Detection of bone marrow oedema in knee joints using a dual-energy CT virtual non-calcium technique

To evaluate bone marrow oedema in knee joints quantitatively and qualitatively using a dual-energy computed tomography (CT) virtual non-calcium (VNCa) technique.

Thirty-five patients with knee joint injuries underwent both dual-energy CT and magnetic resonance imaging (MRI) between March 2018 and November 2018. The presence of bone marrow oedema was assessed by two independent radiologists with the use of colour-coded dual-energy CT VNCa images and measured attenuation on them. The biggest area of bone marrow oedema on axial images was measured by another radiologist using the dual-energy CT and MRI images, respectively. Attenuation values were subjected to receiver operating characteristic (ROC) curve analysis and oedema area sizes were subjected to paired t-test analysis.

In qualitative analysis, colour-coded VNCa images had an overall sensitivity of 88.4%, specificity of 98%, positive predictive value of 92.7%, negative predictive value of 96.8%, and accuracy of 95.9%. Attenuation values obtained from colour-coded VNCa images were significantly different in knee joint regions with and without oedema (p<0.001). ROC curve analysis revealed an area under the curve (AUC) of 0.910. A cut-off value of -67 HU provided a sensitivity of 81.4%, specificity of 99.3%, accuracy of 90.4%, positive predictive value of 99.1%, and negative predictive value of 84.2% for the differentiation of oedematous knee joint regions. Significant differences in the size of oedema area were not found between them.

Dual-energy CT VNCa can be used to evaluate bone marrow oedema effectively.