MRI Wall Thickness Measurement via Normal Direction Alignment
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Solution Overview
Problem
Current methods for determining wall thickness of anatomical details, such as the heart, in medical procedures like radio frequency ablation are prone to errors due to partial volume effects and require precise adjustments, which can be improved by considering anatomical characteristics.
Innovation Solution
A method using magnetic resonance imaging that involves defining locations on a surface representation, generating a line-structure of interest, determining normal directions, and acquiring images in planes with minimal angular deviation to accurately measure wall thickness, reducing systematic measurement errors and leveraging high in-plane resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MRI methods are used for wall thickness measurement, then the measurement process is simple, but measurement precision deteriorates due to partial volume effects
Solution Approach 1:
The method segments the measurement process into distinct steps: defining a line-structure of interest along the anatomical boundary, determining normal directions at multiple locations, calculating angular deviations, and selecting optimal imaging planes for each location. This segmentation allows precise measurement at each point while maintaining overall process manageability
Solution Approach 2:
The method transitions from conventional 2D cross-sectional imaging to a 3D scan geometry planning approach. By determining normal directions and angular deviations in three-dimensional space, the method selects optimal imaging planes that perpendicular to the anatomical surface at each measurement location, eliminating partial volume effects and improving measurement precision
2Reliability
If radio frequency ablation is performed without accurate wall thickness knowledge, then the procedure is faster, but reliability deteriorates due to risk of wall perforation or insufficient lesion creation
Solution Approach 1:
The method performs preliminary anatomical measurements and scan geometry planning before the ablation procedure. By determining wall thickness and normal directions in advance using MRI, the ablation parameters can be pre-configured, ensuring safe and effective treatment while reducing intra-procedural adjustments and time loss
Data Source
AI summary
A method for determining wall thickness of an anatomic detail (52), in particular of the heart, of a subject of interest (20) by magnetic resonance imaging includes: defining (82) a first location (54) and a second location (56) on a surface representation; —generating (84) a line-structure of interest (60), —determining (86), for each location (62) of a plurality of locations (62), a normal direction (64); —determining (88) a mean normal direction (66); —determining (90) a mean imaging plane (68); —determining (92) a measure that is representative of angular deviations (43) of the determined normal directions (64); —based on the determined measure, determining (96) imaging planes (70); —determining (98) deviations of the determined normal directions (64) to the imaging planes (70); —acquiring (100) magnetic resonance images for all imaging planes (68, 70); and —determining (102) the wall thickness at a specific location (62) from the magnetic resonance image acquired in the imaging plane (70) that has the lowest angular deviation to the normal direction (64) at the specific location (62). A magnetic resonance imaging system (10) has a controller (26) configured to carry out steps (78-102) of the method. A software module (50) carries out the method by implementing program code from a memory (28) and executed by a processor (30) of the magnetic resonance imaging system (10).