Application of double-layer detector spectral CT calcicum supression technique in the diagnosis of traumatic bone marrow edema in the knee

Objective: To investigate the accuracy of calcicum supression (CaSupp) technique derived from double-layer detector spectral computed tomography (DSCT) in the diagnosis of traumatic bone marrow edema in the knee.Methods: Twenty-three patients with trauma in the knee who underwent DSCT and Magnetic Resonance Imaging (MRI) in the Third Hospital of Hebei Medical University from October 2021 to March 2022 were retrospectively collected. To make the evaluation more detailed and accurate, each knee was divided into 10 partitions. Bone marrow edema in each partition of the knee was evaluated by two physicians (physician A and B) using CaSupp images combined with conventional CT-CaSupp fusion false-color images. MRI results were used as the gold standard and the accuracy of the CaSupp technique was analyzed in the diagnosis of traumatic bone marrow edema in the knee. The CaSuppCT values of the normal bone marrow area and the bone marrow edema area were delineated, and receiver operating curve (ROC curve) was drawn to find the optimal cut-off value of CaSuppCT as the quantitative parameter for the diagnosis of bone marrow edema. Results: The diagnostic sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of physician A were 83.1 %, 98.1 %, 95.5 % and 92.1 %, respectively; those of physician B were 93.5 %, 97.4 %, 94.7 % and 96.8 %, respectively. The CaSuppCT values in the bone marrow edema areas were higher than those in the normal areas, and the difference was statistically significant. The area under the receiver operating characteristic curve (AUC) of the CaSuppCT values was 0.979, and the cut-off value was 7.05Hu*. The corresponding diagnostic sensitivity was 87.0 %, and specificity was 100.0 %.Conclusion: The CaSupp technique derived from DSCT has high sensitivity and specificity in the detection of traumatic bone marrow edema in the knee, and can provide more imaging information for clinical practice.