A non-ionizing technique for three-dimensional measurement of the lumbar spine

J Biomech. 2016 Dec 8;49(16):4073-4079. doi: 10.1016/j.jbiomech.2016.10.048. Epub 2016 Nov 2.

Abstract

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.

Keywords: Lumbar spine; Magnetic resonance imaging; Registration; Segmental kinematics; Ultrasound.

MeSH terms

  • Animals
  • Biomechanical Phenomena
  • Humans
  • Imaging, Three-Dimensional / methods*
  • Lumbar Vertebrae / anatomy & histology*
  • Lumbar Vertebrae / diagnostic imaging*
  • Lumbar Vertebrae / physiology
  • Magnetic Resonance Imaging
  • Range of Motion, Articular
  • Rotation
  • Swine
  • Tomography, X-Ray Computed
  • Ultrasonography