Kazim Z. Gumus1, Brian Keating1,
Brian Andrews-Shigaki2, Brian Armstrong3, Anders Dale4,
Thomas M. Ernst1
1John A. Burns School of Medicine,
University of Hawaii, Honolulu, HI, United States; 2Department of
Military & Emergency Medicine, Uniformed Services University of the
Health Sciences, Bethesda, MD, United States; 3Electrical
Engineering & Computer Science, University of Wisconsin-Milwaukee,
Milwaukee, WI, United States; 4Department of Radiology, University
of California, San Diego, La Jolla, CA, United States
This study compares two methods to track head motion in real-time, MRI-based PROMO (PROspective Motion Correction) and optical-based Retro Grate Reflector (RGR) tracking system. A volunteer performed head rotations about the scanner X- and Z- axes while being tracked with PROMO and simultaneously with RGR. High resolution MP-RAGE images immediately before and after the scan were realigned with SPM to provide a gold standard. Tracking with RGR and PROMO differed from SPM registration up to 2mm and 2. The possible causes of the non-negligible errors are presented. This study highlights the need for an independent method to evaluate tracking systems for adaptive MRI motion correction.