INNOVATION:  UCLA researchers have developed a novel computer algorithm to reduce motion artifact and improve the quality of PET imaging. There have been many methods proposed to reduce motion artifact by "gating" the acquisition of images. Most methods employ a physical trigger (motion, changes in pressure or airflow) from respiration to signal the scanner when to acquire or how to sort the images. The physical trigger itself can have considerable variation, and recording the physical trigger often requires expensive and cumbersome equipment. Also, traditional gating methods disregard valuable information actually available during the non-acquired phases of the breathing cycle. Our method employs a novel fully automated software algorithm which examines all of the raw data from the PET scan, without the need for cumbersome equipment or additional hardware of any kind. The software is then used to characterize and correct the motion artifacts, resulting in higher quality and more quantitatively accurate PET images. Measurements of respiratory motion obtained using our methodology have been shown to compare well with those derived from hardware-based pressure belt measurements, in the clinical setting.

POTENTIAL APPLICATIONS 

• Can be used to improve PET imaging of the chest, especially helpful in locating small lung nodules and prevent unnecessary surgeries
• Better target localization and volume characterization can be used to improve radiation therapy
• May be used to improve imaging of the subdiaphragmatic and mediastinal structures, including the liver and lymph nodes
• Could be extended to improve imaging modalities other than PET and/or other periodic motion artifacts caused by processes other than respiration.

ADVANTAGES

• Fully automated software
• No expensive or cumbersome external equipment to purchase and maintain
• No need to alter current image acquisition protocols
• Can be incorporated into a software package that can be retrofitted to existing scanners, and can simply provide an additional image to existing scanner output
• Relatively inexpensive but valuable add-on for manufacturers of PET scanners
• Utilizes all available image information from scan acquisition, where traditional PET scanning or respiratory gated PET disregard or throw out information.
• Ability to retrospectively reconstruct PET data at any phase of the breathing cycle

Reference: UCLA Case No. 2007-307