Accurate quantitative myocardial perfusion using single cycle T1 mapping
© Chen et al; licensee BioMed Central Ltd. 2013
Published: 30 January 2013
Quantitative myocardial perfusion MRI depends on accurate determination of the arterial input function (AIF). Unfortunately, typical doses of contrast agent (CA) cause saturation in the AIF signal intensity at peak CA concentrations. Methods using dual boluses  or dual sequences  have been proposed to correct for this effect; however, they require additional data acquisition which complicates the imaging procedure. CA concentrations can be directly found by calculating blood and myocardial T1 values [3, 4]. This method was performed in vivo and compared to the dual sequence method .
Radial AIF correction was performed using the method described in . T1 relaxation following an SR magnetization preparation and FLASH acquisition can be modeled . By acquiring multiple images after a single SR and using the acquisition parameters, pixelwise T1 can be found by solving a simple non-linear data fitting exercise. Gd concentration is found using the known relaxivity of Gd CA .
Ten healthy volunteers underwent perfusion MRI studies on a Siemens 3T Verio system with IRB approval and written consent. Two first pass perfusion scans were performed at rest using a radial acquisition for T1 mapping and a dual TI Cartesian acquisition. The Cartesian scan had a resolution of 3×2×8 mm3 and TI = 120 ms. The short TI scan has TI = 28 ms. The multi-shot radial scan had a resolution of 1.7×1.7×8 mm3; 3 images per SR with TI = 50, 94, and 138 ms respectively. Reconstruction of radial data was performed using a compressed sensing method with a composite reference constraint .
Comparisons of MBF (ml/min/g) measurements using Cartesian and radial techniques. There is no significant difference between radially acquired and Cartesian MBFs.
1.96 ± 0.45
1.88 ± 0.41
1.34 ± 0.41
1.35 ± 0.27
Myocardial perfusion measurement using radial T1-mapping eliminates the need to acquire two datasets to produce an unsaturated AIF with the dual sequence approach, making it more practical for clinical use. The major problem with the dual sequence method is it produces AIF of different signal intensity scale due to different T1 weighting. The AIF needs to be scaled properly with respect to myocardial tissue function for accurate MBF measurements. The proposed method allows the myocardial tissue signal and AIF to be extracted using the same set of the images, thus eliminating a potential source of error.
NIH Grant T32 EB51705
NIH Grant RO1 EB002623
AHA Postdoctoral Fellowship Award 1POST7390063
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.