Lumbar annulus fibrosus biomechanical characterization in healthy children by ultrasound shear wave elastography

Abstract

Objectives Intervertebral disc (IVD) is key to spine biomechanics, and it is often involved in the cascade leading to spinal deformities such as idiopathic scoliosis, especially during the growth spurt. Recent progress in elastographic techniques allowed access to noninvasively measure cervical IVD in adults; the aim of this study was to determine the feasibility and reliability of shear wave elastography in healthy children lumbar IVD.Methods Elastographic measurements were performed in thirty-one healthy children (6 to 17 years old), in the annulus fibrosus and in the transverse plane of L5-S1 or L4-L5 IVD. Reliability was determined by 3 experienced operators repeating measurements.Results Average shear wave speed in IVD was 2.9 ± 0.5 m/s; no significant correlations were observed with sex, age or body morphology. Intra-operator repeatability was 5.0 % while inter-operator reproducibility was 6.2 %. Intraclass correlation coefficient was higher than 0.9 for each operator.Conclusions Feasibility and reliability of IVD shear wave elastography was demonstrated. The measurement protocol is compatible with the clinical routine, and the results show the potential to give an insight into spine deformity progression and early detection.Keywords: Spine; Spinal diseases; Fibrocartilage; Tissue elasticity imaging; Pediatrics Key points: Intervertebral disc mechanical properties are key to spine biomechanics. Feasibility of shear wave elastography in children lumbar disc was assessed. Measurement was fast and reliable. Elastography could represent a novel biomarker for spine pathologies.

Intra- and inter-observer variation and accuracy using different shear wave elastography methods to assess circumscribed objects – a phantom study.

“…US elastography is increasingly used for the diagnosis of stiffness in numerous circumscribed tissues [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17]. To date, there has been a lack of phantom studies which have systematically assessed the current US shear wave elastography techniques (pSWE with fixed ROI vs. 2D-SWE with variable ROI) in an effort to evaluate their suitability/test performance for this condition.…”

“…Hence, the measurement procedure in the second part of the study was repeated five times for each target type, with the stiffness value defined as the mean of the five measurements for each ROI diameter (diameters: 40, 38, 36, 34,32,30,28,26,24,22,20,18,16,14,12,10,8,6, 4 and 2 mm).…”

“…Elastic properties of circumscribed tissues and organs that are not accessible to physicians' hands (a), or which require measurements in a small, localized area (b) are of considerable clinical interest [1,[4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Examples are: tendons/ligaments a/b , lymph nodes a/b , myometria a , prostates b , cervix uteri b , testicles b , anal sphincter muscles b , arterial plaques a/b , muscles a , intervertebral discs a/b , thyroid nodules a/b , and brain tumors a/b .…”

Shear-wave elastography can evaluate annulus fibrosus alteration in adolescent scoliosis

“…SWS was measured in all included subjects following a previously described protocol for lumbar IVD of adolescents [25]. Measurements were performed with an Aixplorer (SuperSonic Imagine, France) and a superlinear Sl 10-2 probe.…”

“…Those authors showed correlations between SWS and the mechanical properties of IVD, as well as in vivo reliability both in children and adults. A standardized, reproducible protocol was determined for the acquisition and processing of images for lumbar AF in healthy children and adolescents [25]. Measurements in scoliotic patients, however, are still lacking.…”