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Can bone ultrasound techniques predict osteoporotic fractures — a review
S28
Abstracts
To further explore why there is such a poor correlation between placental localisation at 18–20 weeks and ultimate placental site at delivery we conducted a blinded inter and intra-observer variability study. This clearly demonstrates that trained personnel disagree both with their colleagues (56%) and even themselves (24%) when presented with the same data on two separate occasions. It is simply not possible to locate eventual placental site in this manner and we argue that this practice should cease. We conclude that an analysis of the inter and intra-observer variability is a useful tool that has a wide application in ultrasound reporting and commend it as good practice. Can bone ultrasound techniques predict osteoporotic fractures — a review Inskip D.M. AuRa Scientific Osteoporosis is the most common disorder of the skeleton. The World Health Organisation, WHO (1994) defines osteoporosis as: ‘a disease characterised by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk’. The most common method of diagnosing osteoporosis is by dual energy X-ray absorptiometry (DXA) which measures bone mineral density. It is widely stated that the WHO defines osteoporosis in terms of bone mineral density (BMD), or bone mineral content (BMC), as being a value for BMD or BMC 2.5 S.D. or more below the young adult mean’. This interpretation clearly excludes the use of ultrasound in the assessment of bone and in so doing ignores other factors that contribute to bone strength such as bone microachitecture and elasticity. However, WHO actually states that ‘the technique [Ultrasound — BUA] discriminates patients with and without osteoporosis at least as well as measurements of bone mineral density’. The interaction of ultrasound with bone has been investigated for over 20 years. For the last 5 years or so instruments, using ultrasound to assess bone, have become commercially available. These instruments assess peripheral sites such as the calcaneum, finger and tibia. In general, two parameters are measured which relate to density and bone architecture; broadband ultrasonic attenuation (BUA) and speed of sound (SOS). The review will contain an up to date assessment of the ability of ultrasound techniques to predict future fractures. The most recent review (Marshall et al., BMJ 1996; 312:1254 – 1259), of techniques for fracture prediction, covered data available up to December 1994. There was no conclusive information about ultrasound as most of the important clinical work on ultrasound has been since the end of 1994. This review will include published work up to October 1996. Simulation of RF-data for use in ultrasonic tissue characterization D’hooge J.; Bijnens B.; Michiels J.; Nuyts J.; Herregods M.C.; Thoen J.; Suetens P.; Van de Werf F. Department of Cardiology, Nuclear Med. Physics and Laboratory for Med. Imag. Research, Catholic Uni6ersity, Leu6en, Belgium
Computer simulation of ultrasonic systems has been introduced for many years. Several research groups have used these simulations to facilitate transducer design, by studying the influence of transducer characteristics on the produced image. We developed a simulation environment to enable us to produce RF-data under well defined circumstances. This way it becomes easier to try out new signal processing algorithms, which seem to have potentials in ultrasonic tissue characterization. We have implemented an object oriented simulation environment on a cluster of UNIX workstations. The impulse response approach, in which the tissue is modelled as a homogeneous medium containing many point scatterers, was used. 1- and 2-D phased arrays emitting a broadband pulse were used (with or without dynamic focusing) to ‘image’ 1-, 2or 3-D distributions of scatterers. To make the computation time smaller, distributed computing based on the client/server paradigm was implemented. Frequency-dependent attenuation was taken into account. So far, we used the simulator to study the influence of transducer and focusing characteristics on the soundfield and hence on the images. To study the quality of certain transducers, we simulate B-scan images of a cystic region. Moreover, we studied the influence of parameters describing the distribution of scatterers, e.g. the mean distance between the scatterers, the degree of randomness on the position of the scatterers, the heterogeneity of the scatterers, the local density of the scatterers, the angle of insonification and others. We also proved that sampling frequencies of 50 MHz, as used by many investigators, are only useful, e.g. speckle analysis or to study global image characteristics. If one wants to use simulated data for spectrum analysis, much higher sampling frequencies are required. This work was supported by the Flemish Institute for the improvement of the Scientific-Technological Research in the Industry (IWT). Novel polymer hydrophone for minimal field perturbation during ultrasound measurements Hurrell A.; Aindow J. Precision Acoustics, 1 Colliton Walk, Dorchester, Dorset DTl lTZ, UK When undertaking measurement of ultrasonic field distributions it has become accepted practice to use a hydrophone probe to interrogate the field at a number of positions; these point measurements are then combined to yield a composite description of the acoustic field. In order that a probe does not adversely perturb the field, physically small probes have been produced. Despite the recent development of very small diameter devices, undesirable effects (attributed to resonances within the metallic structure of the probes) have been noted. The paper describes the development of an all-polymer acoustic probe. This new sensor has both a better acoustic impedance match to water and higher damping than comparable metallic variants. Experimental results comparing frequency response, sensitivity and directionality of both metal and polymer probes are presented. Improvements yielded by the novel polymer hydrophone probe are also discussed.
Abstracts
To further explore why there is such a poor correlation between placental localisation at 18–20 weeks and ultimate placental site at delivery we conducted a blinded inter and intra-observer variability study. This clearly demonstrates that trained personnel disagree both with their colleagues (56%) and even themselves (24%) when presented with the same data on two separate occasions. It is simply not possible to locate eventual placental site in this manner and we argue that this practice should cease. We conclude that an analysis of the inter and intra-observer variability is a useful tool that has a wide application in ultrasound reporting and commend it as good practice. Can bone ultrasound techniques predict osteoporotic fractures — a review Inskip D.M. AuRa Scientific Osteoporosis is the most common disorder of the skeleton. The World Health Organisation, WHO (1994) defines osteoporosis as: ‘a disease characterised by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk’. The most common method of diagnosing osteoporosis is by dual energy X-ray absorptiometry (DXA) which measures bone mineral density. It is widely stated that the WHO defines osteoporosis in terms of bone mineral density (BMD), or bone mineral content (BMC), as being a value for BMD or BMC 2.5 S.D. or more below the young adult mean’. This interpretation clearly excludes the use of ultrasound in the assessment of bone and in so doing ignores other factors that contribute to bone strength such as bone microachitecture and elasticity. However, WHO actually states that ‘the technique [Ultrasound — BUA] discriminates patients with and without osteoporosis at least as well as measurements of bone mineral density’. The interaction of ultrasound with bone has been investigated for over 20 years. For the last 5 years or so instruments, using ultrasound to assess bone, have become commercially available. These instruments assess peripheral sites such as the calcaneum, finger and tibia. In general, two parameters are measured which relate to density and bone architecture; broadband ultrasonic attenuation (BUA) and speed of sound (SOS). The review will contain an up to date assessment of the ability of ultrasound techniques to predict future fractures. The most recent review (Marshall et al., BMJ 1996; 312:1254 – 1259), of techniques for fracture prediction, covered data available up to December 1994. There was no conclusive information about ultrasound as most of the important clinical work on ultrasound has been since the end of 1994. This review will include published work up to October 1996. Simulation of RF-data for use in ultrasonic tissue characterization D’hooge J.; Bijnens B.; Michiels J.; Nuyts J.; Herregods M.C.; Thoen J.; Suetens P.; Van de Werf F. Department of Cardiology, Nuclear Med. Physics and Laboratory for Med. Imag. Research, Catholic Uni6ersity, Leu6en, Belgium
Computer simulation of ultrasonic systems has been introduced for many years. Several research groups have used these simulations to facilitate transducer design, by studying the influence of transducer characteristics on the produced image. We developed a simulation environment to enable us to produce RF-data under well defined circumstances. This way it becomes easier to try out new signal processing algorithms, which seem to have potentials in ultrasonic tissue characterization. We have implemented an object oriented simulation environment on a cluster of UNIX workstations. The impulse response approach, in which the tissue is modelled as a homogeneous medium containing many point scatterers, was used. 1- and 2-D phased arrays emitting a broadband pulse were used (with or without dynamic focusing) to ‘image’ 1-, 2or 3-D distributions of scatterers. To make the computation time smaller, distributed computing based on the client/server paradigm was implemented. Frequency-dependent attenuation was taken into account. So far, we used the simulator to study the influence of transducer and focusing characteristics on the soundfield and hence on the images. To study the quality of certain transducers, we simulate B-scan images of a cystic region. Moreover, we studied the influence of parameters describing the distribution of scatterers, e.g. the mean distance between the scatterers, the degree of randomness on the position of the scatterers, the heterogeneity of the scatterers, the local density of the scatterers, the angle of insonification and others. We also proved that sampling frequencies of 50 MHz, as used by many investigators, are only useful, e.g. speckle analysis or to study global image characteristics. If one wants to use simulated data for spectrum analysis, much higher sampling frequencies are required. This work was supported by the Flemish Institute for the improvement of the Scientific-Technological Research in the Industry (IWT). Novel polymer hydrophone for minimal field perturbation during ultrasound measurements Hurrell A.; Aindow J. Precision Acoustics, 1 Colliton Walk, Dorchester, Dorset DTl lTZ, UK When undertaking measurement of ultrasonic field distributions it has become accepted practice to use a hydrophone probe to interrogate the field at a number of positions; these point measurements are then combined to yield a composite description of the acoustic field. In order that a probe does not adversely perturb the field, physically small probes have been produced. Despite the recent development of very small diameter devices, undesirable effects (attributed to resonances within the metallic structure of the probes) have been noted. The paper describes the development of an all-polymer acoustic probe. This new sensor has both a better acoustic impedance match to water and higher damping than comparable metallic variants. Experimental results comparing frequency response, sensitivity and directionality of both metal and polymer probes are presented. Improvements yielded by the novel polymer hydrophone probe are also discussed.