moving brains mets

[RickyScott]

pt presented with arm weakness. MRI showed several brain mets and patient was put on steroids. Planning CT w/contrast 2 days after steroid admission showed lesions had shifted due to improvement in edema.

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[RadOncDoc21]

ITV expansion… duh!

 

[Ray D. Ayshun]

pt presented with arm weakness. MRI showed several brain mets and patient was put on steroids. Planning CT w/contrast 2 days after steroid admission showed lesions had shifted due to improvement in edema.

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Good illustration of the importance of contrasted sim for these. I see a lot of noncon and MRI fusion. Given the cystic nature of the bigger one, could resim sans contrast prior to treatment and see if the holes match up.

 

[BobbyHeenan]

This is one of the big advantages of same day MRI for gamma knife.

I do linac and GK brain treatments.
I have made it a point to get MRI day of or day before SRS/SBRT for this very reason....We did an internal audit and the amount of change from day of diagnostic MRI when brain met discovered (most often without steroids) and with steroids days/weeks later can be DRAMATIC. some tumors even "shrink" , some shift around a lot.

In the post covid era MRI waits can be a huge PITA but I often do non diagnostic (ie no radiology read) thin cut axial T1+C scans that they'll add on the schedule for me because I'm a nice guy . Admins put up with it because it's a no-charge scan but the linac and GK volume /revenue they're happy with so they acquiesce for now.

Good post @RickyScott .

 

[Ray D. Ayshun]

Was a good paper in the red journal from when they published treatment related papers

Changes in Brain Metastasis During Radiosurgical Planning - PubMed

Measurable changes occur in brain metastasis over a short amount of time, with a change in management required in 41% of patients with 7 days between MRI-1 and MRI-2 and in 78% of patients when there is a delay longer than 7 days. We therefore recommend that the time between planning MRI and RS...

pubmed.ncbi.nlm.nih.gov

 

[salubalu]

head positioning during scans can make it look like things are in different position as well. I have noticed that more towards the vertex.

 

[madchemist89]

I try to stay under 7 days, but sooner is always better.

 

[RickyScott]

The issue here is not the time between mri and sim, but the steroids changing everything. This is a mim fusion, so nothing to do with postioning due to crappy fusion.

 

[madchemist89]

Sorry I was referring to Ray's paper. Very dramatic response to steroids, which is good to keep in mind. Thanks for sharing. I don't usually get contrast at sim, but maybe I should for larger mets.

 

[TheWallnerus]

For me SRS CT sim w/ contrast has always been “mandatory,” as has MRI (w contrast!) within 24-48h of treatment. And when there is an MRI vs CT lesional position discrepancy, the CT lesion position always has primacy.

 

[elementaryschooleconomics]

Aaaaaand

Congratulations, this thread is now in an appeals letter from UTSW justifying dropping 77301 five times in a single adaptive case.