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 2 years 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. © 2011 Elsevier Ireland Ltd. All rights reserved.
Huang, K., Dahele, M., Senan, S., Guckenberger, M., Rodrigues, G. B., Ward, A., … Palma, D. A. (2012, March). Radiographic changes after lung stereotactic ablative radiotherapy (SABR) - Can we distinguish recurrence from fibrosis? A systematic review of the literature. Radiotherapy and Oncology. https://doi.org/10.1016/j.radonc.2011.12.018