Positional localization: three-dimensional transthoracic echocardiographic techniques for the measurement of cardiac mass, volume, and function. 
An accurate and reproducible determination of cardiac volume and mass is important for the selection and timing of therapeutic interventions.  Quantitative three-dimensional echocardiography has evolved to provide these measurements with the use of a noninvasive, readily available, and inexpensive technique.  We introduce and review the principle of positional localization as well as the clinical application of this technique for the measurement of cardiac volume and mass.