Role of MRI in the Use of an Absorbable Hydrogel Spacer in Men Undergoing Radiation Therapy for Prostate Cancer: What the Radiologist Needs to Know

AJR Am J Roentgenol. 2017 Oct;209(4):797-799. doi: 10.2214/AJR.17.18026. Epub 2017 Jul 25.


Objective: Hydrogel spacers have a novel role in the treatment of low- and intermediate-risk prostate cancer with dose-escalated radiation therapy. Given the growing number of patients undergoing treatment with radiation therapy, the use of hydrogel spacers is expected to increase. The purpose of this article is to review what a radiologist needs to know about the imaging of hydrogel spacers, including MRI technique and appearance on CT and MRI.

Conclusion: MRI has a critical role in the evaluation of hydrogel spacer placement and is used to facilitate contouring by the radiation oncologist. The radiologist should be familiar with the imaging appearance of hydrogel spacers on CT and MRI to avoid interpretation pitfalls and errors.

Keywords: dose-escalated radiation therapy; hydrogel spacers; low- and intermediate-risk prostate cancer; prostate MRI.

MeSH terms

  • Absorbable Implants*
  • Aged
  • Humans
  • Hydrogel, Polyethylene Glycol Dimethacrylate*
  • Magnetic Resonance Imaging* / methods
  • Male
  • Prostatic Neoplasms / radiotherapy*
  • Radiology / methods
  • Radiotherapy Dosage


  • Hydrogel, Polyethylene Glycol Dimethacrylate