Left atrial volume assessed by transthoracic three dimensional echocardiography and magnetic resonance imaging: dynamic changes during the heart cycle in children

Objective-To assess the dynamic changes in left atrial volume by transthora cic three dimensional echocardiography and compare the results with those o btained by magnetic resonance imaging (MRI). Design and patients-30 healthy children (15 boys and 15 girls, aged 8 to 13 years) underwent examination by three dimensional echocardiography and MRI . Methods-Three dimensional echocardiography of the left atrium was performed using rotational acquisition of planes at 180 intervals from the parastern al window with ECG gating and without respiratory gating. Volume estimation by MRI was performed with a slice thickness of 4-8 mm and ECG triggering d uring breath holding in deep inspiration. A left atrial time-volume curve w as reconstructed in each child. Results-Left atrial maximum and minimum volumes averaged 24.0 ml/m(2) and 7 .6 ml/m(2) by three dimensional echocardiography, and 22.1 ml/m(2) and 11.9 ml/m(2) by MRT. The greater left atrial minimum volume in the latter was a t least in part a result of breath holding. Dynamic changes in left atrial volume during the heart cycle were detectable by both methods. The higher t emporal resolution of three dimensional echocardiography allowed a more pre cise evaluation of different phases. Conclusions-Three dimensional echocardiography and MRI were both useful met hods for studying the physiological volume changes in the left atrium in ch ildren. These methods may be used for further study of the systolic and dia stolic function of the heart.