E2042. Review of Imaging Findings in Early-Stage Nonsmall Cell Lung Cancer (NSCLC) Treated with Stereotactic Body Radiation Therapy (SBRT)
  1. Michele Bastianelli; The Ottawa Hospital
  2. Anuj Dixit; The Ottawa Hospital
With advances in 3D conformal radiation planning, there has been a rapid growth in the use of stereotactic body radiation therapy (SBRT) to treat a variety of tumors. Its benefits over conventional radiotherapy include primarily the ability to deliver higher doses of radiation to smaller tissue targets, limiting the radiation dose received by normal adjacent tissues. SBRT has now been the standard of care in the treatment of early-stage non-small cell lung cancer (NSCLC) in medically inoperable patients, and newer studies have explored its role in operable disease. Nevertheless, radiologists are heavily involved in assessing treatment response, complications, and evaluating for any recurrence. As SBRT treatment becomes more prevalent, it is imperative that radiologists familiarize themselves with the common post-treatment appearances on CT to reliably contribute to the care of these patients.

Educational Goals / Teaching Points
Understand SBRT and its benefits over conventional radiotherapy. Review the current literature and guidelines for SBRT in treatment of nonsmall cell lung cancer (NSCLC). Discuss the normal parenchymal changes of SBRT-treated lung and their expected timeline. Be able to recognize high-risk imaging features when evaluating SBRT-treated lung for any recurrence. Review common CT appearances of common SBRT complications after treatment.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Within this abstract we will review cases of SBRT-treated NSCLC evaluated on CT and the expected evolution of parenchymal changes after treatment. These include early changes such as consolidation, diffuse ground-glass opacities, and patchy consolidation surrounding the area of treated lung. We will outline the expected timeline of these findings to appear and resolve after treatment. Furthermore, we will review the late parenchymal changes and scarring that can occur up to 1 - 2 years after treatment such as traction bronchiectasis, mass-like fibrosis, and consolidation. These findings often mimic pathology or local recurrence, and can be challenging to delineate from normal expected post-treatment changes. Therefore, we will outline the high-risk imaging features of in-field recurrence that radiologists should be aware of and provide examples of cases at our institution where biopsy-proven recurrence was identified on CT. Finally, we will review common complications of SBRT and their imaging appearances on CT.

SBRT is a growing treatment option for early-stage NSCLC and has many appearances on CT that may mimic disease or complications. It is important for the radiologist to be familiar with these common appearances and be able to distinguish these from pathology.