Pilot Tone MRI Motion Detection for Real-Time Artifact Control
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Solution Overview
Problem
Existing MRI techniques struggle to robustly detect and correct for motion artifacts during image acquisition, particularly in patients who cannot remain still, leading to image corruption, prolonged scans, increased healthcare costs, and potential misinterpretation of brain activity.
Innovation Solution
A method and system using a pilot tone signal emitted near the Larmor frequency to detect motion in real time, processed by existing MRI hardware, and a motion detection algorithm to automatically trigger corrective actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If retrospective motion correction techniques are used to remove motion artifacts after image acquisition, then image quality is improved, but the technique only works well for smaller-scale rigid bulk motion and cannot completely remove motion artifacts
Solution Approach 1:
The patent applies preliminary action by detecting motion during the image acquisition process using a pilot tone signal, rather than attempting to correct motion after the fact. The system continuously monitors the pilot tone signal throughout the MRI scan to detect motion events as they occur, enabling real-time detection and triggering of reacquisition before motion artifacts corrupt the image data.
2Measurement precision
If prospective motion correction methods using cameras or tracking devices are used to quantify and adjust for patient motion during acquisition, then motion detection accuracy is improved, but the technical complexity and cost increase significantly
Solution Approach 1:
The patent applies universality by making the pilot tone signal processing pipeline an integral part of the existing MRI system. The same RF transmit and receive hardware used for MRI imaging is also used to generate and detect the pilot tone signal, eliminating the need for separate tracking devices or cameras. This multi-functional approach allows motion detection using existing infrastructure.
3Measurement precision
If navigator scans are used to estimate patient position during imaging, then motion estimation accuracy is improved, but the acquisition time increases due to interleaved fast scans
Solution Approach 1:
The patent applies merging by combining the motion detection function with the existing MRI acquisition process. The pilot tone signal is continuously present during the entire MRI scan, and motion detection is performed on this signal without requiring separate navigator scans. This integration eliminates the additional time that would be spent on interleaved fast scans while maintaining continuous motion monitoring.
4Measurement precision
If the pilot tone signal frequency is placed close to the Larmor frequency for efficient detection, then detection sensitivity is improved, but the signal may interfere with the imaging frequency band
Solution Approach 1:
The patent applies local quality by assigning different frequency characteristics to different parts of the signal processing. The pilot tone signal uses a frequency close to the Larmor frequency for sensitive detection, while the actual MRI imaging uses a different frequency band. The system processes these signals separately, allowing the pilot tone to be detected sensitively without interfering with the imaging process.
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 early detection and correction of motion artifacts, improving image quality and reducing scan duration, patient discomfort, and healthcare costs by allowing immediate reacquisition when necessary.
Implementation Method 1
The pilot tone signal is modulated by occurring motion and can be recorded during the acquisition along with the actual MR image
Data Source
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AI summary
The invention relates to a system and a method for automatically detecting, during an MRI session, a motion of a biological object (210) placed in an examination volume (221) of an MRI apparatus (220), the method (100) comprising: - emitting (101), in said examination volume (221) and during said MRI session , a pilot tone signal - hereafter PT signal -, wherein the PT signal is emitted at a frequency F_pt close to the Larmor frequency, but outside a range of frequencies used by the MRI apparatus (220) for imaging said biological object (210); - acquiring (102), by the MRI apparatus (220) the PT signal; - detecting (103), by a motion detection algorithm, in real time and from the acquired PT signal, a motion of the biological object; - automatically triggering (104) an action, during said MRI session, in function of the detected motion