Doenja Marina Johanna Lambregts MD, PhD, Presenter: Nothing to Disclose

Max Lahaye MD, PhD, Abstract Co-Author: Nothing to Disclose

Luc Heijnen, Abstract Co-Author: Nothing to Disclose

Monique Maas MD, Abstract Co-Author: Nothing to Disclose

Milou Martens, Abstract Co-Author: Nothing to Disclose

Regina G. H. Beets-Tan MD, PhD, Abstract Co-Author: Nothing to Disclose

Geerard L. Beets MD, PhD, Abstract Co-Author: Nothing to Disclose

Detection of local recurrences after primary treatment of rectal cancer is crucial in order to allow for timely surgical intervention. Standard imaging is known to experience difficulties in differentiating between post-treatment effects (inflammation/fibrosis) and recurrent tumor. Diffusion-weighted MRI (DWI) has in various studies shown to be a powerful technique for the detection of tumors. Hence, DWI may also be a promising tool for follow-up (FU) after treatment. Aim of this study was to evaluate the diagnostic value of DWI for the FU of patients after primary surgical or non-surgical treatment for rectal cancer.

The study group consisted of 117 patients who had previously undergone rectal cancer treatment, consisting of either standard surgical resection +/- neoadjuvant (chemo-)radiotherapy (n=36), a local transanal excision (n=40, of which 15 after chemoradiotherapy), or a non-operative ‘wait-and-see’-policy (n=41). During clinical FU all patients underwent one or more FU-MRIs (1.5T) including DWI (highest b-value b1000), as part of routine FU or because of a suspected local recurrence (e.g. clinical complaints or rising CEA levels) after surgery. Two readers in consensus evaluated each MRI and scored the b1000 DWI-images as ‘no high signal’, ‘high signal suspected of recurrence’ or ‘not adequately assessable due to artefacts’.

Patients underwent a mean number of 3 FU-scans (range 1-11) with a mean FU-time of 44 months (4-144). 27/117 patients developed a local recurrence, of which 23 (85%) were accurately detected on DWI. The other 90 patients (without recurrence) together underwent a total of 261 FU scans, of which 194 (74%) consistently remained true negative on DWI. 57 DWI-scans (19%) could not adequately be assessed due to artefacts. 14 DWI scans were false positive (mainly at the first FU-scan after surgery), of which 50%, however, again normalised during further FU.

DWI can be a useful tool for the FU of patients after primary rectal cancer treatment.  False positive DWI findings may occur shortly after surgery, but the DWI signal generally normalises during further follow-up. This should be taken into acount when using DWI for the clinical FU of rectal cancer patients.  

Diffusion-weighted MRI can be a useful tool for the follow-up of rectal cancer patients after primary surgical or non-surgical treatment and can help detect locally recurrent disease. 

Lambregts, D, Lahaye, M, Heijnen, L, Maas, M, Martens, M, Beets-Tan, R, Beets, G, Diffusion-weighted MR Imaging for the Follow-up of Patients after Primary Surgical and Non-surgical Treatment for Rectal Cancer.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13020539.html