AQP4 and neuromyelitis optica: In a fourth investigation, Kim et al. 2017 employed multiple forms of 1H-NMR spectroscopy, including one-dimensional proton nuclear overhauser effect spectroscopy (1D 1H-NOESY), 1H-13C heteronuclear single quantum coherence spectroscopy (1H-13C HSQC), and two-dimensional proton total correlated spectroscopy (2D 1H-TOCSY), in order to quantify and compare CSF metabolites from 57 NMO patients (of unreported AQP4-Ab or MOG-Ab serology) with 50 RRMS patients and 17 healthy controls [74].