Pattern of muscle involvement in inclusion body myositis: a sonographic study.

OBJECTIVES: Imaging plays a role in myositis assessment by detecting muscle changes indicative of pathology. This study was conducted to determine the ultrasonographic pattern of muscle involvement in patients with inclusion body myositis (IBM) through an assessment of muscle echointensity. METHODS: Sixty-two individuals were consecutively studied, 18 with IBM, 16 with polymyositis or dermatomyositis and 28 normal controls. Standardised scans were completed bilaterally for the deltoids, biceps, flexor digitorum profundus (FDP), flexor carpi ulnaris, rectus femoris, tibialis anterior and gastrocnemius assessing for muscle echointensity changes. RESULTS: Patients with IBM had a markedly increased muscle echointensity when compared with comparator groups for all muscles studied. This was most discriminating at the FDP, gastrocnemius and rectus femoris. Asymmetry between sides and a heterogeneously increased echointensity were also seen. CONCLUSIONS: Ultrasonography can aid in the assessment of IBM by displaying an increased echointensity in characteristically involved muscles, particularly when combined with assessments for asymmetry and echotexture.

Development of a Human Cranial Bone Surrogate for Impact Studies.

In order to replicate the fracture behavior of the intact human skull under impact it becomes necessary to develop a material having the mechanical properties of cranial bone. The most important properties to replicate in a surrogate human skull were found to be the fracture toughness and tensile strength of the cranial tables as well as the bending strength of the three-layer (inner table-diplöe-outer table) architecture of the human skull. The materials selected to represent the surrogate cranial tables consisted of two different epoxy resins systems with random milled glass fiber to enhance the strength and stiffness and the materials to represent the surrogate diplöe consisted of three low density foams. Forty-one three-point bending fracture toughness tests were performed on nine material combinations. The materials that best represented the fracture toughness of cranial tables were then selected and formed into tensile samples and tested. These materials were then used with the two surrogate diplöe foam materials to create the three-layer surrogate cranial bone samples for three-point bending tests. Drop tower tests were performed on flat samples created from these materials and the fracture patterns were very similar to the linear fractures in pendulum impacts of intact human skulls, previously reported in the literature. The surrogate cranial tables had the quasi-static fracture toughness and tensile strength of 2.5 MPa√ m and 53 ± 4.9 MPa, respectively, while the same properties of human compact bone were 3.1 ± 1.8 MPa√ m and 68 ± 18 MPa, respectively. The cranial surrogate had a quasi-static bending strength of 68 ± 5.7 MPa, while that of cranial bone was 82 ± 26 MPa. This material/design is currently being used to construct spherical shell samples for drop tower and ballistic tests.