Hafnium nanoparticles that home onto microfractures in bone make the tiny cracks visible in spectral or color computed tomography (CT) imaging. Researchers at the University of Illinois at Urbana-Champaign and the University of Maryland created the nanotechnology to work in conjunction with spectral molecular imaging developed by New Zealand-based MARS Bioimaging Ltd. (MBI). The research appeared in Advanced Functional Materials.