POSTMORTEM METABOLIC AND MORPHOLOGIC ALTERATIONS OF THE DOG BRAIN THALAMUS WITH USE OF IN-VIVO H-1 MAGNETIC-RESONANCE SPECTROSCOPY AND ELECTRON-MICROSCOPY

RATIONALE AND OBJECTIVES. TO investigate postmortem metabolic and morp hologic alterations in the dog brain thalamus and to contribute diagno stic aids in medicolegal science. METHODS. A homogeneous group of 17 d ogs was used for in vivo H-1 magnetic resonance (MR) spectroscopy and electron microscopic studies, which were performed under intravenous a nd intramuscular anesthesia before and after the dogs were killed. All H-1 MR spectroscopy and electron microscopy examinations were perform ed on a 1.5 T MR imaging/MR spectroscopy system using a stimulated-ech o acquisition mode pulse sequence and an electron microscope, respecti vely. RESULTS. The lactate resonance signal, which could be used as a criterion for tissue survival, appeared during the entire postmortem p eriod, The lactate:creatine ratio significantly increased in the early postmortem metabolic process, The inositol:creatine ratio showed a mi ld gradual increase, However, the N-acetyl-aspartate:creatine and chol ine/creatine ratios generally were unchanged, The decomposition of pro ton metabolites was observed in the MR spectrum 48 hours postmortem. I n the postmortem period, high power field (X10,000) electron microscop ic results showed significant morphologic alterations of the thalamus, revealing nuclear pyknosis and perikaryal condensation, cytoplasmic v acuoles, clumping of nuclear chromatin, and destruction of cellular or ganelles and nuclear membrane. CONCLUSIONS. Results suggest that the c ombination of H-1 MR spectroscopy and electron microscopy may simultan eously provide good quality metabolic and morphologic information of c erebral tissue in the field of thanatochronology.