Individualized assessment of osteoporotic fracture risk at the spine using ultra-low dose MDCT imaging techniques and non-dedicated routine MDCT exams

点击翻译按钮获取中文摘要

Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength predisposing an individual to an increased risk of fractures. In particular, osteoporotic vertebral fractures are associated with a reduced quality of life and increased morbidity and mortality leading to a severe socio-economic burden. Clinical risk factors and Dual-energy-X-ray-absorptiometry (DXA)-based Bone Mineral Density (BMD) measurements are currently used to determine fracture risk and to initiate appropriate (drug) therapy. However, BMD values of subjects with versus without osteoporotic fractures overlap. Vertebral BMD assessment in non-dedicated clinical routine Multi-Detector Computed Tomography (MDCT) exams was superior to DXA-based BMD to predict incidental vertebral fractures. Furthermore, MDCT-based Finite Element Models (FEM) have shown to improve vertebral bone strength prediction beyond BMD. The objectives of our research project are (i) to develop dedicated ultra-low dose MDCT imaging for quantitative bone assessment and (ii) to convert non-dedicated clinical routine MDCT exams to use them adequately to predict vertebral-specific fracture risk. For ultra-low dose imaging, iterative reconstruction algorithms for improved diagnostic image quality will be developed. Furthermore, a compressed sensing inspired strategy, widely known as sparse-sampling CT will be investigated to reduce radiation exposure in a fundamentally different way. This approach allows acquiring a reduced number of projections, while the radiation exposure remains high for each individual projection image. The clear benefit of sparse-sampling acquisitions is an improved quality for each projection while circumventing the influence of electronic readout noise. As the biomechanical modeling of bone strength is dependent on different acquisition parameters and the application of iodine-containing intravenous contrast agent, these have to be taken into account to perform a reliable opportunistic osteoporosis screening. A fully-automated pipeline will be established to read and standardize the non-dedicated routine MDCT data, segment each vertebra and determine vertebra-specific fracture risk using BMD, bone texture analysis, and FEM. The PIs can show project-related publications based on already completed DFG-funded research projects in the context of osteoporosis imaging to successfully perform the proposal, which requires interdisciplinary research effort by radiologists, physicists, and bioengineers.