Skeletal Imaging: Bones

Since the advent of dual-energy CT, improvements have been achieved in CT imaging of the skeleton. Through reconstruction of a virtual monochromatic energy spectrum and corresponding virtual monoenergetic images, significant metal artifact reduction can be achieved compared to conventional CT, allowing for a more detailed assessment of metal implants and surrounding tissue. Furthermore, visualization of bone marrow pathologies is achieved by creation of virtual non-calcium images which enable subtraction of calcium from cancellous bone based on three-material decomposition. In addition, phantomless bone mineral density measurements of trabecular bone can be performed with dual-energy CT, allowing for opportunistic osteoporosis screening in context of routine CT scans, potentially resulting in avoidance of further examinations and—particularly for patients undergoing regular follow-up CT examinations—significant radiation exposure reduction. With introduction of photon-counting CT, advances regarding all mentioned applications are expected due to its technical advances compared to dual-energy CT. In addition, photon-counting CT may also further facilitate visualization of complex and thin skeletal structures by providing highest spatial resolution imaging, as well as bone tumor identification and characterization due to improved material decomposition compared to dual-energy CT.