PRIMARY OBJECTIVES:
I. To test the diagnostic performance of PET- MRI in the staging of preoperative high-grade rectal cancer patients, defined by T3 stage or higher or N1 stage or higher or presence of metastasis, that are referred to PET-CT and MRI.
II. To test the diagnostic performance of PET-MRI the follow up of colorectal cancer patients that are referred to PET-CT with or without a diagnostic MRI request by their physicians.
SECONDARY OBJECTIVES:
I. To test different attenuation correction MR sequences and novel diagnostic MR sequences.
OUTLINE:
Patients undergo fludeoxyglucose F 18 PET-CT and PET-MRI.
