title: Prediction of prone-to-supine tumor displacement in the breast using patient position change: investigation with prone MRI and supine CT.
abstract: BACKGROUND
  One of the challenges for clinical use of preoperative breast magnetic resonance imaging (MRI) is how to transfer prone MRI information to the operating theater with a supine surgical position. The aim of this study was to retrospectively evaluate tumor displacement in the breast by changing the patient position from prone to supine (prone-to-supine tumor displacement), using preoperative prone MRI and supine computed tomography (CT).
  
  
  METHODS
  Preoperatively, 55 Japanese women with 57 breast cancer lesions underwent breast MRI in the prone position and breast CT in the supine position. Tumor positions in both the prone and supine positions were measured on X-, Y-, and Z-coordinates by fixing the nipple to the origin (0, 0, 0). As an indicator of the mobility of the breast, the ratio of the breast projection between the prone MRI and supine CT (prone-to-supine projection ratio) was calculated. The direction and distance of prone-to-supine tumor displacement was analyzed by dividing the breast into four quadrants according to the tumor position.
  
  
  RESULTS
  When changing the patient position from prone to supine, tumors located in the inner-upper and inner-lower quadrants tended to move radially toward the center of the nipple. The movement distance of the tumors in the inner-lower and outer-lower quadrants was very strongly correlated with the prone-to-supine breast projection ratio (r ≥ 0.8, p < 0.05). Conversely, in the outer-upper quadrant, the direction of tumor displacement was variable, and the distance of tumor displacement did not correlate with the prone-to-supine projection ratio.
  
  
  CONCLUSIONS
  The present study showed that prone-to-supine tumor displacement in the breast differs depending on tumor location. The inner-lower quadrant of the breast may be the most predictable area for prone-to-supine tumor displacement.
authors.affiliation: Department of Radiology, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan. shiroko@med.nagoya-u.ac.jp.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Satake
authors.affiliation: Department of Radiology, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Ishigaki
authors.affiliation: Department of Radiology, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Kitano
authors.affiliation: Department of Radiology, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D018270:Carcinoma, Ductal, Breast / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D056888:Patient Positioning; D016684:Prone Position; D012189:Retrospective Studies; D016683:Supine Position; D014057:Tomography, X-Ray Computed
keywords: Breast; CT; MRI; Prone position; Supine position