Downloaded from https://journals.lww.com/thoracicimaging by BhDMf5ePHKav1zEoum1tQfN4a+kJLhEZgbsIHo4XMi0hCywCX1AWnYQp/IlQrHD3jmg6KbmzDt484evlJgyMAH3wCdWsR1tXsfw9bWkoW6/QA7lYWlksDQ== on 03/13/2020 Interobserver Variability in the Computed Tomography Assessment of Pulmonary Injury and Tumor Recurrence After Stereotactic Body Radiotherapy Nicolau F.C. Guerreiro, MD,* Jose A.B. Araujo-Filho, MD, PhD,*† Natally Horvat, MD, PhD,* Hye Ju Lee, MD,* Bernardo S.P. Oliveira, MD,* Fabio Ynoe de Moraes, MD,‡§ Isac Castro, PhD,∥ Fabiana Accioli Miranda Degrande, MD,‡ Carlos E.V. Abreu, MD, PhD,‡ and Karina de S. Giassi, MD, PhD* Purpose: To evaluate the interobserver agreement of chest computed tomography (CT) findings in the diagnosis of expected changes and local recurrence after stereotactic body radiation therapy (SBRT) in patients with early-stage lung cancer or a single pulmonary metastasis. Materials and Methods: A total of 54 patients with early-stage lung cancer or pulmonary metastasis who were treated with SBRT from 2007 to 2015 were included. The exclusion criteria were patients who presented with pulmonary infection during follow-up and patients who underwent a single CT during follow-up. The imaging features on CT were assessed by 3 blinded radiologists at the following 2 time points after SBRT: (a) early follow-up and (b) late follow-up ( ≥ 6 mo). The radiologists classified the findings as expected changes after SBRT or recurrence. Interobserver agreement was assessed by kappa and Wilcoxon statistics. Results: A total of 13 women and 41 men with a mean age of 75.3 ( ± 8.9) years were selected. The total and per fraction SBRT doses were 54 Gy (interquartile range: 45 to 54) and 18 Gy (interquartile range: 15 to 18), respectively. All expected changes and findings suggestive of recurrence had an almost perfect agreement (κ > 0.85) among readers, except for diffuse consolidation in the early period (κ = 0.65). Conclusion: CT findings demonstrate high interobserver agreement for expected changes and for findings indicating recurrence after SBRT. Key Words: stereotactic body radiation therapy, computed tomog- raphy, radiation-induced lung injury (J Thorac Imaging 2020;00:000–000) L ung cancer is a leading cause of cancer-related deaths worldwide. 1–3 Surgical resection is considered the standard treatment for patients diagnosed with early-stage lung tumors, 4–6 with radiotherapy (RT) and chemotherapy historically consid- ered adjuvant or palliative treatments. However, a minority of the patients are diagnosed in a resectable stage and many patients with resectable disease are high-risk surgical candidates. 7 In this scenario, stereotactic body radiation therapy (SBRT) has emerged as a highly effective noninvasive treatment for selected early-stage patients, with higher survival and local control rates compared with conventionally fractionated RT delivered in 5 to 7 weeks. 8 Irrespective of the fact that high ionizing radiation doses per fraction are used and normal tissue injuries are expected, SBRT is considered reasonably safe in the treatment of thoracic lesions, with reported grade III or IV toxicity rates <10% and a treatment-related mortality rate <5%. 6 Computed tomography (CT) is the primary imaging modality for evaluating response and for detecting different changes in pulmonary tissues after lung RT. 9 In older RT techniques, the inflammatory pulmonary changes are easily diagnosed and are typically characterized as lung opacity with straight borders following the edges of the treatment fields. 10 Conversely, the high and sharp gradient doses delivered to the lung during the SBRT are potentially associated with acute inflammatory pulmonary changes 9,11 and with a late and dynamic fibrotic process. 12–14 These acute (first 6 mo after treatment) and late-onset (after 6 mo) CT inflammatory changes are commonly observed—incidence rates of 54% to 79% and 80% to 100%, respectively 15 —and can sometimes mimic disease recurrence, 12,14,16 which may reduce the options for salvage therapies or result in unnecessary scans and interventions. For this differentiation, different qualitative CT features were described and some high-risk features have been validated as predictors of recurrence, 17 but they are subject to significant interobserver variability. 18 Moreover, there is a lack of studies validating the performance and reproducibility of these CT findings among radiologists. For these reasons, it is clear that an early and repro- ducible detection of expected inflammatory changes or local recurrence on chest CT is of key importance during the follow-up after SBRT treatment. The aim of this study was to evaluate the interobserver agreement of chest CT in the diagnosis of recurrence after SBRT in patients with early- stage lung cancer or single pulmonary metastasis. MATERIALS AND METHODS Study Population The Institutional Review Board approved this retro- spective study and waived the requirement of informed written consent. We searched our institutional database for consecutive patients who underwent SBRT due to lung cancer stages I, II, or IIIa , early stage (ie, T1 to T2 N0M0), T3N0M0 (ie, > 1 From the Departments of *Radiology; ‡Radiotherapy; ∥Research Hospital Sírio-Libanês, São Paulo, Brazil; †Department of Oncology, Division of Radiation Oncology, Queen’ s University; and §Kingston Health Science Centre, Kingston, ON, Canada. K.d.S.G. and N.H.: study concepts and study design. J.A.B.A.-F. and K.S.G.: literature search. B.S.P.O., N.F.C.G., and K.d.S.G.: image review. K.d.S.G. and N.F.C.G.: clinical information review. I.C.: statistical analysis. J.A.B.A.-F., N.H., and K.d.S.G.: manuscript drafting and editing. The authors declare no conflicts of interest. Correspondence to: Karina de S. Giassi, MD, PhD, Department of Radiology, Hospital Sírio-Libanês, Rua Dona Adma Jafet, 91, Bela Vista, São Paulo SP 01308-050, Brazil (e-mail: ksgiassi@gmail.com). Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/RTI.0000000000000495 ORIGINAL ARTICLE J Thorac Imaging  Volume 00, Number 00, ’’ 2020 www.thoracicimaging.com | 1 Copyright r 2020 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. This paper can be cited using the date of access and the unique DOI number which can be found in the footnotes.