Assessing bone microstructure and density with photon-counting CT: emerging applications and challenges

Photon-counting computed tomography (PCCT) represents a transformative advancement in bone imaging, compared to conventional energy-integrating detector CT offering superior spatial and contrast resolution, enhanced dose efficiency, and the unique capability to perform both ultra-high-resolution and material decomposition imaging in a single acquisition. This review provides a technical overview and synthesizes evidence from preclinical studies, demonstrating that PCCT offers the possibility of accurate quantification of bone microarchitecture and mineral density with performance similar to high-resolution peripheral quantitative CT. However, translating these benefits to in vivo clinical imaging remains challenging due to the need to balance image quality with acceptable radiation dose. Further research is required to validate PCCT for cortical and trabecular bone analysis in patients. Beyond structural assessment, PCCT facilitates advanced applications such as bone marrow fat quantification and opportunistic osteoporosis screening, with early clinical studies showing strong agreement with established standards. While PCCT holds significant promise for revolutionizing bone research and clinical practice, widespread adoption will depend on optimization of image acquisition protocols, standardized image processing and analysis, and additional clinical validation.