Comparison of ventricular volume and mass measurements from B- and C-scan images with the use of real-time 3-dimensional echocardiography: Studies inan in vitro model

Background: Real-time S-dimensional (3D) echocardiography avoids geometric assumptions in volume analysis and permits immediate visualization in any p lane without the need for cardiac or respiratory gating or computation time . This study compared the accuracy of volume and mass assessments between s tandard long-axis (B-scan) and short-axis (C-scan) views in a simplified bu t quantifiable left ventricular phantom. Methods and Results: The model comprised an inner balloon within an outer b alloon separated by ultrasonographic gel. First, to mimic different chamber volumes, 12 volumes (40 to 180 mL) of water within the inner balloon were scanned with a real-time 3D system. Second, 10 volumes (80 to 170 mL) of ge l were inserted between the balloons to mimic varying cardiac mass, and the gel volume space (mass) was calculated by subtracting the inner from the o uter balloon volume. "Chamber" and "mass" measurements for both B and C sca ns correlated closely with the actual values (r = 0.99). However, chamber v olumes from C scans were consistently less than B-scan values (mean differe nce from reference for C scans: -5.2 +/- 1.2 mL, P < .0001; for the 2 ortho gonal B scans: 0.03 <plus/minus> 1.4 mL and -0.9 +/- 1.5 mL, respectively, P = NS). Similarly, for gel volume measurements, B-scan results were closer to actual mass volumes (mean difference 0.3 +/- 2.5 and 1.7 +/- 2.9 mL) th an those of C scans, which tended to underestimate (-4.5 +/- 2.5 mL, P < .0 001). Conclusion: Our study suggests that real-time 3D echocardiography should pr ovide an accurate means of determining chamber volumes and cardiac mass. Ho wever, measurements performed from B-scan views may be closer to the actual values than those from C-scan views, presumably since they are less highly influenced by distortions related to lateral resolution.