Moving forward with motion reduction, detection and correction in cardiac PET

Excerpt

The heart is a moving organ, depending on heart rate, situated in the chest that is moving due to respiratory motion. The lungs during the heavier breathing (larger tidal volume) associated with stress tend to push the tip of the heart downwards which then slowly creeps upward in its return to rest. Patient’s body tends to move during scanning, usually along the axis of the table, mostly due to physical and/or mental discomfort. The magnitudes of these movements can be significant and highly variable between patients. Our instincts might betray us to accept that motion is a natural component of the imaging process and thus that the best a diagnostician can do is “read around” the problems caused by these motions. As PET scanner technology continues to improve leading to improvements in image quality such as is the case with digital photon counting and time of flight reconstruction, our instincts might also mislead us into expecting a reduction in the detrimental effects of motion. These improvements in image quality actually make motion artifacts more apparent.1 Consider the analogy that you replace your old standard TV with an ultra-high definition set. With this ultra-high definition now you see more blemishes in the face of your favorite news anchor. The ultra-high definition image did not create the blemishes; it just made them easier to see. Understanding the effect that motion creates on our images is important both for improving visual interpretation but more significantly for developing motion correction algorithms that can overcome these effects and improve quantification. …