CT findings of acute radiation-induced pneumonitis in breast cancer

Abstract

Objectives: To evaluate the CT findings of acute radiation pneumonitis (RP) in breast cancer patients undergoing post-operative radiotherapy, and to analyze clinicodosimetric factors associated with acute RP.

Methods: Between 2015 and 2017, 61 patients with breast cancer who underwent follow-up chest CT at 3 months after radiotherapy were analyzed. The degree of acute RP on CT was evaluated by the change of extent and scoring system (grade 0, no RP; Grade 1, ground-glass opacities (GGOs); Grade 2, GGOs and/or consolidations; Grade 3, clear focal consolidation; Grade 4, dense consolidation). The dosimetric parameters were calculated from the dose-volume histogram of RT.

Results: The acute RP on CT was scored as follows: Grade 0, in 37.7%, Grade 1 in 13.1%, Grade 2 in 44.3%, and Grade 3 in 4.9%. The median extent of RP in patients with Grades 1 to 3 was 6.2 ml (range, 0.2-95.9). There were no clinicodosimetric factors significantly associated with the presence of RP or its severity. One patient developed symptomatic RP.

Conclusion: This study showed no correlation between acute RP and clinicodosimetric factors, and acute RP based on CT findings were much more common than symptomatic RP.

Advances in knowledge: CT findings of acute RP or extent of RP were not significantly related to clinicodosimetric factors in breast cancer patients.

Figures

Figure 1.

Representative chest computed tomography image of the area used for assessing the presence of acute radiation pneumonitis. (a), (b), and (c) were scored as Grade 1 (right lung), Grade 2 (left lung), and Grade 3 (right lung), respectively.

Figure 2.

Delineation of the extent of acute radiation pneumonitis (magenta) on follow-up chest CT. (a) transverse, (b) coronal, and (c) sagittal view.