A closer look at right ventricular 3D volume quantification by transthoracic echocardiography and cardiac MRI

To compare right ventricular (RV) volumetry using state-of-the-art three-dimensional (3D) transthoracic echocardiography (3DE) and cardiac magnetic resonance imaging (CMR) near-simultaneously in a clinical setting.

Forty-seven consecutive patients received comprehensive echocardiography including 3DE within 30 minutes of CMR. RV volumetry was performed offline with semi-automated 3D endocardial border tracing as well as manual delineation of the compacted myocardium in short-axis views by CMR.

Forty-two examinations (89%) could be analysed offline by 3D RV reconstruction. Mean RV volumes assessed by CMR and 3DE were 215±63 and 127±42 ml for end-diastole (RV-EDV), as well as 110±43 and 62±27 ml for end-systole (RV-ESV). RV-EDV, RV-ESV, and RV stroke volume measured by 3DE were significantly lower than RV volumetry by CMR. Mean bias were -88, -48, and -41 ml, respectively. Mean RV ejection fraction (-EF) showed a non-significant deviation of +2% between 3DE and CMR and the correlation coefficient was r=0.58 for RV-EF.

RV-EF can be assessed reliably using transthoracic 3DE in patients with good image quality; however, absolute RV volumes measured by 3DE show a systematic deviation to CMR volumetry that has been previously neglected and requires careful interpretation regarding anatomical cardiac imaging.