Respiratory Gating via PET and Pulse Oximetry Signal Merging
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Solution Overview
Problem
Current methods for real-time respiratory motion tracking in tomographic imaging, such as PET, face challenges with low count statistics leading to noise and poor signal-to-noise ratio, especially in clinical settings where radiopharmaceutical doses are kept low to limit radiation exposure, and are hindered by the time lag in pulse oximeter signals used for respiratory monitoring.
Innovation Solution
A system combining data-driven respiratory monitoring from PET list mode data with pulse oximetry, where the time lag in pulse oximeter signals is corrected using data-driven analysis, enabling real-time respiratory gating and improving signal quality by aligning the pulse oximeter signal with PET data-driven signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If list-mode PET data is used for respiratory motion tracking, then real-time respiratory motion detection is achieved, but signal-to-noise ratio deteriorates due to low count statistics
Solution Approach 1:
The patent combines PET list-mode data with pulse oximeter PPG signals to create a hybrid respiratory motion tracking system. The PPG signal, which has higher signal-to-noise ratio, is merged with the PET data to compensate for the low count statistics in PET imaging, thereby improving overall measurement precision without requiring increased radiopharmaceutical dose.
Solution Approach 2:
The pulse oximeter PPG signal acts as an intermediary that provides complementary respiratory motion information to the PET data. This intermediary signal helps bridge the gap caused by insufficient count statistics in PET, enabling more reliable respiratory gating without increasing radiation exposure.
2Object-affected harmful factors
If radiopharmaceutical dose is reduced to limit radiation exposure, then patient safety is improved, but measurement precision deteriorates due to low count statistics
Solution Approach 1:
By merging PET list-mode data with PPG signals from pulse oximetry, the system achieves improved measurement precision without increasing radiopharmaceutical dose. The PPG component provides additional signal information that compensates for the low count statistics in PET, allowing reduced radiation exposure while maintaining imaging quality.
3Measurement precision
If acquisition time is increased to improve signal quality, then signal-to-noise ratio is improved, but temporal resolution deteriorates
Solution Approach 1:
The combination of PET and PPG signals allows the system to achieve improved signal-to-noise ratio without extending acquisition time. The PPG signal provides continuous respiratory motion information that complements PET data, enabling real-time respiratory gating with maintained temporal resolution even when PET acquisition time is limited.
4Ease of operation
If pulse oximeter signal is used for respiratory monitoring, then ease of operation is improved, but measurement precision deteriorates due to time lag
Solution Approach 1:
The system uses feedback from both PET list-mode data and PPG signals to continuously monitor and adjust for time lag. By comparing the two signals and detecting temporal misalignment, the system dynamically corrects the PPG signal timing to maintain precise synchronization with actual respiratory motion, thereby improving measurement precision while keeping the device simple to operate.
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 provides reliable and accurate real-time respiratory gating, improving the signal-to-noise ratio and reducing noise, while allowing for motion-free imaging without the need for external respiratory monitoring devices, thus enhancing the quality of respiratory activity measurement during image acquisition.
Implementation Method 1
acquiring a photoplethysmograph (PPG) signal from the pulse oximeter
Implementation Method 2
a positron emission tomography (PET) or single photon emission computed tomography (SPECT) imaging device
Implementation Method 3
extract a first respiration data signal from emission imaging data of a patient acquired by the PET or SPECT imaging device
Data Source
AI summary
A device (10) for measuring respiration of a patient includes a positron emission tomography (PET) or single photon emission computed tomography (SPECT) imaging device (12). At least one electronic processor (16) is programmed to: extract a first respiration data signal (32) from emission imaging data of a patient acquired by the PET or SPECT imaging device; extract a second respiration data signal (36) from a photoplethysmograph (PPG) signal of the patient; and combine the first and second extracted respiration data signals to generate a respiration signal (40) indicative of respiration of the patient.