DETECTION OF BONE VIBRATION BY SQUID DEVICE

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Development of non-invasive methods for quantitating the bone mass is important in the diagnosis and treatment of many skeletal diseases, particularly for osteoporosis. The objective of this study will be to determine if a SQUID (superconducting quantum interference device) device can be used to detect the magnetic field produced by the flow of stress generated potential in a long bone. Vibration or stress wave propagation of human long bones will be monitored by bonded strain gages and by a SQUID. Subsequently the load carrying capacity of the bones will be determined by mechanical testing. Cortical thickness of the bones will be measured and samples for the bone will be ashed to determine the mineral content. Measured magnetic parameters such as amplitude, attenuation and scattering will be correlated with the measured cortical thickness, bone density, bone mineral content, and the load carrying capacity of each bone. Similarly, correlation coefficients will be calculated between the measured parameters with the radiographic density. An analysis of these data will show the relative accuracy of the SQUID measurements as a non- invasive method of the assessment of the degree of osteoporosis in patients. The outcome of this study may prove valuable in the treatment of osteoporosis, if we can show that small changes in the bone density and cortical thickness can be measured accurately by SQUIDs. The effect of different treatment modalities can then be evaluated on an objective basis. The advantage of SQUID technique will be that the patients will not be exposed to radiation. Similarly, the SQUID may be moved along the length and circumference of a limb and the output can then be plotted as a new method of computed tomography for our skeletal system. A mathematical model of stress wave propagation in long bone will also be developed, and from this model, the magnetic fields due to a known stress pattern in a long bone will be calculated. This data will be utilized to verify our SQUID measurements and also to predict changes in the magnetic field due to changes in the cortical thickness and bone density.