Sets the filtering mode for the ECG signal. All filtering mode except Monitor utilize an adaptive
filter scheme for removal of gradient artifacts generated by MR systems.
The following options are available:
Expression MR400 Instructions for Use Monitoring ECG 5‐31
Select HR Tone Source.
The HR Tone Source menu appears. The current setting is
Select the desired setting for the tone source:
The setting is changed.
Due to the variety of MRI sequence characteristics, if the filter recommendations below do
not provide optimum performance in all cases, the selection may improve ECG performance
during a specific scan sequence.
ECG performance can be affected by electrode placement, the MRI procedure, the image
slice angle and slice thickness. In situations where ECG performance is not optimal, select
the ECG lead view (I, II, III, AVL, AVR, or AVF) that provides the best performance; see
For cases not requiring cardiac gating, start with the Default filter (depending on the MRI
sequence) then switch filters if a gradient artifact is noticed. If a gradient artifact is still
present, check ECG signal strength and try lead I or III.
Monitor is a mode that provides filtering characteristics that meet the specification of the
AAMI and IEC. This mode is useful during patient preparation, transporting, base‐lining, et
cetera, but is not meant for use during active MRI sequences due to noise; see page 5‐18.
Default provides the best possible performance on 0.15 to 3.0T MR systems during Echo
Train type MRI sequences. (Default)
Advanced 1 provides the best possible performance during cardiovascular (CV) MRI scans
that involve steady‐state free precession imaging with balanced gradient (True‐FISP,
FIESTA, or Balanced FFE) sequences on 1.5 and 3.0T MR systems. For cases requiring
cardiac gating, start with the Cardiac filter in Lead II and switch filters if a gradient artifact
is noticed. If gradient artifact is still present, check signal amplitude and try Lead I or III.