Optimal saturation recovery time for minimizing the underestimation of arterial input function in quantitative cardiac perfusion MRI
Lexiaozi Fan, Kyungpyo Hong, Li-Yueh Hsu, James C. Carr, Bradley D. Allen, Daniel C. Lee, Daniel Kim
Abstract
Purpose
The purpose of this study was to determine an optimal saturation-recovery time (TS) for minimizing the underestimation of arterial input function (AIF) in quantitative cardiac perfusion MRI without multiple gadolinium injections per subject.
Methods
We scanned 18 subjects (mean age = 59 ± 14 years, 9/9 males/females) to acquire resting perfusion data and 1 additional subject (age = 38 years, male) to obtain stress-rest perfusion data using a 5-fold accelerated pulse sequence with radial k-space sampling and applied k-space weighted image contrast (KWIC) filters on the same k-space data to retrospectively reconstruct five AIF images with effective TS ranging from 10 to 21.2 ms (2.8 ms steps). Undersampled images were reconstructed using a compressed sensing framework with temporal-total-variation and temporal-principal-component as 2 orthogonal sparsifying transforms. The image processing steps included, same motion correction across five different AIF images, signal normalization by the proton-density-weighted-image, signal-to-T1 conversion using a Bloch equation, T1-to-gadolinium-concentration conversion assuming fast water exchange, T2* correction to the AIF, and gadolinium-concentration to myocardial blood flow (MBF) conversion based on a Fermi model.
Results
Among five TS values, the shortest TS (10 ms) produced significantly (P < 0.05) higher peak AIF and lower resting MBF (13.73 mM, 0.73 mL g−1 min−1) than 12.8 ms (11.24 mM, 0.89 mL g−1 min−1), 15.6 ms (9.56 mM, 1.05 mL g−1 min−1), 18.4 ms (8.55 mM, 1.17 mL g−1 min−1), and 21.2 ms (7.95 mM, 1.27 mL g−1 min−1). Similarly, shorter TS reduced underestimation of AIF (or overestimation of MBF) for both during stress and at rest, but this effect was canceled in myocardial-perfusion-reserve (MPR).
Conclusion
This study demonstrates that TS of 10 ms reduces the underestimation of AIF and, hence, the overestimation of MBF compared with longer TS values (12.8-21.2 ms).