ESTRO 2024 - Abstract Book

S1775

Clinical - Lung

ESTRO 2024

radiation therapy (SBRT), by comparing extensive baseline examinations with post treatment measurements in an early stage NSCLC cohort treated with SBRT.

Material/Methods:

Ten patients were included in this prospective, multicenter trial. The cardiac condition of early stage NSCLC patients with a tumor within 3cm distance to the heart, who were treated with SBRT were collected at baseline, and 3 and 12 months post-treatment, by means of cardiac MRI, echocardiogram, ECG and blood values. Contractility within a cardiac cycle was quantified by measuring the strain of the heart globally, and by using the 17 myocardial segment [2] model as performed by two independent observers using feature tracking CMR software. Longitudinal strain was measured on MRI and echocardiogram. Circumferential strain and Radial strain were measured on MRI only. Dose per segment was determined through co-registration of the planning CT to the cardiac MRI, and extracting the max and mean dose per segment. Furthermore, cardiac condition was assessed based on left ventricular ejection fraction (LVEF), measured on MRI and echocardiogram, serum troponinT and NTproBNP (indicating cardiac distress), lymphocyte counts and ECG values including P-duration and QRS-duration. Differences between baseline and post treatment measurements were assessed using paired t-tests for normally distributed parameters, or Wilcoxon signed rank tests for not-normally distributed parameters. To assess dose-effect relations, linear mixed models with patient as random effect were fitted between dose and the difference in strain between baseline and 3 months, baseline and 12 months, and 3 months and 12 months, for the different types of strains (longitudinal, circumferential, radial) with a forced intercept at zero. Only segments with normal baseline values [3], and with inter-observer variation<25%, were included. The cardiac condition before and after treatment was assessed for 8 patients, 2 patients dropped out after the baseline measurements. Four patients were male, the mean age was 67 years, 6 had WHO performance status 0, mean lung function FEV1 was 72%, mean distance from the edge of the tumor to the pericardium was 0.98cm. Five patients received 8x7.5Gy, one 5x11Gy, one 3x18Gy and one 8x7Gy. Mean lung dose was 3.9Gy, mean heart dose 4.6Gy. There were no significant differences in cardiac condition before and after treatment, nor between the 3 month and 12 months measurements. Mean left ventricular ejection fraction as measured on MRI were 61.1% (baseline), 58.1 (3months) and 59.6% (12months). Mean lymphocytes counts were (per 10-9L-1) 1.81 (baseline), 1.64 (3months) and 1.55 (12months). One patient had lymphopenia grade 2 and 1 after treatment; 0.71*10-9L-1 and 0.80*10-9L-1 at the 3 and 12 months follow-up respectively. Twelve percent of segments were not included in the analyses as the inter-observer variation was >25%. No significant differences were found in strain before and after treatment. The slopes of the linear mixed model for the difference between baseline and 12 months were longitudinal strain (MRI) -0.10 Gy-1, longitudinal strain (echocardiogram) -0.02 Gy-1, circumferential strain -0.02 Gy-1, radial strain 0.03 Gy-1, where a worsening of the strain is indicated by a negative slope for the longitudinal and circumferential slope, and a positive slope for the radial strain. Results:

The figure shows the longitudinal strain as measured on the MRI for the difference in longitudinal strain between baseline and 12 months. The spread of the data points is representative for all other time points or strains.

Made with FlippingBook - Online Brochure Maker