Blood-myocardium Contrast Research Articles

Multishot EPI-SSFP in the heart.

Refocused steady-state free precession (SSFP), or fast imaging with steady precession (FISP or TrueFISP), has recently proven valuable for cardiac imaging because of its high signal-to-noise ratio (SNR) and excellent blood-myocardium contrast. In this study, various implementations of multiecho SSFP or EPI-SSFP for imaging in the heart are presented. EPI-SSFP has higher scan-time efficiency than single-echo SSFP, as two or more phase-encode lines are acquired per repetition time (TR) at the cost of a modest increase in TR. To minimize TR, a noninterleaved phase-encode order in conjunction with a phased-array ghost elimination (PAGE) technique was employed, removing the need for echo time shifting (ETS). The multishot implementation of EPI-SSFP was used to decrease the breath-hold duration for cine acquisitions or to increase the temporal or spatial resolution for a fixed breath-hold duration. The greatest gain in efficiency was obtained with the use of a three-echo acquisition. Image quality for cardiac cine applications using multishot EPI-SSFP was comparable to that of single-echo SSFP in terms of blood-myocardium contrast and contrast-to-noise ratio (CNR). The PAGE method considerably reduced flow artifacts due to both the inherent ghost suppression and the concomitant reduction in phase-encode blip size. The increased TR of multishot EPI-SSFP led to a reduced specific absorption rate (SAR) for a fixed RF flip angle, and allowed the use of a larger flip angle without increasing the SAR above the FDA-approved limits.

Characterization of t1 relaxation and blood-myocardial contrast enhancement of NC100150 injection in cardiac MRI.

A new ultrasmall superparamagnetic iron oxide (Clariscan; NC100150 Injection) was studied in domestic farm pigs. The T1 effects were characterized for blood and myocardium and the blood-myocardial contrast was measured in T1-weighted cine images. The contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were measured at baseline and contrast doses of 1 and 5 mg Fe/kg body weight (bw) at end diastole and late systole. The T1 values for blood and myocardium were reduced by 97 and 43%, respectively, from baseline to 5 mg Fe/kg bw. The CNR was significantly improved with contrast at end diastole and late systole. The maximum improvement shown was 202% at 5 mg Fe/kg bw in late systole. The percent SNR enhancement was significantly higher in blood than myocardium at late systole. NC100150 Injection is an effective T1 shortening agent and can be used to improve blood-myocardial contrast in cine images of the heart. J. Magn. Reson. Imaging 1999;10:784-789.