An Inexpensive Scanner-independent Motion Monitor for Research and Clinical Imaging Applications

Open Access
Author:
Wahi-anwar, Muhammad W
Area of Honors:
Physics
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Susan K Lemieux, Thesis Supervisor
  • Richard Wallace Robinett, Honors Advisor
Keywords:
  • simple
  • motion
  • monitor
  • MRI
  • artifact
  • detection
Abstract:
Purpose: To develop and test an inexpensive optical motion monitor to track patient or participant movement for training prior to scan time and to reduce the repeat rate of longer acquisition scans. Methods: The motion monitor utilizes an optical system to track movement. The components are fiber optic cables, a light source, a light detector and an analog-to-digital converter. A movable cylindrical agar gel phantom with inserts for geometric distortion and spatial resolution was constructed. Movement magnitude and direction were varied during testing on the phantom and human participants. Dynamic echo-planar imaging (EPI) scans were acquired concurrently to compare retrospectively calculated motion to the monitor signal. Anatomical images were acquired to measure the effects of motion. Images were acquired at rest and with discrete movements at distinct times during each scans. Results: Motion monitor tests demonstrated sensitivity smaller than 2 mm, similar to the motion derived from simultaneous EPI scans. Motion near to the center of k-space resulted in higher image distortion. Conclusions: The motion monitor developed was sensitive to movements as small as 2mm. The motion monitor could be used to train patients or participants to hold still and to truncate scans when movements are observed during MRI scanning.