Introduction 1 3 4 5 8 9 10 11 Subjects and methods The study included 30 patients (mean age 34 ± 13 years, 60% were males) who were scheduled for routine MRI examination for evaluation of right ventricular function (10 patients with congenital heart disease, five with chronic pulmonary disease, five with multivalvular affection, and 10 normals). 2DE and RT3DE were performed at the same day of MRI examination after their informed consent for assessment of TA. The inclusion criteria for selection were good 2D image quality, sinus rhythm and mild to moderate tricuspid regurgitation. MRI MRI MRI MRI MRI MRI MRI MRI MRI MRI 2D 2D 2D 2D 2D 3D 3D 1 3D 3D Fig. 1 A B C  Statistical analysis t P 12 Results 1 3D MRI 3D R P 2D 3D MRI R P 2D 2D P 1 2D 3D 3D r P r P Table 1 Comparison between measurements of TA size and function by 2DE, RT3DE and MRI  2DE RT3DE MRI End-diastolic TAD (mm) 33.0 ± 8.5  43.2 ± 10.0 44.1 ± 9.2 2 —- 1835 ± 425 1869 ± 392 End-systolic TAD (mm) 27.0 ± 7.8 32.0 ± 8.7 32.5 ± 8.2 2 — 1120 ± 307 1137 ± 288 TAFS (%)  18.7 ± 4.0 26.3 ± 5.9 26.7 ± 5.7 TAFAC (%) — 39.3 ± 4.9 39.5 ± 4.7 TAD: Tricuspid annular diameter, TAA: Tricuspid annular area, TAFS: Tricuspid annulus fractional shortening and TAFAC: tricuspid annular fractional area change Discussion In the present study, the morphological and functional aspects of TA were assessed by MRI and RT3DE. The main findings of our study are (1) TA shape was not circular but oval, (2) TAD measurement by RT3DE is more accurate than by 2DE, and (3) TA function was fairly correlated with RV function. 13 15 14 15 16 17 11 2D 3D MRI 5 10 18 19 20 Study limitation The main limitation of this study is that RT3DE images more critically depend on image quality than 2DE images and the value of RT3DE should be assessed in a more non-selected (image quality). Due to the high cost of MRI, a small number of patients were included. Conclusions RT3DE helps in accurate assessment of TA comparable to MRI, while 2DE could not be relied on due to underestimation. This may have important implications in the TV surgical decision-making processes. RT3DE analysis of TA function could be used as a marker of RV function.