Fundamentals of Camera-PPG Based Magnetic Resonance Imaging

Area of Science:

• Medical Imaging
• Biomedical Engineering
• Cardiovascular Technology

Background:

• Cardiac triggering synchronizes Magnetic Resonance Imaging (MRI) data acquisition with heartbeats for high-quality images.
• Traditional triggering relies on Electrocardiography (ECG), which involves extra workflow steps and is susceptible to magnetic field interference.
• Alternative triggering methods are needed to streamline MRI procedures and improve signal reliability.

Purpose of the Study:

• To investigate the feasibility of camera-based photoplethysmography (PPG) for cardiac triggering in MRI.
• To compare the performance of camera-based PPG with ECG and finger-based PPG for cardiac triggering.
• To identify challenges and provide insights for designing a camera-based cardiac triggering system.

Main Methods:

• Utilized the in-bore camera of a clinical MRI system for data acquisition.
• Synchronously collected data from ECG, a finger oximeter (finger-PPG), and the in-bore camera (camera-PPG).
• Analyzed signal availability and marker delay relative to the ECG R-peak for each method.

Main Results:

• Camera-based PPG demonstrated higher signal availability compared to finger-based PPG.
• The time delay between the camera-PPG marker and the ECG R-peak was significantly less when the camera monitored the forehead.
• Feasibility of camera-based cardiac triggering was established, highlighting potential advantages over ECG.

Conclusions:

• Camera-based PPG is a viable alternative for cardiac triggering in MRI, offering improved signal availability and reduced R-peak delay.
• Forehead monitoring with an in-bore camera presents a promising approach for non-invasive cardiac triggering in MRI.
• Further research into system design based on these findings could enhance MRI workflow efficiency and image quality.