Investigating new imaging criteria for non-operative treatment following neoadjuvant chemoradiation in rectal cancer patients

Biopsy proven adenocarcinoma of the rectum
Patients with locally advanced rectal cancer who, according to current guidelines, are eligible for treatment with neoadjuvant chemoradiation
Patients treated in the LUMC, HMC, Alrijne Leiderdorp or Groene Hart Ziekenhuis Gouda.
Age 18 years and older;
Willing to participate in all aspects of the study

Patients with rectal cancer, receiving chemoradiation as part of the TESAR trial
Diabetes mellitus
Claustrofobia (low dose benzodiazepines are allowed)
Prior radiotherapy to the pelvis
If female and fertile: signs and symptoms of pregnancy or a positive pregnancy test / breast-feeding (a formal negative pregnancy test is not obligatory
Presence of any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
Contraindications for Magnetic Resonance Imaging
Patient has evidence of infection in the 14 days prior to the FDG-PET/CT scan localised to the lower abdomen, pelvic region, lower back, inguinal region
Inability to tolerate lying supine for the duration of an FDG-PET/CT examination (~30min)