Accurate myocardial T 1 measurements: Toward quantification of myocardial blood flow with arterial spin labeling

In this study, we investigated a method for accurately measuring myocardial T 1 for the quantification of myocardial blood flow (MBF) with arterial spin labeling (ASL). A single‐shot gradient‐echo (GE)‐based ASL sequence with an adiabatic hyperbolic secant inversion recovery pulse was modified to acquire a pair of myocardial T 1 's within a breath‐hold. A multivariable regression algorithm that accounted for the magnetization saturation effects was developed to calculate T 1 . The MBF was then determined with a well‐developed model. The accuracy of our T 1 calculation was first evaluated in a phantom, and then in six dogs for the MBF calculation, with ( N = 4) and without ( N = 2) coronary artery stenosis. In the phantom study, the accuracy of T 1 measured with a slice‐selective inversion prepared pulse was within 2.5% of error. In healthy dogs, the MBF increased 2–5 times during vasodilation. In contrast, regional differences of MBF were well visualized in the stenotic dogs during vasodilation (perfusion reserve of 2.75 ± 0.83 in normal myocardium, and 1.46 ± 0.75 in the stenotic area). A correlation analysis revealed a close agreement in MBF between the ASL and microsphere (MS) in both healthy and stenotic dogs. In summary, the modified ASL technique and T 1 regression algorithm proposed here provide an accurate measurement of myocardial T 1 and demonstrate potential for reliably assessing MBF at steady state. Magn Reson Med 53:1135–1142, 2005. © 2005 Wiley‐Liss, Inc.