Evaluation of five protocols for quantification of two-dimensional MR spectroscopic images

Five protocols were tested for quantification on in vivo two-dimensional spectroscopic imaging datasets. The datasets are duplo measurements from three individuals. The peaks for N-acetyl aspartate, creatines, and cholines were quantified. The first of the protocols is conventional integration of a selected interval around the peak. The others are various implementations of a Gauss-Newton-based least-squares time-domain fitting algorithm. Fitting a half-echo (free-induction decay curve, FID) to a full echo was compared; this was combined with or without filtering out the water signal using the Lanczos-Hankel singular-value decomposition (LHSVD). It appears that conventional integration yields consistent and accurate results in comparison to the fitting methods. The combination of LHSVD and echo fitting performs equally well; advantages and disadvantages are discussed. The protocols using FID fitting perform poorly with these experimental datasets.