Nondisplaced fractures on hip CT: added value of dual-energy CT virtual non-calcium imaging for detection of bone marrow edema using visual and quantitative analyses

Abstract

Background Dual-energy computed tomography (DECT) virtual non-calcium (VNCa) imaging can demonstrate bone marrow edema. Purpose To evaluate the added value of DECT VNCa imaging for detection of non-displaced fractures on hip CT and to determine the attenuation value cut-off to identify bone marrow edema around fractures. Material and Methods We identified 35 patients who underwent DECT due to suspicion of a non-displaced fracture of the proximal femur or pelvic bone. Twenty-seven non-displaced fractures were present in 24 patients, while 11 patients had no fractures. Radiological, clinical follow-up, or surgical record was the standard of reference. Two radiologists visually interpreted CT images in two sessions: one with bone reconstruction images only and one with bone reconstruction images and VNCa images. Diagnostic performances were compared between the two reading sessions. Quantitative analyses of CT numbers on VNCa images were performed and a cut-off value was obtained through receiver operating characteristic (ROC) analysis. Results In the visual analysis, area under the curve, sensitivity, and negative predictive value were improved in the second session with VNCa images for both readers. In the quantitative analysis, a cut-off value of -55.3 HU yielded 100% sensitivity, 94% specificity, 95.4% accuracy, 69.0% positive predictive value, and 100% negative predictive value for detection of non-displaced fractures. Conclusion Visual and quantitative analyses of VNCa images may be useful in detection of non-displaced fractures in the proximal femur and in pelvic bones.