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Pract Radiat Oncol. 2016 Nov - Dec;6(6):e319-e328. doi: 10.1016/j.prro.2016.05.008. Epub 2016 Jun 1.

Distortion inherent to magnetic resonance imaging can lead to geometric miss in radiosurgery planning.

Author information

1
Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California.
2
Department of Radiology, University of California, San Diego, La Jolla, California.
3
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.
4
Department of Radiology, University of California, San Diego, La Jolla, California; Department of Neurosciences, University of California, San Diego, La Jolla, California.
5
Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California. Electronic address: jhattangadi@ucsd.edu.

Abstract

PURPOSE:

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 AND MATERIALS:

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.

PMID:
27523440
PMCID:
PMC5099096
DOI:
10.1016/j.prro.2016.05.008
[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

notification Nathan S. White has no conflicts of interest. Gwe-Ya Kim has no conflicts of interest. Carrie R. McDonald has no conflicts of interest. Nikdokht Farid has no conflicts of interest. Hauke Bartsch has no conflicts of interest. Joshua Kuperman has no conflicts of interest. Roshan Karunamuni has no conflicts of interest. Deborah Marshall has no conflicts of interest. Parag Sanghvi has no conflicts of interest. Daniel R. Simpson has no conflicts of interest. Arno J. Mundt has no conflicts of interest.

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