Accuracy of Cardiac MRI

[vkrietsch]

In Feb of this year I was diagnosed with PPCM (pregnancy induced cardiomyopathy) with an EF of 40-45%.  I had no symptoms so my cardiologist ordered another ECHO in April that showed my EF to still be in the 40-45% range, but he said it looked a little better.  In May, I had a cardiac MRI done and it showed an EF of 57%, which I was obviously very happy about.  My question is, which is more accurate, ECHO or MRI?  I had one cardiologist tell me that MRIs over-read EF and she typically takes the number from most recent ECHO and from MRI and splits the difference and says that is what your EF is.  

[CCFHeartMD11]

Cardiac MRI is the most accurate available noninvasive imaging technique for determination of EF.

[vkrietsch]

In response to your answer, since I am going in for another ECHO in July, should I expect the results of this ECHO to be similar to my cardiac MRI results?  Or it likely that the ECHO will show a lesser EF because it is not as advanced a technology?

Thanks!