Multiple PET, One CT Accurate, Lower Dose in Hybrid Imaging

Multiple PET scans only need one CT scan for accurate hybrid PET/CT imaging, which would significantly reduce the radiation exposure, according to results of a study presented at the Society of Nuclear Medicine’s 2012 Annual Meeting in Miami Beach, Fla.

Multiple PET scans are sometimes required for imaging injected biomarkers. The process can be time consuming because of the amount of time it can take for the biomarkers to bind to their targets. Adding CT scans to these tests each time can greatly increase a patient’s level of exposure to radiation.

To evaluate the effectiveness of using one CT scan with multiple PET scans, researchers assessed five volunteers who were imaged in two sessions of dynamic brain PET/CT scanning with a new biomarker for amyloid plaque, which has been implicated in cognitive decline and Alzheimer’s disease.

Both studies were 80 minutes to 90 minutes long. The researchers compared the images from the second PET study using the original CT image, a realigned CT image, and a second CT to determine if using only the first CT scan was feasible. Researchers found that one CT image could be used during multiple PET studies to achieve satisfactory image quality.

“Computed tomography is useful for reducing PET scan time and improving image quality, but there is room for reducing the radiation dose – especially in brain PET studies - by avoiding the redundancy of repetitive CT scans,” said Jae Sung Lee, PhD, an associate professor of nuclear medicine at Seoul National University in Seoul, Korea. “In this study, we propose a scheme to minimize the radiation dose by performing only a single CT scan per each subject and employing an image registration technique between brain PET scans.”