Spectroscopy In Children Research Articles

Proton MR spectroscopy in children with acute brain injury: Comparison of short and long echo time acquisitions

The aim of this study was to evaluate comparatively the information given by proton magnetic resonance spectroscopy (MRS) with short echo time (TE 20 msec) stimulated echo acquisition mode and long TE (270 msec) point-resolved spectroscopy in predicting long-term outcome in children suffering from acute brain injury. At 1.5 T, we performed single-voxel proton MRS with both methods in occipital gray matter of 70 children. A linear discriminant analysis used to predict outcomes based on MRS variables was compared with actual neurologic outcome assigned at least 6 months after injury by a pediatric neurologist. Using peak area metabolite ratios and lactate presence, the short and long TE methods were equally predictive in children over 1 month of age. In neonates less than 1 month of age, the long TE method produced a higher percentage of correct outcome predictions (91%) than the short TE method (79%). The long TE method detected lactate more often in all age groups. J. Magn. Reson. Imaging 2000;11:9–19. © 2000 Wiley-Liss, Inc.

Proton MR spectroscopy in children with acute brain injury: comparison of short and long echo time acquisitions.

The aim of this study was to evaluate comparatively the information given by proton magnetic resonance spectroscopy (MRS) with short echo time (TE 20 msec) stimulated echo acquisition mode and long TE (270 msec) point-resolved spectroscopy in predicting long-term outcome in children suffering from acute brain injury. At 1.5 T, we performed single-voxel proton MRS with both methods in occipital gray matter of 70 children. A linear discriminant analysis used to predict outcomes based on MRS variables was compared with actual neurologic outcome assigned at least 6 months after injury by a pediatric neurologist. Using peak area metabolite ratios and lactate presence, the short and long TE methods were equally predictive in children over 1 month of age. In neonates less than 1 month of age, the long TE method produced a higher percentage of correct outcome predictions (91%) than the short TE method (79%). The long TE method detected lactate more often in all age groups.

Proton spectroscopy in children with epilepsy and febrile convulsions

An association between complex febrile convulsions and the development of hippocampal atrophy, which is characterized by neuron loss and gliosis, has been suggested but is still controversial. In proton magnetic resonance spectroscopy ( 1H-MRS) a reduction in N-acetylaspartate (NAA), a neuron marker, or in its ratio to other metabolites, that is, creatine and phospocreatine (Cr) and choline-containing compounds (Cho), is considered a sensitive method for detecting neuron loss. We performed 1H-MRS of mesial temporal regions, including hippocampi, in two different groups of children with epilepsy: in children with a history of complex febrile convulsions (CFCs) (n = 7; mean age 7.1 years) and in children without any history of CFCs, referred to herein as the non-CFC group (n = 6; mean age 7.6 years). Changes in the metabolite ratios were detected in 57% of children in the CFC group and in 67% of children in the non-CFC group. In both groups, NAA/(Cho + Cr), NAA/Cho, and NAA/Cr were significantly decreased ipsilaterally to the seizure focus when compared with the control group, but no significant differences were detected between the CFC and non-CFC groups. Also on the contralateral side, NAA/(Cho + Cr) and NAA/Cr were significantly decreased in both patient groups, but the differences were not significant between the CFC and non-CFC groups. Metabolite abnormalities in the mesial temporal region were detected in children with intractable epilepsy and in children whose epilepsy is well controlled by antiepileptic medication. The noninvasive 1H-MRS can be considered an additional diagnostic method to promote early detection of mesial temporal abnormalities that, in the light of this study, seem to be underdiagnosed in children with either temporal lobe epilepsy or other seizure types.

Neuroimaging and spectroscopy in children with epileptic encephalopathies

AIMSTo investigate the nature of the unifocal cortical abnormalities on FDG positron emission tomography (PET) in children with an epileptic encephalopathy but no focal abnormality on electroencephalogram or standard magnetic...

Proton magnetic resonance spectroscopy in children with Moyamoya disease

Proton magnetic resonance spectroscopy (MRS) is an effective method to noninvasively investigate cerebral metabolism. The aim of this study was to evaluate cerebral metabolic changes in children with Moyamoya disease using proton MRS. A total of 11 patients under 15 years old were enrolled, whose main symptoms were transient ischemic attacks. In nine patients, the more and less affected hemispheres could be determined according to their symptoms and/or single-photon emission computed tomography (SPECT). A single voxel point resolved spectroscopy was performed in the frontal or parietal white matter bilaterally by using 1.5 Tesla MR system (repetition time 2000 ms and echo time 272 ms). Voxels were located within areas that were normal on T1- and T2-weighted MR imaging. Choline (Cho), creatine (Cre) and N-acetyl aspartate (NAA) were semiquantitated as a metabolite value using an external standard reference. Pre-operative Cho, Cre and NAA values were within respective normal ranges. No metabolite showed a significant difference between the more and less affected hemispheres. A total of six patients were examined before and after revascularization surgery on one side. Pre- and post-operative comparisons demonstrated that all three metabolites showed statistically significant increases following surgery. These results suggest that, although the mechanism of spectroscopic changes needs to be further investigated, proton MRS provides a valuable method to evaluate cerebral metabolism in children with Moyamoya disease.

Proton magnetic resonance spectroscopy in children with temporal lobe epilepsy.

We performed proton magnetic resonance spectroscopy of the mesial temporal regions in 20 children with intractable temporal lobe epilepsy and compared results with those from 13 normal subjects. Abnormalities of the ratio of N-acetylaspartate to choline plus creatine (NAA/[Cho+Cr]) were seen in 15 patients (75%). The ratio NAA/(Cho+Cr) was correctly lateralizing in 55% and incorrectly lateralizing in none. Bilateral abnormalities were seen in 45%. Overall there was a unilateral decrease in N-acetylaspartate on the side ipsilateral to the seizure focus (mean 19% decrease vs normals, with 5% decrease on the contralateral side), suggesting neuronal loss or dysfunction. There was also a bilateral increase in creatine and choline (mean 18%), consistent with reactive astrocytosis. We conclude that proton magnetic resonance spectroscopy can contribute to lateralization of the seizure focus, and by detection of bilateral abnormalities, can contribute to the understanding of the underlying pathophysiology in temporal lobe epilepsy.

Proton magnetic resonance spectroscopy in children with acute central nervous system injury

Single voxel proton magnetic resonance spectroscopy ( 1H-MRS) was used in 30 infants and children with acute central nervous system injuries to determine the value of changes in specific metabolite ratios in predicting outcome. The mean age of all patients was 38 ± 52 months and the mean time of study after insult was 7 ± 5 days. 1H-MRS was determined in the occipital gray and parietal white matter (8 cm 3 volume, STEAM sequence with TE = 20 ms, TR = 3,000 ms). Data were expressed as ratios of different metabolite peak areas including N-acetylaspartate (NA), choline-containing compounds (Ch), creatine and phosphocreatine (Cr), and lactate (Lac). Statistically significant differences were observed when patients with good/moderate ( G M ) outcomes (n = 17; mean age: 46 months) were compared to patients with bad outcomes (n = 10; mean age: 26 months). NA Cr and NA Ch were significantly lower in the bad outcome group ( NA Cr = 1.15 ± 0.38 ; NA Ch = 1.18 ± 0.52 ) compared to the G M group ( NA Cr = 1.41 ± 0.28 , P < .05; NA Ch = 1.98 ± 0.81 , P < .01). Lactate was present in 80% of bad outcome patients and in none of the G M group ( P < .0001). Using a linear discriminant analysis and combining 4 clinical variables (Glasgow Coma Scale score, initial pH and glucose, number of days unconscious at time of 1H-MRS) allows classification of 94% of patients into their correct outcome group. Use of spectroscopy variables ( NA Cr , NA Ch , Ch Cr , presence of lactate) alone correctly classified 81% of patients. The combination of clinical and 1H-MRS variables correctly classified 100% of patients. Our findings suggest that 1H-MRS adds information which, in combination with clinical examination, may be useful in outcome assessment in children with serious acute central nervous system injury.

Brain metabolite changes on in vivo proton magnetic resonance spectroscopy in children with congenital hypothyroidism

Localized in vivo proton magnetic resonance spectroscopy and imaging were performed in five children with untreated congenital hypothyroidism to look for biochemical markers of abnormal myelin and neuronal development. The patients had high levels of choline-containing compounds, which returned to normal with euthyroidism. These metabolic alterations may reflect blocks in myelin maturation that are reversible by thyroid hormone replacement throughout childhood. (J P EDIATR 1995;126:389-92)

Evaluation of the clinical performance of automated proton magnetic resonance spectroscopy in children

Because expeditious neuroimaging is imperative in pediatric patients, we evaluated automated procedures for proton magnetic resonance spectroscopy (1H MRS) of the brain of children. 1H MRS was performed on a 1.5-T GE Signa. The protocol included stimulated echo-acquisition mode and spin-echo point resolved spectroscopy. The automated routine included adjustment of first-order gradient shims (x, y, z1) to optimize magnetic field homogeneity, transmit power, center frequency, receiver gain, and water suppression. All spectra were processed with the use of spectroscopy analysis software from General Electric on a Sun workstation. The use of the automated procedures reduced the length of our 1H MRS protocol by 50%. Magnetic field homogeneity was within our accepted standards (7 +/- 2 Hz). Water suppression was within range of our accepted factors (1000-10,000). However, on certain occasions, baseline distortions affected resonances in the 3.22-4.04 ppm range. Shortening of the time required for clinical 1H MRS will increase its application in evaluating children.