Analysis of multiple B-value diffusion-weighted imaging in pediatric acute encephalopathy.

Acute encephalopathy is a disease group more commonly seen in children. It is often severe and has neurological sequelae. Imaging is important for early diagnosis and prompt treatment to ameliorate an unfavorable outcome, but insufficient sensitivity/specificity is a problem. To overcome this, a new value (fraction of high b-pair (FH)) that could be processed from clinically acceptable MR diffusion-weighted imaging (DWI) with three different b-values was designed on the basis of a two-compartment model of water diffusion signal attenuation. The purpose of this study is to compare FH with the apparent diffusion coefficient (ADC) regarding the detectability of pediatric acute encephalopathy. We retrospectively compared the clinical DWI of 15 children (1-10 years old, mean 2.34, 8 boys, 7 girls) of acute encephalopathy with another 16 children (1-11 years old, mean 4.89, 9 boys, 7 girls) as control. A comparison was first made visually by mapping FH on the brain images, and then a second comparison was made on the basis of 10 regions of interest (ROIs) set on cortical and subcortical areas of each child. FH map visually revealed diffusely elevated FH in cortical and subcortical areas of the patients with acute encephalopathy; the changes seemed more diffuse in FH compared to DWI. The comparison based on ROI revealed elevated mean FH in the cortical and subcortical areas of the acute encephalopathy patients compared to control with significant difference (P<0.05). Similar findings were observed even in regions where the findings of DWI were slight. The reduction of mean ADC was significant in regions with severe findings in DWI, but it was not constant in the areas with slighter DWI findings. The detectability of slight changes of cortical and subcortical lesions in acute encephalopathy may be superior in FH compared to ADC.

Effective performance of T(1)-weighted FLAIR Imaging with BLADE in pediatric brains.

PURPOSE: In magnetic resonance imaging of the brain, BLADE is used to compensate for head motion. The technique focuses mainly on acquisition of T(2)-weighted or contrast-enhanced T(1)-weighted images in adults; its utility for nonenhanced T(1)-weighted imaging in children is not well established. We compared the quality of T(1)-weighted fluid-attenuated inversion recovery brain imaging with BLADE (T(1)-FLAIR-BLADE) to that of conventional spin-echo T(1)-weighted imaging (T(1)-SE) in pediatric patients who cannot stay still during MR imaging. MATERIALS AND METHODS: Our investigation included a volunteer study and a retrospective clinical study. Six healthy adult volunteers underwent scanning to compare the contrast of T(1)-SE, T(1)-weighted fluid-attenuated inversion recovery imaging (T(1)-FLAIR), and T(1)-FLAIR-BLADE at both 1.5 and 3 tesla. Comparison was based on scores assigned independently by 2 blinded observers and by calculated contrast-to-noise ratio. The clinical study included 20 children who underwent both T(1)-SE and T(1)-FLAIR-BLADE at either 1.5 (n = 9) or 3 T (n = 11). On each sequence, 2 blinded observers independently scored visualization of the cerebral gyri and contrast between gray and white matter. We compared scores between sequences separately for 1.5 and 3T using Wilcoxon signed-rank tests. RESULTS: At both 1.5 and 3T, contrast was better using T(1)-FLAIR and T(1)-FLAIR-BLADE than T(1)-SE in volunteers, and overall scores were significantly higher with T(1)-FLAIR-BLADE (P < 0.05) than T(1)-SE in the clinical study. CONCLUSION: T(1)-FLAIR-BLADE may be superior to T(1)-SE in demonstrating brain structures in children who cannot stay still and may be used to supplement or replace T(1)-SE when T(1)-SE is insufficient for patient motion.