Variable-parameter magnetic resonance imaging

摘要

Abstract: We describe here an implementation of a pulse sequence in which one of the normally fixed scan parameters is varied through the scan. The image contrast that is normally obtained with long sequence repetition time TR, and consequently long scanning times, can be achieved with relatively shorter scan times by systematically varying TR during the data acquisition. By employing the longest TR only while collecting the data for the lowest spatial frequencies and using the shortest available TR elsewhere a flexible trade-off between image features (contrast and resolution) and scan time is possible. Examples of 2-D and 3- D FT MR images at low and middle field strength are presented with sequence details and some comparison scans of similar scan times. !8