SAR reduced black-blood cine TPM for increased temporal resolution at 3T

The objective was to improve the temporal resolution in black-blood CINE tissue phase mapping sequences at high field MR systems. The temporal resolution is limited due to SAR constraints causing idle times into the sequence. The aim was to avoid these idle times and therefore providing an increased number of heart phases.

Thirteen volunteers were enrolled in this study. Each volunteer underwent different myocardial short-axis scans comprising scans with application of both presaturation pulses, with alternating application of presaturation pulses and with an attenuation of the excitation angle. The last two approaches enable a SAR reduction or increased temporal resolution. The contrast to noise ratio (CNR) between myocardium and blood and the influence on the measured tissue motion were investigated.

High CNR between myocardium and blood could be obtained with the application of alternating presaturation-pulses. Reduction of the flip angle of the presaturation-pulses provided reduced CNR relative to both the original and the alternated presaturation-pulses approach. More details of the myocardial motion were observed with increased temporal resolution.

It is feasible to increase the temporal resolution at high field strength by reducing the SAR with either alternating presaturation-pulses or decreased flip angle of these pulses.