Figure 6:

Photo of a manufacturer-supplied reference object for a 9.4 T pre-clinical imaging system from August 2018 (A) and an acceptance image using a similar manufacturer-supplied reference object for a 4.7 T pre-clinical imaging system from June 2005 (B). The pre-clinical imaging reference objects are simply conical 50-cc tubes filled with fluids for contrast (no relaxation time measurements) and small, interlocking, plastic, toy “bricks” for volumetric measurements. There was no significant improvement in reference object design for over a decade.