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ObjectivesMicro-computed tomography (μ-CT) and histology, the current gold standard methods for assessing the formation of new bone and blood vessels, are invasive and/or destructive. With that in mind, a more conservative tool, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), was tested for its accuracy and reproducibility in monitoring neovascularization during bone regeneration. Additionally, the suitability of blood perfusion as a surrogate of the efficacy of osteoplastic materials was evaluated.Materials and methodsSixteen rabbits were used and equally divided into four groups, according to the time of euthanasia (2, 3, 4, and 6 weeks after surgery). The animals were submitted to two 8-mm craniotomies that were filled with blood or autogenous bone. Neovascularization was assessed in vivo through DCE-MRI, and bone regeneration, ex vivo, through μ-CT and histology.ResultsThe defects could be consistently identified, and their blood perfusion measured through DCE-MRI, there being statistically significant differences within the blood clot group between 3 and 6 weeks (p= 0.029), and between the former and autogenous bone at six weeks (p= 0.017). Nonetheless, no significant correlations between DCE-MRI findings on neovascularization and μ-CT (r=−0.101, 95% CI [−0.445; 0.268]) or histology (r= 0.305, 95% CI [−0.133; 0.644]) findings on bone regeneration were observed.ConclusionsThese results support the hypothesis that DCE-MRI can be used to monitor neovascularization but contradict the premise that it could predict bone regeneration as well.

Imaging of the lung with hyperpolarized 3He became a well known technique in the last decade. Being able to image ventilation and the microstructure of the lung an increase of SNR and a shortage of scan time is eligible. By using a 32-channel phased array the sensitivity was increased dramatically. High resolution 2D-images with a resolution of 1 × 1 mm2 having a 3 mm slice was realized, showing highly detailed images of the lung. By applying parallel imaging techniques the SNR could be increased and scan time was reduced drastically by using a 2D acceleration of R = 4 × 2 with a 3D-protocol covering the whole lung.