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Michael D. Abràmoff, Ad P. G. Van Gils, Gerard H. Jansen, Maarten P. Mourits; MRI Dynamic Color Mapping: A New Quantitative Technique for Imaging Soft Tissue Motion in the Orbit. Invest. Ophthalmol. Vis. Sci. 2000;41(11):3256-3260.
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purpose. To investigate both feasibility and clinical potential of magnetic
resonance imaging–dynamic color mapping (MRI-DCM) in measuring the
motion of soft tissues in the orbit and in the diagnosis of orbital
disorders by detecting changes in motion.
methods. Sequences of MRI scans were acquired (acquisition time, 5 seconds) in a
shoot–stop manner, while the patient fixated at a sequence of 13 gaze
positions (8° intervals). Motion was quantified off-line (in
millimeters per degree of gaze change) using an optical flow algorithm.
The motion was displayed in a color-coded image in which color
saturation of a pixel shows the displacement and the hue the
displacement’s orientation. Six healthy volunteers and four patients
(two with an orbital mass and two with acrylic ball implant after
enucleation) were studied.
results. The technique was found to be clinically feasible. For a gaze change of
1°, orbital tissues moved between 0.0 and 0.25 mm/deg, depending on
the type of tissue and location in the orbit. In the patients with an
orbital mass, motion of the mass was similar to that of the medial
rectus muscle, suggesting disease of muscular origin. In the enucleated
orbits, soft tissue motion was decreased. One eye showed attachment of
the optic nerve to the implant, which could be verified by biopsy.
conclusions. MRI-DCM allows noninvasive and quantitative measurement of soft tissue
motion and the changes in motion due to pathologic conditions. In cases
in which the diagnosis of a tumor in the apex is in doubt, it may
reduce the need for biopsy. In contrast to static computed tomographic
(CT) scans and MRIs, it can differentiate between juxtaposition and
continuity and may be a new and promising tool in the differential
diagnosis of intraorbital lesions.
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