Motion Correction in PET via MR Subregion Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for motion correction in emission computed tomography, such as PET, face challenges with noisy signals and high radiation exposure when correcting periodic or pseudoperiodic motions, especially when trying to achieve sufficient temporal resolution for precise motion tracking, like heart movements.
Innovation Solution
A method that records emission computed tomography data and magnetic resonance data from specific subregions at multiple instants, determining motion information and creating a motion model to correct the PET data, allowing for high temporal and spatial resolution without increasing overall measurement time by focusing on key regions and using MR data for transformation calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic resonance data is recorded for the entire examination region at high temporal resolution to correct fast motions, then motion correction precision is improved, but measurement time increases and spatial resolution deteriorates
Solution Approach 1:
The examination region is divided into multiple subregions, and magnetic resonance data is recorded only for selected subregions rather than the entire region. This segmentation allows high temporal resolution measurement in specific areas of interest while reducing overall measurement time and maintaining spatial resolution in unmeasured regions.
Solution Approach 2:
Different regions of the examination object are measured with different temporal resolutions based on their motion characteristics. Regions with fast motion (e.g., heart) are measured at high temporal resolution, while regions with slower motion are measured at lower temporal resolution, optimizing the trade-off between motion correction precision and measurement time.
2Measurement precision
If magnetic resonance data is recorded for the entire examination region at high spatial resolution, then spatial resolution is improved, but measurement time increases
Solution Approach 1:
The examination region is divided into multiple subregions, and high spatial resolution magnetic resonance data is recorded only for selected subregions where high resolution is critical for motion tracking. Other regions are measured at lower spatial resolution, reducing overall measurement time while maintaining adequate spatial resolution where needed.
Solution Approach 2:
Different spatial resolutions are applied to different subregions based on their importance for motion correction. Regions containing organs with significant motion (e.g., heart, lungs) are measured at high spatial resolution, while other regions use lower spatial resolution, optimizing the balance between spatial resolution and measurement time.
3Reliability
If multiple recordings are made for each motion cycle to correct periodic motion, then motion correction reliability is improved, but radiation exposure increases
Solution Approach 1:
Magnetic resonance data serves as an intermediary to track organ motion without exposing the patient to additional radiation. The MR data provides motion information that is used to correct the emission computed tomography data, allowing multiple recordings per motion cycle for reliable motion correction while avoiding increased radiation exposure from repeated CT scans.
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 enables reliable and precise motion correction with reduced radiation exposure and improved image quality by using MR data to enhance the transformation calculations and motion field mapping, suitable for fast motions like cardiac contractions.
Implementation Method 1
Measurement of magnetic resonance data of at least two subregions of the examination region at at least two instants during the recording period of the emission computed tomography data
Implementation Method 2
Determination of a motion model which describes the motion of the examination object, for the entire examination object, from the motion information for the subregions
Data Source
AI summary
A method includes introducing the examination object into an examination region of a combination device; recording emission computed tomography data over a measurement period and storing detection events and detection instants associated therewith; measuring magnetic resonance data of at least two subregions of the examination region at at least two instants during the recording period of the emission computed tomography data and storing the magnetic resonance data and the recording instants; determining motion information describing a motion of a region of the examination object at a first instant relative to the position at a second instant from the magnetic resonance data recorded at the first instant and the second instant, for each subregion; determining a motion model describing motion of the examination object, for the entire object, from information for the subregions; and calculating motion-corrected emission tomography data from detection events, detection instants and the motion model.