Objective: We evaluated the prevalence of myocardial perfusion defects using myocardial perfusion imaging (MPI) after chemoradiation or radiation therapy (CRT/RT) in lung cancer patients and described their patterns in relation to tumor location.
Methods: MPI in 44 patients who received RT for lung cancer and 44 control patients were compared. The two groups were comparable in risk factors for coronary artery disease. Data regarding tumor stage and location, interval between CRT/RT and MPI, and mean radiation dose to the heart was collected. The level of radiation delivered to the affected segments of the left ventricle versus the normal segments was compared using the isodose lines on the simulation computed tomography.
Results: Considering all tumor locations, 8 patients (18%) demonstrated MPI defects after CRT/RT versus 9 (20%) in the controls. However, 7 of 18 patients (39%) with centrally located tumors in the CRT/RT group versus only 1 of 15 patients (7%) in the control group demonstrated MPI defect (p= 0.04). The defects in the CRT/RT group were in the anterior and septal segments while the defects were in different segments in the controls. The median interval between end of RT and MPI was 12.3 months. The affected segments in the CRT/RT group received a mean radiation dose of 39.6 versus 11.4 Gy (p = 0.003) to the normal segments.
Conclusions: CRT/RT to centrally located lung tumors tends to cause anterior/septal MPI defects. Abnormal MPI segments in the CRT/RT group have received significantly higher radiation than normal segments.