SYNCHRONIZED INVERSION RECOVERY-SPIN ECHO SEQUENCES FOR PRECISE INVIVO T1 MEASUREMENT OF HUMAN MYOCARDIUM - A PILOT-STUDY ON 22 HEALTHY-SUBJECTS

An ECG-triggered, two-sequence MRI technique is proposed for the preci se measurement of proton T1 relaxation times of the human myocardium a t a field strength of 0.5 T. The combination of an inversion recovery (IR) sequence and a spin echo (SE) sequence is not new. It is, however , rarely used in quantitative in vivo cardiac studies. Our approach em ploys a synchronization of the 90-degrees read pulse to the systolic p eriod. In a study of 22 healthy volunteers, the globally measured T1 v alue was estimated to be 714 +/- 23 ms. Four of the volunteers also un derwent additional imaging scans for the purposes of reproducibility a ssessment. The T1 precision was found to be 3.9 +/- 1.1% for the IR/SE combination and 16.9 +/- 5.3% for a combination of SE sequences. Tota l imaging time for the IR and SE sequences was 19.2 +/- 3.0 mins. The relative rapidity of this classic technique and the T1 precision obtai ned give this technique an obvious application in the discrimination o f normal and diseased myocardium. In the same study, valuable suppleme ntary tissue characterization is provided by T2, calculated from the S E sequence. T2 was evaluated to be 50 +/- 3 Ms.