Abstract
1982
Objectives Head and neck motion during PET/CT imaging results in reduced diagnostic image quality and may result in repeat imaging. Patients with certain neurological conditions are specifically susceptible to such issues during PET/CT data acquisition. Many of the products available today for motion correction of this type rely on external markers or uncomfortable equipment fitted to the patient. This work describes a novel external video-based monitoring system from Innovative Vision Solutions coupled with full 64-bit listmode event repositioning to create a streamlined head and neck motion correction workflow for routine clinical use.
Methods High resolution, high frame rate cameras, originally designed for small animal motion tracking, were mounted to a Siemens mCT Flow PET/CT gantry (1, 2). Following calibration of the cameras to the gantry geometry, patients were imaged with planned head movements at 3 minute intervals during a 9 minute 64-bit listmode acquisition. During this time, the video system monitored the patient’s head motion with a sampling rate of 20 frames/sec. For each time interval, a transformation matrix was calculated to transform the video-based camera measurement to the scanner geometry. The transformation matrices were then applied sequentially to the 64-bit listmode data file to reposition each event independently. The corrected listmode data were then histogrammed and reconstructed using the manufacturer-provided software for that specific scanner hardware. All data were set to a threshold of 70% of maximum for visual analysis.
Results Uncorrected images show significant motion artifacts compared to images corrected using the real-time tracking system with visible overlapping head and brain structures in the reconstructed images as well as significant ghosting and rotational artifacts. Misalignment and ghosting are especially apparent in defined regions, such as the nose. Corrected data also appears sharper with improved overall contrast and peak to valley ratios greater than 2x that of uncorrected regions.
Conclusions The video-based motion correction system described provides real-time, accurate monitoring and correction of head and neck PET/CT imaging data. This system can be mounted into any existing PET/CT gantry for use in real-time motion correction of patient data. $$graphic_93F10F2C-1CA3-4738-818F-C5653B716F91$$