From the Guidelines

Echocardiography (echo) is generally more sensitive than computed tomography (CT) for detecting right ventricular (RV) dilation.

Echo is the preferred first-line imaging modality for evaluating RV size and function because it provides real-time assessment of cardiac chambers and is widely available, relatively inexpensive, and does not expose patients to radiation 1.
Echo allows for both qualitative visual assessment and quantitative measurements of RV dimensions, including basal diameter, mid-cavity diameter, and longitudinal dimension.
Additionally, echo can assess RV function through various parameters such as tricuspid annular plane systolic excursion (TAPSE), fractional area change, and tissue Doppler imaging.
While CT can provide excellent anatomical detail of the RV, particularly in patients with poor echo windows, it is limited by being a static imaging technique that captures the heart at specific moments in the cardiac cycle, potentially missing dynamic changes in RV size.
CT also has limitations in functional assessment compared to echo, as noted in the 2018 AHA/ACC guideline for the management of adults with congenital heart disease, which highlights the value of CMR in assessing RV size and function, but also mentions the emerging role of real-time 3D echocardiography 1.
The superior sensitivity of echo for RV dilation makes it the standard approach for initial evaluation, though CT may be complementary in specific clinical scenarios where additional anatomical information is needed.

The choice between echo and CT should be guided by the individual patient's needs and characteristics, such as the presence of poor echo windows or the need for detailed anatomical information.
The use of 3D transthoracic echocardiography has been validated in patients with various cardiac conditions, including pulmonary regurgitation, secundum atrial septal defects, tetralogy of Fallot repair, Ebstein’s anomaly, and RV cardiomyopathy 1.
Assessment of RV function is crucial in cardiovascular surgery, as right-sided heart failure is a common cause of morbidity and mortality after valvular and congenital surgery, coronary artery bypass, and heart transplantation.

From the Research

Echocardiography is a commonly used imaging modality for assessing right ventricular (RV) size and function, with parameters such as RV end diastolic area (RVEDA) and RV fractional area change (RVFAC) showing good correlation with RV volume and function 2.
Computed Tomography (CT) can also be used to assess RV function, with findings such as septal deviation and increased RV/left ventricular ratio showing varying degrees of sensitivity and specificity for RV dysfunction compared to echocardiography 3.
A study comparing CT and echocardiography for detecting RV dysfunction in acute pulmonary embolism found that CT had a sensitivity of 0.83 and specificity of 0.75 for RV dysfunction, although the diagnostic accuracy varied depending on the specific CT findings 3.
Another study found that RV dilatation was more commonly associated with bilateral pulmonary embolism, main pulmonary artery embolism, and lobar pulmonary embolism, and that echocardiography could be used to diagnose RV dilatation in these patients 4.

Echocardiography has been shown to have a sensitivity of 84% and specificity of 100% for detecting RV dilatation using the RVEDA parameter 2.
CT has been shown to have a sensitivity of 0.31 and specificity of 0.98 for detecting RV dysfunction using the septal deviation parameter, and a sensitivity of 0.83 and specificity of 0.75 using the increased RV/left ventricular ratio parameter 3.
The sensitivity and specificity of CT for detecting RV dilation may vary depending on the specific findings and the population being studied 3.

While echocardiography and CT can both be used to assess RV size and function, cardiac magnetic resonance imaging (CMR) is considered the gold standard for RV assessment due to its high spatial resolution 2, 5.
Further studies are needed to compare the diagnostic accuracy of echocardiography and CT for RV dilation and to determine the optimal imaging modality for specific clinical scenarios 3.