Aims: Comparison of breath-hold MR phase contrast technique in the estimation of cardiac shunt volumes with the invasive oximetric technique.
Methods and results: Seventeen patients with various cardiac shunts (10 ASD, 3 VSD, 1 PDA, 3 PFO) and five healthy volunteers were investigated using a 1.5 Tesla system. The mean flow velocity, the mean volume flow and the transverse area in the ascending aorta and the left and right pulmonary artery were measured using the MR phase contrast breath-hold technique (through plane, FLASH 2D-sequence, TR/TE 11/5 ms, phase length 106 ms, VENC 250 cm/s). The ratio of mean flow in the pulmonary (Qp: sum of mean flows in the left and right pulmonary arteries) and the systemic circulation (Qs: mean flow in the ascending aorta) was calculated and compared with invasively measured Qp:Qs ratios. Oximetry was performed within 24 h of the MR investigation. The non-invasive shunt measurement in the 17 patients showed a mean Qp:Qs ratio of 2.00 +/- 0.86. Comparing the MR data with the invasively measured Qp:Qs showed a correlation coefficient of r = 0.91 (p < 0.001).
Conclusion: Cardiac shunt volumes can be measured reliably using a shorter acquisition time with breath-hold MR phase contrast technique.