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Publication Date: 2016-Jul-07
Document File: 6 page(s) / 182K

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The Prior Art Database


A technique to detect motion of a patient by utilizing a fiber optic shape sensing technology is disclosed. Fiber optic shape sensing technology is a commercially-available technology. By accumulating bending of every small segment of the fiber, the technology can reconstruct shape of a whole fiber in 3D space with high accuracy and acceptable time resolution. There are multiple ways to implement fiber optical shape sensing technology into MRI for shape sensing, which include but are not limited to two methods. According to an embodiment of the technique, fiber is applied on a scanned object, such as a patient while using a rigid receiving coil. Another embodiment of the technique includes applying fiber on a flexible coil, such as a wearable coil, which is mounted on the scanned object.

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The present invention relates generally to a magnetic resonance imaging (MRI) motion correction and more particularly to a technique for detecting patient motion based on fiber optical shape sensing technology.

Generally, magnetic resonance imaging (MRI) scan requires patient to remain motionless for good image quality. However, lying still is difficult for children, animals, seniors, myoclonus patients, or a mentally sick patient. Therefore, motion correction is a critical issue in MR imaging.  Motion of patients usually produces motion artifact and, consequently, results in loss of image quality. It is found that patient motion is one of the biggest challenges in most of the conditions of neuro MRI scan. More than 40% of brain MRI scans encountered patient motion problems.

A conventional technique includes capturing a navigation image before acquiring an actual image. The navigation image follows a tracker position in the image to calculate a displacement and rotation of a scanning volume.  Then, a sequencer adjusts acquisition parameters, such as, orientation and amplitude of a gradient to follow motion of the scanning volume. However, the above mentioned conventional technique requires a scanner to insert one or more special pulse sequences for a navigator.

The special pulse sequences are usually different from imaging pulse sequences and may interfere in steady state of the imaging pulse sequences. As such, the technique can only be applied to limited applications, where image contrast and image quality are not impacted by the steady state. Also, the navigation sequences require extra time, therefore the navigation sequences cannot be scanned frequently. Typically, there is a 3-5 seconds of interval between two navigator images, so the time resolution is not high enough for fast motions. In addition, typically only 5~10 degrees of pivoting and 5~10mm displacements are able to be corrected using the technique.

Another conventional technique also includes capturing a navigation image before acquiring an actual image.  However, the navigation image is acquired by a video camera and a tracker position constitutes a group of markers on a head of a patient. When the head of the patient moves, the technique captures motion by image processing. The technique is good in time resolution and does not have interference to the pulse sequence. However, image analysis is not 100% reliable, as the technique requires clearance between the patient and the video camera. If the patient moves arms or hands between head and the camera, or if there is a blanket or cloth, video camera imaging acquisition faces problems. Additionally, the technique is applied only for head scan. Besides it is difficult to put a camera into a strong magnetic field and the camera is required to be specially designed for using in strong magnetic field.

One other conventio...