title: Functional MRI for quantitative treatment response prediction in locally advanced rectal cancer.
abstract: Despite advances in multimodality treatment strategies for locally advanced rectal cancer and improvements in locoregional control, there is still a considerable variation in response to neoadjuvant chemoradiotherapy (CRT). Accurate prediction of response to neoadjuvant CRT would enable early stratification of management according to good responders and poor responders, in order to adapt treatment to improve therapeutic outcomes in rectal cancer. Clinical studies in diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI have shown promising results for the prediction of therapeutic response in rectal cancer. DWI allows for assessment of tumour cellularity. DCE-MRI enables evaluation of factors of the tumour microvascular environment and changes in perfusion in response to treatment. Studies have demonstrated that predictors of good response to CRT include lower tumour pre-CRT apparent diffusion coefficient (ADC), greater percentage increase in ADC during and post CRT, and higher pre-CRT Ktrans. However, the mean ADC and Ktransvalues do not adequately reflect tumour heterogeneity. Multiparametric MRI using quantitative DWI and DCE-MRI in combination, and a histogram analysis technique can assess tumour heterogeneity and its response to treatment. This strategy has the potential to improve the accuracy of therapeutic response prediction in rectal cancer and warrants further investigation.
authors.affiliation: 1 Department of Radiation Oncology, Liverpool Hospital, Sydney, NSW, Australia.|2 Sydney West Radiation Oncology Network, Westmead, Blacktown and Nepean Hospitals, Sydney, NSW, Australia.|3 Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.|4 Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.
authors.forename: Trang T
authors.identifier: http://orcid.org/0000-0002-7759-8296
authors.initials: TT
authors.lastname: Pham
authors.affiliation: 1 Department of Radiation Oncology, Liverpool Hospital, Sydney, NSW, Australia.|3 Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.|4 Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.|5 Faculty of Radiation and Medical Physics, University of Wollongong, NSW, Australia.
authors.forename: Gary P
authors.initials: GP
authors.lastname: Liney
authors.affiliation: 1 Department of Radiation Oncology, Liverpool Hospital, Sydney, NSW, Australia.|3 Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.|4 Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.
authors.forename: Karen
authors.initials: K
authors.lastname: Wong
authors.affiliation: 1 Department of Radiation Oncology, Liverpool Hospital, Sydney, NSW, Australia.|3 Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.|4 Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Barton
mesh_terms: D059186:Chemoradiotherapy, Adjuvant / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D020360:Neoadjuvant Therapy / Q000379:methods*; D012004:Rectal Neoplasms / Q000628:therapy*; D012007:Rectum / Q000000981:diagnostic imaging / Q000187:drug effects / Q000528:radiation effects; D016896:Treatment Outcome