Static PET Metabolic Rate Estimation Using Population Input Functions
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Solution Overview
Problem
Conventional nuclear imaging methods, such as PET scans, struggle to accurately determine tissue metabolic rates due to their dependence on post-injection time and the need for periodic blood sampling, while parametric PET scans are not commonly available and require longer scan times, making them impractical for clinical use.
Innovation Solution
A method to estimate tissue metabolic rate using a static PET scan by identifying a blood pool region, determining a scale factor based on population-based input functions, and calculating a specific uptake ratio (SUR) to derive a pseudo-Fractional Uptake Rate (pFUR) without requiring blood sampling or parametric scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional static PET scan is used, then scan time is short and clinical protocol is simple, but metabolic rate determination is inaccurate due to post-injection time dependency
Solution Approach 1:
The patent applies preliminary action by using a population-based input function that is pre-determined from arterial input function data collected from multiple subjects. This pre-characterized function allows the system to estimate blood pool activity over time without performing actual blood sampling during the scan, thereby enabling accurate metabolic rate determination from a single static PET scan while maintaining short scan times and simple clinical protocols.
2Measurement precision
If parametric PET scan is used, then metabolic rate can be accurately determined, but scan time is significantly longer and clinical protocol is complex
Solution Approach 1:
The patent applies copying by using a population-based input function that replicates the arterial input function characteristics observed in a population of subjects. Instead of performing complex parametric scans or actual blood sampling on each patient, the system copies the essential temporal activity pattern from population data and applies it to individual metabolic rate calculations, achieving accurate results with simplified protocols and shorter scan times.
3Ease of operation
If specific uptake ratio (SUR) is calculated without blood sampling, then scan time is reduced and protocol is simplified, but blood glucose and other physiological factors are not accounted for
Solution Approach 1:
The patent introduces an intermediary element - the population-based input function - that mediates between the simplicity of non-invasive imaging and the accuracy requirements of metabolic rate determination. This intermediary function encapsulates the effects of blood glucose and other physiological factors that would otherwise require direct blood sampling, allowing accurate SUR calculation without actual blood draws while maintaining protocol simplicity.
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
Enables accurate estimation of metabolic rates using a static PET scan, eliminating the need for blood sampling and reducing scan time, thereby facilitating efficient clinical diagnosis.
Implementation Method 1
The radiopharmaceutical tracer emits gamma rays (in the case of single-photon-emission-computer-tomography (SPECT) imaging) or positrons which annihilate with electrons to produce gamma rays (in the case of positron-emission-tomography (PET) imaging)
Implementation Method 2
positrons which annihilate with electrons to produce gamma rays
Data Source
AI summary
A system and method include identification of a blood pool region of the body based on the acquired positron emission tomography data, determination of activity in the blood pool region associated with a first time based on the acquired positron emission tomography data, determination of a scale factor based on the determined activity in the blood pool region and on an input function associated with one or more other human bodies, determination of activity in a tissue region associated with a second time based on the acquired positron emission tomography data, determination of a specific uptake ratio associated with the second time based on the activity in the tissue region, the scale factor and a value of the input function at the second time, determination of an estimate of metabolic rate in the tissue region based on the specific uptake ratio and the input function, and determination of a diagnosis associated with the tissue region based on the estimate of metabolic rate.