99Tcm-HMPAO SPET and 1H-MRS (proton magnetic resonance spectroscopy) in patients with ischaemic cerebral infarction

Mesial temporal lobe Cho to Cr(PCr) ratio asymmetry in chronic schizophrenics

Proton magnetic resonance spectra (MRS) were acquired from 1.5 x 1.5 x 1.5-cm voxels in the left and right mesial temporal lobes of 20 schizophrenic patients and 20 non-psychiatric comparison subjects. Choline (Cho) to creatine (and phosphocreatine) (Cr(PCr)) ratios were estimated as were the percent gray matter, white matter and CSF contributing to the voxel. The Cho/Cr(PCr) metabolite ratio was significantly lower in the left temporal lobe than in the right temporal lobe for both the schizophrenia subjects and control group. This difference was greater in the schizophrenia subjects. Left temporal lobe gray matter voxel content was significantly higher and white matter content was significantly lower than in the right temporal lobe for both the schizophrenia subjects and control group. This difference was the same for the schizophrenia subjects and control group. Left voxel gray matter and white matter content correlated with Cho/Cr(PCr) metabolite ratios for the schizophrenic subjects but not for the control subjects. No such correlations were noted on the right side. No significant difference was found between Cho/Cr(PCr) in the left temporal lobe or in the right temporal lobe of the schizophrenia subjects vs. the control group.

Quantitative evaluation of cerebral metabolites and cerebral blood flow in patients with carotid stenosis

We examined the metabolic and hemodynamic status of patients with severe carotid stenosis and evaluated the effectiveness of carotid endarterectomy (CEA) by comparing pre- and post-operative results of quantitative proton magnetic resonance spectroscopy (1H-MRS) and single-photon emission computed tomography (SPECT). Quantitative 1H-MRS and SPECT were performed in 17 patients with severe carotid stenosis before CEA; in 10 patients the examinations were repeated after CEA. There was a significant correlation between the degree of internal carotid artery (ICA) stenosis and the N-acetyl-aspartate (NAA) concentration, and between CBFand NAA in the basal ganglia. In 10 of the 17 patients (58.8%) we noted a decrease of NAA on 1H-MRS. After CEA in these patients, NAA was significantly increased, and in 7 of 8 patients whose pre-operative SPECT had indicated impairment of cerebral vasoreactivity, it was improved. Quantitative 1H-MRS and CBF measurements can indicate the severity of metabolic and hemodynamic impairment in patients with severe carotid stenosis, and can help to assess the effectiveness of CEA.

Comparison of metabolite levels and water diffusion between cortical and subcortical strokes as monitored by MRI and MRS

Labelle M, Khiat A, Durocher A, et al. Comparison of metabolite levels and water diffusion between cortical and subcortical strokes as monitored by MRI and MRS. Invest Radiol 2001;36:155-163.

RATIONALE AND OBJECTIVES

Proton magnetic resonance spectroscopy (MRS) and functional imaging techniques are increasingly recognized as useful tools for the characterization of strokes. The aim of this study was to compare cortical and subcortical (lacunar) strokes by MRS and diffusion-weighted imaging (DWI) experiments as a function of time.

METHODS

Single-voxel MRS, DWI, and perfusion-weighted imaging data were recorded on patients with cortical (n = 7) or subcortical (n = 7) strokes in the acute, subacute, and chronic periods. Magnetic resonance spectra were acquired in three regions: hyperintense DWI area, adjacent area with normal DWI intensity, and contralateral area. Neurological deficits were estimated by the National Institutes of Health Stroke Scale.

RESULTS

Decreases in N-acetylaspartate, choline-containing compounds, and creatine/phosphocreatine signal intensity as well as the presence of lactate were observed at all times in the hyperintense DWI area of all lesions. Small decreases were measured in the subacute and chronic phases for the adjacent area of cortical strokes but not for the adjacent area of subcortical strokes. The existence of a surrounding affected area in subcortical strokes is deduced from a combination of MRS and DWI results, possibly corresponding to the ischemic penumbra. Differences were found between the two types of lesion, especially an increased time variability of apparent diffusion coefficients in subcortical strokes.

CONCLUSIONS

Magnetic resonance spectroscopy provides evidence for the existence of affected tissue outside the hyperintense DWI regions in subcortical strokes. Cortical and subcortical strokes display different DWI and MRS characteristics.

Clinical studies on three cases of the interval form of carbon monoxide poisoning: serial proton magnetic resonance spectroscopy as a prognostic predictor

Three patients with the interval form of carbon monoxide (CO) poisoning were studied for associations between their clinical courses and serial changes on: (1) MRI; (2) EEG; (3) single photon emission computed tomography with N-isopropyl-p-[123I]iodoamphetamine ([123I]IMP SPECT); and (4) proton magnetic resonance spectroscopy ([1HIMRS) to evaluate their usefulness as prognostic predictors. A hyperintense area on MRI T2-weighted images and a hypointense area on T1-weighted images, appearing in the deep white matter, persisted for a prolonged period even after improvement of the clinical symptoms, and did not become an accurate indicator of clinical evaluation or prognosis. [1H]MRS studies with the volume of interest set in the frontal lobe white matter revealed increases in choline-containing compounds, and reductions of N-acetylaspartate in all cases. These findings normalized in one subclinical case over time. Distinctive findings in the severe cases included increased lactate in two cases showing akinetic mutism, with a difference in prognosis noted according to the degree and period of persistence of this increase. EEG findings were relatively well correlated with clinical symptoms in the early period, with a good correlation no longer consistent after a certain period was exceeded. [123I]IMP SPECT findings did not always reflectclinical symptomatology either. These results indicate that [1H]MRS is the most useful indicator in the clinical evaluation of patients with the interval form of CO poisoning.