Radiographic changes after lung stereotactic ablative radiotherapy (SABR)--can we distinguish recurrence from fibrosis? A systematic review of the literature

Radiother Oncol. 2012 Mar;102(3):335-42. doi: 10.1016/j.radonc.2011.12.018. Epub 2012 Feb 1.


Background: Changes in lung density on computed tomography (CT) are common after stereotactic ablative radiotherapy (SABR) and can confound the early detection of recurrence. We performed a systematic review to describe post-SABR findings on computed tomography (CT) and positron-emission tomography (PET), identify imaging characteristics that predict recurrence and propose a follow-up imaging algorithm.

Methods: A systematic review was conducted of studies providing detailed radiologic descriptions of anatomic and metabolic lung changes after SABR. Our search returned 824 studies; 26 met our inclusion criteria. Data are presented according to PRISMA guidelines.

Results: Acute changes post-SABR predominantly appear as consolidation or ground glass opacities. Late changes often demonstrate a modified conventional pattern of fibrosis, evolving beyond 2years after treatment. Several CT features, including an enlarging opacity, correlate with recurrence. Although PET SUVmax may rise immediately post-SABR, an SUVmax⩾5 carries a high predictive value of recurrence.

Conclusions: CT density changes are common post-SABR. The available evidence suggests that recurrent disease should be suspected if high-risk CT changes are seen with SUVmax⩾5 on PET. Further studies are needed to validate the predictive values of such metrics, and for advanced analysis of CT changes to allow early detection of potentially curable local recurrence.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Diagnosis, Differential
  • Humans
  • Lung Neoplasms / diagnostic imaging
  • Lung Neoplasms / surgery*
  • Neoplasm Recurrence, Local / diagnosis*
  • Positron-Emission Tomography
  • Pulmonary Fibrosis / diagnosis*
  • Radiosurgery*
  • Tomography, X-Ray Computed