Validation of separate multi-atlases for auto segmentation of cardiac substructures in CT-scans acquired in deep inspiration breath hold and free breathing

Background and purpose: Developing NTCP-models for cardiac complications after breast cancer (BC) radiotherapy requires cardiac dose-volume parameters for many patients. These can be obtained by using multi-atlas based automatic segmentation (MABAS) of cardiac structures in planning CT scans. We investigated the relevance of separate multi-atlases for deep inspiration breath hold (DIBH) and free breathing (FB) CT scans. Materials and methods: BC patients scanned in DIBH (n = 10) and in FB (n = 20) were selected to create separate multi-atlases consisting of expert panel delineations of the whole heart, atria and ventricles. The accuracy of atlas-generated contours was validated with expert delineations in independent datasets (n = 10 for DIBH and FB) and reported as Dice coefficients, contour distances and dose-volume differences in relation to interobserver variability of manual contours. Dependency of MABAS contouring accuracy on breathing technique was assessed by validation of a FB atlas in DIBH patients and vice versa (cross validation). Results: For all structures the FB and DIBH atlases resulted in Dice coefficients with their respective reference contours > 0.8 and average contour distances < 2 mm smaller than slice thickness of (CTs). No significant differences were found for dose-volume parameters in volumes receiving relevant dose levels (WH, LV and RV). Accuracy of the DIBH atlas was at least similar to, and for the ventricles better than, the interobserver variation in manual delineation. Cross-validation between breathing techniques showed a reduced MABAS performance. Conclusion: Multi-atlas accuracy was at least similar to interobserver delineation variation. Separate atlases for scans made in DIBH and FB could benefit atlas performance because accuracy depends on breathing technique

Is the coronary artery calcium score associated with acute coronary events in breast cancer patients treated with radiotherapy?

BACKGROUND AND PURPOSE: The main objective of this study was to test whether pre-treatment coronary artery calcium (CAC) was associated with the cumulative incidence of acute coronary events (ACE) among breast cancer (BC) patients treated with postoperative radiotherapy (RT). MATERIAL AND METHODS: The study population consisted of 939 consecutive female BC patients treated with RT. The association between CAC and ACE was tested using Cox-proportional hazard models. Known risk factors for ACE and the mean heart dose (MHD), collected from three-dimensional computed tomography planning data, were tested for confounding. RESULTS: CAC scores varied from 0 to 2,859 (mean 27.3). The 9-year cumulative incidence of ACE was 3.2%, this was significantly associated with the pre-treatment CAC score. After correction for confounders, age, history of ischemic heart disease, diabetes, Body Mass Index ≥30, MHD, hypercholesterolemia and hypertension, the hazard ratio for ACE for the low and the combined intermediate and high CAC score category were 1.42 (95%CI: 0.49-4.17; p = 0.519) and 4.95 (95%CI: 1.69-14.53; p = 0.004) respectively, compared to the CAC zero category. CONCLUSIONS: High pre-treatment CAC is associated with ACE in BC patients treated with postoperative RT, even after correction for confounding factors such as MHD

Is the coronary artery calcium score associated with acute coronary events in breast cancer patients treated with radiotherapy?

BACKGROUND AND PURPOSE: The main objective of this study was to test whether pre-treatment coronary artery calcium (CAC) was associated with the cumulative incidence of acute coronary events (ACE) among breast cancer (BC) patients treated with postoperative radiotherapy (RT). MATERIAL AND METHODS: The study population consisted of 939 consecutive female BC patients treated with RT. The association between CAC and ACE was tested using Cox-proportional hazard models. Known risk factors for ACE and the mean heart dose (MHD), collected from three-dimensional computed tomography planning data, were tested for confounding. RESULTS: CAC scores varied from 0 to 2,859 (mean 27.3). The 9-year cumulative incidence of ACE was 3.2%, this was significantly associated with the pre-treatment CAC score. After correction for confounders, age, history of ischemic heart disease, diabetes, Body Mass Index ≥30, MHD, hypercholesterolemia and hypertension, the hazard ratio for ACE for the low and the combined intermediate and high CAC score category were 1.42 (95%CI: 0.49-4.17; p = 0.519) and 4.95 (95%CI: 1.69-14.53; p = 0.004) respectively, compared to the CAC zero category. CONCLUSIONS: High pre-treatment CAC is associated with ACE in BC patients treated with postoperative RT, even after correction for confounding factors such as MHD