Synchronized inversion recovery-spin echo sequences for precise in vivo T1 measurement of human myocardium: A pilot study on 22 healthy subjects

An ECG-triggered, two-sequence MRI technique is proposed for the precise measurement of proton T₁ relaxation times of the human myocardium at 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 employs a synchronization of the 90° read pulse to the systolic period. In a study of 22 healthy volunteers, the globally measured T₁ value was estimated to be 714 ± 23 ms. Four of the volunteers also underwent additional imaging scans for the purposes of reproducibility assessment. 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. Total 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 obtained give this technique an obvious application in the discrimination of normal and diseased myocardium. In the same study, valuable supplementary tissue characterization is provided by T₂, calculated from the SE sequence. T₂ was evaluated to be 50 ± 3 ms.