Diagnostic Value of Whole-Body MRI for Rectal Cancer Preoperative Staging

• Evaluate the diagnostic accuracy of whole-body MRI for the staging of rectal cancer before and after neoadjuvant treatment [ Time Frame: baseline and 1 week before surgery ] [ Designated as safety issue: No ]
  We will compare for each body region the findings of the whole-body MRI to the FDG-PET-CT considered as the gold-standard and measure sensibility/specificity and diagnostic accuracy of the whole-body MRI for distant lesions of rectal cancer.
  
  

• Tumoral regression after neoadjuvant treatment [ Time Frame: baseline and six weeks after the end of the neoadjuvant treatment ] [ Designated as safety issue: No ]
  Evaluate the tumoral regression after neoadjuvant treatment on the MRI by the measurement of the ADC (attenuation diffusion coefficient) increase and compare the results to the measure of the SUV (standard uptake value) decrease on the FDG-PET-CT.
  
  

Rectal cancer is the second cause of mortality after lung cancer in industrialized countries and represent 28% of colorectal carcinomas. Despite major improvements in diagnosis and treatment made those last years,mortality and morbidity remains high, because of high prevalence of metastasis and local recurrence. A accurate initial staging is of paramount importance for an appropriate treatment (neoadjuvant chemiotherapy and radiotherapy, surgery).

Actually, there is no international consensus concerning imaging for the staging of rectal cancer and modalities used are variable from one center to another.

WB-MRI represented a attractive and promising technique for the staging of rectal cancer, free of ionizing radiation .