Locally advanced rectal cancer (LARC) –defined by the parameters cT3-T4, N -/+, M0– has a 5year survival rate equal to 50-65%, with a local recurrence rate of 30-40%. Currently the treatment of LARC is oriented towards the use of neoadjuvant therapies, which further reduces the recurrence rate,leading to volume reduction and tumor downstaging. In patients affected by LARC, a complete histopathologic response after CRT occurs in 10-30% of cases at the time of surgery and is related with better prognosis. A "wait and see" approach...

Fifty patients with MRI diagnosis of LARC between December 2009 and January 2014 were considered for inclusion in our retrospective study based on the following criteria: endoscopic diagnosis and histopathologic (biopsy) proved rectal carcinoma; conventional MR pre-CRT completed with DWI;combined neoadjuvant therapy: the treatment protocol included external beam radiotherapy for a total of 45 to 50.4 Gy (1.8 Gy/fraction) and chemotherapy with 5-fluorouracil (continuous infusion of 225/mg/m²/day for 7 days for the duration of radiation therapy) or Capecitabine per os (825 mg/m² 2 times/day from...

Fourteen of the 32 patients included in our study underwent anterior resection of the rectum and 15/32 abdominoperineal resection. Three patients were monitored with endoscopy and concomitant biopsy and underwent FU with MRI investigation every 3-6 months for the first year and then annually. The mean time between the end of neoadjuvant therapy and restaging MR imaging was 53.4 days (range: 38-82 days) and the mean time between the post-CRT MR imaging and surgery (or biopsy) was 21.2 days (range: 2-60 days). Pathologic examination revealed...

Conventional MR sequencesare not sufficiently reliable in distinguishing between residual tumor and post-CRT tissue fibrosis. However, it has been shown that thequalitative assessment of DWI sequencessignificantly improves the diagnostic performance of conventional MRI in the evaluation of tumor response to CRT: particularly, in distinguishing between CR and n-CR patients, DWI has shown a higher sensitivity (52-64% vs. 0-40%) and an almost comparable specificity (89-97% vs. 92-98% ) vs. standard MR sequences. However, DW images have limitations, as complete tumor regression is not always accompanied by...

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