The Application Of Spectral CT Plain Scan In Acute Vertebral Compression Fractures

Objective:To investigate the clinical application of Revolution spectral CT plain scan water-calcium separated VNCa images and water-hydroxyapatite separated VNHAP images in acute vertebral compression fractures with bone marrow edema and adjacent disc injuries.Methods:Between January 2022 and January 2023,51 patients with 494 vertebral bodies and 75 target intervertebral discs who had acute vertebral compression fractures and completed Revolution spectral CT and MRI scans within 3 days at our hospital were included in this study.1.Using MRI results as a reference standard,the bone marrow edema and the extent of it in vertebral compression fractures were visually assessed by spectral CT VNCa and VNHAP color-coded fusion images,respectively.The receiver operation characteristic curve(ROC)was used to analyze and compare the diagnostic efficacy of VNCa and VNHAP color-coded fusion images.Spearman correlation analysis was used to assess the correlation between endplate injuries in spectral CT 70ke V monochromatic bone window images and disc injuries in MRI images.2.The relative water content of vertebrae was measured in VNCa and VNHAP images,respectively.The quantitative diagnostic efficacy of the two images for bone marrow edema in vertebral compression fractures was assessed and compared by ROC curves.The vertebrae were divided into a young-and-middle aged group(<60years old)and an elderly group(≥60 years old).According to the vertebral segment level,vertebrae were divided into thoracic and lumbar groups.ROC curves were plotted to determine the quantitative diagnostic value of VNCa and VNHAP images in different age subgroups and different vertebral segment level subgroups for vertebral bone marrow edema,and the optimal cut-off values for relative water content were calculated separately.Finally,the differences in the relative water content of the target and reference discs in VNCa and VNHAP images were measured quantitatively.The relative water content of target and reference discs in VNCa and VNHAP images was measured and the differences between them were compared.Results:1.In terms of visual assessment,the AUC values of spectral CT VNCa and VNHAP images for the diagnosis of bone marrow edema in vertebral compression fractures were 0.966 and 0.967,respectively,with no statistically significant difference between them(Z=1.402,P=0.161).The accuracies were both 97.57%,sensitivities were 93.10%and 91.95%,specificities were 98.53%and 98.77%,positive predictive values were 93.10%and 94.12%,and negative predictive values were 98.53%and 98.29%,respectively.The AUC values of VNCa and VNHAP images to identify the extent of bone marrow edema were 0.889 and 0.902,respectively,with no statistically significant difference between them(Z=0.422,P=0.673),accuracies were 83.91%and 89.66%,sensitivities were 80.00%and93.33%,specificities were 92.60%and 81.50%,positive predictive values were96.00%and 91.80%,and negative predictive values were 67.57%and 84.62%,respectively.The association between endplate injuries on spectral CT 70ke V monochromatic bone window images and disc injuries on MRI images was statistically different(r_s=0.701,P<0.001).2.Regarding quantitative assessment,the AUC values for diagnosing vertebral bone marrow edema with relative vertebral water content on spectral CT VNCa and VNHAP images were 0.963 and 0.969,respectively,and the difference between the two images was not statistically significant(Z=0.636,P=0.525).The AUC values of VNCa and VNHAP images were 0.951 and 0.936 in the young-and-middle aged group,with optimal cut-off values of 1069.50mg/cm~3and 1008.00mg/cm~3,respectively.The AUC values of VNCa and VNHAP images in the elderly group were0.976 and 0.985,respectively,and the best cut-off values were 1047.50mg/cm~3and1003.00mg/cm~3,respectively.The AUC values of VNCa and VNHAP images in the thoracic spine group were 0.962 and 0.946,respectively,and the best cut-off values were 1055.50mg/cm~3and 1004.00mg/cm~3,respectively.The AUC values of VNCa and VNHAP images in the lumbar group were 0.976 and 0.986,respectively,and the best cut-off values were 1047.50mg/cm~3and 1002.50mg/cm~3,respectively.The relative water content values of target discs in the spectral CT VNCa and VNHAP images were(1066.44±9.88)mg/cm~3and(1060.51±8.76)mg/cm~3,respectively.The relative water content values of reference discs were(1063.33±8.44)mg/cm~3and(1058.16±8.71)mg/cm~3,respectively.The relative water content values differences between the target and reference discs were not statistically significant(P=0.092 and P=0.102,respectively).Conclusion:1.In the diagnosis of bone marrow edema in acute vertebral compression fractures,both spectral CT VNCa images and VNHAP images can visualize and quantify the presence of bone marrow edema,while color-coded fusion images conveniently and clearly provide the extent of bone marrow edema in fractured vertebral bodies.The diagnostic value of VNHAP and VNCa images is similar.In addition,VNCa and VNHAP images have different optimal cut-off values of relative water content in different age subgroups and different vertebral segment level subgroups.Therefore,a further grouping of patients with acute vertebral compression fractures in clinical applications can help improve the diagnostic value of spectral CT for vertebral bone marrow edema,which is expected to become an alternative examination option for patients with contraindications to MRI,thus having good application and development prospects.2.Although the diagnostic value of quantitative assessment for disc injuries on spectral CT VNCa and VNHAP images is limited,there is a close correlation between endplate injuries on spectral CT 70ke V monochromatic bone window images and disc injuries on MRI images,suggesting that patients with endplate injuries found on spectral CT should undergo additional MRI examinations to confirm the disc condition and reduce the underdiagnosis of disc injuries.