ECG: Cardiac Contamination

ECG: Cardiac Contamination#

ECG views quantify coupling between ECG reference activity and MEG channels.

For execution steps, see Tutorial.

Subject-report ECG views#

View

Encoding

What it reveals

ECG quality overview

reference-channel diagnostics

whether ECG-driven analysis is reliable

Raw ECG recording

time series context

signal quality and heartbeat structure

Mean R-wave template

averaged cardiac waveform

template quality used for coupling analysis

Affected-channel ranking

channels ordered by coupling magnitude

strongest vs weakest cardiac contamination

ECG topomap

coupling burden on sensor layout

spatial distribution of cardiac contamination

1) ECG quality overview#

ECG overview

Use this first to verify reference quality before interpreting channel rankings.

2) Raw ECG recording#

ECG raw recording

Confirms cardiac waveform detectability and obvious corruption.

3) Mean R-wave template#

ECG mean R wave

A clean template indicates stable event-locked cardiac structure.

4) Channel ranking by contamination#

Most affected ECG channels Mid affected ECG channels Least affected ECG channels

Ranking separates high, medium, and low contamination channel sets.

5) ECG contamination topomap#

ECG topomap

Shows spatial concentration of ECG coupling burden.

ECG in QC summary#

QC summary -> ECG includes affected-channel counts and percentages (by task/run) derived from GQI task rows when available.

QC implications#

  • high affected-channel percentage indicates stronger need for cardiac artifact handling,

  • task-specific shifts may indicate condition-dependent contamination sensitivity,

  • if reference quality is poor, interpret ECG burden with caution.

ECG contamination patterns are similar for MAG and GRAD channels, though the spatial distribution may differ slightly. The QC summary provides compact metrics for quick assessment across runs.