Feasibility of chest spiral 3D ultrashort echo time magnetic resonance imaging for intrathoracic metastasis work-up in breast cancer

BACKGROUND: Chest computed tomography (CT) is routinely performed to evaluate intrathoracic metastasis in patients with breast cancer, but radiation exposure and its potential carcinogenic risks are major drawbacks. Furthermore, pulmonary imaging by magnetic resonance imaging (MRI) is limited by low proton density, rapid signal decay, and sensitivity to respiratory and cardiac motions in lung tissue. Recently, a respiratory gating spiral three-dimensional (3D) ultrashort echo time (UTE) volume interpolated breath-hold examination (VIBE) sequence for lung MRI provides high spatial-resolution images with reasonable scan times. Our objective was to investigate the feasibility of chest spiral 3D UTE VIBE MRI to detect intrathoracic metastasis in breast cancer patients. METHODS: This retrospective study of a prospectively collected database was conducted between February and July 2019 after institutional review board approval. All participants provided informed consent for MRI scans. Ninety-three female patients with breast cancer were retrospectively enrolled and underwent preoperative breast MRI, including a chest spiral 3D UTE VIBE sequence. Two chest radiologists evaluated image qualities of intrapulmonary vessels and bronchial wall visibilities, the presence of pulmonary nodules, significant lymph nodes (LNs), and other lung abnormalities on spiral 3D UTE magnetic resonance (MR) images and compared them using chest CT as a reference standard. RESULTS: Intrapulmonary vessels and bronchial walls were visible up to sub-subsegmental and sub-subsegmental levels, respectively, on spiral 3D UTE MR images, and better than fair quality was obtained for artifact/noise and overall image quality for 95.7% and 98.9% of the patients, respectively. The overall detection rate for pulmonary nodules was 62.8% (59/94). Furthermore, 59 of the 81 solid nodules detected by CT were detected by spiral 3D UTE MRI (72.8%), and 31 of the 33 solid nodules (≥5 mm in diameter) detected by CT were identified by spiral 3D UTE MRI (93.9%). Significant LNs in the axillary area were similarly detected by spiral 3D UTE MRI and chest CT. CONCLUSIONS: Preoperative breast MRI with a chest spiral 3D UTE sequence could be used to evaluate breast cancer and axillary LNs and intrathoracic metastasis simultaneously and offers a potential alternative to chest CT for breast cancer patients without additional radiation exposure.