Aim  Cerebral palsy (CP) is frequently linked to white matter injury in children born preterm. Diffusion tensor imaging (DTI) is a powerful technique providing precise identification of white matter microstructure. We investigated the relationship between DTI‐observed thalamocortical (posterior thalamic radiation) injury, motor (corticospinal tract) injury, and sensorimotor function. Method  Twenty‐eight children born preterm (16 males, 12 females; mean age 5y 10mo, SD 2y 6mo, range 16mo–13y; mean gestational age at birth 28wks, SD 2.7wks, range 23–34wks) were included in this case–control study. Twenty‐one children had spastic diplegia, four had spastic quadriplegia, two had hemiplegia, and one had ataxic/hypotonic CP; 15 of the participants walked independently. Normative comparison data were obtained from 35 healthy age‐matched children born at term (19 males, 16 females; mean age 5y 9mo, SD 4y 4mo, range 15mo–15y). Two‐dimensional DTI color maps were created to evaluate 26 central white matter tracts, which were graded by a neuroradiologist masked to clinical status. Quantitative measures of touch, proprioception, strength (dynamometer), and spasticity (modified Ashworth scale) were obtained from a subset of participants. Results  All 28 participants with CP had periventricular white‐matter injury on magnetic resonance imaging. Using DTI color maps, there was more severe injury in the posterior thalamic radiation pathways than in the descending corticospinal tracts. Posterior thalamic radiation injury correlated with reduced contralateral touch threshold, proprioception, and motor severity, whereas corticospinal tract injury did not correlate with motor or sensory outcome measures. Interpretation  These findings extend previous research demonstrating that CP in preterm children reflects disruption of thalamocortical connections as well as descending corticospinal pathways.

Highly reproducible values of ADC and FA were obtained with the polygonal method on intra-rater (coefficients of variation

BACKGROUND AND PURPOSE:Conventional MR imaging shows evidence of brain injury and/or maldevelopment in 70%-90% of children with cerebral palsy (CP), though its capability to identify specific white matter tract injury is limited. The great variability of white matter lesions in CP already demonstrated by postmortem studies is thought to be one of the reasons why response to treatment is so variable. Our hypothesis is that diffusion tensor imaging (DTI) is a suitable technique to provide in vivo characterization of specific white matter tract lesions in children with CP associated with periventricular leukomalacia (PVL).

EBM2BACKGROUND AND PURPOSE: Language impairments are observed in a subset of individuals with ASD. To examine microstructural brain white matter features associated with language ability in ASD, we measured the DTI parameters of language-related white matter tracts (SLF) as well as nonlanguage-related white matter tracts (CST) in children with ASD/ϩLI and ASD/ϪLI) and in TD.

ObjectiveTo compare the prevalence of an incomplete circle of Willis in patients with migraine with aura, migraine without aura, and control subjects, and correlate circle of Willis variations with alterations in cerebral perfusion.MethodsMigraine with aura, migraine without aura, and control subjects were prospectively enrolled in a 1∶1∶1 ratio. Magnetic resonance angiography was performed to examine circle of Willis anatomy and arterial spin labeled perfusion magnetic resonance imaging to measure cerebral blood flow. A standardized template rating system was used to categorize circle of Willis variants. The primary pre-specified outcome measure was the frequency of an incomplete circle of Willis. The association between circle of Willis variations and cerebral blood flow was also analyzed.Results170 subjects were enrolled (56 migraine with aura, 61 migraine without aura, 53 controls). An incomplete circle of Willis was significantly more common in the migraine with aura compared to control group (73% vs. 51%, p = 0.02), with a similar trend for the migraine without aura group (67% vs. 51%, p = 0.08). Using a quantitative score of the burden of circle of Willis variants, migraine with aura subjects had a higher burden of variants than controls (p = 0.02). Compared to those with a complete circle, subjects with an incomplete circle had greater asymmetry in hemispheric cerebral blood flow (p = 0.05). Specific posterior cerebral artery variants were associated with greater asymmetries of blood flow in the posterior cerebral artery territory.ConclusionsAn incomplete circle of Willis is more common in migraine with aura subjects than controls, and is associated with alterations in cerebral blood flow.

Diffusion tensor imaging (DTI) of the substantia nigra has shown promise in detecting and quantifying neurodegeneration in Parkinson disease (PD). It remains unknown, however, whether differences in microstructural changes within the basal ganglia underlie PD motor subtypes. We investigated microstructural changes within the basal ganglia of mild to moderately affected PD patients using DTI and sought to determine if microstructural changes differ between the tremor dominant (TD) and postural instability/gait difficulty (PIGD) subtypes. Fractional anisotropy, mean diffusivity, radial, and axial diffusivity were obtained from bilateral caudate, putamen, globus pallidus, and substantia nigra of 21 PD patients (12 TD and 9 PIGD) and 20 age-matched healthy controls. T-tests and ANOVA methods were used to compare PD patients, subtypes, and controls, and Spearman correlations tested for relationships between DTI and clinical measures. We found our cohort of PD patients had reduced fractional anisotropy within the substantia nigra and increased mean and radial diffusivity within the substantia nigra and globus pallidus compared to controls, and that changes within those structures were largely driven by the PIGD subtype. Across all PD patients fractional anisotropy within the substantia nigra correlated with disease stage, while in PIGD patients increased diffusivity within the globus pallidus correlated with disease stage and motor severity. We conclude that PIGD patients have more severely affected microstructural changes within the substantia nigra compared to TD, and that microstructural changes within the globus pallidus may be particularly relevant for the manifestation of the PIGD subtype.

Objective Brain metabolism, as studied by magnetic resonance spectroscopy (MRS), has been previously shown to be abnormal in Rett syndrome (RTT). However the relationship of MRS findings to age, disease severity and genotype is unknown. This study reports MRS findings in 40 RTT girls (1–14 years old) and 12 age-matched controls. Methods Single voxel, short echo time proton MRS of left frontal lobe white matter was performed. Levels of myo-inositol (mI), total choline (Cho), glutamate/glutamine (Glx), and N-acetyl aspartate (NAA) were expressed as ratios relative to creatine (Cr). Results NAA/Cr ratios decreased and mI/Cr ratios increased with age in RTT (both p<0.03) while these ratios were stable in controls. The mean Glx/Cr ratio was 36% higher in RTT than in controls (p=0.043). The mean NAA/Cr ratio was 12.6% lower in RTT patients with seizures compared to those without seizures (p=0.017). NAA/Cr ratios also decreased with increasing clinical severity score (p=0.031). Compared to patients with T158X, R255X, and R294X mutations, and C-terminal deletions, patients with the R168X mutation tended to have the highest severity score (0.01≤p≤0.11) and the lowest NAA/Cr ratio (0.029≤p<0.14). Interpretation Decreasing NAA/Cr and increasing mI/Cr with age are suggestive of progressive axonal damage and astrocytosis in RTT respectively, while increased Glx/Cr ratio may be secondary to increasing glutamate-glutamine cycling at the synaptic level. The relationships between NAA/Cr, presence or absence of seizures, and disease severity suggest that MRS provides a non-invasive measure of cerebral involvement in RTT, with greatest impairment in patients with the R168X mutation.

Natalizumab (Tysabri) is a monoclonal antibody (α4 integrin antagonist) approved for treatment of multiple sclerosis, both for patients who fail therapy with other disease modifying agents and for patients with aggressive disease. Natalizumab is highly effective, resulting in significant decreases in rates of both relapse and disability accumulation, as well as marked decrease in MRI evidence of disease activity. As such, utilization of natalizumab is increasing, and the presentation of its associated complications is increasing accordingly. This review focuses on the clinical and neuroimaging features of the major complications associated with natalizumab therapy, focusing on the rare but devastating progressive multifocal leukoencephalopathy (PML). Associated entities including PML associated immune reconstitution inflammatory syndrome (PML-IRIS) and the emerging phenomenon of rebound of MS disease activity after natalizumab discontinuation are also discussed. Early recognition of neuroimaging features associated with these processes is critical in order to facilitate prompt diagnosis, treatment, and/or modification of therapies to improve patient outcomes.