Accurate T₁ determination from inversion recovery images: Application to human brain at 4 Tesla

It is well known that the signal polarity in inversion‐recovery (IR) images changes with inversion time, complicating the determination of T₁ To avoid this problem, a simple subtraction method is implemented. In this method, k‐space data of the longest inversion time are subtracted from the corresponding data of each inversion time. This subtraction yields IR images of same polarity, making it straightforward to derive T₁ using a standard fitting routine. Phantom T₁ studies with IR Turbo‐FLASH images demonstrate that this technique is robust and accurate. Four Tesla T₁ values of the human brain were also determined by this method to demonstrate its in vivo utility.