ECG-Gated Temporal Sampling for Cardiac Kinetic Modeling
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Solution Overview
Problem
Dynamic imaging techniques, such as PET and cardiac gated imaging, face challenges in accurately capturing the dynamic changes in moving anatomy due to patient motion and the integration over partial cardiac or other cycles, leading to degraded image quality and inaccurate representation of biological processes over time.
Innovation Solution
A diagnostic imaging system that monitors periodic biological cycles, detects a common reference point, and synchronizes sampling segments with these cycles to ensure each segment contains an integral number of cycles, allowing for accurate data collection and image reconstruction that reflects the true dynamic changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If dynamic imaging is performed over relatively long imaging periods, then more complete data can be collected, but image quality is degraded by patient motion
Solution Approach 1:
The imaging process is divided into multiple cardiac phases (e.g., 16 segments per cardiac cycle), allowing data to be collected and processed in discrete temporal segments. This segmentation enables motion compensation by aligning data from multiple cardiac cycles to a reference cycle, thereby maintaining image quality while collecting sufficient data over time.
Solution Approach 2:
The imaging system utilizes the periodic nature of cardiac cycles to acquire data repeatedly over multiple cycles. By synchronizing data acquisition with the periodic cardiac rhythm and using a reference cycle for alignment, the system collects adequate data quantity while compensating for motion variations between cycles, thus resolving the contradiction between data completeness and image quality.
2Measurement precision
If gated imaging is used to sort data by cardiac phase, then motion artifacts are reduced, but temporal resolution is degraded because images are averaged over multiple cycles
Solution Approach 1:
A reference cardiac cycle is established before the actual imaging data is processed. This reference cycle serves as a template for aligning and sorting data from subsequent cardiac cycles. By having this preliminary reference in place, the system can accurately sort data into cardiac phases without losing temporal information, thereby maintaining both motion artifact reduction and temporal resolution.
Solution Approach 2:
The patent replaces traditional mechanical averaging of gated images with a computational approach using Fourier transformation and phase correction algorithms. Instead of simply averaging images across cycles (which loses temporal dynamics), the system uses mathematical transformations to preserve temporal information while still benefiting from motion correction, thus maintaining temporal resolution while reducing motion artifacts.
3Speed
If imaging segments span a fraction of a cardiac cycle, then temporal sampling is achieved, but image accuracy is degraded due to differences in the fraction of the cardiac cycle contributing to each image
Solution Approach 1:
The system dynamically adjusts the temporal parameters of each imaging segment to ensure that corresponding segments across different cardiac cycles contain the same fractional portion of the cardiac cycle. By normalizing the temporal parameters based on the reference cycle duration and using phase correction techniques, the system maintains consistent physiological representation across all images, thereby preserving image accuracy while achieving high temporal sampling rates.
Data Source
AI summary
In a diagnostic imaging system (10), a monitor (50) monitors periodic biological cycles of the subject (14). A trigger point detector (60) detects a time (t1, t2, . . . , tn) of a common, reoccurring reference point (R1, R2, . . . , Rn) in each periodic cycle of the subject (14). A sequence selector (62) selects a sequence (64) of nominal sampling segments (Si, S2, . . . , Sn). An adjustor (70) adjusts duration of each nominal sampling segment (Si, S2, . . . , Sn) to coincide with the times of detected reference points (R1, R2, . . . , Rn). A scaling processor (72) scales each adjusted segment based on a difference in duration between the corresponding nominal (Si, S2, . . . , Sn) and adjusted sampling segments (S′i, S′2, . . . , S′n).