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Radiation-Induced Cardiovascular Changes Assessed by Computed Tomography

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M Thor

M Thor1*, A Hotca1 , A Jackson1 , E Yorke1 , A Rimner1 , J Deasy1 , (1) Memorial Sloan Kettering Cancer Center, New York, NY, US


MO-RPM-GePD-JT-6 (Monday, July 31, 2017) 3:45 PM - 4:15 PM Room: Joint Imaging-Therapy ePoster Theater

Purpose: To quantify radiation-induced changes in cardiac structures after intensity-modulated radiotherapy (IMRT) for Non-Small Cell Lung Cancer (NSCLC) using non-contrast-enhanced Computed Tomography (CT) scans.

Methods: For each of 28 locally-advanced NSCLC patients treated with IMRT to 50.0-70.2Gy@1.8-2.0Gy/fraction, radiation-induced CT changes were quantified in eight structures (atria, aorta, inferior- and superior vena cava, pulmonary artery, and ventricles) as the ratio of the median Hounsfield Units between the pre-treatment and the first CT scan post-IMRT (HUpre/HUpost). The post-IMRT scan was acquired at a median of 2 (range: 0.1-5.8) months after RT completion. For each structure, HUpre/HUpost was correlated with time-to-death (median: 12 (range: 0.8-54) months), and trends were studied stratified by radiation pneumonitis status (Cutoff: ≥Grade 2; n=5 (18%); median time-to-pneumonitis: 4 (range: 3-8) months). In addition, HUpre/HUpost of each structure was correlated to that of the remaining structures. Correlation was assessed using Spearman’s rank (Rs); strong correlation: |Rs|≥0.70.

Results: In general, HUpre/HUpost was >1 for all structures (median: 1.03-1.10) except for inferior vena cava (median: 0.96). The correlation between HUpre/HUpost and time-to-death was low (Rs=-0.11, 0.07) but increased when focusing only on the patients with a time-to-death less than the population median (Rs=-0.05, 0.57). HUpre/HUpost of the aorta was strongly correlated with that of the left atrium and the pulmonary artery (Rs=0.75, 0.88). Similarly, HUpre/HUpost between the left and right ventricle was strongly correlated (Rs=0.71). The left atrium trended towards lower HUpre/HUpost for patients with versus without radiation pneumonitis (median: 1.04 vs. 1.09); a contradictory pattern was observed for the right atrium (median: 1.56 vs. 1.09).

Conclusion: A strong correlation was observed in radiation-induced CT changes between the intrinsic cardiac segments aorta and left atrium, and between the left and right ventricle. In addition, CT changes of the aorta were strongly correlated with those of the pulmonary artery.

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