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IN VIVO TISSUE CHARACTERIZATION OF INTERVERTEBRAL DISCS USING T2-MAPPING AND DIFFUSION-BASED MRI
S604
Presentation 1255 − Topic 40. Spine biomechanics
IN VIVO TISSUE CHARACTERIZATION OF INTERVERTEBRAL DISCS USING T2-MAPPING AND DIFFUSION-BASED MRI Tien Tuan Dao (1), Philippe Pouletaut (1), Ludovic Robert (2), Fabrice Charleux (2), Marie Christine Ho Ba Tho (1)
1. UTC CNRS UMR 6600, BMBI Biomécanique et Bioingénierie, Université de Technologie de Compiègne, France; 2. ACRIM-Polyclinique St Compiègne, France
Introduction Low back pain is one of chronic musculoskeletal disorders which influenced significantly the working and daily activities of human being. Characterization and modelling of lumbar spine structures, especially intervertebral discs (IVD) allow us to get a better understanding of normal and abnormal loading effect on these structures leading to best clinical treatment. In fact, the modelling of lumbar spine discs in normal or degraded states needs more intrinsic local mechanical and biochemical properties to perform an accurate model at the tissue level (Westin et al. 2002). In this present study, we investigated two advanced MRI sequences such as T2 Mapping and Diffusion Weighted to in vivo characterize the biochemical properties (e.g. water and proteoglycan contents) of lumbar spine discs composition.
Figure 1: T2- (A) and ADC- (B) maps of a subject. T2 and ADC values of different regions of interest of IVD are summarized in Figure 2.
Methods MRI acquisitions were performed on seven male healthy subjects (mean age: 34.4±11.4 years). All participants signed an informed consent agreement. Each participant’s L4/5 disc was scanned in the axial plane using two sequences: 1) T2 Mapping sequence (slice thickness = 5mm, TR/TE = 1000/66ms, matrix = 512×512, FOV = 310×310 mm2); 2) Diffusion weighted sequence (slice thickness=4 mm, TR/TE = 3000/67.4ms, matrix = Water and 256×256, FOV=310×310mm2). proteoglycan contents (T2 relaxation time and apparent diffusion coefficient (ADC)) were quantified using regression analysis with least squares and signal intensity-based directionoriented method (Bernstein et al. 2004). A custom made software was developed using Python and VTK/ITK programming tools. Different regions of interest with 4mm diameter were used to quantify the values of T2 and ADC in the annulus fibrosus (AF) and nucleus pulposus (NP). Furthermore, their respective areas were also computed.
Results T2- and ADC-maps of a subject are illustrated in Figure 1. Two regions of NP have been defined for T2 mapping: border part in green color (NP_b) and center part (NP_c) in red color. For ADC mapping, regions of NP_b and NP_c are green and yellow respectively. Journal of Biomechanics 45(S1)
Figure 2: Range of values of T2 and ADC.
Discussion Our values demonstrated significant variation within normal subjects (p<0.05, Student t-test). Values of T2 for the different structures of the IVD were found within the ranges provided in the literature, and partially concerning ADC values (Ludescher et al 2008). In the present study, the area values provided spatial distribution giving additional information valuable for the quantification of the composition evolution of the disc. In perspectives, in vitro characterization of lumbar spine structures will be performed in order to correlate biochemical and mechanical properties for modelling and simulation purposes.
Acknowledgement This research study has been funded by EU Programme (MYSPINE project - n°269909).
References Bernstein et al, Elsevier Acad. Press, 1-1041, 2004. Ludescher et al, J. of MRI 28:252-7, 2008. Westin et al, Med. Image Analysis 6:93-108, 2002.
ESB2012: 18th Congress of the European Society of Biomechanics
Presentation 1255 − Topic 40. Spine biomechanics
IN VIVO TISSUE CHARACTERIZATION OF INTERVERTEBRAL DISCS USING T2-MAPPING AND DIFFUSION-BASED MRI Tien Tuan Dao (1), Philippe Pouletaut (1), Ludovic Robert (2), Fabrice Charleux (2), Marie Christine Ho Ba Tho (1)
1. UTC CNRS UMR 6600, BMBI Biomécanique et Bioingénierie, Université de Technologie de Compiègne, France; 2. ACRIM-Polyclinique St Compiègne, France
Introduction Low back pain is one of chronic musculoskeletal disorders which influenced significantly the working and daily activities of human being. Characterization and modelling of lumbar spine structures, especially intervertebral discs (IVD) allow us to get a better understanding of normal and abnormal loading effect on these structures leading to best clinical treatment. In fact, the modelling of lumbar spine discs in normal or degraded states needs more intrinsic local mechanical and biochemical properties to perform an accurate model at the tissue level (Westin et al. 2002). In this present study, we investigated two advanced MRI sequences such as T2 Mapping and Diffusion Weighted to in vivo characterize the biochemical properties (e.g. water and proteoglycan contents) of lumbar spine discs composition.
Figure 1: T2- (A) and ADC- (B) maps of a subject. T2 and ADC values of different regions of interest of IVD are summarized in Figure 2.
Methods MRI acquisitions were performed on seven male healthy subjects (mean age: 34.4±11.4 years). All participants signed an informed consent agreement. Each participant’s L4/5 disc was scanned in the axial plane using two sequences: 1) T2 Mapping sequence (slice thickness = 5mm, TR/TE = 1000/66ms, matrix = 512×512, FOV = 310×310 mm2); 2) Diffusion weighted sequence (slice thickness=4 mm, TR/TE = 3000/67.4ms, matrix = Water and 256×256, FOV=310×310mm2). proteoglycan contents (T2 relaxation time and apparent diffusion coefficient (ADC)) were quantified using regression analysis with least squares and signal intensity-based directionoriented method (Bernstein et al. 2004). A custom made software was developed using Python and VTK/ITK programming tools. Different regions of interest with 4mm diameter were used to quantify the values of T2 and ADC in the annulus fibrosus (AF) and nucleus pulposus (NP). Furthermore, their respective areas were also computed.
Results T2- and ADC-maps of a subject are illustrated in Figure 1. Two regions of NP have been defined for T2 mapping: border part in green color (NP_b) and center part (NP_c) in red color. For ADC mapping, regions of NP_b and NP_c are green and yellow respectively. Journal of Biomechanics 45(S1)
Figure 2: Range of values of T2 and ADC.
Discussion Our values demonstrated significant variation within normal subjects (p<0.05, Student t-test). Values of T2 for the different structures of the IVD were found within the ranges provided in the literature, and partially concerning ADC values (Ludescher et al 2008). In the present study, the area values provided spatial distribution giving additional information valuable for the quantification of the composition evolution of the disc. In perspectives, in vitro characterization of lumbar spine structures will be performed in order to correlate biochemical and mechanical properties for modelling and simulation purposes.
Acknowledgement This research study has been funded by EU Programme (MYSPINE project - n°269909).
References Bernstein et al, Elsevier Acad. Press, 1-1041, 2004. Ludescher et al, J. of MRI 28:252-7, 2008. Westin et al, Med. Image Analysis 6:93-108, 2002.
ESB2012: 18th Congress of the European Society of Biomechanics