Patient-Specific PPG Triggering for Accurate Cardiac Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cardiac-triggered imaging methods, such as ECG-based MRI triggering, suffer from patient discomfort due to electrode placement and magnetic field interference, while camera-based PPG triggering introduces patient-specific delays leading to inaccurate imaging.
Innovation Solution
A method and system that measures patient-specific characteristics outside the imaging bore, generates a patient-specific model, and uses a triggering waveform inside the bore to determine an accurate imaging trigger signal, utilizing camera-based PPG without ECG electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ECG-based triggering is used for cardiac-triggered MRI, then accurate cardiac synchronization is achieved, but patient comfort deteriorates and imaging quality is disturbed due to electrode placement complexity and magnetic field interference
Solution Approach 1:
The patent extracts the triggering function from ECG electrodes and relocates it to camera-based PPG sensors positioned outside the MRI bore. This removes the harmful ECG leads and electrodes from the imaging environment, eliminating magnetic field interference while maintaining cardiac triggering capability through optical detection of pulse waves at peripheral sites.
Solution Approach 2:
The patent replaces the electrical contact-based ECG measurement system with an optical, contactless camera-based PPG system. This substitution eliminates the need for physical electrode contact and electrical signal transmission through the MRI bore, thereby removing the source of magnetic field interference while preserving the ability to detect cardiac timing events.
2Object-affected harmful factors
If camera-based PPG triggering is used to eliminate ECG electrodes, then patient comfort and imaging quality are improved, but patient-specific delays occur leading to inaccurate triggering
Solution Approach 1:
The patent performs preliminary measurement of the pulse transit time delay between the PPG detection site and the heart during a calibration phase before actual imaging. This advance characterization of the patient-specific delay allows the system to pre-compensate for the timing offset, ensuring accurate cardiac synchronization despite the use of peripheral PPG signals.
Solution Approach 2:
The patent implements a feedback mechanism where the measured pulse transit time delay is used to adjust and optimize the triggering timing. By continuously refining the trigger signal based on the observed delay between PPG detection and actual cardiac events, the system achieves accurate synchronization that compensates for the inherent time lag in peripheral pulse detection.
3Reliability
If camera-based PPG processing is performed to achieve robust trigger detection, then triggering reliability is improved, but workflow delays increase reducing imaging speed
Solution Approach 1:
The patent performs complex PPG signal processing and patient-specific model generation during the patient setup phase before imaging begins. By completing the computationally intensive tasks of signal filtering, feature extraction, and delay calibration in advance, the system establishes a ready-to-use triggering model that enables fast, real-time trigger detection during the actual imaging workflow without causing delays.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances imaging speed and accuracy by reducing workflow delays and eliminating the need for in-bore electrode placement, improving patient comfort and imaging quality.
Implementation Method 1
camera-based PPG of the human face has been shown
Data Source
Figure 1a~1b
Figure 2a~2f
Figure 3
AI summary
A system (100) and method for determining a trigger signal for imaging with an imaging system (40) are provided. The method comprises the steps of: - measuring (S10) a patient-specific characteristic of a patient (30). The patient-specific characteristic is measured when the patient (30) is located at a first position (51) relative to the imaging system (40); - generating (S20) a patient-specific model based on the patient-specific characteristic; - measuring (S30) a triggering waveform of the patient (30). The triggering waveform is measured when the patient (30) is located at a second position (52) relative to the imaging system (40). The second position (52) is different from the first position (51); - determining (S40) the trigger signal based on the patient-specific model and the triggering waveform. The trigger signal is configured to trigger the imaging system (40) to acquire an image of the patient (30) in a time-resolved manner.