ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

Five healthy volunteers (age: 38.3 ± 10.5 years, weight: 78.8 ± 11.2 Kg, height: 175 ±
0.09 cm, BMI: 25.8 ± 4.7) without low back pain or disability participated in this study.
Each participated subject signed an informed consent form. Before acquiring the MRI
images, the purposes of the study and the protocol were clearly explained to every
subject. An extra session was performed to familiarize subjects with the different
postures proposed in this study. Thus, from a supine standard position in the MRI,
subjects are asked to perform and maintain hyper-lordosis and hypo-lordosis by rotating
their pelvis respectively forward and backward (Figure 1).
(a) (b) (c)
Figure 1 Three typical postures performed during MRI acquisition:
(a) hypo-lordosis, (b), normal supine and (c) hyper-lordosis
The data acquisition of the lumbar spine images was performed using a sagittal T2 SE
MRI sequence (GE Medical Systems) at the Polyclinique St Côme (Compiègne,
France). The slice thickness was set up as 3 mm. The field of view (FOV) is 36x36 cm².
The repetition time (TR) is 3780 ms. The echo time (TE) is 104.4 ms. Each acquisition
has 19 adjoining slices with a resolution of 512 x 512 pixels leading to a voxel
resolution of 0.70x0.70x3 mm 3 (around 1.47 mm 3 ). The acquisition time of T2 SE MRI
sequence is around 5 minutes.
3.2 Data processing
After MRI recording sessions, images segmentation was manually achieved using
ScanIP software (Vers. 4.3 Build 577). Three trials from the 15 recorded trials are not
used in this study due to the insufficient quality of the data. The reconstruction and the
biomechanical modelling of the lumbar spine and the low back surface (Figure 2) were
realised for all trials using MatLab software (Vers. 7 R2010b).
L 5
L 4
Figure 2 (a) Reconstructed lumbar spine and low back surface during normal supine posture
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L 2
L 1