Motion pattern adapted real‐time respiratory gating

The information about the current respiratory motion state used in conventional gating to accept or to reject data can further be used to obtain motion statistics during an MR scan. This can serve to monitor changes in the respiratory pattern of the patient by comparison of motion statistics subsequently obtained during scanning. Two indicators are introduced: first a parameter that registers changes of the motion pattern, and second an indicator that expresses the quality of the data set already obtained. Based on these indicators, the gating algorithm decides to change gating parameters during scanning automatically. This new approach has the potential to increase the scan efficiency considerably without the need of operator interaction and/or significant patient cooperation. The basic principle is described and illustrated for the motion‐adapted gating technique, and first in vivo results are presented to underline the feasibility of this concept. Magn Reson Med 41:148‐155, 1999. © 1999 Wiley‐Liss, Inc.