- Red five-pointed stars represent the effect of the image: Three stars indicate a good effect and could be considered the first choice for patients. Two stars indicate a moderate effect and could be considered the second choice for patients. One star indicates a poor effect and could be considered the third choice for patients
- *Diagnostic information: CT could obtain tumor anatomy and morphology information; MRI could obtain anatomy, morphology, and physiology information; PET could obtain tumor physiology and molecular information; PET/CT could obtain tumor anatomy, morphology, physiology, and molecular information; PET/MRI could obtain tumor anatomy, morphology, physiology, and molecular information
- †Soft tissue density resolution: MRI is better than CT for soft tissue with more water. On PET, which reflects molecular metabolism, lesions usually show high metabolism and poor recognition of morphological structure
- ‡Radiation exposure dose: The radiation dose of CT is mainly from ionizing radiation, and the radiation dose of PET is mainly from radioactive tracers, while the radiation exposure dose of CT examination is higher than that of radio pharyngology. MRI produces no radiation. The radiation dose of PET/MRI mainly comes from PET. Most of the radiation dose in PET/CT comes from the CT, and a small part comes from the PET radiotracer
- §Limitation of patient types: CT examination has radiation, so pregnant women and children should try to avoid using it. However, since it only takes a few minutes, most patients can tolerate it, and it can be used as the first choice in emergencies. MRI, PET, PET/CT, and PET/MRI take a long time to examine, which is unsuitable for emergency patients or some people who find it difficult to stay still for a long time. In addition, PET requires injection of radioactive drugs to image, so it is unsuitable for patients with drug allergies. MRI is noisy and narrow, which is not friendly for claustrophobic or obese patients and unsuitable for patients carrying metal objects. PET/CT and PET/MRI are integrated imaging modalities and, therefore, have the same problems as individual imaging modalities. ||Inspection time: CT usually takes a few minutes. MRI, PET, and PET/CT take about 30 min. PET/MRI takes an hour or longer
