Radiation therapy or not post excision of meningioma

[Pihl]

3/9/06 large convexity meningioma over parietal lobe excised.  Per operative report all tumor removed but dura margin not resected but heavily coagulated.  Referred for radiation therapy.
3/22/05  radiation oncologist recommended therapy.
4/4/06  first post op MRI..conclusion 3.9cm ap oblique x 2.2 cm tranverse oblique residual.
5/17/06 MRI for treatment planning...conclusion...no convincing evidence of residual or recurrent tumor.  Some enchancement around margins.
   Therapy was canceled by radiation oncologist to reassess.
   Discussion one week later she said the options were to irradiate now,  but she would narrow the field;  or to have MRIs every 2 months and treat if regrowth.  She would review all and we would talk the next week.
    2nd dicussion.."no wrong decision".  Treatment would be the same and could be done now or MRI every 4 months and watch.
   Question:  The results of the 2 MRIs seem so radically different and the decision would be based on what is or isn't left.  Don't understand how a residual tumor of this size would magically disapper in a little more than a month.  Surgeon merely states he left some...has no further input.  Radiation oncologist does not  offer opinion one way or the other.  Both options ok.
Also said after radiation if recurrence surgery is the only option.  If there is significant tumor left we would choose radiation now.  If not would probably watch and hope to avoid doing it; but would still have that option open.  No one seems to want to discuss the difference in these 2 MRIs. Suggestions to help with decision?  Thx

[aerotunes]

Hello,
I had a Meningioma resection in 2002 with ~ 5% of the lesion remaining on my optic nerve.  I also have an acoustic Neuroma on my right cranial nerve.  Both were radiated using Fractionated Stereotatic Radiation.  The remaining 5% has not grown since 2-2006 and the AN has reduced in volume by 25%.   That

[CCF-Neuro-M.D.-PW]

I cannot comment on the MRIs scans without seeing them - to a certain extent MRIs are reader dependent. Did the same radiologist read both scans, and did they make a comment that they compared both scans in the second report - if so, the change may be true. It is sometimes difficult to interpret postop MRIs because there is a lot of 'post-sugical' changes lrealted to the surgery and not related to residual tumor etc.

The Cleveland Clinic Radiology Dept has a formal internet service to review and get a second opinion on radiology images if you like

Good luck