Dariush Askari - Assistant Professor, Department of Radiology Technology, Faculty of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Darband St, Ghods Sq., Tehran, Iran.
Mohsen Bakhshandeh - Assistant Professor, Department of Radiology Technology, Faculty of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Darband St, Ghods Sq., Tehran, Iran. Phone: +۹۸-۲۱-۲۲۷۱۷۵۰۳, Fax: +۹۸-۲۱-۲۲۷۱۷۵۰۳, E-mail: mbakhshandeh@sbmu.
Mahasti Amoui - Department of Nuclear Medicine, Shohada-e Tajrish Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Hamidreza Mirzaee - Cancer Research Center, Shohada-e Tajrish Hospital, Department of Radiation Oncology, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Mona Malekzadeh - Cancer Research Center, Shohada-e Tajrish Hospital, Department of Radiation Oncology, Shahid Beheshti University of Medical Sciences, Tehran, Iran

Introduction: Radiation-induced cardiovascular damage is a potential side effect of radiation therapy in patients with left-sided breast cancer. This prospective study compares the severity and reversibility of perfusion and functional abnormalities before, and six months after, ۳D-Conformal radiation therapy treatment in left-side breast cancer patients with conventional and hypofractionated schedule radiation therapy by stress/rest gated myocardial perfusion imaging.   Materials and Methods: Stress/rest gated myocardial perfusion imaging with Tc-۹۹m MIBI was performed in ۳۶ patients with left-sided breast cancer before, and six months after, completion of radiation therapy schedules. Results: Myocardial perfusion defects were detected in ۸۲.۶% and ۷۶.۹۰% of patients with conventional and hypofractionated radiation therapy schedule, which were prominently located in anteroseptal (۶۰.۹% vs. ۶۹.۲%), anterior (۵۲.۲% vs. ۶۱.۵%), anterolateral (۴۷.۸% vs. ۲۳.۱%), apex (۳۴.۸% vs. ۳۸.۵%), lateral (۲۱.۷% vs. ۷.۷%) and inferior (۸.۷%Vs ۰.۰%) walls, respectively. Frequency of mild, moderate and severe perfusion defects in the radiation therapy schedules were ۳۹.۱% vs. ۱۵.۴%, ۲۱.۷% vs. ۳۸.۵% and ۲۱.۷% vs. ۲۳.۱%, respectively. Myocardial perfusion defects were reversible, partial reversible or fixed in ۲۶.۰۹% vs. ۳۰.۸%, ۳۴.۷۸% vs. ۳۰.۸% and ۲۱.۷۴% vs. ۱۵.۰۴% patients, respectively. A statistically significant increase was found in the summed stress score, summed difference score and summed rest score of patients treated with conventional and hypofractionated radiation therapy schedule at six months after treatment, compared to the baseline study. Also, between the dosimetric parameters and semi-quantitative SPECT data of patients, a significant correlation was observed. Conclusion: Radiation-induced cardiovascular damage is a common finding six months after radiation therapy. Cardiac complications show no statistically significant differences between the two radiation therapy schedules. Both stress and resting gated MPI are required for assessment of changes in myocardial perfusion in patients with left-sided BC

Breast Cancer, Hypo-fractionated, Cardiovascular damage, myocardial perfusion imaging, Radiation Therapy