title: Respiratory-induced prostate motion: characterization and quantification in dynamic MRI.
abstract: OBJECTIVE
  To investigate prostate movement during deep breathing and contraction of abdominal musculature by means of dynamic MRI and analyze implications for image-guided radiotherapy of prostate cancer.
  
  
  METHODS
  A total of 43 patients and 8 healthy volunteers were examined with MRI. Images during deep respiration and during contraction of abdominal musculature (via a coughing maneuver) were obtained with dynamic two-dimensional (2D) balanced SSFP; 3 frames/s were obtained over an acquisition time of 15 s. Images were acquired in sagittal orientation to evaluate motion along both the craniocaudal (cc)-axis and anteroposterior (ap)-axis. Prostate motion was quantified semi-automatically using dedicated software tools.
  
  
  RESULTS
  Respiratory induced mean cc-axis displacement of the prostate was 2.7 ± 1.9 (SD) mm (range, 0.5-10.6 mm) and mean ap-axis displacement 1.8 ± 1.0 (SD) mm (range, 0.3-10 mm). In 69% of the subjects, breathing-related prostate movements were found to be negligible (< 3 mm). The prostate displacement for abdominal contraction was significantly higher: mean cc-axis displacement was max. 8.4 ± 6.7 (SD) mm (range, 0.6-27 mm); mean anteroposterior movement was 8.3 ± 7.7 (SD) mm (range, 0.7-26 mm).
  
  
  CONCLUSIONS
  Dynamic MRI is an excellent tool for noninvasive real-time imaging of prostate movement. Further investigations regarding possible applications in image-guided radiotherapy, e.g., for individualized planning and in integrated linac/MRI systems, are warranted.
authors.affiliation: Department of Radiology, German Cancer Research Center, Heidelberg, Germany. j.dinkel@dkfz-heidelberg.de
authors.forename: Julien
authors.initials: J
authors.lastname: Dinkel
authors.forename: Christian
authors.initials: C
authors.lastname: Thieke
authors.forename: Christian
authors.initials: C
authors.lastname: Plathow
authors.forename: Patrick
authors.initials: P
authors.lastname: Zamecnik
authors.forename: Hermann
authors.initials: H
authors.lastname: Prüm
authors.forename: Peter E
authors.initials: PE
authors.lastname: Huber
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schlemmer
authors.forename: Christian M
authors.initials: CM
authors.lastname: Zechmann
mesh_terms: D000009:Abdominal Muscles / Q000503:physiopathology; D000230:Adenocarcinoma / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009068:Movement; D009119:Muscle Contraction / Q000502:physiology; D009367:Neoplasm Staging; D011467:Prostate / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects*; D011471:Prostatic Neoplasms / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity