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Diffraction Enhanced Imaging of Spine Fusion 2006

General Spine

R. Cole Beavis, MD, FRCSC, Non ASSR Member
Michael E. B. Kelly, MD, FRCSC, Non ASSR Member
Lauren A. Allen, MD, Non ASSR Member
Bernhard H. J. Juurlink, Ph.D, Non ASSR Member
Zhong Zhong, Ph.D, Non ASSR Member
L. Dean Chapman, Ph.D, Non ASSR Member

Scientific Poster

Purpose

Conventional medical imaging allows visualization of normal anatomy and disease states. However imaging after spine fusion remains challenging and controversial. Synchrotron supported medical imaging technology is a growing field of research. Diffraction enhanced imaging (DEI)is a synchrotron based technique that capitalizes on scatter and refractive properties of objects in addition to X-ray absorption to improve image contrast. DEI has been shown to produce excellent visualization of bony and soft tissues but has never been used to image spine fusion.

Methods & Materials

Adult male Wistar rats were divided into groups: (1) control (n=3), (2) decortication alone (n=6), (3) decortication with iliac crest bone grafting (n=6), and (4) decortication with iliac crest bone grafting and interspinous wiring (n=6). Surgery was performed at the lower lumbar levels. Animals were sacrificed at 2, 4 and 6 weeks and spine-muscle blocks excised. DEI and conventional absorption radiography was performed at the National Synchrotron Light Source, Brookhaven, NY. Images were compared and graded for 1) image quality 2) ability to assess fusion mass and 3) presence of metal artifact.

Results

DEI images were of higher quality with greater bony detail. Compared with conventional radiography, DEI was superior in assessing spine fusion. Bridging trabeculae and fusion mass were clearly seen in specimens using DEI that was not visible with conventional radiography. With DEI, small amounts of bone graft material (as little as 0.075g on each side) was visible at 2, 4 and 6 weeks postoperatively which was not seen with conventional radiography. DEI did not produce any metal artifact.

Conclusion

DEI produced superior quality images and improved ability to assess fusion when compared with conventional absorption radiograph in this animal model. No metal artifact was present on any images. This represents the first known attempt to image spine fusions with DEI. This novel synchrotron supported imaging technique offers promise for future applications in musculoskeletal imaging.

References

1. Chapman D, Thomlinson W, Johnston RE, et al: Diffraction enhanced x-ray imaging. Phys Med Biol 42:2015-2025, 1997
2. Kelly M, Beavis C, Fourney D, et al: Diffraction enhanced imaging of the rat spine. Can Assoc Rad J (in print 2006)

Financial support from research grants from the following:

1. Saskatchewan Synchrotron Institute
2. American Association of Neurological Surgeons
3. University of Saskatchewan
4. Royal University Hospital Foundation

Images

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