Inter-observer variations of the tumor bed delineation for patients after breast conserving surgery in preoperative magnetic resonance and computed tomography scan fusion

• Published in: BMC cancer Vol. 21; no. 1; pp. 1 - 838
• Main Authors: Jiang, Jie, Chen, Jinhu, Li, Wanhu, Li, Yongqing, Chen, Yiru, Zhang, Zicheng, Liu, Chengxin, Han, Dan, Sun, Hongfu, Li, Baosheng, Huang, Wei
• Format: Journal Article
• Language: English
• Published: London BioMed Central Ltd 20.07.2021; BioMed Central; BMC
• Subjects: Breast cancer; Cancer therapies; Care and treatment; Chemotherapy; Computed tomography; Localization; Lumpectomy; Magnetic resonance imaging; Mammography; Management; Methods; Patients; Preoperative care; Radiation therapy; Radiotherapy; Registration; Reproducibility; Simulation; Surgery; Tomography; Tumor bed; China
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/s12885-021-08546-5

Purpose Tumor bed (TB) delineation based on preoperative magnetic resonance imaging (pre-MRI) fused with postoperative computed tomography (post-CT) were compared to post-CT only to define pre-MRI may aid in improving the accuracy of delineation. Methods and materials The pre-MRI imaging of 10 patients underwent radiotherapy (RT) after breast conserving surgery (BCS) were reviewed. Post-CT scans were acquired in the same prone position as pre-MRI. Pre-MRI and post-CT automatically match and then manual alignment was given to enhance fusion consistency. Three radiation oncologists and 2 radiologists delineated the clinical target volume (CTV) for CT-based. The gross target volume (GTV) of pre-MRI-based was determined by the volume of tumor acquired with 6 sequences: T1, T2, T2W-SPAIR, DWI, dyn-eTHRIVE and sdyn-eTHRIVE, expended 10 mm to form the CTV-pre-MRI. Planning target volume (PTV) for each sequence was determined by CTV extended 15 mm, trimmed to 3 mm from skin and the breast-chest wall interface. The variability of the TB delineation were developed as follows: the mean volume, conformity index (CI) and dice coefficient (DC). Results The mean volumes of CTV and PTV delineated with CT were all larger than those with pre-MRI. The lower inter-observer variability was observed from PTV, especially in sdyn-eTHRIVE in all sequences. For each sequence of pre-MRI, all DCs were larger than post-CT, and the largest DC was observed by sdyn-eTHRIVE sequence fusion to post-CT. The overlap for PTV was significantly improved in the pre-MRI-based compared with the CT-based. Conclusions TB volumes based on pre-MRI were smaller than post-CT with CVS increased. Pre-MRI provided a more precise definition of the TB with observers performed a smaller inter-observer variability than CT. Pre-MRI, especially in sdyn-eTHRIVE sequence, should help in reducing treatment volumes with the improved accuracy of TB delineation of adjuvant RT of breast cancer. Keywords: Breast cancer, Radiotherapy, Tumor bed, Magnetic resonance imaging, Computed tomography