Step-by-Step Guide for Chest Lead Placement in Cardiac MRI, Preparation, Placement Technique, Tips for Good Signal, During Scan,

Chest (ECG) Lead Placement in Cardiac MRI

1. Preparation

• Use MRI-compatible ECG electrodes (carbon fiber, no metal).

• Clean skin with alcohol swab → remove oil/sweat.

• Shave chest hair if thick → ensures good contact.

• Avoid placing directly over ribs or fatty tissue → use flat muscle areas.

2. Standard MRI Setup

Most scanners use 3-lead or 4-lead ECG gating.
The aim is to get a clear R-wave (since T-wave is distorted in MRI due to magnetohydrodynamic effect).

3. Placement Technique

🔹 3-Lead Setup (Most Common in MRI):

• RA (Right Arm) → Upper right chest (below clavicle, right parasternal).

• LA (Left Arm) → Upper left chest (below clavicle, left parasternal).

• LL (Left Leg / Chest Lead) → Below left rib margin (left lower chest, mid-axillary line).

🔹 4-Lead Setup (Some scanners):

• Same as above, plus RL (Right Leg / Ground) → right lower chest or abdomen.

4. Tips for Good Signal

• Place leads in a triangular pattern around the heart (not exactly in standard 12-lead ECG spots).

• Ensure equal distance between leads.

• Avoid leads directly under the coil → reduces artifacts.

• Keep wires twisted & straight → prevent loop formation (reduces RF burns).

5. During Scan

• Check gating signal on console before starting cine/LGE sequences.

• If ECG is noisy or mistriggering →

  • Re-adjust electrodes.

  • Try different positions slightly lateral or inferior.

  • Switch to VCG gating if available.

• Always monitor HR and rhythm throughout scan.

✅ Summary for Techs:

• Use MRI-safe electrodes.

• Clean skin → triangular 3-lead placement around heart.

• Focus on R-wave clarity.

• Avoid loops & keep leads away from coils.