Simultaneous Multi-Orientation MRI for Out-of-Plane Motion Detection
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Solution Overview
Problem
Current medical imaging techniques in MRI-guided radiation therapy struggle to accurately detect out-of-plane motion of targets due to limitations in imaging only in a single 2D plane, leading to potential misalignment during radiation therapy, especially for abdominal or thoracic tumors.
Innovation Solution
A method for simultaneous multi-orientation (SMO) magnetic resonance imaging that involves exciting and acquiring data from two or more arbitrarily oriented slices in each repetition time period, using a specific pulse sequence with spatial encoding gradients to enhance spatial information and improve temporal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single 2D plane imaging is used, then frame rate is maintained, but out-of-plane motion detection capability deteriorates
Solution Approach 1:
The patent transitions from single 2D plane imaging to simultaneous multi-orientation 3D imaging by acquiring data from multiple non-coplanar slices (e.g., axial, coronal, sagittal orientations) at the same time. This dimensional expansion enables detection of out-of-plane motion while maintaining high temporal resolution through efficient k-space sampling strategies and parallel imaging techniques.
2Measurement precision
If multiple orthogonal planes are imaged interleaved, then pseudo-3D motion estimation is improved, but temporal resolution deteriorates
Solution Approach 1:
The patent combines multiple slice acquisitions into a single TR period by simultaneously exciting and acquiring data from multiple non-coplanar slices. This merging of acquisitions eliminates the temporal gap inherent in interleaved sequencing, achieving true simultaneous multi-orientation imaging that maintains high frame rates while providing comprehensive 3D motion coverage.
Solution Approach 2:
The patent applies preliminary phase encoding gradients and slice selection RF pulses to multiple slices before data acquisition begins, allowing all slices to be prepared and excited within the same TR period. This preliminary preparation enables synchronized acquisition across all orientations without sequential delays.
3Productivity
If conventional sequential slice imaging is used, then spatial coverage is achieved, but imaging speed deteriorates
Solution Approach 1:
The patent acquires data from multiple non-coplanar slices simultaneously, effectively adding the dimension of slice orientation diversity to the imaging process. This enables comprehensive 3D spatial coverage to be achieved in the time it would take to acquire a single 2D plane, dramatically improving imaging speed while maintaining or enhancing spatial coverage.
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
The SMO technique allows for improved visualization of targets and nearby structures, enhancing the accuracy of dose delivery in MRI-guided radiation therapy by increasing the frame rate and enabling real-time monitoring of intrafraction motion.
Implementation Method 1
A pulse sequence is performed with the MRI system, wherein the pulse sequence includes in each repetition time ("TR") period: a first radio frequency ("RF") excitation pulse that excites spins in a first slice
Implementation Method 2
a first set of spatial encoding gradients to provide slice encoding and phase encoding of the spins in the first slice
Data Source
AI summary
Simultaneous multi-orientation (“SMO”) magnetic resonance imaging (“MRI”), in which arbitrarily-oriented slices are simultaneously imaged, is described. The SMO techniques can include any number of pulse sequences that are adapted to acquire data from two or more arbitrarily oriented slices. In general, an SMO acquisition includes sequentially exciting two or more arbitrarily rotated slices that share a common spatial encoding axis (e.g., a common frequency encoding direction) and simultaneously acquiring data from the excited slices.