Kathy
going to throw out my 2 cents (take how you want).
head MRI's have a "total margin of error" of +/- 2mm. If measurements made of the AN, post treatment, fall within the +/-2mm from the measurements given pre-treatment, it's pretty much deemed same size, which in the case of a radio-treated patient is fine. The goal of the radio-treatments is to kill the core DNA of the AN to stop it from growing anymore. Example, if the original AN size was 7mm x 4mm... and the post-treatment read showed as 12mm x 10mm.... then, there is reason for concern.
Please keep in mind that different people will read the films and give different interpretations. They actually measure differently (ie: corner to corner or across straight across, etc). Different MRI machine technologies may come into play and most importantly, the MRI "slices" may be different as well.
My CK team will read my films... my neuro-onc is always guaranteed to read my MRI differently than my radio-onc... and they are on the same team! So, for me, I take the averages of what they say and deem it as my size.
The key is this... if there is no enhanced growth... and if we are lucky... if some shrinkage does occur (not the goal of any radio-treatment but great if it happens!), then you are in good shape.
Again, just my 2 cents. May there be no enhanced growth, may you stay healthy... and may I stop overloading on coffee so early in the am!
Hang in there!
Phyl