phosphorus-radioisotopes and Cerebral-Infarction

Magnetic resonance spectroscopy (MRS) allows the noninvasive study of metabolism in vivo. In order to further understand the time course of biochemical changes during cerebral infarction, we performed the MRS study with pathological analysis. The left middle cerebral artery (MCA) was occluded in spontaneously hypertensive male rats (SHR) by the method of Tamura et al. The spectra were obtained from the infarcted hemisphere by placing the surface coils over the left side of the calvarium. 31P and 1H-MRS were performed at 3 hours, 24 hours and 7 days after MCA occlusion. Ischemic lesions caused by the left MCA occlusion extended into the parietal lobe and caudate putamen. After 3 hours of ischemia, vacuolated neurophils and shrunken neurons were observed. At 24 hours, these changes were severe. After 7 days, infiltration of monocytes and capillary hyperplasia were seen, and neurons had disappeared. At the acute stage of ischemia the phosphocreatine/inorganic phosphate (PCr/Pi) peak ratio decreased. After 7 days of ischemia, these changes became obscure. The intracellular pH (pHi) decreased after 3 hours of ischemia and recovered almost to the control level at 24 hours post ischemia. Alkalosis was apparent 7 days after ischemia. This alkalosis might be due to increased permeability of the deteriorated blood brain barrier. Although the lactate level was high 24 hours post ischemia, the pHi was almost normal. The N-acetylaspartate/creatine ratio decreased significantly from the acute stage of stroke. This decrease correlated with pathological changes. The correlation of the magnetic resonance spectra with the histological results may opens aspects for monitoring stroke therapy and a new approach to tissue characterization.

Topics: Animals; Brain; Brain Chemistry; Cerebral Infarction; Hydrogen; Magnetic Resonance Spectroscopy; Male; Phosphates; Phosphorus Radioisotopes; Rats; Rats, Inbred SHR

Longitudinal study of metabolic change after cerebral infarction was done using nuclear magnetic resonance spectroscopy (MRS). Localized completed infarction model induced by intra-cranial ligation of the middle cerebral artery and extra-cranial ligation of common carotid artery in rats was utilized. In acute study the proton MRS revealed a sharp increase of lactic acid but the phosphorus -31 MRS did not show prominent changes. This increase of lactic acid persists 24 hours after the induction of infarction. In chronic study the spectroscopic pattern of the infarcted brain showed minimum difference from the control normal brain. However the signal intensity of phosphomonoester was significantly higher in the infarcted brain. Our study in acute phase suggests that the proton MRS is a sensitive probe to detect an early metabolic deterioration induced by ischemic insult. And the increase of phosphomonoester in chronic infarcted brain may imply that a gliosis seen in chronic infarction has a metabolic resemblance to neonate brain and neoplasm.

Topics: Animals; Brain; Cerebral Infarction; Disease Models, Animal; Energy Metabolism; Lactates; Lactic Acid; Magnetic Resonance Spectroscopy; Male; Phosphates; Phosphorus Radioisotopes; Protons; Rats; Rats, Inbred Strains

Topics: Aged; Basal Ganglia; Bloodletting; Cerebral Infarction; Chorea; Female; Humans; Phosphorus Radioisotopes; Polycythemia Vera; Regional Blood Flow; Tomography, X-Ray Computed