title: Impact of positional difference on the measurement of breast density using MRI.
abstract: OBJECTIVE
  This study investigated the impact of arms/hands and body position on the measurement of breast density using MRI.
  
  
  METHODS
  Noncontrast-enhanced T1-weighted images were acquired from 32 healthy women. Each subject received four MR scans using different experimental settings, including a high resolution hands-up, a low resolution hands-up, a high resolution hands-down, and finally, another high resolution hands-up after repositioning. The breast segmentation was performed using a fully automatic chest template-based method. The breast volume (BV), fibroglandular tissue volume (FV), and percent density (PD) measured from the four MR scan settings were analyzed.
  
  
  RESULTS
  A high correlation of BV, FV, and PD between any pair of the four MR scans was noted (r > 0.98 for all). Using the generalized estimating equation method, a statistically significant difference in mean BV among four settings was noted (left breast, score test p = 0.0056; right breast, score test p = 0.0016), adjusted for age and body mass index. Despite differences in BV, there were no statistically significant differences in the mean PDs among the four settings (p > 0.10 for left and right breasts). Using Bland-Altman plots, the smallest mean difference/bias and standard deviations for BV, FV, and PD were noted when comparing hands-up high vs low resolution when the breast positions were exactly the same.
  
  
  CONCLUSIONS
  The authors' study showed that BV, FV, and PD measurements from MRI of different positions were highly correlated. BV may vary with positions but the measured PD did not differ significantly between positions. The study suggested that the percent density analyzed from MRI studies acquired using different arms/hands and body positions from multiple centers can be combined for analysis.
authors.affiliation: Tu & Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, California 92697-5020 and Department of Radiology, E-Da Hospital and I-Shou University, Kaohsiung 82445, Taiwan.
authors.forename: Jeon-Hor
authors.initials: JH
authors.lastname: Chen
authors.affiliation: Department of Radiology, Taichung Veterans General Hospital, Taichung 40705, Taiwan.
authors.forename: Siwa
authors.initials: S
authors.lastname: Chan
authors.affiliation: Department of Radiological Technology, China Medical University, Taichung 40402, Taiwan.
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Tang
authors.affiliation: Department of Radiological Technology, China Medical University, Taichung 40402, Taiwan.
authors.forename: Jia Shen
authors.initials: JS
authors.lastname: Hon
authors.affiliation: Tu & Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, California 92697-5020.
authors.forename: Po-Chuan
authors.initials: PC
authors.lastname: Tseng
authors.affiliation: Tu & Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, California 92697-5020.
authors.forename: Angela T
authors.initials: AT
authors.lastname: Cheriyan
authors.affiliation: Tu & Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, California 92697-5020.
authors.forename: Nikita Rakesh
authors.initials: NR
authors.lastname: Shah
authors.affiliation: Department of Surgery, Taichung Veterans General Hospital, Taichung 40705, Taiwan.
authors.forename: Dah-Cherng
authors.initials: DC
authors.lastname: Yeh
authors.affiliation: Department of Radiology, Taichung Veterans General Hospital, Taichung 40705, Taiwan.
authors.forename: San-Kan
authors.initials: SK
authors.lastname: Lee
authors.affiliation: Department of Epidemiology, University of California, Irvine, California 92697-5020.
authors.forename: Wen-Pin
authors.initials: WP
authors.lastname: Chen
authors.affiliation: Department of Epidemiology, University of California, Irvine, California 92697-5020.
authors.forename: Christine E
authors.initials: CE
authors.lastname: McLaren
authors.affiliation: Tu & Yuen Center for Functional Onco-Imaging, Department of Radiological Sciences, University of California, Irvine, California 92697-5020.
authors.forename: Min-Ying
authors.initials: MY
authors.lastname: Su
mesh_terms: D000328:Adult; D000375:Aging / Q000473:pathology / Q000502:physiology; D001132:Arm / Q000033:anatomy & histology / Q000502:physiology; D044466:Asian People; D015992:Body Mass Index; D001940:Breast / Q000033:anatomy & histology / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006225:Hand / Q000033:anatomy & histology / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D055815:Young Adult