Effective Performance of T1-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.\nMATERIALS 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.\nRESULTS: 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.\nCONCLUSION: 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

Monitoring the brain metabolites of children with acute encephalopathy caused by the H1N1 virus responsible for the 2009 influenza pandemic: a quantitative in vivo 1H MR spectroscopy study

Background and Purpose: Influenza viral infection, which results in central nervous system dysfunction, is a major cause of acute encephalopathy (AE). The purpose of this study was to investigate the changes in the concentrations of brain metabolites in children with AE using single-voxel magnetic resonance spectroscopy (MRS) and to provide diagnostic information about the relationship between the symptoms of AE and metabolite concentrations.Materials and Methods: The subjects were 10 children (mean age: 6.2 years; range: 1-13) with AE caused by the novel influenza A virus responsible for the 2009 influenza pandemic. The serial MRS data (TE/TR=30/5000 ms, 3 T) acquired from the basal ganglia (BG) and centrum semiovale (CS) of each patient were categorized into three periods: (1) initial neurological symptom presentation and the start oftreatment (n=10), (2) short-term follow-up (n=9) and (3) long-term follow-up (n=3). As controls, the magnetic resonance (MR) spectra of eight age-matched children were also investigated.Results: In both regions, the concentrations of the major metabolites (N-acetylaspartate, creatine, choline, myo-inositol, glutamate/glutamine complex and glutamate) only showed minor fluctuations between the three periods. On the other hand, higher levels of taurine (Tau) were observed in the BG during the second period (P=.005), and increased levels of glucose were observed in the CS during the first (P=.005) and second (P=.036) periods.Conclusions: Serial monitoring of brain metabolite changes was carried out with a clinical MR system. The concentrations of major metabolites only displayed very minor fluctuations in response to mild H1N1-related AE. However, a higher Tau concentration was found to be associated with neurological symptoms. Further studies are required to improve our understanding of the detailed activity of Tau in AE

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&#8211;10 years old, mean 2.34, 8 boys, 7 girls) of acute encephalopathy with another 16 children (1&#8211;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

Relationship between brain metabolite concentrations/volumes during neonatal

[Purpose] It is well known that the premature birth is associated with increased risk of neurological and physical problems. The purpose of this study is to investigate whether the brain metabolite concentration (conc) and/or volumes in neonates can be an index of the prognosis for the premature birth.[Methods] Twenty-six subjects with premature birth (gestational age: 23-33 weeks) were included. At their postconceptional age of 34-40 weeks, they had brain MRI (Siemens 3T) including MRS (PRESS, TE 30ms, TR 5s). The metabolite conc were calculated using LCModel with water conc of 46.9M. Using T2W images (TE 119-123ms, TR 5s), the volumes were measured using ROI editor (John Hopkins). At a corrected age of 1.5 years, they had developmental quotient (DQ) by Kyoto Scale of Psychological Development. Correlations between the conc and DQ, and the volume and DQ were investigated using Spearman’s rank correlation coefficients. The conc change with development was considered. [Results] The creatine, choline, N-acetylaspartate, myo-inositol, and glutamate/glutamine complex conc were 5.4-9.0, 1.3-2.6, 3.0-6.4, 4.8-8.8, and 3.8-11.5mM, in the basal ganglia, respectively, and 3.8-5.9, 1.5-2.3, 2.4-6.1, 5.7-9.3, and 3.9-8.9mM, in the centrum semiovale. The supratentorial, cerebellum, and intracranial volumes were 222-332, 13-22, and 352-550mL, respectively; The DQ were 44-119. No correlations were found between the metabolite conc or volumes and DQ. [Discussion] The DQ is overall index, and in this study fine classification of the DQ was not considered. Also, the volume change with development was not considered. Although we could not find any correlation, more detail studies are needed to confirm whether the MR data in neonates can be an index of the prognosis for premature birth.第44回日本磁気共鳴医学会大

Analysis of Multiple B-Value Diffusion-Weighted Imaging in Pediatric Acute Encephalopathy

<div><p>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 (F_H)) 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 F_H 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 F_H 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. F_H map visually revealed diffusely elevated F_H in cortical and subcortical areas of the patients with acute encephalopathy; the changes seemed more diffuse in F_H compared to DWI. The comparison based on ROI revealed elevated mean F_H 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 F_H compared to ADC.</p></div

Regions of interest (ROIs) for the ROI-based study.

<p>A, B: Images acquired from a 1-year-old boy of unspecific acute encephalopathy. The images show the two specific slice levels selected for evaluation: the slice at the level of cerebral hemisphere (A), and the slice at the level of cerebral basal ganglia (B). Ten regions of interests (ROIs) were set as schematically illustrated for further assessments. C, D: A sample of accurate ROI 1 (frontal lobe of left cerebral hemisphere) acquired from a 2-year-old boy with suspected labium dyskinesia but which regressed a while after the examination (control group). C: Diffusion-weighted image before setting ROIs. D: Brightened area indicates the selected ROI, from which the pixels of cerebrospinal fluid and deep white matter were excluded as much as possible.</p

Outline of 4bDWI sequence.

<p>4bDWI: Four b-value diffusion-weighted imaging sequence, TR: repetition time, TE: echo time, NEX: number of excitations, FOV: field of view.</p

Calculation of F_H.

<p>The graph illustrates typical in vivo signal attenuation of diffusion-weighted imaging (DWI). S₀ to S₂₅₀₀ are the signal intensities of the corresponding b-values. S_0high and S_0low are the theoretical S₀ values calculated from a different data pair (pair of S₅₀₀ and S₁₅₀₀, and pair of S₁₅₀₀ and S₂₅₀₀, respectively) using a monoexponential fitting (which becomes a straight line in this semi-logarithmic graph). Fraction of high b-pair (F_H) equals S_0high/S_0low.</p

Categorization of ROIs of each patient in encephalopathy group.

<p>ROIs: regions of interest, AESD: acute encephalopathy with biphasic seizures and late reduced diffusion, ANE: acute necrotizing encephalopathy, UC: uncategorizable.</p