Phosphorous and Proton Spectroscopy in Relation to near Incarceration and Incarceration of the Human Brain

We report 3 cases of ³¹P and ¹H MR spectroscopy (MRS) performed at different stages on patients with clinical signs of near or fulminant incarceration of the brain. The measurements were made on a whole body, 1.5 T scanner. ¹H-MRS was obtained with the STEAM sequence and ³¹P-spectra were obtained using the chemical shift imaging technique. Medical treatment including controlled ventilation and sedation of the patients was carried out during the examination. The first patient was evaluated on days 6 and 10 after evacuation of an acute subdural haematoma. An intracranial pressure of 35 mm Hg was registered during the first examination. The 2nd patient had suffered a spontaneous intracerebral haemorrhage and showed clinical signs of imminent incarceration during the examination. The 3rd patient showed clinical signs of incarceration just prior to the examination. In the 1st patient ¹H-MRS showed a 3-fold increase in the concentration of choline-containing compounds and a small decrease in N-acetyl aspartate from the 1st to the 2nd examination, which we interpret as a loss of neurones. In case 2 only small changes in metabolism could be detected, indicating that, despite signs of imminent clinical incarceration, the energy supply to the brain was substantial. ¹H-MRS of the 3rd patient showed massive lactate concentration, and ³¹P-MRS revealed the total absence of high-energy phosphorous compounds leaving only one single peak of inorganic phosphate, indicating irreversible brain death.