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ChristianToennes / VirtMRI

VirtMRI: Generate images for different MRI Sequences in your Browser. Written in JavaScript and C compiled to WebASM
https://virtmri.keks.li
MIT License
9 stars 1 forks source link

Most scans default to many days to acquire? #3

Open dkp opened 6 months ago

dkp commented 6 months ago

Maybe the scan times are correct. I'm not an MR physicist, just a user. But it seems odd that the scans default time is typically several days (Maybe I misunderstand what total measuring time is?).

Here's a snapshot:

VirtMRI

I'm on Mac Ventura; using the Chrome Browser: 120.0.6099.199. I tried Safari and see the same thing. These values don't feel right. Resolution is pretty typical. Am I missing something, or is there a glitch here?

hcmh commented 6 months ago

The problem is that it defaults to a 3D-Scan and Inversion Recovery, which is quite unusual. To calculate the time it takes, you have to multiply: Y (256) Z (214) and TR (6666 ms == 6.666 s)

which gives 365190.144 s or 101.4 hours

It gives more reasonable results for a 2D scan (by setting Z to 1):

28 minutes for a 2D Inversion Recovery scan. That is long, but MRI just takes a long time, and Inversion Recovery is one of the slowest methods.

If you take the original 3D scan, go to "Balanced SSFP", and then change TE to something reasonably fast (like 4 ms), you will get a very normal ~7 minutes for the entire 3D volume.

I hope that helps :)