Nuclear magnetic resonance imaging and spectroscopy following asphyxia

Nuclear magnetic resonance imaging and spectroscopy have added significant new information about the newborn brain during and following asphyxia. NMR imaging has permitted sequential in vivo analysis of CNS maturation in the perinatal period that is superior in anatomic resolution, and especially in the characterization of myelination, to either cranial ultrasound or radiographic computed tomography. As a result, the accurate detection and recognition of the brain lesions associated with hypoxic-ischemic encephalopathy is now possible, including PVL, cerebral infarction, intraparenchymal and intraventricular hemorrhage, and delayed myelination. This has improved our understanding of the associated potential risk for abnormal neuro-developmental outcome with specific lesions. NMR spectroscopy has provided a metabolic window into the biochemical events during and following asphyxia. 31P MRS captures the phosphorous metabolites as levels rise and fall and shift in relation to each other to maintain cellular energy homeostasis in the face of oxygen depletion. Meanwhile, proton NMR spectroscopy promises to sustain the metabolic purview beyond the immediate cellular response to asphyxia to the chronic adaptation phase. Appropriately applied, this noninvasive technology may yet enable us to identify brain injury that is reversible in sufficient time to intervene and to diagnose accurately what is irreversible for timely prognostication. Furthermore, the integration of clinical imaging and spectroscopy capabilities is both feasible and desirable; information provided by each being mutually complementary. Imaging could improve spectroscopy interpretation by identifying the observed tissue, whereas MRS should clarify diagnosis of anatomic lesions detected by MRI. Advances in spatial resolution and speed of data acquisition may soon make integrated MRI/MRS a clinical reality.