Which body systems can affect the registration of PET imaging results due to motion?

The correct choice highlights that cardiac and respiratory movements can significantly impact the registration of PET imaging results. This is primarily because PET imaging requires the patient to remain as still as possible during the scan to capture accurate spatial information about the distribution of radiotracers in tissues.

The heart's contractions and the rise and fall of the diaphragm and lungs during breathing create motion artifacts that can blur the images and lead to misinterpretation of the PET scans. Such motion can reduce the effectiveness of the imaging by causing the uptake areas to appear larger or misplaced, which can complicate diagnosis or treatment monitoring.

Other body systems, while they may contribute to general patient movement, do not have the same direct and substantial impact on the specific registration of PET imaging data. Therefore, understanding the role of the cardiac and respiratory systems in the context of imaging is crucial for producing high-quality and reliable PET scans.