Abstract
BackgroundQuantitative estimates of myocardial perfusion generally require accurate measurement of the arterial input function (AIF). The saturation of signal intensity in the blood that occurs with most doses of contrast agent makes obtaining an accurate AIF challenging. This work seeks to evaluate the performance of a method that uses a radial k-space perfusion sequence and multiple saturation recovery times (SRT) to quantify myocardial perfusion with cardiovascular magnetic resonance (CMR).MethodsPerfusion CMR was performed at 3 Tesla with a saturation recovery radial turboFLASH sequence with 72 rays. Fourteen subjects were given a low dose (0.004 mmol/kg) of dilute (1/5 concentration) contrast agent (Gd-BOPTA) and then a higher non-dilute dose of the same volume (0.02 mmol/kg). AIFs were calculated from the blood signal in three sub-images with differing effective saturation recovery times. The full and sub-images were reconstructed iteratively with a total variation constraint. The images from the full 72 ray data were processed to obtain six tissue enhancement curves in two slices of the left ventricle in each subject. A 2-compartment model was used to determine absolute flowsResultsThe proposed multi-SRT method resulted in AIFs that were similar to those obtained with the dual-bolus method. Myocardial blood flow (MBF) estimates from the dual-bolus and the multi-SRT methods were related by MBFmulti-SRT = 0.85MBFdual-bolus + 0.18 (r = 0.91).ConclusionsThe multi-SRT method, which uses a radial k-space perfusion sequence, can be used to obtain an accurate AIF and thus quantify myocardial perfusion for doses of contrast agent that result in a relatively saturated AIF.
Highlights
Quantitative estimates of myocardial perfusion generally require accurate measurement of the arterial input function (AIF)
The 72 ray combined image shows better discrimination of the myocardium and the left ventricular blood pool, each of the sub-images is of sufficient quality to obtain the multi-saturation recovery times (SRT) blood enhancement signals
The curve from the shortest effective saturation recovery times (eSRTs) has the lowest signal and the signal increases with eSRT
Summary
Quantitative estimates of myocardial perfusion generally require accurate measurement of the arterial input function (AIF). The saturation of signal intensity in the blood that occurs with most doses of contrast agent makes obtaining an accurate AIF challenging. Quantitative estimates of perfusion require that the gadolinium concentration in the arterial input function (AIF) and the myocardial tissue curves be known. This is achieved by estimating the T1 values at each time frame of the blood and tissue. Dual-bolus methods with a 1 ml first injection [3] and with dilute matched volume injections [4,5,6] have been used to enable quantitative perfusion CMR With these methods, an unsaturated AIF is obtained from a low dose injection, which is scaled and used to replace the saturated AIF from the high dose injection. The requirement of two injections can be logistically challenging and may reflect different physiological states, during vasodilation
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