Can MRI results vary per machine and radiologist

[ankur320]

I did first MRI on 3T machine in May 2018, and it measured 10*5 mm. I did next one in another hospital again on 3T MRI machine and result were 13*7mm. I am surprised with the growth in 4 months. Has anyone experienced this vast difference so early.
Can MRI result depend upon MRI machine and how pathologist reads it?

[notaclone13]

Many posts have stated that there can be variation from one MRI machine to another.  My otologist instructed me to have my 6 month post-diagnosis MRI performed on the same machine as my previous one so that we could get the most accurate comparison.   I have also read that MRIs done on the same machine can vary from 1-2 mm depending on what cut of the tumor was used for the measurement and which radiologist was doing the measuring.  Has your doctor seen these results and commented?  You may want to see if you can find a neuro-radiologist to read the 2 MRIs and give an opinion. 

[ankur320]

Thanks for reply, that gives some relief though. I have appointment in 2 days with neuroSurgeon, He may give more clarity.

[notaclone13]

I just found this info in a post from Cityview:

I like what Dr. Haynes said on the Vanderbilt Facebook Live event...that a person could have two MRIs on the same day and it could look like there was growth just because of the way the technology works.  He also mentioned something about not needing contrast every time. (I'm summarizing)
I found that Facebook Live event very good in so many ways....very interesting.
Lots of good stuff.

I did not see this event, but will ask Cityview how to access it. So you see, MRIs can be quite variable. Hope this will make you feel more at ease.

[Citiview]

Hi
The Facebook Live event was the one currently found on the ANA Facebook page. Allison Feldman did the event at Vanderbilt. Dr. Haynes said they once gave the same patient an MRI twice in one day on the same machine and it looked like there was growth.

Another doctor on a different webinar (can't remember which one) said that they wouldn't consider there to be growth unless there's a 3mm difference.

I would try not to react too strongly based on a small difference in measurements, given the fact that the machines and Radiologists were different.

Every once and a while I look at a ruler at how big a millimeter is just to remind myself - Wow that's small!

[ANSydney]

You can certainly get MRI size assessment changes for a variety of reasons:
1) The slice location of the image (is it along the greatest diameter or just to the side of it)
2) Measurement criteria (do you include the IAC portion or not)
3) Measurement point (do you go to the middle of the tumor outline, just inside or just outside when performing a measurement)
4) Do you measure perpendicular to the axis of the IAC or the greatest diameter.

Fortunately, all these can be accounted for. For the first, taking the measurement for the slice either side of the one that has the greatest size will tell you if your at the greatest diameter (the slices either side will be roughly equal) or you'er off to the side (the slices either side will be quite different). There are methods that take the greatest diameter slice and the diameter of the slice either side that work out what the real greatest diameter is. Don't ask a radiologist how, it's more a job for a mathematician (or a regular person who can do a curve fit in Excel).

For the next three, give the older and current images to a single radiologist to measure again. This way you don't get inter-operator variation.

Or, just get the CD and take a look yourself. Does it look bigger?

[ankur320]

Thanks all, Thanks ANSydney for detailed technical answer

[notaclone13]

Can anyone tell me how to access Dr. Haynes presentation at Vanderbilt without using Facebook? Is it available through the ANA website?  I am not a Facebook user and don't feel inclined to establish a Facebook page so that I can to join the ANA Facebook group.  I admit I am not savvy to the ins and outs of Facebook use, but some of the things about Facebook in the news of late have not been flattering.