Imaging for Staging and Response Assessment in Rectal Cancer

Improvements in surgical technique, advances in neoadjuvant chemoradiation regimes, and more aggressive treatment of metastatic disease have led to significant improvements in rectal cancer outcome. High-spatial resolution MRI remains the imaging modality of choice to plan treatment and to identify patients most likely to benefit from neoadjuvant chemoradiation. However, imaging is evolving to meet the need for better risk stratification. This article reviews current state-of-the-art imaging of rectal cancer and explores the potential role of functional imaging, including ultrasmall superparamagnetic iron oxide-enhanced MRI, diffusion-weighted MRI, dynamic contrast-enhanced MRI, dynamic contrast-enhanced CT, and fluorodeoxyglucose positron emission tomography, in staging rectal cancer and response assessment.