Quantitative ultrasound of cortical bone in the femoral neck predicts femur strength: Results of a pilot study

Abstract

A significant risk of femoral neck (FN) fracture exists for men and women with an areal bone mineral density (aBMD) higher than the osteoporotic range, as measured with dual-energy X-ray absorptiometry (DXA). Separately measuring the cortical and trabecular FN compartments and combining the results would likely be a critical aspect of enhancing the diagnostic capabilities of a new technique. Because the cortical shell determines a large part of FN strength a novel quantitative ultrasound (QUS) technique that probes the FN cortical compartment was implemented. The sensitivity of the method to variations of FN cortical properties and FN strength was tested. Nine femurs (women, mean age 83 years) were subjected to QUS to measure the through transmission time-of-flight (TOF) at the FN and mechanical tests to assess strength. Quantitative computed tomography (QCT) scans were performed to enable analysis of the dependence of TOF on bone parameters. DXA was also performed for reference. An ultrasound wave propagating circumferentially in the cortical shell was measured in all specimens. Its TOF was not influenced by the properties of the trabecular compartment. Because the method involves mechanical guided waves, the QUS variable is related to the geometric and material properties of the cortical shell (cortical thickness, tissue elasticity, and porosity). This work opens the way to a multimodal QUS assessment of the proximal femur, combining our approach targeting the cortical shell with the existing modality sensitive to the trabecular compartment. In vivo feasibility of our approach has to be confirmed with experimental data in patients. ß

A hybrid FDTD-Rayleigh integral computational method for the simulation of the ultrasound measurement of proximal femur

“…It is cylindrically pre-focused in order to concentrate the beam energy in a plane perpendicular to the FN axis, which is placed at the focal distance. A similar setup with a monoelement probe was used previously to measure femurs in vitro [11].…”

“…The interest for these waves was reinforced by the results of a pilot in vitro study [11] which suggested that there is a strong relationship between femur strength and the time-of-flight of the first arriving signal associated with waves traveling circumferentially. Furthermore, it is likely that several modes of circumferential guided waves can be measured in the cortical bone of the FN using multi-emitter and multi-receiver ultrasonic arrays and dedicated signal processing techniques such as the DORT method [12,13].…”

Ultrasound Osteoporosis Score: A novel parameter for the estimation of spine mineral density

“…calcaneus), with a limited clinical effectiveness [16]. In this context, the latest research frontier is represented by the development of an US approach to osteoporosis diagnosis that is applicable on femoral neck [ [7][8][9][10][11][12][13][14][15][16][17][18][19] and/or lumbar spine [20,21].…”

Osteoporosis detection in postmenopausal women using axial transmission multi-frequency bone ultrasonometer: Clinical findings

“…During recent years, several novel technologies based on different physical principles targeting the cortical bone have been tested in human studies. Experimental study with the proximal femur through-transmission scanner showed potential to measure propagation parameters of guided waves in the cortical shell of the femoral neck with an ultrasound beam targeted to the bone through a bulk of the surrounding soft tissues [12]. Correlation of ultrasound propagation parameters with BMD in the distal radius was demonstrated by through transition measurements in the forearm at locations containing composition of soft tissues and bone [13].…”