Question

Increasing TI (inversion time) will do what to SAR?

1) Increase SAR
2) Decrease SAR
3) Have no effect on SAR
4) Cannot be determined

Answer 1

Increasing the inversion time (TI) in MRI sequences generally decreases the specific absorption rate (SAR). This is because a longer TI extends the time between RF pulses, resulting in fewer pulses and consequently lower energy absorption by the body.

Step-by-step explanation:

The question relates to magnetic resonance imaging (MRI) principles, particularly focusing on the inversion time (TI) and its impact on the specific absorption rate (SAR). In the context of MRI, SAR is a measure of the rate at which energy is absorbed by the body when exposed to a radio frequency (RF) pulse. SAR is an important safety consideration as it reflects the potential for heating tissues.

Increasing the inversion time (TI) will generally decrease SAR. TI is a parameter in certain MRI pulse sequences that defines the duration between the inversion pulse and the subsequent excitation pulse. A longer TI allows more time for recovery between RF pulse applications, which in turn means fewer pulses are needed per unit of time, leading to decreased SAR. Therefore, the correct answer is: 2) Decrease SAR.

Different MRI sequences and settings can impact SAR in various ways. However, when considering solely the effect of increasing TI, SAR will be reduced, which is a crucial consideration for patient safety during MRI scans.