REFERENCE TECHNIQUES FOR LEFT-VENTRICULAR VOLUME MEASUREMENT BY 3-DIMENSIONAL ECHOCARDIOGRAPHY - DETERMINATION OF PRECISION, ACCURACY, AND FEASIBILITY

The use of multiple in vitro reference methods to validate three-dimen sional (3-D) echocardiographic techniques makes comparison difficult. In an attempt to establish a reference standard, we studied precision, accuracy, and feasibility of a true Left ventricular (LV) volume meas urement in, six dog heart specimens using three techniques, called flu id, sheath, and cast. LV volumes ranged from 30 to 105 mL. Intraobserv er variability was minimal in all combinations (1.26% to 2.8%) with a statistically insignificant tendency to higher values in the cast meth od. The cast method, however, exhibited significantly higher interobse rver variability (5.78%) as compared to that ranging from 1.47% to 1.5 9% in the remaining two techniques. Regression analysis demonstrated h igh correlations among the three techniques assessed by 95% confidence Limits and correlation coefficient (R-2 > 0.98, P < 0.01). Mean diffe rences among the techniques (0.12 to 1.08 mL) were not significant. Th e fluid technique was easy to perform. The sheath technique required s ome practice. The cast method was sensitive to accurate preparation of a gelatin mixture. We conclude that the fluid and sheath techniques a re precise, accurate, and feasible. We recommend their use as referenc e standards in Laboratory LV volume measurement. Validation. 3-D echoc ardiographic studies using either of these two techniques will be comp arable. Although the accuracy of the cast technique is excellent, its lower precision makes it a second choice. It could be used in cases wh ere an LV cavity cast is required and higher interobserver variability is acceptable.