ECG-Gated 99mTc Single-Photon Emission CT for Assessment of Right Ventricular Structure and Function: Is the Information Provided Similar to Echocardiography?

Abstract

(99m)Tc single-photon emission CT (SPECT) and ECG-gated SPECT can visualize well the right ventricle (RV) in most patients, but their utility for assessment of the RV has not been formally evaluated. We examined whether (99m)Tc SPECT/ECG-gated SPECT provide similar information to transthoracic two-dimensional Doppler echocardiography (2D-ECHO) regarding RV cavity size, wall thickness, and systolic function. Retrospective analysis. A major university teaching hospital. A consecutive series of 194 patients with good quality stress SPECT and 2D-ECHO studies performed within 1 day of each other and no significant interim cardiac events. RV size and function were visually assessed by SPECT/ECG-gated SPECT and 2D-ECHO. RV wall thickness was visually assessed by SPECT and measured in mm in end-diastole by 2D-ECHO. Of 142 patients with normal RV cavity size by SPECT, 134 patients (94%) had normal RV cavity size by 2D-ECHO. However, of 52 patients with RV dilation by SPECT, only 9 patients (17%) had RV dilation by 2D-ECHO. A perfusion abnormality in the right coronary artery territory was significantly associated with RV dilation by SPECT (p < 0.005) and 2D-ECHO (p < 0.05). Among 150 patients with ECG-gated SPECT, only 2 patients had abnormal RV systolic function, as compared with 18 patients by 2D-ECHO. RV wall thickness measurements by SPECT and 2D-ECHO did not correlate. For normal interpretations regarding RV cavity size, wall thickness, and systolic function, there is good agreement between (99m)Tc stress SPECT/ECG-gated SPECT and 2D-ECHO. However, there is poor overall agreement between gated SPECT/ECG-gated SPECT and 2D-ECHO regarding the presence of RV dilation, hypertrophy, and systolic dysfunction.