Proof of concept: In vitro measurement of correlation between radiodensity and ultrasound echo response of ovine vertebral bodies.
An acoustic guidance method for pedicle screw placement during spine fixation surgery was recently investigated, with a view toward preventing complications such as injury to the spinal cord, thecal sac, and spinal nerve roots due to screw misplacement. The method relies upon the change in the ultrasound amplitude reflected at different sites-from the outer posterior cortex, through the pedicle, and towards the distal ventral cortex. The amplitude change was empirically observed through in vitro measurement of ultrasound amplitude at the different sites by inserting a 2.5-MHz single element transducer into a vertebral body through insertion pathway created by an advancing screw. This paper provides a theoretical and experimental rationale behind these empirical findings and distance-dependent correlation coefficients between amplitude and bone mineral density within the vertebral body, which approached 97%.
Sogang Institute of Advanced Technology, Sogang University, Seoul, Republic of Korea. jhchang@sogang.ac.kr
Jin Ho
JH
Chang
David T
DT
Raphael
Yao Ping
YP
Zhang
K Kirk
KK
Shung
D000818:Animals; D015519:Bone Density; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D066298:In Vitro Techniques; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D015641:Radiography, Interventional; D034561:Sheep, Domestic; D014159:Transducers; D018084:Ultrasonography, Interventional / Q000379:methods*; D055114:X-Ray Microtomography