A non-ionizing technique for three-dimensional measurement of the lumbar spine.
Comprehensive assessments of scoliotic deformity and spinal instability require repetitive three-dimensional (3D) measurements of motion segments at different functional postures. However, accurate 3D measurement of the spine is a challenging task. In this paper, we present a novel, non-invasive, non-ionizing technique to quantify 3D poses of lumbar motion segments in terms of clinically meaningful anatomical coordinates. The technique used ultra-short echo time (UTE) magnetic resonance (MR) images to construct subject-specific geometrical models of individual vertebrae and registered them with 3D ultrasound dataset acquired during pose measurements. A hierarchical registration approach was used to minimize the detrimental effects of speckle noise and artifacts within soft tissues on registration accuracy. The technique was validated using a human dry bone specimen as well as a fresh porcine cadaver. Registration errors were determined by comparing with a gold standard fiducial-based registration. Results showed that the technique is accurate and reliable with bias in sub-degree and sub-millimeter level (except for the flexion-extension of the porcine cadaver experiment, which was -1.74°), and average precision of 1.11° in rotation and 0.86mm in position for the human dry bone experiment, and 1.26° and 1.23mm for the porcine cadaver experiment. Given its non-ionizing nature, the UTE MR-ultrasound registration technique is particularly useful for repeated measurements and longitudinal follow-up. With further refinement and validation, it could be a powerful tool for 3D spinal assessment.
Foot Levelers Biomechanics Research Laboratory, New York Chiropractic College, 2360 State Route 89, Seneca Falls, NY 13148, United States. Electronic address: tkoo@nycc.edu.
Terry K
TK
Koo
Department of Imaging Science, University of Rochester, Rochester, NY, United States; Rochester Center of Brain Imaging, University of Rochester, Rochester, NY, United States.
Wingchi Edmund
WE
Kwok
D000818:Animals; D001696:Biomechanical Phenomena; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000502:physiology; D008279:Magnetic Resonance Imaging; D016059:Range of Motion, Articular; D012399:Rotation; D013552:Swine; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
Lumbar spine; Magnetic resonance imaging; Registration; Segmental kinematics; Ultrasound