MRI Relaxation Map Calibration via Low-Resolution Reference
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Solution Overview
Problem
Current methods for characterizing and quantifying the three-dimensional architecture of fibrotic tissue in the heart are laborious and limited, particularly in detecting scar tissue and differentiating tissue types, with existing MRI techniques like MOLLI and delayed enhancement facing challenges in achieving high-resolution T1 mapping due to low spatial resolution and variability in patient-specific imaging.
Innovation Solution
A method is described for producing high-resolution relaxation parameter maps by calibrating high-resolution MRI images using a computer system, where a calibration curve is created from low-resolution relaxation parameter maps to convert image intensity values into relaxation parameter values, enabling the generation of high-resolution T1 and T2 maps with improved spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MOLLI imaging is used to directly provide T1 magnetization recovery values, then T1 tissue evaluation is enabled, but the acquisition time is long (10-15 seconds) and spatial resolution is limited (1.3×1.3×8.0 mm)
Solution Approach 1:
The patent performs preliminary action by acquiring a low-resolution relaxation parameter map first, then using it to generate a calibration curve that converts high-resolution image intensity values into relaxation parameter values. This preliminary calibration step enables subsequent high-resolution mapping without requiring lengthy acquisition times, thus resolving the contradiction between measurement precision and time loss.
2Measurement precision
If multiple sample points are acquired along the T1 recovery curve, then T1 magnetization recovery values are obtained, but it becomes difficult to achieve sub-millimeter or close to sub-millimeter isotropic resolution
Solution Approach 1:
The patent segments the measurement process into two distinct stages: first acquiring a low-resolution relaxation parameter map with multiple sample points for accurate T1 recovery measurement, then using that calibration to generate high-resolution relaxation parameter maps from separate high-resolution images. This segmentation allows each stage to optimize for its specific requirement, resolving the contradiction between measurement precision and spatial resolution.
3Illumination intensity
If delayed enhancement imaging is used to provide scar tissue information, then large signal intensity is achieved, but the results are difficult to standardize due to uncontrollable variables like imaging time post contrast and heart rate
Solution Approach 1:
The patent transforms the imaging approach from relying on uncontrollable variables (imaging time post contrast, heart rate) to using a calibration-based parameter transformation. By establishing a calibration curve that relates image intensity values to relaxation parameter values, the method enables standardization of results across different patients and imaging conditions while maintaining high signal intensity for scar tissue detection.
Data Source
AI summary
Described here are systems and methods for producing high-resolution three-dimensional (“3D”) relaxation parameter maps by calibrating high-resolution 3D magnetic resonance images. As one example, high-resolution longitudinal relaxation time (“T1”) maps can be generated based on images acquired using a T1-weighted pulse sequence, and as another example high-resolution transverse relaxation time (“T2”) maps can be generated based on images acquired using a T2-weighted pulse sequence. The high-resolution images can be calibrated, for example, using a lower resolution single slice relaxation parameter map. The methods described here utilize high-resolution 3D scans and low-resolution relaxation parameter maps that are commonly available on MRI systems. The calibration is a post-processing step used to create the high-resolution 3D relaxation parameter maps from these two types of scans.