European journal of radiology
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This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. ⋯ Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures.
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In the assessment of osteoporosis, the measurement of bone mineral density (BMD(a)) obtained from dual energy X-ray absorptiometry (DXA; g/cm(2)) is the most widely used parameter. However, bone strength and fracture risk are also influenced by parameters of bone quality such as micro-architecture and tissue properties. This article reviews the radiological techniques currently available for imaging and quantifying bone structure, as well as advanced techniques to image bone quality. ⋯ The quantification of the trabecular architecture included parameters of scale, shape, anisotropy and connectivity. Finite element analyses required highest resolution, but best predicted the biomechanical properties of the bone. MR diffusion and perfusion imaging and MR spectroscopy may provide measures of bone quality beyond trabecular micro-architecture.
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The aim of this study was to investigate the maximum height, area under the curve (AUC) and full width at half maximum (FWHM) of the aortic input function (AIF) in renal dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) studies. We evaluated the significance of choice of size for regions of interest (ROI) in the aorta, reproducibility and inter-observer agreement of AIF measurements in healthy volunteers for renal DCE-MRI studies. ⋯ Paired t-tests for inter-observer comparison on the pooled 30 DCE-MRI studies, showed good correlations (correlation coefficients >0.85) with no significant differences (p-values >0.82) when comparing the peak value, AUC and FWHM of the AIFs. Thus the results were operator independent. The size of the aortic ROIs significantly affected all measured parameters of the AIF (p-values <0.039). However, correlation coefficients when comparing AIF 1 and AIF 2 were high for all evaluated AIF parameters (correlation coefficients >0.88), indicating a similar shape and temporal dynamic of the passage of the contrast agent through the aorta. When comparing the intra-individual DCE-MRI studies for each volunteer all AIF parameters had p-values >0.22 and correlation coefficients <0.82, with the exception of the FWHM, which had a correlation coefficient of 0.96 showing a significant variation in AIF parameters in the same volunteer on different days.