title: Distortion inherent to magnetic resonance imaging can lead to geometric miss in radiosurgery planning.
abstract: OBJECTIVE
  Anatomic distortion is present in all magnetic resonance imaging (MRI) data because of nonlinearity of gradient fields; it measures up to several millimeters. We evaluated the potential for uncorrected MRI to lead to geometric miss of the target volume in stereotactic radiosurgery (SRS).
  
  
  METHODS
  Twenty-eight SRS cases were studied retrospectively. MRI scans were corrected for gradient nonlinearity distortion in 3 dimensions, and gross tumor volumes (GTVs) were contoured. The manufacturer-specified distortion field was then reapplied to GTV masks to allow measurement of GTV displacement in uncorrected images. The uncorrected GTV was used for SRS planning, and the dose received by the true (corrected) GTV was measured.
  
  
  RESULTS
  Median displacement of the GTV resulting from gradient distortion was 1.2 mm (interquartile range, 0.1-2.3 mm), with a minimum of 0 mm and a maximum of 3.9 mm. Eight of the 28 cases met a priori criteria for "geometric miss."
  
  
  CONCLUSIONS
  Although MRI distortion is often subtle on visual inspection, there is a significant clinical impact of this distortion on SRS planning. Distortion-corrected MRI should uniformly be used for intracranial radiosurgery planning because uncorrected MRI can lead to potential geometric miss.
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Tyler M
authors: TM
authors: Seibert
authors: Department of Radiology, University of California, San Diego, La Jolla, California.
authors: Nathan S
authors: NS
authors: White
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Gwe-Ya
authors: GY
authors: Kim
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Vitali
authors: V
authors: Moiseenko
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California; Department of Psychiatry, University of California, San Diego, La Jolla, California.
authors: Carrie R
authors: CR
authors: McDonald
authors: Department of Radiology, University of California, San Diego, La Jolla, California.
authors: Nikdokht
authors: N
authors: Farid
authors: Department of Radiology, University of California, San Diego, La Jolla, California.
authors: Hauke
authors: H
authors: Bartsch
authors: Department of Radiology, University of California, San Diego, La Jolla, California.
authors: Joshua
authors: J
authors: Kuperman
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Roshan
authors: R
authors: Karunamuni
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Deborah
authors: D
authors: Marshall
authors: Department of Radiology, University of California, San Diego, La Jolla, California.
authors: Dominic
authors: D
authors: Holland
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Parag
authors: P
authors: Sanghvi
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Daniel R
authors: DR
authors: Simpson
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
authors: Arno J
authors: AJ
authors: Mundt
authors: Department of Radiology, University of California, San Diego, La Jolla, California; Department of Neurosciences, University of California, San Diego, La Jolla, California.
authors: Anders M
authors: AM
authors: Dale
authors: Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California. Electronic address: jhattangadi@ucsd.edu.
authors: Jona A
authors: JA
authors: Hattangadi-Gluth
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D056888:Patient Positioning; D016634:Radiosurgery; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D012189:Retrospective Studies; D047368:Tumor Burden