Gabriele Ende

Effects of age, medication, and illness duration on the N-acetyl aspartate signal of the anterior cingulate region in schizophrenia

The authors performed a MRSI study of the anterior cingulate gyrus in 19 schizophrenic patients under stable medication and 16 controls in order to corroborate previous findings of reduced NAA in the anterior cingulate region in schizophrenia. Furthermore, correlations between NAA in the anterior cingulate gyrus and age or illness duration have been determined. A decreased NAA signal was found in the anterior cingulate gyrus of patients compared to controls. Subdividing the patient group into two groups depending on medication revealed that the group of patients receiving a typical neuroleptic medication showed a lower mean NAA in comparison to the group of patients receiving atypical antipsychotic drugs. No significant group differences in the creatine and phosphocreatine signal or the signal from choline-containing compounds were found. The NAA signal significantly correlated with age, and therefore, individual NAA values were corrected for the age effect found in the control group. The age-corrected NAA signal in schizophrenia correlated significantly with the duration of illness. The detected correlations of NAA decrease with age and illness duration are consistent with recent imaging studies where progressing cortical atrophy in schizophrenia was found. Further studies will be needed to corroborate a possible favorable effect of atypical antipsychotics on the NAA signal.

Temporal lobectomy for epilepsy: Recovery of the contralateral hippocampus measured by 1H MRS

1H MRS imaging was obtained from 10 patients with mesial temporal lobe epilepsy before and after surgery. After surgery, metabolic recovery in the contralateral hippocampus was detected. Preoperatively, reduced N-acetylaspartate (p < 0.04) increased after surgery nonsignificantly to equal control values. Cholines increased after surgery (p < 0.02) and creatine–phosphocreatine showed a trend to higher values. The results suggest that the contralateral hippocampus is affected by repeated seizure activity in the ipsilateral hippocampus, rather than presence of bilateral mesial temporal sclerosis.

In vivo hippocampal glucose metabolism in mesial temporal lobe epilepsy

Background: The appearance of decreased 2-[18F]fluoro-2-deoxy-d-glucose (FDG) uptake in the mesial temporal region in temporal lobe epilepsy may simply reflect loss of gray matter due to hippocampal atrophy. Increased partial volume effects due to atrophic hippocampi may further increase appearance of hypometabolism. Methods: The authors used a combination of MRI-PET coregistration, with MRI-based gray matter segmentation, and partial volume correction to improve the examination of hippocampal specific glucose uptake in FDG PET. The goal was to determine 1) if relative mesial temporal hypometabolism is an artifact of gray matter (hippocampal) atrophy, 2) whether hippocampal metabolism correlates with atrophy evaluated on MRI, and 3) if MRI-based partial volume correction influences measurement of hippocampal metabolic-volume relationships, including epilepsy lateralization. Results: Findings showed that ipsilateral hippocampi of mesial temporal lobe epilepsy (MTLE) are relatively hypometabolic per unit of gray matter volume, and that hippocampal metabolism directly correlates with hippocampal volume. Specifically, partial volume corrected hippocampal metabolism correlated strongly (r = 0.613, p < 0.001) with hippocampal volume. Without partial volume correction, a weaker, but still significant, correlation was present (r = 0.482, p < 0.001). Degree of asymmetry was consistently greater and provided higher sensitivity of lateralization with partial volume vs non–partial volume corrected metabolic measurements. Conclusions: Although, decreased metabolism may occur in the absence of neuronal cell loss, hippocampal atrophy and presumed degree of neuronal cell loss appears to be a primary factor involved in the cause of decreased metabolism in epileptogenic hippocampi. Partial volume correction is recommended for optimal interpretation of hippocampal structure and function relationships.

Alcohol consumption significantly influences the MR signal of frontal choline-containing compounds

The aim of this work was to evaluate the relationship between the amount of alcohol consumption of a group of social drinkers and the magnetic resonance spectroscopy signal of choline-containing compounds (Cho) in the frontal lobe. Two independent long echo (TE = 135 ms) (1)H MRSI studies, the first comprising 24 subjects with very low alcohol consumption, the second 18 subjects with a more widespread alcohol consumption were conducted. Significant correlations of Cho measures from frontal white matter and from the anterior cingulate gyrus with alcohol consumption in the last 90 days prior to the MR examination were found. Age, gender, and smoking did not show significant effects on the metabolite measures. Partialling out the effect of the voxel white matter content did not change the correlation of choline measures with alcohol consumption. The main conclusion from the repeated finding of a positive correlation of alcohol consumption and frontal Cho signals is that monitoring for alcohol consumption is mandatory in MRS studies where pathology depended Cho changes are hypothesized.

Multiregional 1H-MRSI of the hippocampus, thalamus, and basal ganglia in schizophrenia

Abstract.Background: The hippocampus, thalamus and basal ganglia are among the brain regions of major interest in schizophrenia. Aims: The purpose of this study was to corroborate previous findings of reduced N-acetylaspartate in the hippocampal and thalamic regions and to investigate possible metabolite changes in the putamen in schizophrenia. Method: MRSI study of the thalamus, basal ganglia, and hippocampus in 13 schizophrenic patients under stable medication and age-matched healthy controls. Results A decrease of the N-acetylaspartate signal was found in the hippocampal region and the thalamus but not in the putamen of patients compared to controls. No significant group differences in the signals from creatine and phosphocreatine, and choline-containing compounds were found in the hippocampal region and the putamen but the signal from choline-containing compounds was decreased in the thalamus of patients. Conclusion: Metabolic processes in the basal ganglia of schizophrenic patients seem to be opposite the hippocampal and thalamus findings.

Subcortical and medial temporal MR-detectable metabolite abnormalities in unipolar major depression

The purpose of the present study was to determine whether MR-detectable alterations of choline-containing compounds in two key neural systems involved in major depression disorder namely the hippocampus and the basal ganglia can be detected. Multislice proton magnetic resonance spectroscopic imaging was applied in 11 patients with major depressive disorder (MDD) and ten matched healthy subjects. Voxels were selected from the left and right side of the hippocampus and the putamen. Significantly lower choline-containing compounds in the hippocampus and significantly higher choline-containing compounds in the putamen of patients with MDD compared to healthy subjects were found. No significant differences were found for the other metabolites in the two regions evaluated. Abnormal levels of choline-containing compounds most likely reflect altered membrane phospholipid metabolism. A reduced level in the hippocampus and an increased level in the putamen suggest regionally opponent membrane abnormalities.