In standard MRI sequences, what does 'TR' stand for?

Repetition Time, often abbreviated as TR, refers to the time interval between successive radiofrequency (RF) pulses delivered to a specific slice of tissue in MRI imaging. In standard MRI sequences, TR is a critical parameter that influences the contrast between different tissues in the images produced.

The length of the TR affects the amount of time that tissues have to relax before the next RF pulse is applied. This relaxation allows for the re-establishment of spin magnetization in the tissues, which is critical for producing high-quality images. Short TRs can lead to better visualization of tissues with short T1 relaxation times, while longer TRs can be employed to highlight tissues with longer T1 times.

Understanding TR is essential for MRI technologists and radiologists because it helps in optimizing imaging protocols for different clinical scenarios, enhancing image quality, and improving diagnostic accuracy.