Motion study on upright patient positioning in walk-through PET: evaluation in a clinical setting

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• The novel upright walk-through PET (WT-PET) scanner offers improved patient throughput over conventional cylindrical PET systems.
• Upright imaging presents unique patient motion challenges, necessitating evaluation of motion reduction strategies.
• Ergonomic features like headrests and hand supports are incorporated into WT-PET designs to minimize motion.

Purpose of the Study:

• To evaluate rigid body motion (head, shoulders, chest, abdomen) in patients using a WT-PET mock-up.
• To assess the effectiveness of ergonomic features and breath-holding in reducing motion during upright PET imaging.
• To compare motion in WT-PET imaging with conventional PET scans and healthy volunteers.

Main Methods:

• Motion data collected from 30 patients on WT-PET, 13 patients on conventional PET, and 12 healthy volunteers on both systems.
• Infrared markers tracked 3D positions during 30-second normal breathing and breath-hold periods in WT-PET mock-up.
• Motion quantified using Euclidean distance (ED) of marker centroids; conventional PET used 8-minute acquisitions.

Main Results:

• Breath-holding reduced mean abdominal motion by 24% in WT-PET patients (2.31 mm to 1.76 mm).
• Patient motion on WT-PET was higher than healthy volunteers (head: 3x, abdomen: 36%).
• WT-PET patients showed slightly lower head motion but 44% lower abdominal motion compared to conventional PET patients.

Conclusions:

• The WT-PET scanner introduces distinct motion control challenges requiring specific management strategies.
• Ergonomic supports and breath-holding protocols effectively reduce motion, but full 30-second breath-holds are not feasible for most patients.
• A two-step 15-second acquisition protocol is feasible for ~50% of patients, and comparisons confirm WT-PET's feasibility and limitations.