Quantification of myocardial perfusion MRI using radial data acquisition: comparison of Ktrans from dual-bolus and T1 estimation methods
Journal of Cardiovascular Magnetic Resonance volume 12, Article number: M9 (2010)
Myocardial perfusion MRI is a useful modality to detect myocardial ischemia. Quantitative perfusion estimates require an accurate arterial input function (AIF). Recently, a method for estimating T1 and thus gadolinium concentration from a radial k-space perfusion sequence was proposed . The method created four sub-images with differing effective saturation recovery times (eSRTs) from 96 ray acquisitions to estimate T1. No measures of truth were used to evaluate the method in vivo. In this work, we employ a similar technique for obtaining T1 estimates and compare to perfusion estimates from a dual-bolus method, a current standard for quantifying myocardial perfusion .
Perfusion MRI studies were performed on Siemens 3 T Trio and Verio systems. 12 subjects (8 female, 4 male) without ischemia were given a low dose (0.004 mmol/kg) of dilute (1/5 concentration) contrast agent (CA: Gd-BOPTA) and then a higher non-dilute dose (0.02 mmol/kg). In two subjects, an additional dose (0.06 mmol/kg) was used. We employed a saturation recovery radial turboFLASH sequence with 72 rays acquired in an interleaved manner, TR/TE = 2.6/1.14 msec, flip 14° and slice-thickness 8 mm. We used an iterative total variation constrained reconstruction on 72 rays for tissue curves and on two subsets of 24 rays . T1 estimates were obtained from the blood signal in the two sub-images using the equation in  and the resulting T1 curves of the AIFs were converted to concentration curves to remove the saturation effects. The images from 72 rays were processed to obtain 6 tissue curves per slice. A 2-compartment model was used to determine Ktrans.
The proposed T1 method gave AIFs that were similar to those obtained with the dual-bolus method (Fig. 1). Ktransvalues estimated from the dual-bolus and the proposed T1 methods were 0.68 ± 0.18 and 0.79 ± 0.22, respectively. (Fig. 2) shows the Ktransvalues from the new method correlate well (r = 0.83) with the dual-bolus method.
The multi-SRT T1 estimation method using an undersampled radial k-space perfusion sequence accurately quantifies myocardial perfusion for moderate (20~50%) saturation of the AIF. The method appears to also work well for higher doses (0.06 mmol/kg) although further study is needed. Unlike the dual-bolus method, the multi-SRT method requires only a single CA injection, which can greatly simplify stress studies.
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Kim, T.H., Pack, N., Chen, L. et al. Quantification of myocardial perfusion MRI using radial data acquisition: comparison of Ktrans from dual-bolus and T1 estimation methods. J Cardiovasc Magn Reson 12 (Suppl 1), M9 (2010). https://doi.org/10.1186/1532-429X-12-S1-M9