If the flip angle is decreased, how does that affect patient heating?

Decreasing the flip angle during an MRI procedure plays a crucial role in reducing patient heating. The flip angle refers to the angle by which the magnetic moments of hydrogen nuclei in the body are rotated in the magnetic field during an RF pulse. When the flip angle is decreased, the energy deposited in the tissue is reduced proportionally.

Lower flip angles result in less energy being imparted to the tissues, leading to a decrease in the specific absorption rate (SAR), which is a measure of the amount of RF energy absorbed by the body. Lower SAR corresponds directly to reduced heating of the tissues, making the procedure safer for the patient.

In MRI, controlling the flip angle is an important aspect of ensuring patient safety and comfort, particularly for lengthy examinations or for patients who may be more susceptible to heating effects. Therefore, decreasing the flip angle is a beneficial approach to minimize the risk of thermal injury to the patient during the scan.