COMPARISON OF EJECTION FRACTION USING MUGA AND 3D ECHOCARDIOGRAPHY
Author Block PM DeJong, R Pal, A Johri, PA Dutchak, D Brouillard, M Matangi
BACKGROUND: In Canada MUGA scanning is an accepted standard for measurement of ejection fraction (EF). We compared EF as measured by 3D echocardiography (ECHO) with MUGA scanning.
METHODS: 65 patients referred for MUGA scanning also underwent 3D ECHO for measurement of EF. 3D ECHO was performed first and was followed immediately by MUGA scanning with Technetium 99m labelled red blood cells using an in-vivo technique. 3D images were acquired using a GE VIVID E9 system with a 4V probe. These images were then analysed offline using the TOMTEC 4D LV volumes and EF analysis software. The 3D ECHO and MUGA scanning analysis were performed by two separate investigators. Each investigator was blinded to the EF results of the other. The EF data from 3D ECHO and MUGA scanning was then collected and analyzed by a third investigator. A paired t test was used to assess differences between the mean values for each method. A p value of 95% of data points were within ± 1.96 standard deviations from the mean difference between the two methods.
RESULTS: Of the 65 MUGA scans only 50 3D ECHOs had analysable images in at least two orthogonal views. There were 13 females and 37 males with a mean age of 64.8 ± 13.6. The mean EF by MUGA was 45.7 ± 12.2% compared to 46.2 ± 11.3% by 3D ECHO (P = 0.5538). The Bland-Altman scatter plot (see figure 1.) shows that 98% of data points lay within ± 1.96 standard deviations from the mean difference of the two methods.
CONCLUSION: When image quality allows, 3D ECHO offers a comparable alternative to MUGA scanning for the measurement of ejection fraction. The Bland-Altman scatter plot indicates these methods are interchangeable. This may have important clinical implications with respect to patients requiring frequent serial measurements of EF which can be done reliably in the absence of radiation exposure.