Rapid measurement of T1 with spatially selective pre-inversion pulses.

A method is described for rapidly obtaining a multipoint estimate of T1 from a sample that is homogeneous over a few millimeters. An image of the longitudinal recovery curve is produced through the application of successive "pre-inversion" slices that are perpendicular to the imaging slice. These pre-inversion pulses are analogous to pre-saturation pulses, but they are much thinner and the tip angle is 180 degrees. The baseline for the recovery is measured from sections of the sample that have not been perturbed by the slice selective pre-inversion pulses. The existence of the baseline value and the lack of slice profile effects allows a quick T1 estimate (QT1) to be made with a simple linear regression algorithm. The QT1 values are found to correlate very well with T1 values measured with the scanner in "spectrometer' mode, for volumes as small as 5 x 5 x 5 mm. Possible applications are T1 estimates in homogeneous samples and tissues, and scouting the T1 range of a tissue to be measured with higher resolution volume localization techniques.