In concurrent NIRS-MRI experiments, you often need to know exactly where the NIRS probes are in the MRI iamges. In this case, a fiducial marker becomes important.
In our 2011 publication titled “A quantitative comparison of NIRS and fMRI across multiple cognitive tasks“, we used some fiducial markers and they work really well. Below you will find a picture (see B, C and E) where the fiducial markers are shown clearly in MRI images.
Please be sure to use ring-shaped markers as you will know exactly where the markers are.
Where did we buy the markers? They are from MRIEquip (https://www.mriequip.com/store/pc/viewPrd.asp?idcategory=72&idproduct=270)
(MRIEquip, SKU: BP-103X, Model: BP-1015, 15-mm 233 outer diameter, 3.5 mm thick, 5-mm central axis hole)
And below is a sentense in our paper:
MRI fiducial markers were affixed to the inner side of the measurement patch at the location of each of the 24 channels (i.e., between every emitter–detector pair) to identify the positions of NIRS cannels in the MRI structural images.