Assessment of brain death in children by means of P-31 MR spectroscopy: preliminary note. Work in progress. The authors examined the possibility of assessing cerebral damage with phosphorus-31 magnetic resonance (MR) spectroscopy in 24 patients (three infants, four children older than age 5 years, and 17 adults) who met the adult criteria for brain death. In all patients except patient 3 (an infant 8 months old), inorganic phosphate with phosphodiester was observed, and adenosine triphosphate (ATP) and phosphocreatine (PCr), which are detectable in healthy brains, were not detected. In 22 of these 23 patients, cardiac death occurred within 7 days after clinical brain death, and in one infant 14 months old, cardiac death occurred 38 days after clinical brain death. In patient 3, ATP and PCr were detected with P-31 MR spectroscopy, and now, more than 20 months after brain death, cardiac death has not yet occurred. In children younger than age 5 years, P-31 MR spectroscopic findings were predictive of the patient's clinical outcome. These findings may help establish criteria for the diagnosis of brain death in children younger than age 5 years. 