Improving the Accuracy of T1 Measurements In Vivo: The Use of the Hyperbolic Secant Pulse in the Saturation Recovery/Inversion Recovery Sequence

Abstract

Proton NMR relaxation times reflect some of the physical properties of tissues and provide a basis for objectively measuring change in NMR images. In vivo NMR relaxation times are being measured to quantitate tumour response to therapy. This requires measurement methods that give reproducible and accurate values of relaxation times in a manner that is fast and convenient to use. The saturation recovery/inversion recovery (SR/IR) sequence (Fig. 1) is an efficient method of measuring T1. Only one sequence needs to be loaded and run, and this produces two images from which a T1 map may be readily calculated. This method has been shown to be more efficient than either the multipoint inversion recovery sequence (Kurland 1985) or the SE/SE two-point method (Gowland et al. 1988).