Distributional theory for the DIA method

The DIA method for the detection, identification and adaptation of model misspecifications combines estimation with testing. The aim of the present contribution is to introduce a unifying framework for the rigorous capture of this combination. By using a canonical model formulation and a partitioning of misclosure space, we show that the whole estimation–testing scheme can be captured in one single DIA estimator. We study the characteristics of this estimator and discuss some of its distributional properties. With the distribution of the DIA estimator provided, one can then study all the characteristics of the combined estimation and testing scheme, as well as analyse how they propagate into final outcomes. Examples are given, as well as a discussion on how the distributional properties compare with their usage in practice

Shear Wave Elastography can evaluate Annulus Fibrosus Alteration in Adolescent Scoliosis

ObjectivesIn vitro studies showed that annulus fibrosus lose its integrity in idiopathicscoliosis. Shear wave ultrasound elastography can be used for noninvasivemeasurement of shear wave speed (SWS) in vivo in the annulus fibrosus, aparameter related to its mechanical properties. The main aim was to assess SWSin lumbar annulus fibrosus of scoliotic adolescents and compare it to healthysubjects.MethodsSWS was measured in 180 lumbar IVDs (L3L4, L4L5, L5S1) of thirty healthyadolescents (13 yo ± 1.9) and thirty adolescent idiopathic scoliosis patients (13 yo± 2, Cobb angle: 28.8° ± 10.4°). SWS was compared between scoliosis andhealthy control group.ResultsIn healthy subjects, average SWS (all disc levels pooled) was 3.0 ± 0.3 m/swhereas, in scoliotic patients it was significantly higher at 3.5 ± 0.3 m/s (p =0.0004; Mann-Whitney test). Differences were also significant at all disc levels.No difference was observed between males and females. No correlation wasfound with age, weight and height.ConclusionNon-invasive shear wave ultrasound is a novel method of assessment toquantitative alteration of annulus fibrosus. These preliminary results arepromising to consider shear wave elastography as a biomechanical marker forassessment of idiopathic scoliotic