Quantitative spectroscopic imaging of the human brain

Abstract

A method to provide B₁ correction and cerebrospinal fluid (CSF) referencing is developed and applied to spectroscopic imaging of the human brain at 4.1 T using a volume head coil. The B₁ image allows rapid determination of the spatially dependent B₁ that is then used to compensate for the B₁ sensitivity of the spectroscopic sequence. The reference signal is acquired from CSF located in a lateral ventricular position using a point‐resolved echo spectroscopy (PRESS) acquisition. The CSF spectrum is also corrected for B₁ dependence. Together with T₂ and T₁ corrections, this method is used to provide quantitative values of N‐acetylaspartate (NAA), creatine (Cr), and choline (Ch). The metabolite concentrations obtained from a spectroscopic imaging slice through the ventricles in seven normal controls are in good agreement with previously published literature values. This method is applied in a patient with secondary progressive multiple sclerosis, showing separate areas of abnormalities in both NAA and Cr.