THE PULMONARY-ARTERY ACCELERATION TIME DETERMINED WITH THE MR-RACE-TECHNIQUE - COMPARISON TO PULMONARY-ARTERY MEAN PRESSURE IN 12 PATIENTS

The goal of our study was to evaluate a rapid noninvasive MR technique for quantification of the pulmonary artery acceleration time (PAT) an d other parameters of pulmonary hemodynamics and to correlate with pul monary artery mean pressure (mPAP). The PAT known as ''time-to-peak'' out of Doppler echocardiographic measurements normally shows significa nt inverse correlation with mPAP. With the MR-RACE-Technique (RACE: Re al time ACquisition and Evaluation of motion) blood velocity measureme nts can be obtained with a total acquisition time of a few seconds. Th e application of this technique to the pulmonary artery has not been r eported before. Out of the RACE velocity wave form PAT can be obtained with a temporal resolution of about 15 ms. To explore the relationshi p between PAT and mPAP, right heart catheterization and MR-RACE measur ements were performed in 12 patients with different pulmonary vascular abnormalities. Results of MR-RACE were compared with those of mPAP me asured by right heart catheter and showed significant inverse correlat ion (r = -0.82, p =.0011, n = 12). The ability of MR-RACE to enable me asurements of blood flow with profiles may be important for characteri zing pulmonary and cardiovascular abnormalities.