Increasing the speed of relaxometry-based compartmental analysis experiments in STEAM spectroscopy

• Published in: Journal of magnetic resonance (1997) Vol. 173; no. 1; pp. 169 - 174
• Main Authors: Knight-Scott, Jack, Dunham, S. Andrea, Shanbhag, Dattesh D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2005
• Subjects: Adolescent; Adult; Brain Chemistry; Female; Humans; Magnetic Resonance Spectroscopy - methods; Male; MRS; Signal Processing, Computer-Assisted; Spin–lattice relaxation; Spin–spin relaxation; Transverse relaxation; Water - analysis; Spin–spin relaxation; Spin–lattice relaxation; Transverse relaxation; T 2; MRS
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2004.12.001

In this work we present a method for improving the speed of spin–spin relaxation time ( T 2) measurements for compartmental analysis in stimulated echo localized magnetic resonance spectroscopy without reducing the sampling density. The technique uses a progressive repetition time (TR) to compensate for echo time (TE) dependent variations in saturation effects that would otherwise modulate the received signal at short TRs. The method was validated in T 2 studies on 10 young healthy subjects in spectroscopic voxels localized along either the right or left Sylvian fissure (2 × 2 × 1.5 cm 3, 10 ms mixing time (TM), 2048 data points, 819.2 ms acquisition time). The TR was automatically adjusted so that TR–TM–TE/2 was kept constant as the TE was incremented. Compared to long TR T 2 experiments, the progressive TR technique consistently replicated the T 2 relaxation times and reference signals of the tissue water compartment while reducing the data acquisition time by more than 50%. The percent error was on average less than 2% for estimates of T 2 and S 0 for the tissue water, an indication that the progressive TR technique is a useful method for determining the tissue water signal for internal referencing.