Lactate editing and lipid suppression by continuous wavelet transform analysis: Application to simulated and H-1 MRS brain tumor time-domain data

Determination of lactate concentrations in vivo is required in the noninvas ive diagnosis, staging, and therapeutic monitoring of diseases such as canc er, heart disease, and stroke. An iterative filtering process based on the continuous wavelet transform (CWT) method in the time domain is proposed to isolate the lactate doublet signal from overlapping lipid resonances and e stimate the magnetic resonance spectroscopy (MRS) parameters of the lactate methyl signal (signal amplitude, chemical shift, J-coupling and apparent t ransverse relaxation time (T-2(*)). This method offers a number of advantag es over the multiple quantum (MQ) and difference spectroscopy approaches, i ncluding: 1) full recovery of the lactate methyl signal, whereas the Mo met hods usually detect 50% of the signal intensity; 2) in contrast to Mo metho ds, the lipid signal is retained together with J-coupling data on the lacta te peak; 3) the CWT method is much less sensitive to motion artifacts than difference spectroscopy. Application of the method to simulated and real H- 1 MRS data collected from human blood plasma and brain tumors demonstrated that this filter provides accurate estimates of the MRS parameters of the l actate doublet and efficiently removes lipid contributions. Magn Reson Med 43:649-656, 2000. (C) 2000 Wiley-Liss, Inc.