Whole-Brain DTI Assessment of White Matter Damage in Children with Bilateral Cerebral Palsy: Evidence of Involvement beyond the Primary Target of the Anoxic Insult.

BACKGROUND AND PURPOSE: Cerebral palsy is frequently associated with both motor and nonmotor symptoms. DTI can characterize the damage at the level of motor tracts but provides less consistent results in nonmotor areas. We used a standardized pipeline of analysis to describe and quantify the pattern of DTI white matter abnormalities of the whole brain in a group of children with chronic bilateral cerebral palsy and periventricular leukomalacia. We also explored potential correlations between DTI and clinical scale metrics. MATERIALS AND METHODS: Twenty-five patients (mean age, 11.8 years) and 25 healthy children (mean age, 11.8 years) were studied at 3T with a 2-mm isotropic DTI sequence. Differences between patients and controls were assessed both voxelwise and in ROIs obtained from an existing DTI atlas. Clinical metrics included the Gross Motor Function Classification System, the Manual Ability Classification System, and intelligence quotient. RESULTS: The voxel-level and ROI-level analyses demonstrated highly significant (P < .001) modifications of DTI measurements in patients at several levels: cerebellar peduncles, corticospinal tracts and posterior thalamic radiations, posterior corpus callosum, external capsule, anterior thalamic radiation, superior longitudinal fasciculi and corona radiata, optic nerves, and chiasm. The reduction of fractional anisotropy values in significant tracts was between 8% and 30%. Statistically significant correlations were found between motor impairment and fractional anisotropy in corticospinal tracts and commissural and associative tracts of the supratentorial brain. CONCLUSIONS: We demonstrated the involvement of several motor and nonmotor areas in the chronic damage associated with periventricular leukomalacia and showed new correlations between motor skills and DTI metrics.

Peripheral benzodiazepine receptors and glucose metabolism in human gliomas.

Peripheral benzodiazepine receptors (PBR) are increased in gliomas and augmented glucose metabolism is seen in malignant brain tumors. We investigated the relationship between PBR density (Bmax) and glucose utilization rate (GUR) in 17 patients with cerebral gliomas of different grades. PBR Bmax was assessed by [3H]PK-11195 in vitro binding in surgical specimens and GUR was measured by Positron Emission Tomography with [18F]2-Fluorodeoxyglucose before the surgery. In untreated tumors there was a positive correlation between PBR Bmax and GUR (2r = 0.84). This correlation was not observed in patients who had been treated with radiation and/or chemotherapy prior to surgery (r2 = 0.13). In addition, in untreated patients, the increase in PBR density and GUR appeared to be related to the degree of malignancy.

Frequency dependence of MR relaxation times. II. Iron oxides.

The frequency dependence of T1 and T2 was measured for homogeneous suspensions of magnetite and iron oxyhydroxide particles in water with various concentrations of gelatin. The transverse relaxivity showed two types of behavior: (a) For magnetic particles, there was a rapid increase in T2 relaxivity with frequency, followed by a saturation plateau, which accorded with the Langevin magnetization function. From these curves, the magnetic moment of the particle domains was estimated to range from 0.8 to 6.3 x 10(4) Bohr magnetons. (b) For iron oxyhydroxide (ferritin, ferrihydrite, and akaganéite) particles, T2 relaxivity increased linearly with frequency, the slope of the increase characteristic for each particle. T2 relaxivity generally increased with increasing gelatin concentration, corresponding to the measured decrease in the water diffusion coefficient. For iron oxides, homogeneously distributed either as iatrogenic agents or endogenous biominerals, these findings may aid in the interpretation of in vivo relaxivity and the effect on MR imaging.