SAM

A new quasi-invariant parameter characterizing the postural alignment of young asymptomatic adults

AMABILE, Célia — Fri, 01 Jan 2016 00:00:00 GMT

A new quasi-invariant parameter characterizing the postural alignment of young asymptomatic adults AMABILE, Célia; LAFAGE, Virginie; BARREY, Cédric; VITAL, Jean-Marc; SKALLI, Wafa; PILLET, Helene Purpose Our study aims to describe the postural alignment of young asymptomatic subjects from head to feet from bi-planar standing full-body X-rays, providing database to compare to aging adults. Novelty resides in the inclusion of the head and lower limbs in the erected posture’s analysis. Methods For 69 young asymptomatic subjects (18–40 years old) 3D reconstructions of the head, spine, pelvis and lower limbs segments were performed from biplanar full-body X-rays. Usual studied spinal, pelvic and lower limbs’ parameters were computed in 3D, sagittal and frontal planes of the patient. Relationships between these parameters were investigated. Inclinations of different lines were studied to characterize the erected posture. Results Values found for spinal curvatures, pelvic parameters and lower limbs geometrical parameters agreed with the literature: thoracic kyphosis, lumbar lordosis, pelvic incidence, pelvic tilt and sagittal vertical axis were respectively in average of 26.9 (SD 7.2 ), 30.5 (SD 7.5 ), 51.0 (SD 9.4 ), 11.1 (SD 5.6 ) and -8.9 mm (SD 21.6 mm). The angle between the vertical and the line joining the most superior point of dentiform apophyse of C2 (OD) and the center of the bi-coxofemoral axis (HA) was the less variable one (SD 1.6 ). Conclusions This study on 3D postural alignment reports the geometry of the spine, pelvis and lower limbs, of the young asymptomatic adult. The less variable angle is the one of the line OD–HA with the vertical, highlighting the vertical alignment of the head above the pelvis. This study provides a basis for future comparisons when investigating aging populations.

Lumbar spinal muscles and spinal canal study by MRI three-dimensional reconstruction in adult lumbar spinal stenosis

BOISSSIERE, Louis — Sun, 01 Jan 2017 00:00:00 GMT

Lumbar spinal muscles and spinal canal study by MRI three-dimensional reconstruction in adult lumbar spinal stenosis BOISSSIERE, Louis; MOAL, Bertrand; GILLE, Olivier; DE-ROQUEFEUIL, Elise; DURIEUX, Muriel; OBEID, Ibrahim; DOUSSET, Vincent; VITAL, Jean-Marc; SKALLI, Wafa Background: Lumbar spinal stenosis is degenerative disc disease most common manifestation. If stenosisdegree seems poorly related to symptom severity, lumbar muscles role is recognized. Many studiesreport imaging methods, to analyze muscle volumes and fat infiltration (FI), but remain limited due tothe difficulty to represent entire muscle volume variability. Recently a 3D muscle reconstruction protocol(using the deformation of a parametric specific object method (DPSO) and three-point Dixon images) wasreported. It offers the ability to evaluate, muscles volumes and muscle FI.Purpose: To describe, in a lumbar spinal stenosis population, muscle volumes, muscle FI and lumbarspinal canal volume with 3D MRI images reconstructions.Materials and methods: Ten adults presenting L4–L5 lumbar stenosis, were included. After specific MRIprotocol, three-dimensional, muscle and spinal canal, reconstructions were performed. Muscle (psoasand paraspinal muscles) volumes and fat infiltration (FI), the spinal canal volume, age, and height werecorrelated one to each other with Spearman correlation factor. An ANOVA was performed to evaluate theintervertebral level influence (P ≤ 0.05).Results: Muscle volumes correlated with height (r = 0.68 for psoas). Muscles FI correlated with age (r = 0.66for psoas) and lumbar spinal canal volume (r = 0.91). Psoas and paraspinal volumes were maximum atL3–L4 level whereas FI increased from L1–L2 to L5–S1 level.Discussion: These first results illustrate the importance to consider muscles entirely and report correla-tions between muscles FI, lumbar spinal canal volume and age; and between muscle volumes and patientsheight. Muscle degeneration seems more related to muscle FI than muscle volume.Level of evidence: 3.

Volume and fat infiltration of spino-pelvic musculature in adults with spinal deformity.

MOAL, Bertrand — Thu, 01 Jan 2015 00:00:00 GMT

Volume and fat infiltration of spino-pelvic musculature in adults with spinal deformity. MOAL, Bertrand; BRONSARD, Nicolas; RAYA, Jose G.; VITAL, Jean-Marc; SCHWAB, Frank; SKALLI, Wafa; LAFAGE, Virginie AIM: To investigate fat infiltration and volume of spino-pelvic muscles in adults spinal deformity (ASD) with magnetic resonance imaging (MRI) and 3D reconstructions. METHODS: Nineteen female ASD patients (mean age 60 ± 13) were included prospectively and consecutively and had T1-weighted Turbo Spin Echo sequence MRIs with Dixon method from the proximal tibia up to T12 vertebra. The Dixon method permitted to evaluate the proportion of fat inside each muscle (fat-water ratio). In order to investigate the accuracy of the Dixon method for estimating fat vs water, the same MRI acquisition was performed on phantoms of four vials composed of different proportion of fat vs water. With Muscl'X software, 3D reconstructions of 17 muscles or group of muscles were obtained identifying the muscle's contour on a limited number of axial images [Deformation of parametric specific objects (DPSO) Method]. Musclar volume (Vmuscle), infiltrated fat volume (Vfat) and percentage of fat infiltration [Pfat, calculated as follow: Pfat = 100 × (Vfat/Vmuscle)] were characterized by extensor or flexor function respectively for the spine, hip and knee and theirs relationship with demographic data were investigated. RESULTS: Phantom acquisition demonstrated a non linear relation between Dixon fat-water ratio and the real fat-water ratio. In order to correct the Dixon fat-water ratio, the non linear relation was approximated with a polynomial function of degree three using the phantom acquisition. On average, Pfat was 13.3% ± 5.3%. Muscles from the spinal extensor group had a Pfat significantly greater than the other muscles groups, and the largest variability (Pfat = 31.9% ± 13.8%, P < 0.001). Muscles from the hip extensor group ranked 2(nd) in terms of Pfat (14% ± 8%), and were significantly greater than those of the knee extensor (P = 0.030). Muscles from the knee extensor group demonstrated the least Pfat (12% ± 8%). They were also the only group with a significant correlation between Vmuscle and Pfat (r = -0.741, P < 0.001), however this correlation was lacking in the other groups. No correlation was found between the Vmuscle total and age or body mass index. Except for the spine flexors, Pfat was correlated with age. Vmuscle and Vfat distributions demonstrated that muscular degeneration impacted the spinal extensors most. CONCLUSION: Mechanisms of fat infiltration are not similar among the muscle groups. Degeneration impacted the spinal and hip extensors most, key muscles of the sagittal alignment.

CT-based semi-automatic quantification of vertebral fracture restoration

LE PENNEC, Gilles — Sun, 01 Jan 2012 00:00:00 GMT

CT-based semi-automatic quantification of vertebral fracture restoration LE PENNEC, Gilles; CAMPANA, Sophie; JOLIVET, Erwan; VITAL, Jean-Marc; BARREAU, Xavier; SKALLI, Wafa Minimally invasive surgeries aiming to restore fractured vertebral body are increasing; therefore, our goals were to create a 3D vertebra reconstruction process and design clinical indices to assess the vertebral restoration in terms of heights, angles and volumes. Based on computed tomography (CT)-scan of the vertebral spine, a 3D reconstruction method as well as relevant clinical indices were developed. First, a vertebra initial solution requiring 5 min of manual adjustments is built. Then an image processing algorithm places this solution in the CT-scan images volume to adjust the model's nodes. On the vertebral body's anterior and posterior parts, nine robust heights, volume and endplate angle measurement methods were developed. These parameters were evaluated by reproducibility and accuracy studies. The vertebral body reconstruction accuracy was 1.0 mm; heights and volume accuracy were, respectively, 1.2 and 179 mm3. In conclusion, a 3D vertebra reconstruction process requiring little user time was proposed as well as 3D clinical indices assessing fractured and restored vertebra.