Adaptive ECG Trigger Jitter Compensation for Medical Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing medical imaging systems face inaccuracies in image acquisition timing due to noise, clock jitter, and analogue to digital conversion timing variations, leading to imprecision in detecting cardiac ECG signals like the P wave, R wave, and T wave, which affects cardiac function analysis and introduces distortion and noise in image scanning.
Innovation Solution
A system that estimates and compensates for ECG trigger pulse timing jitter using adaptive, controllable timing thresholds and closed-loop ECG image acquisition trigger signal generation, employing adaptive statistical correlation and dynamic adaptive threshold-based ECG segment waveform analysis to provide accurate image acquisition gating signals, reducing the effects of digitization, data transmission, and processing jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform sampling at a fixed rate (e.g., 2000 Hz) is used for ECG signal detection, then the system is simple to implement, but timing jitter and uncertainty increase due to oversampling and pipeline transmission variations
Solution Approach 1:
The patent implements dynamic sampling rate adjustment where the sampling frequency is varied based on the detected ECG waveform characteristics. Instead of uniform sampling, the system adapts the sampling rate to match the instantaneous frequency content of the ECG signal, thereby reducing timing jitter while maintaining detection accuracy. This dynamic approach resolves the contradiction by making the sampling system flexible rather than fixed.
Solution Approach 2:
The system changes the sampling rate parameter dynamically based on ECG signal analysis. By adjusting the sampling frequency according to the detected waveform features (such as R-wave amplitude and interval), the system optimizes timing precision without requiring uniformly high sampling rates throughout, thus reducing overall jitter while maintaining simplicity.
2Measurement precision
If high sampling rate is used to reduce timing jitter, then trigger timing precision improves, but oversampling occurs leading to increased pipeline transmission jitter and uncertainty
Solution Approach 1:
The patent applies partial sampling by using variable sampling rates that are adjusted to match the actual ECG signal frequency content. Instead of continuously using high sampling rates (excessive action), the system uses higher rates only when necessary for accurate detection and lower rates otherwise, thereby achieving sufficient timing precision without causing excessive pipeline transmission jitter from constant oversampling.
3Reliability
If ECG signal synchronization is used to reduce patient artifacts, then image quality improves, but the trigger signal becomes sensitive to jitter from multiple sources including electrical surgery noise and heart rate control device noise
Solution Approach 1:
The patent implements feedback mechanisms where the detected ECG waveform characteristics are continuously monitored and used to adjust the trigger signal generation. By using the actual detected R-wave timing and amplitude information as feedback, the system can compensate for jitter introduced by electrical surgery noise and heart rate control devices, thereby maintaining image acquisition stability while reducing sensitivity to external noise sources.
Solution Approach 2:
The system introduces an intermediary processing stage that analyzes the ECG waveform and generates adjusted trigger signals based on detected features. This intermediary layer filters out jitter from external sources (electrical surgery, heart rate controllers) by using only the essential timing information from the ECG R-wave, thereby protecting the image acquisition system from harmful jitter while maintaining synchronization benefits.
4Loss of information
If R wave detection is used for triggering image acquisition, then cardiac function analysis is enabled, but trigger delay of 10-100 ms occurs relative to cardiac activity
Solution Approach 1:
The patent implements preliminary detection and prediction of R-wave timing by analyzing ECG waveform trends before the actual trigger point. By detecting early ECG features (such as P-wave or QRS complex onset) and predicting the upcoming R-wave timing, the system can prepare and issue trigger signals earlier, reducing the effective trigger delay while still maintaining accurate cardiac function analysis based on R-wave correlation.
Data Source
AI summary
A system provides an image acquisition trigger signal compensated for signal processing time delay. An interface receives waveform signal data representing electrical activity of a patient heart over at least one heart beat cycle. A detector detects a particular point associated with a particular signal portion within successive heart beat cycles of the signal data. A first time variation detector provides a first timing adjustment signal in response to detected change in time of occurrence of the detected particular point. A second time variation detector provides a second timing adjustment signal in response to comparison of relative timing of the trigger signal and the detected particular point. An output processor generates the trigger signal in response to the detected particular point and the first timing adjustment signal and the second timing adjustment signal.