Thoracic complications post stereotactic body radiotherapy (SBRT) for lung cancer - what the radiologist needs to know Poster No.: C-1700 Congress: ECR 2014 Type: Educational Exhibit Authors: G. E. Khanda, L. Jimenez-Juan, G. Bastarrika, P. Cheung, A. Oikonomou; Toronto, ON/CA Keywords: Cancer, Diagnostic procedure, Conventional radiography, CT, Thorax, Lung DOI: 10.1594/ecr2014/C-1700 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 32
Learning objectives To familiarize with the spectrum of imaging findings and potential complications post stereotactic body radiotherapy (SBRT) for stage I non-small cell lung cancer (NSCLC). Page 2 of 32
Background SBRT employs image guidance and precise treatment planning to deliver high dose of radiation to tumors while sparing surrounding normal tissue [1, 2]. This technique uses high doses per fraction, and has become standard treatment option for stage I NSCLC patients who are medically inoperable or refuse surgery [3]. Following SBRT acute and late-onset lung injury develops causing diagnostic dilemmas [4]. Acute radiological changes develop in about 60% of patients, while late changes occur in almost all patients [5, 6]. Late fibrotic changes can be dynamic and in one fourth of the cases the first CT changes may become apparent after 1 year of treatment with almost half of the cases showing signs of evolution more than 2 years of radiotherapy, rendering it difficult to differentiate post-sbrt fibrosis from recurrence [4]. Page 3 of 32
Findings and procedure details In contrast to radiation changes post conventional radiotherapy, where benign CT changes typically follow the edges of the treatment field, post-sbrt CT changes may present with "mass-like pattern" mimicking local recurrence (figure 1, 2). Misinterpretation of injury as recurrence can cause patients to undergo unnecessary interventions and treatment with no benefit. On the other hand misinterpretation of recurrence as injury may result in a missed opportunity for salvage [7]. Acute post-sbrt changes include diffuse and patchy consolidation (figure 3) or ground glass opacity (figure 4, 5). Occasionally acute change may appear as the "orbit sign" characterized by the presence of a central lesion surrounded by an inner zone of relatively spared lung and an outer zone of ground-glass opacification or consolidation (figure 6, 7, 8). Initial increase in size of the lesion is not uncommon with later decrease in size and shrinkage (figure 9, 10). An enlarging mass may not represent recurrence: according to a recent study based on further imaging and biopsy, only a few patients with enlarging masses are deemed to ultimately have recurrence [8]. On the other hand the opposite may also be seen with initial decrease in size and subsequent increase in size and the follow-up CT (figure 11, 12). Late onset post-sbrt changes include "modified conventional pattern with evolving radiation fibrosis" (figure 13-16), mass-like (figure 17, 18) and scar-like fibrosis (figure 19) and atelectasis (figure 20). Other complications include lung infection (figure 21), pericardial (figure 22) and pleural effusion (figure23), chest wall toxicity (figure 24) and rib fractures (figure 25). Bronchial stenosis or necrosis and brachial plexopathy are rare complications. They may occur more than 6 months after treatment and evolve for up to 2 years. When lung cancer develops near hilum or mediastinum there is increased risk from radiation exposure to vital structures causing rarely massive hemoptysis from tracheobronchial or esophageal ulcers. Patients with poor respiratory function and interstitial lung disease are at increased risk for fatal radiation pneumonitis. Page 4 of 32
Images for this section: Fig. 1: Pre SBRT CT (a) shows a left upper lobe peripheral lesion, which 13 months post SBRT (b, c) shows increase in size with a "mass-like appearance" not representing recurrence. Page 5 of 32
Fig. 2: Pre SBRT CT (a) shows a left upper lobe peripheral lesion which 21 months post SBRT (b) shows increase in size with a "mass-like appearance" not representing recurrence. Bilateral pleural effusion post SBRT and rib sclerosis and fracture at the site of SBRT is also noted (b). Page 6 of 32
Fig. 3: Pre SBRT CT (a) shows a right lower lobe peripheral lesion, which 7 months post SBRT (b, c) shows an adjacent area of air-space consolidation not representing recurrence. Page 7 of 32
Fig. 4: Pre SBRT CT (a) shows a middle lobe lesion, which 7 months post SBRT (b, c) shows an adjacent area of air-space consolidation and ground-glass not representing recurrence. Page 8 of 32
Fig. 5: Pre SBRT CT (a) shows a left lower lobe cavitary lesion, which 5 months post SBRT became more homogeneously solid (b, c) surrounded by an area of ground-glass opacification. Page 9 of 32
Fig. 6: Pre SBRT CT (a) shows a left upper lobe lesion, which 5 months post SBRT became more ground glass opacified (b) and 9 months later (c) it demonstrated the "orbitsign" characterized by the presence of a central lesion surrounded by an inner zone of relatively spared lung and an outer zone of ground-glass opacifcation or consolidation. Page 10 of 32
Fig. 7: Pre SBRT CT (a) shows a right upper lobe lesion, which 8 months post SBRT (b) demonstrated the "orbit-sign" characterized by the presence of a central lesion surrounded by an inner zone of relatively spared lung and an outer zone of ground-glass opacifcation or consolidation. Page 11 of 32
Fig. 8: Pre SBRT CT (a) shows a right upper lobe lesion, which in 6 (b) and 10 months (c) post SBRT gradually developed the "orbit-sign". Page 12 of 32
Fig. 9: Pre SBRT CT (a) shows a left lower lobe lesion, which 12 months post SBRT initially increased in size (b) and 20 months later mildly shrunk (c). Page 13 of 32
Fig. 10: Pre SBRT CT (a) shows a right lower lobe lesion, which 6 months post SBRT initially increased in size (b) and 12 months later shrunk (c). Page 14 of 32
Fig. 11: Pre SBRT CT (a) shows a right upper lobe lesion, which 5 months post SBRT initially decreased in size (b) and 8 months later increased in size on follow-up CT (c). Page 15 of 32
Fig. 12: Pre SBRT CT (a) shows a right lower lobe lesion, which 5 months post SBRT initially decreased in size (b) and 10 months later increased in size on follow-up CT (c). Page 16 of 32
Fig. 13: Pre SBRT CT shows a right lower lobe lesion (a), which 15 months post SBRT developed the "modified conventional pattern with evolving radiation fibrosis" (b). Page 17 of 32
Fig. 14: Pre SBRT CT shows a right lower lobe lesion (a), which 36 months post SBRT developed the "modified conventional pattern with evolving radiation fibrosis" (b). Page 18 of 32
Fig. 15: Pre SBRT CT shows a right upper lobe lesion (a), which 6 months post SBRT developed the "modified conventional pattern with evolving radiation fibrosis" (b, c). Page 19 of 32
Fig. 16: Pre SBRT CT shows a left upper lobe lesion (a), which 21 months (b) and 36 months post SBRT (c) developed gradually -the "modified conventional pattern with evolving radiation fibrosis". Page 20 of 32
Fig. 17: Pre SBRT CT shows a small left upper lobe nodule (a), which 28 months post SBRT (b) developed a "mass-like pattern". Page 21 of 32
Fig. 18: Pre SBRT CT shows a right upper lobe lesion (a), which 5 months post SBRT (b) developed a "mass-like pattern". Page 22 of 32
Fig. 19: Pre SBRT CT shows a right upper lobe lesion (a), which 19 months post SBRT (b) developed gradually a "scar-like fibrosis pattern". Page 23 of 32
Fig. 20: Pre SBRT CT shows a left lower lobe lesion (a), which 8 months (b) and 13 months post SBRT (c, d) developed gradually atelectasis. Page 24 of 32
Fig. 21: Pre SBRT CT shows a left lower lobe lesion (a, b), which 24 months later increased in size (c, d) and gradually became cavitary secondary to atypical mycobacterial infection (d, e). Page 25 of 32
Fig. 22: Pre SBRT CT shows a middle lobe lesion (a), which 6 months later developed a small radiation-induced pericardial effusion (b). Page 26 of 32
Fig. 23: Pre SBRT CT shows a right upper lobe lesion (a), which 5 months later developed a large radiation-induced right pleural effusion (b). Page 27 of 32
Fig. 24: Pre SBRT CT shows a subpleural lingular lesion (a), which 5 months later developed toxicity of the adjacent chest wall with edema and thickening of the regional musculature (arrow) (b). Page 28 of 32
Fig. 25: Four different cases (a, b, c, d) with rib fracture at the site of SBRT. Page 29 of 32
Conclusion Radiologists should be aware of the imaging findings of CT changes post SBRT and of the possible thoracic complications in order to accurately diagnose them and guide decision making. Page 30 of 32
Personal information Anastasia Oikonomou, MD, PhD work address: Department of Medical Imaging Sunnybrook Health Sciences centre 2075 Bayview Avenue, M4N3M5, Toronto email: anastasia.oikonomou@sunnybrook.ca Page 31 of 32
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