SPECT Imaging Protocol for Dopamine Transporter Selectivity
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Solution Overview
Problem
Current diagnostic methods fail to selectively target and distinguish dopamine transporter sites from serotonin transporter sites effectively, particularly in neurodegenerative disorders like Parkinson's disease and Lewy Body Dementia, where the dopamine:serotonin transporter ratio is significantly altered.
Innovation Solution
The method involves administering a labeled dopamine transporter ligand, such as 123I-Altropane, and using SPECT imaging to assess dopamine transporter levels in the central nervous system, specifically in the striatum, by initiating a SPECT acquisition 15 minutes post-administration and continuing for 30 minutes to achieve optimal signal-to-noise ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional imaging methods are used to assess transporter levels, then imaging can be performed, but the ability to selectively distinguish dopamine transporter from serotonin transporter is insufficient
Solution Approach 1:
The patent applies local quality by using a ligand with specific molecular characteristics that selectively binds to dopamine transporter sites rather than serotonin transporter sites. The ligand's local chemical properties at the binding site enable differentiation between the two transporter types, achieving measurement precision without requiring complex dual-imaging protocols.
Solution Approach 2:
The patent changes the binding affinity parameter of the ligand to optimize its selectivity for dopamine transporter over serotonin transporter. By adjusting the ligand's chemical structure to achieve a specific binding affinity ratio, the method achieves high measurement precision for dopamine transporter assessment while maintaining a straightforward imaging protocol.
2Measurement precision
If SPECT imaging is performed immediately after ligand administration, then imaging time is reduced, but signal-to-noise ratio is insufficient
Solution Approach 1:
The patent applies preliminary action by scheduling the SPECT imaging acquisition to commence at a predetermined time (about 15 minutes) after ligand administration. This timing allows the ligand to reach optimal binding equilibrium at dopamine transporter sites before imaging begins, ensuring high signal-to-noise ratio without requiring excessively long waiting periods.
Solution Approach 2:
The patent maintains continuous useful action by performing SPECT imaging for an optimized duration (about 30 minutes) that captures the peak binding signal while minimizing unnecessary imaging time. This continuous imaging approach ensures adequate signal accumulation and statistical quality without extending the procedure longer than necessary.
3Measurement precision
If imaging duration is extended to improve signal quality, then signal-to-noise ratio increases, but patient exposure time and procedural complexity increase
Solution Approach 1:
The patent applies partial action by determining the minimum necessary imaging duration (about 30 minutes) required to achieve adequate signal-to-noise ratio for accurate dopamine transporter assessment. This optimized duration provides sufficient measurement precision while avoiding excessive imaging time that would reduce clinical throughput and increase patient burden.
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 allows for accurate assessment and differentiation of dopamine transporter levels, enabling effective diagnosis and monitoring of neurological disorders like Parkinson's disease and Lewy Body Dementia by providing clear separation between healthy and affected subjects.
Implementation Method 1
wherein the labeled dopamine transporter ligand is 123I-Altropane
Data Source
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AI summary
Presented is a method for assessing dopamine transporter levels in a selected area of a subject's central nervous system by SPECT imaging comprising administering an injection of a labeled dopamine transporter ligand at approximately the time the subject is positioned for SPECT imaging and initiating a SPECT acquisition for a duration of about 30 minutes commencing at about 15 minutes after administration of labeled dopamine transporter ligand; and assessing, based on said SPECT acquisition, the amount of labeled dopamine transporter ligand that is bound to dopamine transporter.