABA) therapies by Verbal Behavior Milestones Assessment and Placement Program (VB-MAPP).Methods: DTI scans were performed on 17 ASD toddlers/pre-schoolers and seven age-matched controls. Nine ASD patients had follow-up MRI 12 months following early intervention and ABA therapy. VB-MAPP was assessed and compared at diagnosis, 6 and 12 months after therapies. Tract-Based Spatial Statistics (TBSS) was used to measure fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial (RD) diffusivity.Results: VB-MAPP scores improved at 6 and 12 months after early intervention and ABA therapy compared to scores at baseline. TBSS analysis showed significant FA decrease and/or RD increase in ASD patients before therapy vs. controls in inferior fronto-occipital fasciculi, uncinate fasciculi, left superior fronto-occipital fasciculus, forceps minor, left superior fronto-occipital fasciculus, right superior longitudinal fasciculus, corona radiate bilaterally, and left external capsule. A significantly FA increase in 21 tracts and ROIs is reported in post- vs. pre-therapy DTI analysis.Conclusion: DTI findings highlighted ASD patient WM abnormalities at diagnosis and confirmed the benefits of 12 months of early intervention and ABA therapy on clinical and neuro imaging outcomes.

B-58 Post-traumatic Stress Symptoms Are Associated with Worse Neuropsychological Functioning, but not Diffusion Tensor Imaging Findings, in Military Service Members Following Mild Traumatic Brain Injury.

Abstract Objective The purpose of this study was to examine neurobehavioral and neurocognitive functioning, and white matter integrity (using Diffusion Tensor Imaging [DTI]), in service members with versus without PTSD following mild traumatic brain injury (MTBI). Method Participants were 101 U.S. military service members who had sustained an uncomplicated MTBI (n = 80) or an injury without TBI (i.e., Injured Control [IC], n = 21) prospectively enrolled from the Walter Reed National Military Medical Center (Bethesda, Maryland). Participants completed a battery of neuropsychological tests, as well as DTI of the brain, on average 4-years post-injury. Measures of FA, MD, AD, and RD were generated for 18 regions of interest [ROIs]. Participants in the MTBI group were divided into two sub-groups based on DSM-IV-TR diagnostic criteria for PTSD: MTBI/PTSD-Present (n = 22) and MTBI/PTSD-Absent (n = 58). Results The MTBI/PTSD-Present group reported a significantly higher number of postconcussion symptoms, had higher scores on the majority of MMPI-2-RF scales, and had worse scores on the vast majority of cognitive domains (i.e., Attention, Processing Speed, Immediate Memory, Delayed Memory, Executive Functioning, Visuospatial Ability) compared to both the MTBI/PTSD-Absent group (all p’s &lt; .05) and IC/PTSD-Absent group (all p’s &lt; .05). For the DTI variables, there were no significant group differences for all DTI measures in all regions of the brain, with the exception of a handful of measures (i.e., right cingulum–cingulate gyrus, and bilaterally in the corticospinal tract). Conclusion These results provide support for a (a) strong relationship between PTSD and poor neurobehavioral and neurocognitive outcome following MTBI, and (b) weak relationship between PTSD and white matter integrity following MTBI.

Structural and Diffusion MRI Analyses With Histological Observations in Patients With Lissencephaly.

The development of cortical convolutions, gyri and sulci, is a complex process that takes place during prenatal development. Lissencephaly, a rare genetic condition characterized by the lack of cortical convolutions, offers a model to look into biological processes that lead to the development of convolutions. Retrospective, qualitative, and quantitative analyses of structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) were performed in patients with lissencephaly (N = 10) and age-/sex-matched controls (N = 10). In order to identify microstructural correlates of structural MRI and DTI findings, postmortem brains of patients with lissencephaly (N = 4) and age-matched controls (N = 4) were also examined with histology. Patients with lissencephaly had significantly smaller gyrification index and volumes of hemispheric white and gray matter, compared to the age-/sex-matched control group. However, there was no significant difference between groups in the subcortical gray matter volumes. Although the majority of patients with lissencephaly had a preserved normal-like appearance of major fissures and primary sulci, the spatial distribution of agyric cortical regions was different in patients with lissencephaly-1 (LIS1) and doublecortin (DCX) mutations. Lastly, in patients with lissencephaly, the spatiotemporal distribution of projection pathways was preserved while short- to medium-range cortico-cortical pathways were absent or fewer in number. Our results indicate that in the patients with lissencephaly cortical system is affected more than the subcortical one.

Diffusion Tensor Imaging in Preclinical and Human Studies of Huntington's Disease: What Have we Learned so Far?

Huntington's Disease is an irreversible neurodegenerative disease characterized by the progressive deterioration of specific brain nerve cells. The current evaluation of cellular and physiological events in patients with HD relies on the development of transgenic animal models. To explore such events in vivo, diffusion tensor imaging has been developed to examine the early macro and microstructural changes in brain tissue. However, the gap in diffusion tensor imaging findings between animal models and clinical studies and the lack of microstructural confirmation by histological methods has questioned the validity of this method. This review explores white and grey matter ultrastructural changes associated to diffusion tensor imaging, as well as similarities and differences between preclinical and clinical Huntington's Disease studies. A comprehensive review of the literature using online-resources was performed (Pub- Med search). Similar changes in fractional anisotropy as well as axial, radial and mean diffusivities were observed in white matter tracts across clinical and animal studies. However, comparative diffusion alterations in different grey matter structures were inconsistent between clinical and animal studies. Diffusion tensor imaging can be related to specific structural anomalies in specific cellular populations. However, some differences between animal and clinical studies could derive from the contrasting neuroanatomy or connectivity across species. Such differences should be considered before generalizing preclinical results into the clinical practice. Moreover, current limitations of this technique to accurately represent complex multicellular events at the single micro scale are real. Future work applying complex diffusion models should be considered.

Diffusion Tensor Imaging of Brain Malformations

Diffusion tensor imaging (DTI) is an advanced MR imaging technique that provides noninvasive qualitative and quantitative information about the white matter microarchitecture. By measuring the three-dimensional directional characteristics of water molecule diffusion/mobility, DTI generates unique tissue contrasts that are used to study the axonal organization of the central nervous system. Its applications include quantitative evaluation of the brain connectivity, development, and white matter diseases. This article reviews DTI and fiber tractography findings in several brain malformations and highlights the added value of DTI and fiber tractography compared with conventional MR imaging.

Disrupted White Matter Microstructure of the Cerebellar Peduncles in Scholastic Athletes After Concussion.

Concussion, or mild traumatic brain injury (mTBI), is a major public health concern, linked with persistent post-concussive syndrome, and chronic traumatic encephalopathy. At present, standard clinical imaging fails to reliably detect traumatic axonal injury associated with concussion and post-concussive symptoms. Diffusion tensor imaging (DTI) is an MR imaging technique that is sensitive to changes in white matter microstructure. Prior studies using DTI did not jointly investigate white matter microstructure in athletes, a population at high risk for concussive and subconcussive head traumas, with those in typical emergency room (ER) patients. In this study, we determine DTI scalar metrics in both ER patients and scholastic athletes who suffered concussions and compared them to those in age-matched healthy controls. In the early subacute post-concussion period, athletes demonstrated an elevated rate of regional decreases in axial diffusivity (AD) compared to controls. These regional decreases of AD were especially pronounced in the cerebellar peduncles, and were more frequent in athletes compared to the ER patient sample. The group differences may indicate differences in the mechanisms of the concussive impacts as well as possible compound effects of cumulative subconcussive impacts in athletes. The prevalence of white matter abnormality in cerebellar tracts lends credence to the hypothesis that post-concussive symptoms are caused by shearing of axons within an attention network mediated by the cerebellum, and warrant further study of the correlation between cerebellar DTI findings and clinical, neurocognitive, oculomotor, and vestibular outcomes in mTBI patients.

Perivascular space fluid contributes to diffusion tensor imaging changes in white matter

Diffusion tensor imaging (DTI) has been extensively used to map changes in brain tissue related to neurological disorders. Among the most widespread DTI findings are increased mean diffusivity and decreased fractional anisotropy of white matter tissue in neurodegenerative diseases. Here we utilize multi-shell diffusion imaging to separate diffusion signal of the brain parenchyma from non-parenchymal fluid within the white matter. We show that unincorporated anisotropic water in perivascular space (PVS) significantly, and systematically, biases DTI measures, casting new light on the biological validity of many previously reported findings. Despite the challenge this poses for interpreting these past findings, our results suggest that multi-shell diffusion MRI provides a new opportunity for incorporating the PVS contribution, ultimately strengthening the clinical and scientific value of diffusion MRI.

Correlation of Preoperative Cranial Nerve Diffusion Tensor Tractography with Intraoperative Findings in Surgery of Cerebellopontine Angle Tumors

Imaging to visualize nerves around tumors preoperatively could help the surgeon to plan the surgery and excise the tumor with preservation or improvement in patients' quality of life. In the present prospective study, we attempted to correlate the preoperative cranial nerves (i.e., trigeminal, abducens, facial, and vestibulocochlear diffusion tensor tractography and anatomic magnetic resonance imaging [MRI] findings) with intraoperative findings during cerebellopontine angle (CPA) tumor surgery. The 40 enrolled patients had CPA tumors (31 vestibular schwannomas, 5 epidermoid tumors, 2 meningiomas, 2 trigeminal schwannomas). All the patients were undergoing microsurgery for the first time. They underwent preoperative MRI for anatomic and diffusion tensor imaging (DTI) data. The imaging series were postprocessed, and 3-dimensional images were obtained. The location of the involved nerves around the tumors was recorded during surgery by the senior surgeon, who was kept unaware of the results of the fiber tracking, and a correlation was performed. We evaluated the correlation between the DTI and intraoperative findings for the nerve location in relation to the tumor in the CPA. The correlation between the DTI and intraoperative findings for the facial, trigeminal, and vestibulocochlear nerves was 85% (34 of 40), 85% (34 of 40), and 75% (12 of 16), respectively. The modified technical parameters proposed could lead to better preservation of cranial nerve function, especially for patients with large tumors. To the best of our knowledge, the present study is the first systematic study of relevant cranial nerves in 40 patients with demonstration of the vestibulocochlear bundle by preoperative MRI in the most common CPA tumors using advanced MRI sequences such as diffusion tensor tractography and capturing the data in a multiplanar format.

Isolated cerebrospinal fluid hypertension in chronic headache: diagnostic innovations and clinical implications.

Isolated cerebrospinal fluid hypertension (ICH) is a condition of increased cerebrospinal fluid (CSF) pressure in the cranial-spinal compartment without an identifiable cause. Isolated headache is the most common symptom of ICH, while missing may be signs such as papilledema or sixth nerve palsy. This fact makes difficult the clinical diagnosis of headache attributable to ICH in headache sufferers. Another source of confusion stems from the CSF pressure measurement. It has been observed that a single-spot CSF opening pressure measurement may be insufficient to identify elevated CSF pressure in headache sufferers. A new method of CSF pressure measurement has been able to identify pressure-related features of isolated CSF hypertension (ICH). In fact, nocturnal or postural headache and abnormal pressure pulsations are the more common pressure-related features of ICH in patients with chronic headache. The compressive action of these abnormal pressure pulsations causes the periventricular white matter microstructure alterations leading to the focal diffusion tensor imaging findings in patients with ICH. Abnormal pressure pulsations are a marker of ICH in chronic headache. The identification of the CSF pressure-related features may be useful for differentiating headache sufferers with ICH from those with primary headache disorder in clinical practice. The therapeutic strategy in these headache sufferers with ICH includes the CSF removal and a medical treatment.

Postconcussion symptom reporting is not associated with diffusion tensor imaging findings in the subacute to chronic phase of recovery in military service members following mild traumatic brain injury

ABSTRACTIntroduction: The purpose of this study was to examine the relation between white matter integrity of the brain and postconcussion symptom reporting following mild traumatic brain injury (MTBI).Method: Participants were 109 U.S. military service members (91.7% male) who had sustained a MTBI (n = 88) or orthopedic injury without TBI (trauma controls, TC, n = 21), enrolled from the Walter Reed National Military Medical Center, Bethesda, Maryland. Participants completed a battery of neurobehavioral symptom measures and underwent diffusion tensor imaging (DTI; General Electric 3T) of the whole brain, on average 44.9 months post injury (SD = 42.3). Measures of fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were generated for 18 regions of interest (ROIs). Participants in the MTBI group were divided into two subgroups based on International Classification of Diseases–10th Revision (ICD–10) Category C criteria for postconcussion syndrome (PCS): PCS-present (n = 41) and PCS-absent (n = 47).Results: The PCS-present group had significantly worse scores on all 13 neurobehavioral measures than the PCS-absent group (p < .001, d = 0.87–2.50) and TC group (p < .003, d = 0.84–2.06). For all ROIs, there were no significant main effects across the three groups for FA, MD, AD, and RD (all ps >.03). Pairwise comparisons revealed no significant differences for all ROIs when using FA and RD, and only two significant pairwise differences were found between PCS-present and PCS-absent groups when using MD and AD [i.e., anterior thalamic radiation and cingulate gyrus (supracallosal) bundle].Conclusions: Consistent with past research, but not all studies, postconcussion symptom reporting was not associated with white matter integrity in the subacute to chronic phase of recovery following MTBI.

Role of the intact hemisphere in determining the rehabilitation potential in the acute period of ischemic stroke: a diffusion and perfusion model

The promising approaches to determining the rehabilitation potential of ischemic stroke (IS) patients include an assessment of the microstructural integrity of the brain matter by diffusion tensor imaging (DTI), the main indicator of which is fractional anisotropy (FA). The role of the intact hemisphere in the rehabilitation process after IS remains a controversial subject. The hypothesis for the investigation is that the development of a diffusion and perfusion model (DPM) based on the assessment of FA in combination with data on cerebral blood flow velocity (CBFV) and the impact of the focus will be able to predict the patients' neurological status by the end of the acute period of IS. Objective: to investigate the role of diffusion and perfusion characteristics of the intact hemisphere in determining the rehabilitation potential in the acute period of IS and to develop a prognostic DPM. Patients and methods. The investigation enrolled 100 patients with IS and 10 individuals in the control group. All the examinees underwent brain MRI. Perfusion-weighted sequence without bolus injection of a contrast agent was used to quantify CBFV in 10 areas according to the Alberta stroke program early CT score (ASPECTS). Values for FA in 10 areas of both hemispheres were calculated using DTI findings. Neurological and functional statuses were evaluated over time with the National Institute of Health Stroke Scale (NIHSS) and the modified Rankin scale. Results. The NIHSS score at discharge was associated with FA and CBFV in 4 and 6 of the 10 areas of the intact hemisphere, respectively. DPM for predicting the rehabilitation potential included the key parameters correlating with a discharge NIHSS score (in order of decreasing the significance): admission NIHSS value (r = 0.55; p < 0.001), the size of a focus (r = 0.42; p < 0.001), FA in the contralateral cingulum bundle FA (r = -0.28; p = 0.007), and CBFV in M2 white matter [r = -0.24; p = 0.025; R2 = 0.642; p(F) <0.001]. Conclusion. In addition to the NIHSS score at admission, the size of a focus, DPM values (FA in the contralateral cingulum bundle and CBFV in the white matter) allow prediction of the rehabilitation potential in IS.

Early neuropathological and neurobehavioral consequences of preterm birth in a rabbit model

Preterm birth is the most significant problem in contemporary obstetrics accounting for 5–18% of worldwide deliveries. Encephalopathy of prematurity encompasses the multifaceted diffuse brain injury resulting from preterm birth. Current animal models exploring the underlying pathophysiology of encephalopathy of prematurity employ significant insults to generate gross central nervous system abnormalities. To date the exclusive effect of prematurity was only studied in a non-human primate model. Therefore, we aimed to develop a representative encephalopathy of prematurity small animal model only dependent on preterm birth. Time mated New-Zealand white rabbit does were either delivered on 28 (pre-term) or 31 (term) postconceptional days by caesarean section. Neonatal rabbits underwent neurobehavioral evaluation on 32 days post conception and then were transcardially perfuse fixed. Neuropathological assessments for neuron and oligodendrocyte quantification, astrogliosis, apoptosis and cellular proliferation were performed. Lastly, ex-vivo high-resolution Magnetic Resonance Imaging was used to calculate T1 volumetric and Diffusion Tensor Imaging derived fractional anisotropy and mean diffusivity. Preterm birth was associated with a motoric (posture instability, abnormal gait and decreased locomotion) and partial sensory (less pain responsiveness and failing righting reflex) deficits that coincided with global lower neuron densities, less oligodendrocyte precursors, increased apoptosis and less proliferation. These region-specific histological changes corresponded with Magnetic Resonance Diffusion Tensor Imaging differences. The most significant differences were seen in the hippocampus, caudate nucleus and thalamus of the preterm rabbits. In conclusion this model of preterm birth, in the absence of any other contributory events, resulted in measurable neurobehavioral deficits with associated brain structural and Magnetic Resonance Diffusion Tensor Imaging findings.

Diffusion kurtosis imaging in mild traumatic brain injury and postconcussional syndrome.

Aims of this study were to investigate white matter (WM) and thalamus microstructure 72 hr and 3 months after mild traumatic brain injury (TBI) with diffusion kurtosis imaging (DKI) and diffusion tensor imaging (DTI), and to relate DKI and DTI findings to postconcussional syndrome (PCS). Twenty‐five patients (72 hr = 24; 3 months = 23) and 22 healthy controls were recruited, and DKI and DTI data were analyzed with Tract‐Based Spatial Statistics (TBSS) and a region‐of‐interest (ROI) approach. Patients were categorized into PCS or non‐PCS 3 months after injury according to the ICD‐10 research criteria for PCS. In TBSS analysis, significant differences between patients and controls were seen in WM, both in the acute stage and 3 months after injury. Fractional anisotropy (FA) reductions were more widespread than kurtosis fractional anisotropy (KFA) reductions in the acute stage, while KFA reductions were more widespread than the FA reductions at 3 months, indicating the complementary roles of DKI and DTI. When comparing patients with PCS (n = 9), without PCS (n = 16), and healthy controls, in the ROI analyses, no differences were found in the acute DKI and DTI metrics. However, near‐significant differences were observed for several DKI metrics obtained in WM and thalamus concurrently with symptom assessment (3 months after injury). Our findings indicate a combined utility of DKI and DTI in detecting WM microstructural alterations after mild TBI. Moreover, PCS may be associated with evolving alterations in brain microstructure, and DKI may be a promising tool to detect such changes.

Diffusion MRI abnormalities in adolescent rats given repeated mild traumatic brain injury.

ObjectiveMild traumatic brain injury (mTBI) is a serious health concern in the adolescent population. Repeated mTBI may result in more pronounced deficits, and has been associated with long‐term neurological consequences including neurodegeneration. As such, there is a critical need for the development of objective mTBI biomarkers to help guide medical management. Diffusion‐weighted imaging (DWI) is an advanced magnetic resonance imaging (MRI) technique that may detect brain abnormalities after mTBI. Diffusion tensor imaging (DTI) is the most commonly applied DWI method, and initial studies have reported DTI changes in mTBI patients. Furthermore, new DWI methods (e.g., track‐weighted imaging; TWI) are being developed that may also be sensitive to mTBIs, but remain to be comprehensively studied.MethodsThis study utilized the Awake Closed Head Injury (ACHI) model of mTBI to investigate changes in DTI and TWI following repeated mTBI in adolescent male and female rats. A total of four ACHI impacts, two/day over two consecutive days, were delivered beginning on postnatal day 25. At 1 day and 7 days postinjury, rats were euthanized and brains were collected for DWI analyses.ResultsRats given repeated mTBI displayed changes in fractional anisotropy and radial diffusivity (i.e., DTI measures), as well as track density (i.e., TWI).InterpretationThese findings are consistent with initial DTI findings in mTBI patients, suggest that TWI may complement DTI, support the utility of DWI measures as biomarkers in mTBI, and further validate the ACHI rat model of mTBI.

Disruption of neurite morphology parallels MS progression.

ObjectivesTo apply advanced diffusion MRI methods to the study of normal-appearing brain tissue in MS and examine their correlation with measures of clinical disability.MethodsA multi-compartment model of diffusion MRI called neurite orientation dispersion and density imaging (NODDI) was used to study 20 patients with relapsing-remitting MS (RRMS), 15 with secondary progressive MS (SPMS), and 20 healthy controls. Maps of NODDI were analyzed voxel-wise to assess the presence of abnormalities within the normal-appearing brain tissue and the association with disease severity. Standard diffusion tensor imaging (DTI) parameters were also computed for comparing the 2 techniques.ResultsPatients with MS showed reduced neurite density index (NDI) and increased orientation dispersion index (ODI) compared with controls in several brain areas (p < 0.05), with patients with SPMS having more widespread abnormalities. DTI indices were also sensitive to some changes. In addition, patients with SPMS showed reduced ODI in the thalamus and caudate nucleus. These abnormalities were associated with scores of disease severity (p < 0.05). The association with the MS functional composite score was higher in patients with SPMS compared with patients with RRMS.ConclusionsNODDI and DTI findings are largely overlapping. Nevertheless, NODDI helps interpret previous findings of increased anisotropy in the thalamus of patients with MS and are consistent with the degeneration of selective axon populations.

Recent advances in diffusion neuroimaging: applications in the developing preterm brain.

Measures obtained from diffusion-weighted imaging provide objective indices of white matter development and injury in the developing preterm brain. To date, diffusion tensor imaging (DTI) has been used widely, highlighting differences in fractional anisotropy (FA) and mean diffusivity (MD) between preterm infants at term and healthy term controls; altered white matter development associated with a number of perinatal risk factors; and correlations between FA values in the white matter in the neonatal period and subsequent neurodevelopmental outcome. Recent developments, including neurite orientation dispersion and density imaging (NODDI) and fixel-based analysis (FBA), enable white matter microstructure to be assessed in detail. Constrained spherical deconvolution (CSD) enables multiple fibre populations in an imaging voxel to be resolved and allows delineation of fibres that traverse regions of fibre-crossings, such as the arcuate fasciculus and cerebellar–cortical pathways. This review summarises DTI findings in the preterm brain and discusses initial findings in this population using CSD, NODDI, and FBA.

Diffusion tensor imaging findings of the median nerve before and after carpal tunnel corticosteroid injection in patients with carpal tunnel syndrome: a preliminary study.

Corticosteroid injections are a popular technique for carpal tunnel syndrome (CTS) treatment and are believed to provide rapid symptom relief. To use magnetic resonance diffusion tensor imaging (MR-DTI) to determine the association between diffusion values of the median nerve (MN) at several anatomic locations and symptom relief in patients with CTS following corticosteroid injection. MR-DTI was performed on 15 wrists of 12 patients with CTS before and two weeks after ultrasound-guided corticosteroid injections. We recorded the patients' clinical data including sex, age, side of injection, satisfaction, and symptom relief. Satisfaction and symptom relief were rated using a Likert scale and the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scale. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the MN at the levels of the distal radioulnar joint (DRUJ), pisiform bone, and hamate bone were determined. All patients had ≥50% satisfaction on the injection side. In comparison with baseline values, post-injection ADC was significantly lower ( P = 0.001) but FA was not significantly higher ( P = 0.11) at the pisiform bone level on the injected wrists. At the DRUJ and hamate bone levels, no obvious inter-scan change in FA and ADC ( P > 0.05) was observed. The decrease in ADC at the pisiform bone level strongly correlated with the decrease in BCTQ scores (r = 0.628; P = 0.012). Symptom relief in patients with CTS receiving corticosteroid injection is related to the change in ADC of the median nerve at the level of the pisiform bone, as determined using MR-DTI.

Diffusion tensor imaging findings in the multiple sclerosis patients and their relationships to various aspects of disability

BackgroundThe aim of the study was to assess microstructural changes within strategic brain regions in multiple sclerosis (MS) patients, using diffusion tensor imaging (DTI), with regard to various aspects of disability. Material and methodsThe study comprised 50 patients with relapsing-remitting MS (37 women, 13 men, mean age 36.4 yrs) and 27 age- and sex-matched controls. Using DTI, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were obtained within corpus callosum (CC), both thalami (TH) and middle cerebellar peduncles (MCP). Disability was assessed using Expanded Disability Status Scale (EDSS), MS Functional Composite (MSFC), Symbol Digit Modalities Test (SDMT) and Fatigue Severity Scale (FSS). DTI indices were compared between the patients and controls and in the MS group - referred to disability measures. ResultsSignificant decrease in FA and increase in ADC within CC and both TH were found in MS patients compared to the controls. DTI indices within CC and TH correlated significantly with SDMT score, and within TH and MCP - with MSFC manual dexterity measure. ConclusionsChanges in DTI measures in normal appearing white and grey matter in the MS patients indicate subtle alterations of the tissue integrity. An occult damage to the strategic brain regions may contribute to various aspects of disability due to MS.