Hello doctor, I was directed to you in the hopes you could answer a technical question for me regarding MRI soft tissue neck SAR limits and RF exposure. Does one receive a higher SAR limit and RF exposure if they weigh more? For example, if a patient weighs 225 lbs would his or her SAR limits and subsequent RF exposure be higher or lower than someone who is 250 pounds? Thank you in advance.
Hello. The SAR (specific absorption rate) is directly dependant on the patient's weight and would definitely be more for a 250 lb person than a 225 lb. The second issue is that radiation heat is more at the surface than the deeper layers of the tissue. So, to conclude, chances of burns are more in patients with more weight than lean patients. However, there are FDA guidelines to prevent such incidences. In case you are suspecting burns, please inform the respective MRI unit regarding management and also to prevent such incidents in the future. Take care. For more information consult a radiologist online -->