Insights into Imaging (Aug 2021)

MRI-detected extramural venous invasion of rectal cancer: Multimodality performance and implications at baseline imaging and after neoadjuvant therapy

  • Akitoshi Inoue,
  • Shannon P. Sheedy,
  • Jay P. Heiken,
  • Payam Mohammadinejad,
  • Rondell P. Graham,
  • Hee Eun Lee,
  • Scott R. Kelley,
  • Stephanie L. Hansel,
  • David H. Bruining,
  • Jeff L. Fidler,
  • Joel G. Fletcher

DOI
https://doi.org/10.1186/s13244-021-01023-4
Journal volume & issue
Vol. 12, no. 1
pp. 1 – 14

Abstract

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Abstract MRI is routinely used for rectal cancer staging to evaluate tumor extent and to inform decision-making regarding surgical planning and the need for neoadjuvant and adjuvant therapy. Extramural venous invasion (EMVI), which is intravenous tumor extension beyond the rectal wall on histopathology, is a predictor for worse prognosis. T2-weighted images (T2WI) demonstrate EMVI as a nodular-, bead-, or worm-shaped structure of intermediate T2 signal with irregular margins that arises from the primary tumor. Correlative diffusion-weighted images demonstrate intermediate to high signal corresponding to EMVI, and contrast enhanced T1-weighted images demonstrate tumor signal intensity in or around vessels. Diffusion-weighted and post contrast images may increase diagnostic performance but decrease inter-observer agreement. CT may also demonstrate obvious EMVI and is potentially useful in patients with a contraindication for MRI. This article aims to review the spectrum of imaging findings of EMVI of rectal cancer on MRI and CT, to summarize the diagnostic accuracy and inter-observer agreement of imaging modalities for its presence, to review other rectal neoplasms that may cause EMVI, and to discuss the clinical significance and role of MRI-detected EMVI in staging and restaging clinical scenarios.

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