What does the specific absorption rate (SAR) measure in MRI?

The specific absorption rate (SAR) is a critical measurement in magnetic resonance imaging (MRI), as it quantifies the rate at which energy is absorbed by the body tissues during the MRI process. SAR is expressed in watts per kilogram (W/kg) and is important for assessing patient safety, as it relates to the heat generated within the tissues as a result of the radiofrequency (RF) energy used during imaging.

Understanding the SAR helps in ensuring that the levels of RF energy applied during an MRI scan remain within safe limits to prevent excessive heating of tissues, which could lead to burns or other thermal injuries. This is why the measurement of energy deposition in tissue is central to the function of SAR, highlighting its role in both safety protocols and the effective operation of MRI systems.

While other factors such as magnetic field strength, image resolution, and contrast agent effectiveness are important to MRI, they do not relate directly to the SAR, which specifically focuses on how energy is absorbed by the tissues. This understanding is vital for maintaining patient safety during MRI procedures.