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Do Intervertebral Kinematics Correlate with T2 Relaxation Times in the Lower Human Cervical Spine?
98S
Proceedings of the NASS 30th Annual Meeting / The Spine Journal 15 (2015) 87S–267S
DDD is still unclear. Lumbar DDD is thought to be related to the abnormal kinematics and biomechanics of the discs. Knowledge of in-vivo lumbar disc deformation is critical for further understanding of lumbar disc function and pathology. PURPOSE: The purpose of this study was to investigate the in vivo deformation of the L4-5 and L5-S1 intervertebral discs during a weight-lifting activity. STUDY DESIGN/SETTING: In-vivo laboratory study. PATIENT SAMPLE: Eight asymptomatic subjects were recruited for this study, which had been previously approved by the authors’ Institutional Review Board. The presence of any spinal disorders, symptoms, or anatomic abnormalities was used as indication for exclusion from the study. A signed consent form was obtained from each subject before testing. OUTCOME MEASURES: This study analyzed the overall disc deformation (tensile train and anterior-posterior [AP] shear strain) of the L4-5 and L5-S1 lumbar discs during dynamic motion. Strains were calculated at the anterior edge, center and posterior edge of the discs in the mid-sagittal plane. METHODS: 3D models of the L4-S1 vertebrae were constructed from MRI images in solid modeling software (Rhinoceros). The lumbar spine of each subject was imaged during a dynamic weight-lifting activity, from a flexion position (~45 ) to the maximal extension position, using a dual fluoroscopic imaging system (DFIS). The captured fluoroscopic images and the 3D vertebral models were input into the Rhinoceros software to create a virtual DFIS. Each 3D vertebral model was independently translated and rotated in the virtual DFIS until its projection best matched the osseous outlines captured on the two fluoroscopic images. For each vertebral segment, the coordinate system of the lower disc surface was selected to be the reference coordinate system. The overall deformations of the disc were calculated using the relative positions of the corresponding disc surfaces. The non–weight bearing MRI scanning position was used as a zero deformation reference condition for the calculation of the disc deformations. RESULTS: The maximum tensile, compressive and shear strains were located on the edges of the discs during the extension motion. The compressive deformation at the anterior and center points of both L4-5 and L5-S1 gradually decreased with extension of the body. At the posterior point, L5-S1 was ~6% compressive during the extension motion, while the L4-5 disc experienced increased compression with extension of the body (12.5% at late stage extension). At all three points, the AP shear deformation of L4-5 changed from anterior to posterior during the extension motion, while L5-S1 experienced an anterior shear deformation along the entire path. At the posterior point, L4-5 experienced a change in shear deformation of 34%, while the L5-S1 was under a relatively constant anterior shear of 22%. CONCLUSIONS: The lower lumbar discs experienced different deformations during the extension motion. The data may provide insight into disease development mechanisms and segment-dependent treatments in the lower lumbar segments. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
PURPOSE: The purpose of this research was to investigate the correlation between in-vivo T2 relaxation times and six-degree-of-freedom (6DOF) intervertebral motion during dynamic flexion-extension in the lower cervical spine (C3-7). STUDY DESIGN/SETTING: In-vivo laboratory study. PATIENT SAMPLE: Nine asymptomatic subjects (5 males, 4 females, average age: 39.9611.5 years, average BMI 24.163.0 kg/m2) were recruited for this study, which was previously approved by the authors’ Institutional Review Board. The presences of any spinal disorders, symptoms or anatomic abnormalities were used as indications for exclusion from the study. A signed consent form was obtained from each subject before testing. OUTCOME MEASURES: AverageT2 relaxation times in the geometric center of each disc were correlated with intervertebral dynamic range of motion (DROM) in all 6DOF during flexion-extension using Pearson Correlation Tests. 6DOF kinematics included three rotations: flexion-extension (FE), lateral side-bending (SB), and axial twisting; and three translations: medial-lateral (ML), anterior-posterior (AP), and superior-inferior (SI). Statistical significance was defined as p!0.05. METHODS: Subjects were imaged using a 3.0 T MR scanner and a sagittal multi-echo spin-echo sequence (TE: 21.8, 32.7, 43.6, 54.5, 65.4, 76.3, 87.2, 98.1, 109.0 ms; TR: 1810 ms; voxel size: 0.9375 x 0.9375 x 4.0000 mm; image size: 256 x 188 pixels). The mid-sagittal image was selected for T2 relaxation time analysis. Intervertebral discs were then divided into five equal area rectangular regions-of-interest (ROIs), centered along the mid-line of the disc. T2 relaxation time values of the center ROI were calculated using a mono-exponential fit (OsiriX). Subjects were also imaged using a 3D dual-fluoroscopic imaging system as they moved dynamically through their full flexion-extension range of motion. 3D vertebral models of the C3-7 vertebrae were constructed for all subjects from a proton density weighted MRI sequence. The models and fluoroscopic images were then used to reproduce the vertebral positions along the dynamic motion path of one full flexion-extension cycle. Intervertebral DROM was calculated from the maximum and minimum values of each DOF throughout the cycle. RESULTS: No significant correlations between T2 relaxation times and intervertebral kinematics were found. However, increased T2 relaxation times of the C6-7 disc with increased coupled rotations of lateral sidebending (r-value: 0.608, p-value: 0.083) and twisting (r-value: 0.660, p-value: 0.053) approached significance. Additionally, increased T2 relaxation times of the C4-5 disc with increased primary FE rotation (r-value: 0.665, p-value: 0.051) also approached significance. CONCLUSIONS: The results did not reveal any significant correlations between disc composition and 6DOF kinematics. This is the first study to examine the relationship between in-vivo T2 relaxation times and functional motion. Future work will expand our sample size of asymptomatic subjects and examine this relationship in patients with cervical disc degeneration. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
http://dx.doi.org/10.1016/j.spinee.2015.07.041
http://dx.doi.org/10.1016/j.spinee.2015.07.042
27. Do Intervertebral Kinematics Correlate with T2 Relaxation Times in the Lower Human Cervical Spine? Sean J. Driscoll, Haiqing Mao, MD, Shaobai Wang, PhD, Weiye Zhong, MD, PhD, Martin Torriani, MD, Guoan Li, MD, Kirkham B. Wood, MD, Thomas D. Cha, MD, MBA; Massachusetts General Hospital, Boston, MA, US BACKGROUND CONTEXT: Quantitative MRI protocols, such as T2 mapping, have recently been used to evaluate intervertebral disc health. T2 relaxation times have been shown to indicate disc biochemical composition (water content). While disc composition likely affects spinal segment motion, the relationship between T2 relaxation times and in-vivo intervertebral kinematics during functional activities is unclear.
Wednesday, October 14, 2015 1:00 – 2:00 pm Lumbar Procedures 28. Therapeutic Sustainability and Durability of CoflexÒ Interlaminar Stabilization after Decompression for Lumbar Spinal Stenosis: A Four-Year Assessment Hyun W. Bae, MD1, Michael J. Musacchio, Jr., MD2, Carl Lauryssen, MD3, Greg Maislin, MS4, Scott Leary, MD5; 1Spine Institute St. John’s Health Center, Los Angeles, CA, US; 2NorthShore University
Refer to onsite Annual Meeting presentations and postmeeting proceedings for possible referenced figures and tables. Authors are responsible for accurately reporting disclosures and FDA device/drug status at time of abstract submission.
Proceedings of the NASS 30th Annual Meeting / The Spine Journal 15 (2015) 87S–267S
DDD is still unclear. Lumbar DDD is thought to be related to the abnormal kinematics and biomechanics of the discs. Knowledge of in-vivo lumbar disc deformation is critical for further understanding of lumbar disc function and pathology. PURPOSE: The purpose of this study was to investigate the in vivo deformation of the L4-5 and L5-S1 intervertebral discs during a weight-lifting activity. STUDY DESIGN/SETTING: In-vivo laboratory study. PATIENT SAMPLE: Eight asymptomatic subjects were recruited for this study, which had been previously approved by the authors’ Institutional Review Board. The presence of any spinal disorders, symptoms, or anatomic abnormalities was used as indication for exclusion from the study. A signed consent form was obtained from each subject before testing. OUTCOME MEASURES: This study analyzed the overall disc deformation (tensile train and anterior-posterior [AP] shear strain) of the L4-5 and L5-S1 lumbar discs during dynamic motion. Strains were calculated at the anterior edge, center and posterior edge of the discs in the mid-sagittal plane. METHODS: 3D models of the L4-S1 vertebrae were constructed from MRI images in solid modeling software (Rhinoceros). The lumbar spine of each subject was imaged during a dynamic weight-lifting activity, from a flexion position (~45 ) to the maximal extension position, using a dual fluoroscopic imaging system (DFIS). The captured fluoroscopic images and the 3D vertebral models were input into the Rhinoceros software to create a virtual DFIS. Each 3D vertebral model was independently translated and rotated in the virtual DFIS until its projection best matched the osseous outlines captured on the two fluoroscopic images. For each vertebral segment, the coordinate system of the lower disc surface was selected to be the reference coordinate system. The overall deformations of the disc were calculated using the relative positions of the corresponding disc surfaces. The non–weight bearing MRI scanning position was used as a zero deformation reference condition for the calculation of the disc deformations. RESULTS: The maximum tensile, compressive and shear strains were located on the edges of the discs during the extension motion. The compressive deformation at the anterior and center points of both L4-5 and L5-S1 gradually decreased with extension of the body. At the posterior point, L5-S1 was ~6% compressive during the extension motion, while the L4-5 disc experienced increased compression with extension of the body (12.5% at late stage extension). At all three points, the AP shear deformation of L4-5 changed from anterior to posterior during the extension motion, while L5-S1 experienced an anterior shear deformation along the entire path. At the posterior point, L4-5 experienced a change in shear deformation of 34%, while the L5-S1 was under a relatively constant anterior shear of 22%. CONCLUSIONS: The lower lumbar discs experienced different deformations during the extension motion. The data may provide insight into disease development mechanisms and segment-dependent treatments in the lower lumbar segments. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
PURPOSE: The purpose of this research was to investigate the correlation between in-vivo T2 relaxation times and six-degree-of-freedom (6DOF) intervertebral motion during dynamic flexion-extension in the lower cervical spine (C3-7). STUDY DESIGN/SETTING: In-vivo laboratory study. PATIENT SAMPLE: Nine asymptomatic subjects (5 males, 4 females, average age: 39.9611.5 years, average BMI 24.163.0 kg/m2) were recruited for this study, which was previously approved by the authors’ Institutional Review Board. The presences of any spinal disorders, symptoms or anatomic abnormalities were used as indications for exclusion from the study. A signed consent form was obtained from each subject before testing. OUTCOME MEASURES: AverageT2 relaxation times in the geometric center of each disc were correlated with intervertebral dynamic range of motion (DROM) in all 6DOF during flexion-extension using Pearson Correlation Tests. 6DOF kinematics included three rotations: flexion-extension (FE), lateral side-bending (SB), and axial twisting; and three translations: medial-lateral (ML), anterior-posterior (AP), and superior-inferior (SI). Statistical significance was defined as p!0.05. METHODS: Subjects were imaged using a 3.0 T MR scanner and a sagittal multi-echo spin-echo sequence (TE: 21.8, 32.7, 43.6, 54.5, 65.4, 76.3, 87.2, 98.1, 109.0 ms; TR: 1810 ms; voxel size: 0.9375 x 0.9375 x 4.0000 mm; image size: 256 x 188 pixels). The mid-sagittal image was selected for T2 relaxation time analysis. Intervertebral discs were then divided into five equal area rectangular regions-of-interest (ROIs), centered along the mid-line of the disc. T2 relaxation time values of the center ROI were calculated using a mono-exponential fit (OsiriX). Subjects were also imaged using a 3D dual-fluoroscopic imaging system as they moved dynamically through their full flexion-extension range of motion. 3D vertebral models of the C3-7 vertebrae were constructed for all subjects from a proton density weighted MRI sequence. The models and fluoroscopic images were then used to reproduce the vertebral positions along the dynamic motion path of one full flexion-extension cycle. Intervertebral DROM was calculated from the maximum and minimum values of each DOF throughout the cycle. RESULTS: No significant correlations between T2 relaxation times and intervertebral kinematics were found. However, increased T2 relaxation times of the C6-7 disc with increased coupled rotations of lateral sidebending (r-value: 0.608, p-value: 0.083) and twisting (r-value: 0.660, p-value: 0.053) approached significance. Additionally, increased T2 relaxation times of the C4-5 disc with increased primary FE rotation (r-value: 0.665, p-value: 0.051) also approached significance. CONCLUSIONS: The results did not reveal any significant correlations between disc composition and 6DOF kinematics. This is the first study to examine the relationship between in-vivo T2 relaxation times and functional motion. Future work will expand our sample size of asymptomatic subjects and examine this relationship in patients with cervical disc degeneration. FDA DEVICE/DRUG STATUS: This abstract does not discuss or include any applicable devices or drugs.
http://dx.doi.org/10.1016/j.spinee.2015.07.041
http://dx.doi.org/10.1016/j.spinee.2015.07.042
27. Do Intervertebral Kinematics Correlate with T2 Relaxation Times in the Lower Human Cervical Spine? Sean J. Driscoll, Haiqing Mao, MD, Shaobai Wang, PhD, Weiye Zhong, MD, PhD, Martin Torriani, MD, Guoan Li, MD, Kirkham B. Wood, MD, Thomas D. Cha, MD, MBA; Massachusetts General Hospital, Boston, MA, US BACKGROUND CONTEXT: Quantitative MRI protocols, such as T2 mapping, have recently been used to evaluate intervertebral disc health. T2 relaxation times have been shown to indicate disc biochemical composition (water content). While disc composition likely affects spinal segment motion, the relationship between T2 relaxation times and in-vivo intervertebral kinematics during functional activities is unclear.
Wednesday, October 14, 2015 1:00 – 2:00 pm Lumbar Procedures 28. Therapeutic Sustainability and Durability of CoflexÒ Interlaminar Stabilization after Decompression for Lumbar Spinal Stenosis: A Four-Year Assessment Hyun W. Bae, MD1, Michael J. Musacchio, Jr., MD2, Carl Lauryssen, MD3, Greg Maislin, MS4, Scott Leary, MD5; 1Spine Institute St. John’s Health Center, Los Angeles, CA, US; 2NorthShore University
Refer to onsite Annual Meeting presentations and postmeeting proceedings for possible referenced figures and tables. Authors are responsible for accurately reporting disclosures and FDA device/drug status at time of abstract submission.