The size of an intracardiac mass (vegetation, tumor, or thrombus) is an important predictor for embolic events and for response to treatment. Maximum diameter measurements from two-dimensional (2D) echocardiography are routinely used to determine mass size. However, most masses are irregularly shaped, making it difficult to accurately image or select the largest diameter. The selection of a diameter that is not truly the largest may lead to underestimation of the true size of the mass and a misrepresentation of the patients' prognosis. Three-dimensional (3D) echocardiography images the entire volume of a mass allowing for accurate measurements in multiple planes. We tested the hypothesis that measurements of the maximum diameter of a mass by 3D echocardiography are larger than those obtained by 2D echocardiography.
Methods: Patients with findings of an intracardiac mass by 2D transthoracic (TTE) or transesophageal (TEE) echocardiogram were imaged using real-time three-dimensional echocardiography (RT3DE) within 24 hours. The complete mass was acquired on RT3DE. Maximum mass diameter was measured on 2D and RT3DE. Comparison of measurements between RT3DE and 2D was performed using correlation coefficients and Bland-Altman analyses.
Results: In 19 masses evaluated in 17 patients, there was a strong correlation between 2D TTE and RT3DE maximum diameter measurements (R2 = 0.88, P < 0.01) but correlation was fair for 2D TEE (R2 = 0.48, P = 0.02). In addition, 2D maximum diameter also correlated with 3D volumes (R2 = 0.72, P < 0.01 for TTE and R2 = 0.56, P < 0.01 for TEE). However, there was a consistent underestimation of maximum diameter measured by 2D (TTE and TEE) regardless of the size, location, and etiology of the mass. 2D TTE underestimates cardiac mass size by 24.6% (P < 0.001) compared to RT3DE and 2D TEE underestimated size by 19.8% (P = 0.01).
Conclusion: These findings suggest that RT3DE may be the technique of choice for the noninvasive evaluation of intracardiac mass size.