title: Comparison of Magnetic Resonance Imaging and Computed Tomography for Breast Target Volume Delineation in Prone and Supine Positions.
abstract: To determine whether T2-weighted MRI improves seroma cavity (SC) and whole breast (WB) interobserver conformity for radiation therapy purposes, compared with the gold standard of CT, both in the prone and supine positions.
  
  
  
  Eleven observers (2 radiologists and 9 radiation oncologists) delineated SC and WB clinical target volumes (CTVs) on T2-weighted MRI and CT supine and prone scans (4 scans per patient) for 33 patient datasets. Individual observer's volumes were compared using the Dice similarity coefficient, volume overlap index, center of mass shift, and Hausdorff distances. An average cavity visualization score was also determined.
  
  
  
  Imaging modality did not affect interobserver variation for WB CTVs. Prone WB CTVs were larger in volume and more conformal than supine CTVs (on both MRI and CT). Seroma cavity volumes were larger on CT than on MRI. Seroma cavity volumes proved to be comparable in interobserver conformity in both modalities (volume overlap index of 0.57 (95% Confidence Interval (CI) 0.54-0.60) for CT supine and 0.52 (95% CI 0.48-0.56) for MRI supine, 0.56 (95% CI 0.53-0.59) for CT prone and 0.55 (95% CI 0.51-0.59) for MRI prone); however, after registering modalities together the intermodality variation (Dice similarity coefficient of 0.41 (95% CI 0.36-0.46) for supine and 0.38 (0.34-0.42) for prone) was larger than the interobserver variability for SC, despite the location typically remaining constant.
  
  
  
  Magnetic resonance imaging interobserver variation was comparable to CT for the WB CTV and SC delineation, in both prone and supine positions. Although the cavity visualization score and interobserver concordance was not significantly higher for MRI than for CT, the SCs were smaller on MRI, potentially owing to clearer SC definition, especially on T2-weighted MR images.
authors: Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia.
authors: Elise M
authors: EM
authors: Pogson
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia; School of Medicine, University of Western Sydney, Sydney, Australia.
authors: Geoff P
authors: GP
authors: Delaney
authors: Crown Princess Mary Cancer Care Centre, Westmead Hospital, Westmead, Australia.
authors: Verity
authors: V
authors: Ahern
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors: Miriam M
authors: MM
authors: Boxer
authors: Department of Radiology, Liverpool Hospital, Liverpool, Australia.
authors: Christine
authors: C
authors: Chan
authors: Peter MacCallum Cancer Centre, Melbourne, Australia.
authors: Steven
authors: S
authors: David
authors: Department of Radiology, Liverpool Hospital, Liverpool, Australia.
authors: Marion
authors: M
authors: Dimigen
authors: School of Medicine, University of Queensland, Herston, Australia; Princess Alexandra Hospital, Woolloongabba, Australia.
authors: Jennifer A
authors: JA
authors: Harvey
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors: Eng-Siew
authors: ES
authors: Koh
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors: Karen
authors: K
authors: Lim
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia.
authors: George
authors: G
authors: Papadatos
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia; School of Medicine, University of Western Sydney, Sydney, Australia.
authors: Mei Ling
authors: ML
authors: Yap
authors: Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors: Vikneswary
authors: V
authors: Batumalai
authors: Department of Radiology, Liverpool Hospital, Liverpool, Australia.
authors: Elizabeth
authors: E
authors: Lazarus
authors: Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia.
authors: Kylie
authors: K
authors: Dundas
authors: Ingham Institute for Applied Medical Research, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia.
authors: Jesmin
authors: J
authors: Shafiq
authors: Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia.
authors: Gary
authors: G
authors: Liney
authors: Department of Radiology, Stanford University, Stanford, USA.
authors: Catherine
authors: C
authors: Moran
authors: Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia.
authors: Peter
authors: P
authors: Metcalfe
authors: Centre for Medical Radiation Physics, Faculty of Engineering and Information Sciences, University of Wollongong, Wollongong, Australia; Liverpool and Macarthur Cancer Therapy Centres, Liverpool, Australia; Ingham Institute for Applied Medical Research, Liverpool, Australia; South Western Sydney Clinical School, University of New South Wales, Sydney, Australia. Electronic address: lois.holloway@sswahs.nsw.gov.au.
authors: Lois
authors: L
authors: Holloway
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000000981:diagnostic imaging* / Q000473:pathology; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D015412:Mastectomy, Segmental; D008875:Middle Aged; D015588:Observer Variation; D009929:Organ Size; D056888:Patient Positioning / Q000379:methods*; D016684:Prone Position; D000072378:Radiation Oncologists; D000072177:Radiologists; D018714:Radiotherapy, Adjuvant; D049291:Seroma / Q000000981:diagnostic imaging* / Q000473:pathology; D016683:Supine Position; D014057:Tomography, X-Ray Computed