Radiofrequency (RF) pulse sequences, particularly those with high specific absorption rate (SAR), cause the greatest tissue heating during magnetic resonance imaging (MRI).
In magnetic resonance imaging (MRI), the issue of tissue heating is associated with the application of radiofrequency (RF) pulse sequences. RF pulses are utilized to excite the magnetic nuclei in the body, leading to the emission of signals that are detected and used to generate images. However, the energy deposition during RF pulses can result in tissue heating, and this is a critical consideration in MRI safety.
The specific absorption rate (SAR) is a key parameter that quantifies the rate at which RF energy is absorbed by the body tissues. Higher SAR values are indicative of increased energy absorption and, consequently, greater tissue heating. Sequences with high SAR, such as fast spin-echo and echo-planar imaging, are more likely to cause significant temperature elevation in the imaged tissues.
While MRI is generally considered safe, excessive tissue heating can pose risks, particularly in situations where the body's ability to dissipate heat is compromised, such as in patients with impaired thermoregulation or those with certain medical devices. It underscores the importance of adhering to safety guidelines, monitoring SAR levels, and selecting appropriate pulse sequences to minimize the potential for adverse effects related to tissue heating during MRI examinations.