1. It is important to shift the color baseline to get a lower aliasing velocity in order to get an adequate hemispherical flow convergance profile. An aliasing velocity around 40cm/s is recommended.
2. Whether you are doing TEE or TTE a simple rule of thumb is to shift the baseline in the direction of the MR jet (this means changing the lower velocity in TTE apical views and the upper aliasing velocity in the mid esophageal TEE views.)
3. This method is only reliable for quantifying a single centrallly directed jet. In patients with multiple MR jets, or those which are eccentric the PISA method is not reliable.
4. This is just one of many ways to quantify MR. A more detailed description of others can be found in the textbook section.