Medical labs and implants desingers need to certify their products before putting them into the market. If the implant is not FDA approved for example in the US, or MDR (formerly MDD) approved in Europe, the designs need to be revised in order to comply with those standards.

Even though measurments are needed to certify a product, it is done on a simple Gel phantom with an equivalent material, but recently, simulation is playing a very important role in order to consider heterogeneous human body models, which cannot be done in measurments and which predicts more accurate results.

In this simulation, we are evaluating if the tibia implant is safe or not:

• when the MRI machine sends the RF signal, high concentration of field is found on the sharp edges of the implant 

• this leads to increasing the local dissipated power 

• the first result to be evaluated is the SAR (Specific Absorption Rate), which gives an idea of how much power (watts) is absorbed by one Kg of tissue. It has to comply with the standards (less than 4 W/Kg).

  

  By Joule's effect, the temperature is subject to a local increase with time around the implant. the 4th figure shows the increase of the temperature after 15 minutes of exposure. Not to forget that depending on the area to be scanned, longer exposure time is needed. so the implant is to be certified for longer exposure time as well. In the thermal simulation, the bioheat is considered. the bioheat takes into consideration the blood flow in all tissues, and eventually the convection due to the bloodstream (fun fact: you hand becomes red when you burn it because the bloodflow is increased in the burning area, to help with reducing the temperature. same thing for your face after an effort).