repetition time
The time interval between successive radiofrequency pulses in an MRI sequence, critically affecting image contrast and temporal resolution in functional studies.
Full Definition
Repetition time (TR) is a fundamental MRI acquisition parameter that defines the time between the start of one radiofrequency pulse sequence and the start of the next. In structural imaging, TR affects tissue contrast, with longer TRs providing T1-weighted contrast and shorter TRs used for proton density weighting. In functional MRI, TR determines the temporal sampling rate of brain activity, with typical values ranging from 0.5 to 3 seconds. The choice of TR involves trade-offs between temporal resolution, spatial coverage, signal-to-noise ratio, and the ability to resolve rapid neural dynamics. Neuroinformatics standards require precise TR documentation for proper data analysis and cross-study comparisons.
Usage
Usage note: Commonly abbreviated as TR in technical contexts but should be spelled out on first use in manuscripts.
In Context
- "The study employed a repetition time of 2000ms to achieve whole-brain coverage with adequate temporal resolution." — methods section
- "Repetition time must be specified in the BIDS dataset description file for proper analysis pipeline execution." — data management protocol