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1.
Purpose
It is unclear how white matter hyperintensities disrupt surrounding white matter tracts. The aim of this tractography study was to determine the spatial relationship between diffusion characteristics along white matter tracts and the distance from white matter hyperintensities.Methods
Diffusion tensor 3-T MRI scans were acquired in 29 participants with white matter hyperintensities. In each subject, tractography by the fiber assignment by continuous tracking method was used to segment corticospinal tracts. Mean diffusivity, radial diffusivity, axial diffusivity, and fractional anisotropy were measured along corticospinal tracts in relation to white matter hyperintensities. Diffusion characteristics along tracts were correlated with distance from white matter hyperintensities and were also compared between tracts traversing and not traversing white matter hyperintensities.Results
In tracts not traversing through white matter hyperintensities, increasing distance from white matter hyperintensities was associated with decreased mean diffusivity (p?=?0.002) and increased fractional anisotropy (p?=?0.006). In tracts traversing white matter hyperintensities, compared to tracts not traversing white matter hyperintensites, the mean diffusivity was higher at 6–8 voxels, axial diffusivity higher at 4–8 voxels, and radial diffusivity higher at 7 voxels away from white matter hyperintensities (all p?<?0.006).Conclusion
White matter hyperintensities are associated with two patterns of altered diffusion characteristics in the surrounding white matter tract network. Diffusion characteristics along white matter tracts improve further away from white matter hyperintensities suggestive of a local penumbra pattern. Also, altered diffusion extends further along tracts traversing white matter hyperintensities suggestive of a Wallerian-type degenerative pattern.2.
Purpose
Diffusion tensor imaging (DTI) is commonly used to evaluate white matter integrity in multiple sclerosis (MS), but the relationship between DTI measures and functional changes during disease remains ambiguous. Using a mouse model of MS, we tested the hypothesis that DTI measures would correlate to the visual evoked potential (VEPs) dynamically at different disease stages.Methods
In vivo DTI, gadolinium-enhanced T1WI (Gd-T1WI) and VEPs were performed in 5 control and 25 mice after 2–12 weeks of experimental autoimmune encephalomyelitis (EAE). DTI indices, including fractional anisotropy (FA), axial and radial diffusivities (AD and RD), and Gd-T1WI enhancement, were measured in the optic nerve and tract (ON and OT), which were compared with measured VEPs.Results
Gd-T1WI showed a 3- to 4-fold enhancement over controls beginning after 2 weeks of EAE. Across the time course, we found progressive reductions in FA and increases in RD with increases in VEP latency and reductions in amplitude. Significant correlations between DTI (FA and RD) and VEP evolved; in control/early asymptomatic EAE mice, both FA and RD were highly correlated with VEP latency (but not amplitude), while in late EAE, both DTI indices were highly correlated with VEP amplitude (but not latency).Conclusion
DTI measures FA and RD are associated to VEP latency in early stages of EAE but associated to VEP amplitude in later stages, suggesting that the patterns of DTI related to the functional decline may depend on the stage of disease progression.3.
Objective
To identify demographic determinants of peripheral nerve diffusion tensor imaging (DTI) and to establish normal values for fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and mean diffusivity (MD).Methods
Sixty subjects were examined at 3 Tesla by single-shot DTI. FA, AD, RD, and MD were collected for the sciatic, tibial, median, ulnar, and radial nerve and were correlated with demographic variables.Results
Mean FA of all nerves declined with increasing age (r = ?0.77), which could be explained by RD increasing (r = 0.56) and AD declining (r = ?0.40) with age. Moreover, FA was inversely associated with height (r = ?0.28), weight (r = ?0.38) and BMI (r = ?0.35). Although FA tended to be lower in men than women (p = 0.052), this difference became completely negligible after adjustment to body weight. A multiple linear regression model for FA was calculated with age and weight as predictors (defined by backward variable selection), yielding an R 2 = 0.71 and providing a correction formula to adjust FA for age and weight.Conclusion
Peripheral nerve DTI parameters depend on demographic variables. The most important determinants age and weight should be considered in all studies employing peripheral nerve DTI.Key points
? Peripheral nerve diffusion tensor imaging (DTI) parameters depend on demographic variables. ? Fractional anisotropy (FA) declines with increasing age and weight. ? Gender does not systematically affect peripheral nerve DTI. ? The formula presented here allows adjustment of FA for demographic variables.4.
Introduction
The objective of this study was to evaluate the cortical thickness and the volume of deep gray matter structures, measured from 3D T1-weighted gradient echo imaging, and white matter integrity, by diffusion tensor imaging (DTI) in patients with typical absence epilepsy (AE).Methods
Patients (n = 19) with typical childhood AE and juvenile AE, currently taking antiepileptic medication, were compared with control subjects (n = 19), matched for gender and age. 3D T1 magnetization-prepared rapid gradient echo-weighted imaging and DTI along 30 noncolinear directions were performed using a 1.5-T MR scanner. FreeSurfer was used to perform cortical volumetric reconstruction and segmentation of deep gray matter structures. For tract-based spatial statistics analysis of DTI, a white matter skeleton was created, along with a permutation-based inference with 5000 permutations. A threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The mean, radial, and axial diffusivities were also projected onto the mean FA skeleton.Results
Patients with AE presented decreased FA and increased mean diffusivity and radial diffusivity values in the genu and the body of the corpus callosum and right anterior corona radiata, as well as decreased axial diffusivity in the left posterior thalamic radiation, inferior cerebellar peduncle, right cerebral peduncle, and right corticospinal tract. However, there were no significant differences in cortical thickness or deep gray matter structure volumes between patients with AE and controls.Conclusion
Abnormalities found in white matter integrity may help to better understand the pathophysiology of AE and optimize diagnosis and treatment strategies.5.
Jing?Li Can?Zhao Jia-Sheng?Rao Fei-Xiang?Yang Zhan-Jing?Wang Jian-Feng?Lei Zhao-Yang?Yang Xiao-Guang?Li
Purpose
The understanding of microstructural and metabolic changes in the post-traumatic brain injury is the key to brain damage suppression and repair in clinics.Methods
Ten female Wistar rats were traumatically injured in the brain CA1 region and above the cortex. Next, diffusion tensor magnetic resonance imaging (DTI) and proton magnetic resonance spectroscopy (1H MRS) were used to analyze the microstructural and metabolic changes in the brain within the following 2 weeks.Results
Anisotropy fraction (FA) and axial diffusivity (AD) of the corpus callosum (CC) began to decrease significantly at day 1, whereas radial diffusivity (RD) significantly increased immediately after injury, reflecting the loss of white matter integrity. Compared with day 3, RD decreased significantly at day 7, implicating the angioedema reduction. In the hippocampus, FA significantly increased at day 7; the choline-containing compounds (Cho) and myo-inositol (MI) remarkably increased at day 7 compared with those at day 3, indicating the proliferation of astrocytes and radial glial cells after day 7. No significant differences between DTI and 1H MRS parameters were observed between day 1 and day 3.Conclusion
Day 1–3 after traumatic brain injury (TBI) may serve as a relatively appropriate time window for treatment planning and the following nerve repair.6.
Påvel G. Lindberg Fidan Ozcan François Rannou Serge Poiraudeau Antoine Feydy Marc A. Maier 《European radiology》2016,26(3):733-742
Objectives
The aim of this study was to investigate spinal cord structure in patients with cervical spondylosis where conventional MRI fails to reveal spinal cord damage.Methods
We performed a cross-sectional study of patients with cervical spondylosis without conventional MRI findings of spinal cord damage and healthy controls. Subjects were studied using spinal diffusion tensor imaging (DTI), precision grip and foot force-tracking tasks, and a clinical examination including assessment of neurological signs. A regional analysis of lateral and medial spinal white matter across multiple cervical levels (C1–C5) was performed.Results
DTI revealed reduced fractional anisotropy (FA) and increased radial diffusivity (RD) in the lateral spinal cord at the level of greatest compression (lowest Pavlov ratio) in patients (p?<?0.05). Patients with spondylosis had greater error and longer release duration in both grip and foot force-tracking. Similar spinal cord deficits were present in patients without neurological signs. Increased error in grip and foot tracking (low accuracy) correlated with increased RD in the lateral spinal cord at the level of greatest compression (p?≤?0.01).Conclusions
Spinal DTI can detect subtle spinal cord damage of functional relevance in cervical spondylosis, even in patients without signs on conventional T2-imaging and without neurological signs.Key Points
? DTI reveals spinal cord changes in cervical spondylosis with few symptoms ? DTI changes were present despite normal spinal cord on conventional MRI ? DTI parameters correlated with force control accuracy in hand and foot ? Spinal DTI is a promising technique for patients with cervical spondylosis7.
Purpose
This paper aims to analyze the contribution of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in the detection of microstructural abnormalities in amyotrophic lateral sclerosis (ALS) and to evaluate the degree of agreement between structural and functional changes through concomitant diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), and clinical assessment.Methods
Fourteen patients with ALS and 11 healthy, age- and gender-matched controls were included. All participants underwent magnetic resonance imaging including DTI. TMS was additionally performed in ALS patients. Differences in the distribution of DTI-derived measures were assessed using tract-based spatial statistical (TBSS) and volume of interest (VOI) analyses. Correlations between clinical, imaging, and neurophysiological findings were also assessed through TBSS.Results
ALS patients showed a significant increase in AD and MD involving the corticospinal tract (CST) and the pre-frontal white matter in the right posterior limb of the internal capsule (p?<?0.05) when compared to the control group using TBSS, confirmed by VOI analyses. VOI analyses also showed increased AD in the corpus callosum (p?<?0.05) in ALS patients. Fractional anisotropy (FA) in the right CST correlated significantly with upper motor neuron (UMN) score (r?=???0.79, p?<?0.05), and right abductor digiti minimi central motor conduction time was highly correlated with RD in the left posterior internal capsule (r?=???0.81, p?<?0.05). No other significant correlation was found.Conclusion
MD, AD, and RD, besides FA, are able to further detect and characterize neurodegeneration in ALS. Furthermore, TMS and DTI appear to have a role as complementary diagnostic biomarkers of UMN dysfunction.8.
Purpose
Despite improved acute treatment and new tools to facilitate recovery, most patients have motor deficits after stroke, often causing disability. However, motor impairment varies considerably among patients, and recovery in the acute/subacute phase is difficult to predict using clinical measures alone, particularly in severely impaired patients. Accurate early prediction of recovery would help rationalize rehabilitation goals and improve the design of trials testing strategies to facilitate recovery.Methods
We review the role of diffusion tensor imaging (DTI) in predicting motor recovery after stroke, in monitoring treatment response, and in evaluating white matter remodeling. We critically appraise DTI studies and discuss their limitations, and we explore directions for future study.Results
Growing evidence suggests that combining clinical scores with information about corticospinal tract (CST) integrity can improve predictions about motor outcome. The extent of CST damage on DTI and/or the overlap between the CST and a lesion are key prognostic factor that determines motor performance and outcome. Three main strategies to quantify stroke-related CST damage have been proposed: (i) measuring FA distal to the stroke area, (ii) measuring the number of fibers that go through the stroke with tractography, and (iii) measuring the overlap between the stroke and a CST map derived from healthy age- and gender-matched controls.Conclusion
Recovery of motor function probably involves remodeling of the CST proper and/or a greater reliance on alternative motor tracts through spontaneous and treatment-induced plasticity. DTI-metrics represent promising clinical biomarkers to predict motor recovery and to monitor and predict the response to neurorehabilitative interventions.9.
Purpose
Cognitive decline in Down syndrome generally shows neurodegenerative aspects similar to what is observed in Alzheimer’s disease. Few studies reported information on white matter integrity. The aim of this study was to evaluate white matter alterations in a cohort of young Down subjects, without dementia, by means of DTI technique, compared to a normal control group.Methods
The study group consisted of 17 right-handed subjects with DS and many control subjects. All individuals participating in this study were examined by MR exam including DTI acquisition (32 non-coplanar directions); image processing and analysis were performed using FMRIB Software Library (FSL version 4.1.9, http://www.fmrib.ox.ac.uk/fsl)) software package. Finally, the diffusion tensor was estimated voxel by voxel and the FA map derived from the tensor. A two-sample t test was performed to assess differences between DS and control subjects.Results
The FA is decreased in DS subjects, compared to control subjects, in the region of the anterior thalamic radiation, the inferior fronto-occipital fasciculum, the inferior longitudinal fasciculum, and the cortico-spinal tract, bilaterally.Conclusions
The early white matter damage visible in our DS subjects could have great impact in the therapeutic management, in particular in better adapting the timing of therapies to counteract the toxic effect of the deposition of amyloid that leads to oxidative stress.10.
Introduction
To investigate the extraocular muscle (EOM) changes in thyroid-associated orbitopathy (TAO) on DTI and the correlations between DTI parameters and clinical features.Methods
Twenty TAO patients and 20 age- and sex-matched controls provided informed consent and were enrolled. Ten-directional DTI was acquired in orbit. Fractional anisotropy (FA), mean, axial, and radial diffusivities were obtained at medial and lateral EOMs in both orbits. EOM thickness was measured in patients using axial CT images. FA and diffusivities were compared between patients and controls. The relationships between DTI values and muscle thickness and exophthalmos were evaluated. DTI values compared between patients in active and inactive phases by clinical activity score of TAO. DTI values were also compared between acute and chronic stages by the duration of disease.Results
In medial EOM, FA was significantly lower in patients (p < 0.001) and negatively correlated with muscle thickness (r = ?0.604, p < 0.001). Radial diffusivity was significantly higher in patients (p = 0.010) and correlated with muscle thickness (r = 0.349, p = 0.027). In lateral EOM, DTI values did not differ between patients and controls. In the acute stage, the diffusivities of the medial rectus EOM were increased compared with the chronic stage. DTI values of the medial and lateral rectus EOM did not differ significantly between active and inactive phases.Conclusion
DTI can be used to diagnose TAO with FA and radial diffusivity change in EOM. Diffusivities can be used to differentiate acute and chronic stage of TAO. However, DTI values showed limitation in reflecting TAO activity according to the CAS.11.
Purpose
Although epilepsy in the elderly has attracted attention recently, there are few systematic studies of neuroimaging in such patients. In this study, we used structural MRI and diffusion tensor imaging (DTI) to investigate the morphological and microstructural features of the brain in late-onset temporal lobe epilepsy (TLE).Methods
We recruited patients with TLE and an age of onset >?50 years (late-TLE group) and age- and sex-matched healthy volunteers (control group). 3-Tesla MRI scans, including 3D T1-weighted images and 15-direction DTI, showed normal findings on visual assessment in both groups. We used Statistical Parametric Mapping 12 (SPM12) for gray and white matter structural normalization and comparison and used Tract-Based Spatial Statistics (TBSS) for fractional anisotropy and mean diffusivity comparisons of DTI. In both methods, p <?0.05 (family-wise error) was considered statistically significant.Results
In total, 30 patients with late-onset TLE (mean?±?SD age, 66.8?±?8.4; mean?±?SD age of onset, 63.0?±?7.6 years) and 40 healthy controls (mean?±?SD age, 66.6?±?8.5 years) were enrolled. The late-onset TLE group showed significant gray matter volume increases in the bilateral amygdala and anterior hippocampus and significantly reduced mean diffusivity in the left temporofrontal lobe, internal capsule, and brainstem. No significant changes were evident in white matter volume or fractional anisotropy.Conclusions
Our findings may reflect some characteristics or mechanisms of cryptogenic TLE in the elderly, such as inflammatory processes.12.
Purpose
Diffusion tensor imaging (DTI) in flexion (F) and extension (E) may serve as a sensitive diagnostic tool in early symptoms of myelopathy. The aim of this study was to compare values of water diffusion parameters on dynamic cervical DTI in early stage of myelopathy.Methods
Study enrolled 10 patients with an early stage of cervical myelopathy, in grade I/II of Nurick classification. All subjects were scanned with flexion-extension 3T MRI. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), RD (radial diffusivity), AD (axial diffusivity) and TRACEW (trace diffusion) were measured at C2, compression level (CL) and C7. Parameters were compared between 3 levels and F and E positions.Results
Flexion DTI revealed significant difference only for TRACEW between C2 and C7 (105.8?±?18.9 vs. 83.7?±?14, respectively; p?=?0.0029). Extension DTI showed differences for ADC between CL and C7 (1378.9?±?381.8 vs. 1227.2?±?269.2; p?=?0.001), reduced FA from 664.6?±?56.3 at C2 down to 553.1?±?75.5 (p?=?0.001) at CL and 584.7?±?40.7 at C7 (p?=?0.002). Differences of RD in E were significant through all levels and reached 612.9?±?105.1, 955.3?±?319.4 and 802.1?±?194.1 at C2, CL and C7, respectively. TRACEW lowered from 92.3?±?14.4 at C2 to 66.9?±?21.1 at CL (p?=?0.0001) and 64.4?±?15.5 at C7 (p?=?0.0002). Comparison of DTI between F and E showed differences for all parameters except AD. RD was significantly higher in E at CL (p?=?0.003) and C7 (0.013), but TRACEW increased in F at CL by 27.4% (p?=?0.001) and at C7 by 23.1% (p?=?0.013). FA was reduced at CL in E (p?=?0.027) and similarly ADC in F (p?=?0.048).Conclusion
Dynamic DTI of the cervical spine is feasible and can detect subtle spinal cord damage of functional relevance in cervical myelopathy. A marked increase of RD and decrease of FA and TRACEW values in extension were found to be indicative for an early structural cord injury in myelopathy.13.
Ramona Woitek Daniela Prayer Michael Weber Gabriele Amann Rainer Seidl Dieter Bettelheim Veronika Schöpf Peter C Brugger Julia Furtner Ulrika Asenbaum Gregor Kasprian 《European radiology》2016,26(5):1274-1283
Objectives
This prenatal MRI study evaluated the potential of diffusion tensor imaging (DTI) metrics to identify changes in the midbrain of fetuses with Chiari II malformations compared to fetuses with mild ventriculomegaly, hydrocephalus and normal CNS development.Methods
Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from a region of interest (ROI) in the midbrain of 46 fetuses with normal CNS, 15 with Chiari II malformations, eight with hydrocephalus and 12 with mild ventriculomegaly. Fetuses with different diagnoses were compared group-wise after age-matching. Axial T2W-FSE sequences and single-shot echo planar DTI sequences (16 non-collinear diffusion gradient-encoding directions, b-values of 0 and 700 s/mm2, 1.5 Tesla) were evaluated retrospectively.Results
In Chiari II malformations, FA was significantly higher than in age-matched fetuses with a normal CNS (p?=?.003), while ADC was not significantly different. No differences in DTI metrics between normal controls and fetuses with hydrocephalus or vetriculomegaly were detected.Conclusions
DTI can detect and quantify parenchymal alterations of the fetal midbrain in Chiari II malformations. Therefore, in cases of enlarged fetal ventricles, FA of the fetal midbrain may contribute to the differentiation between Chiari II malformation and other entities.Key Points
? FA in the fetal midbrain is elevated in Chiari II malformations. ? FA is not elevated in hydrocephalus and mild ventriculomegaly without Chiari II. ? Measuring FA may help distinguish different causes for enlarged ventricles prenatally. ? Elevated FA may aid in the diagnosis of open neural tube defects. ? Elevated FA might contribute to stratification for prenatal surgery in Chiari II.14.
Introduction
Few studies assessed diffusion tensor imaging (DTI) changes in the acute phase of subarachnoid haemorrhage (SAH). We prospectively evaluated DTI parameters in the acute phase of SAH and 8–10 days after and analysed whether changes could be related to SAH severity or to the development of delayed cerebral ischemia (DCI).Methods
Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) changes over time were assessed in a prospective cohort of patients with acute SAH. Two MRI studies were performed at <72 h (MRI-1) and 8–10 days (MRI-2). DTI parameters were recorded in 15 ROIs. Linear mixed regression models were used.Results
Forty-two patients were included. Subtle changes in DTI parameters were found between MRI-1 and MRI-2. At the posterior limb of internal capsule (PLIC), a weak evidence of a 0.02 mean increase in FA (p = 0.064) and a 17.55 × 10?6 mm2/s decrease in ADC (p = 0.052) were found in MRI-2. Both FA and ADC changed over time at the cerebellum (increase of 0.03; p = 0.017; decrease of 34.73 × 10?6 mm2/s; p = 0.002, respectively). Patients with DCI had lower FA values on MRI-1 and lower ADC on MRI-2, although not reaching statistical significance, compared to non-DCI patients. DTI parameters on MRI-1 were not correlated to clinical admission scales.Conclusion
ADC and FA values show subtle changes over time in acute SAH at the PLIC and cerebellum although not statistically associated with the severity of SAH or the occurrence of DCI. However, DTI changes occurred mainly in DCI patients, suggesting a possible role of DTI as a marker of DCI.15.
Objectives
An ill-defined hyperintense edge and hypointense core on diffusion-weighted imaging (DWI) is typical of progressive multifocal leukoencephalopathy (PML). We aimed to investigate whether a b-value of 3,000 s/mm2 (b3000) can improve visualisation of PML, or provide different structural information compared to 1,000 s/mm2 (b1000).Methods
We retrospectively identified HIV-positive patients with confirmed PML studied under a clinical protocol including both b1000 and b3000 DWI. The rim and core of each PML lesion and normal-appearing white matter (NAWM) were outlined on trace-weighted DWI. Signal intensities, apparent diffusion coefficient (ADC) values and volumes were measured and compared between b1000 and b3000.Results
Nine lesions from seven patients were analysed. The rim and core were better visualised on b3000, with higher signal of the rim and lower signal of the core compared to NAWM. The hyperintense rim had non-restricted average ADCs, but included foci of low ADC on both b3000 and b1000. Despite similar total lesion volumes, b3000 displayed significantly larger core and smaller rim volumes than b1000.Conclusion
b3000 improves visualisation of this important PML hallmark. Moreover, b3000 partly reclassifies tissue from rim into core, and might provide potentially more accurate biomarkers of PML activity and prognosis.Key Points
? B3000 improves contrast resolution between lesion rim, core and normal-appearing white matter.? B3000 improves identification of the typical rim-and-core pattern of PML lesions.? B3000 and b1000 similarly identify lesions, but b3000 results in smaller rims and larger cores.? B3000 excludes some high diffusion components from rim, reclassifying them into core.? B3000 DWI may provide more precise PML biomarkers of disease activity and tissue damage.16.
Miho Ota Noriko Sato Norihide Maikusa Daichi Sone Hiroshi Matsuda Hiroshi Kunugi 《Japanese journal of radiology》2017,35(10):584-589
Purpose
The new diffusional magnetic resonance imaging (dMRI) techniques, diffusional kurtosis imaging (DKI) and neurite orientation dispersion and density imaging (NODDI) have been developed to clarify the microstructural changes. To our knowledge, however, there is little information on the similarities and differences of these metrics evaluated by the image-by-image paired t test.Materials and methods
Twenty-three healthy subjects underwent dMRI. We estimated the relationships of these metrics evaluated by the image-by-image paired t-test and compared aging effects on each metric.Results
We found that fractional anisotropy (FA), mean kurtosis (MK) derived from DKI and neurite density index (NDI) values derived from NODDI correlated with each other positively, and mean diffusivity (MD) and orientation dispersion index (ODI) values from NODDI correlated negatively with the FA value. There were no significant relationships of age with FA or MD values, while MK, ODI and NDI values showed significant correlations with age.Conclusion
These results may indicate not only the similar tendency among the metrics, but also the higher sensitivity of NODDI and DKI to the changes in microstructural tissue organization with advancing age. These techniques could shed light on both normal and degenerated brain changes.17.
Jilu?Princy?Mole Leena?Subramanian Tobias?Bracht Huw?Morris Claudia?Metzler-Baddeley David?E.?J.?Linden
Objective
To determine the differences in motor pathways and selected non-motor pathways of the basal ganglia in Parkinson’s disease (PD) patients compared to healthy controls (HCs).Methods
We analysed diffusion weighted imaging data of 24 PD patients and 26 HCs. We performed deterministic tractography analysis using the spherical deconvolution-based damped Richardson-Lucy algorithm and subcortical volume analysis.Results
We found significantly increased fractional anisotropy (FA) in the motor pathways of PD patients: the bilateral corticospinal tract (right; corrected p?=?0.0003, left; corrected p?=?0.03), bilateral thalamus-motor cortex tract (right; corrected p?=?0.02, left; corrected p?=?0.004) and the right supplementary area-putamen tract (corrected p?=?0.001). We also found significantly decreased FA in the right uncinate fasiculus (corrected p?=?0.01) and no differences of FA in the bilateral supero-lateral medial forebrain bundles (p?>?0.05) of PD patients compared to HCs. There were no subcortical volume differences (p?>?0.05) between the PD patients and HCs.Conclusion
These results can inform biological models of neurodegeneration and neuroplasticity in PD. We suggest that increased FA values in the motor tracts in PD may reflect compensatory reorganization of neural circuits indicative of adaptive or extended neuroplasticity.Key points
? Fractional anisotropy was higher in motor pathways of PD patients compared to healthy controls. ? Fractional anisotropy was lower in the uncinate fasciculus of PD patients compared to healthy controls. ? Increased fractional anisotropy could suggest adaptive neuroplasticity or selective neurodegeneration.18.
Objectives
To evaluate the kidneys of patients with haemolytic uraemic syndrome (HUS) using diffusion-weighted imaging (DWI) and Doppler ultrasound (US) compared with healthy controls.Materials and Methods
Fifteen patients (mean age 33.3 years; three male; 12 female) with diarrhoea-positive HUS and 15 healthy volunteers were prospectively evaluated with DWI and Doppler US. A total apparent diffusion coefficient (ADCTOT), and ADCs predominantly reflecting microperfusion (ADCLOW) and diffusion (ADCHIGH) were calculated. Doppler US evaluated renal vascularity and flow.Results
When compared with controls, kidneys affected by HUS showed reduced cortical ADC values (ADCTOT 1.79±0.22 vs. 2.04±0.1x10-3 mm2/s, P 0.001), resulting in either low corticomedullary differences (11/15 patients) or an inverted corticomedullary pattern (4/15 patients). Reduction of cortical ADC values was associated with a decrease of cortical vascularity on Doppler US (ADCTOT, P<0.001; ADCLOW, P 0.047). Kidneys with complete absence of the cortical vasculature on Doppler US (four patients) also demonstrated limited diffusion (ADCHIGH, P 0.002). Low glomerular filtration rate, requirement for haemodialysis during hospitalization, and longer duration of haemodialysis were associated with decreased cortical diffusivity (ADCTOT: P 0.04, 0.007, and <0.001, respectively).Conclusion
DWI shows qualitative and quantitative abnormalities in kidneys affected by HUS, thereby extending the non-invasive assessment of renal parenchymal damage.Key Points
? In HUS, DWI is feasible for functional characterization of kidney involvement. ? Kidneys affected by HUS showed reduced cortical diffusivity. ? Decreased cortical diffusivity was associated with lower kidney function. ? Requirement and duration of haemodialysis was linked to degree of cortical alterations.19.
Inroduction
White matter injury and abnormal maturation are thought to be major contributors to the neurodevelopmental disabilities observed in children and adolescents who were born preterm. Early detection of abnormal white matter maturation is important in the design of preventive, protective, and rehabilitative strategies for the management of the preterm infant. Diffusion-weighted magnetic resonance imaging (d-MRI) has become a valuable tool in assessing white matter maturation and injury in survivors of preterm birth. In this review, we aim to (1) describe the basic concepts of d-MRI; (2) evaluate the methods that are currently used to analyse d-MRI; (3) discuss neuroimaging correlates of preterm brain injury observed at term corrected age; during infancy, adolescence and in early adulthood; and (4) explore the relationship between d-MRI measures and subsequent neurodevelopmental performance.Methods
References for this review were identified through searches of PubMed and Google Scholar before March 2013.Results
The impact of premature birth on cerebral white matter can be observed from term-equivalent age through to adulthood. Disruptions to white matter development, identified by d-MRI, are related to diminished performance in functional domains including motor performance, cognition and behaviour in early childhood and in later life.Conclusion
d-MRI is an effective tool for investigating preterm white matter injury. With advances in image acquisition and analysis approaches, d-MRI has the potential to be a biomarker of subsequent outcome and to evaluate efficacy of clinical interventions in this population.20.