Table 5.

Advantages and disadvantages/pitfalls of combined PET-CT.

Advantages	Disadvantages/potential pitfalls
Physiological information with poor spatial resolution of FDG-PET combined with the high spatial resolution of CT yields a study that is better than either component on their own	Potential for false-positive results in the postoperative bed within 4 weeks of surgery
Improved sensitivity and specificity for staging colorectal cancer, detecting local recurrence and metastases	High radiation dose Potential false-negative results with variations in rectal distension and mucinous adenocarcinomas which often do not take up FDG and in lymph nodes measuring less than 1 cm in size
Can be used to predict response to chemoradiotherapy and plan radiotherapy	Potential false-positive results due to the presence of abscesses, sinus, or fistulous tracts