Magnetic Resonance Imaging (MRI) Practice Test

Which MRI sequence is known to provide T1-weighted imaging?

1. Spin echo

2. Steady-state free precession

3. Fast gradient echo

4. Conventional gradient echo

The correct answer is: Spin echo

The spin echo sequence is known for its ability to produce T1-weighted imaging. This is primarily due to its specific parameters and the way it manipulates the timing of radiofrequency (RF) pulses. In a spin echo sequence, a 90-degree RF pulse is followed by a 180-degree RF pulse. The timing between these pulses, particularly the echo time (TE) and repetition time (TR), can be adjusted to emphasize T1 relaxation, which highlights fat and makes it appear brighter relative to fluid and other tissues. When optimized for T1 weighting, the repetition time is kept relatively short, allowing the longitudinal magnetization of tissues with shorter T1 times, such as fat, to recover more fully by the time of signal acquisition. This results in enhanced contrast between tissues based on their T1 properties. While other sequences, such as fast gradient echo and steady-state free precession, may also yield T1-weighted images under specific conditions, they are less commonly used for standard T1 imaging. In comparison, a conventional gradient echo sequence typically demonstrates T2*-weighted imaging, and while it can be manipulated for T1 weighting, it does not have the same robust relationship with T1 as spin echo sequences do, making spin echo