title: The use of MRI deformable image registration for CT-based brachytherapy in locally advanced cervical cancer.
abstract: Incorporation of MRI into image-based brachytherapy (IBBT) is limited by logistics, reimbursement, and workflow demands. Our goal is to determine if deformable image registration (DIR) using a preimplantation MRI is feasible to construct a high-risk target volume during IBBT.
  
  
  
  From 2010 to 2013, 20 patients were treated with high-dose-rate IBBT for cervical cancer. A preimplantation MRI was fused to the planning CT, and DIR was performed using MIM v6.1. The gross tumor volume (GTV) and high-risk clinical target volume were contoured on the MRI (HR-CTV MRI), and a separate high-risk clinical target volume was made from the deformable image registration of the preimplantation MRI to the planning CT (HR-CTV'). The treated target volume from the planning CT without the DIR or fusion (HR-CTV BT) was compared with the HR-CTV'. The geometric means of the GTV, HR-CTV MRI, HR-CTV', and HR-CTV BT were analyzed. Statistical analysis using Wilcoxon rank and analysis of variance were performed.
  
  
  
  There was a significant larger difference between the GTV and the HR-CTV MRI, HR-CTV', and HR-CTV BT (p < 0.0001). There was also a significant difference between the HR-CTV MRI vs. the HR-CTV BT (p < 0.040). There was no significant difference between the HR-CTV MRI and HR-CTV'. DIR was advantageous in the setting of residual disease pre-IBBT.
  
  
  
  DIR is feasible to define an HR-CTV for MRI-guided, CT IBBT. The HR-CTV MRI predicted a smaller treatment volume in comparison with the HR-CTV BT. DIR is limited by patient anatomy and is most beneficial in patients with gross disease.
authors.affiliation: Department of Radiation Oncology, Davis Medical Center, University of California, Sacramento, CA.
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Tait
authors.affiliation: Department of Radiation Oncology, Davis Medical Center, University of California, Sacramento, CA.
authors.forename: David
authors.initials: D
authors.lastname: Hoffman
authors.affiliation: Department of Radiation Oncology, Davis Medical Center, University of California, Sacramento, CA.
authors.forename: Stanley
authors.initials: S
authors.lastname: Benedict
authors.affiliation: Department of Radiation Oncology, Davis Medical Center, University of California, Sacramento, CA.
authors.forename: Richard
authors.initials: R
authors.lastname: Valicenti
authors.affiliation: Department of Radiation Oncology, Davis Medical Center, University of California, Sacramento, CA. Electronic address: jmayadev@ucdavis.edu.
authors.forename: Jyoti S
authors.initials: JS
authors.lastname: Mayadev
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D011880:Radiotherapy Planning, Computer-Assisted; D061089:Radiotherapy, Image-Guided / Q000379:methods; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000532:radiotherapy*
keywords: Cervical cancer; HDR brachytherapy; Image-based brachytherapy; MRI