The Value Of Dual Energy CT In Detecting Bone Marrow Lesions In Knee Osteoarthritis Joint

Purpose: Bone marrow lesions are commonly seen in knee osteoarthritis.Using magnetic resonance imaging(MRI)as a reference standard,the aim of this study was to evaluate the diagnostic value of bone marrow lesions of knee osteoarthritis by dual-energy computed tomography virtual noncalcium technology.Materials and Methods: Twenty-two patients with knee osteoarthritis a total of 27 knee joints were examined by DECT and MRI,the mean age was 58.9 years ± 8.0[standard deviation],age range was 43-76,including 15 females(mean age,61.8years ± 6.2[standard deviation];age range,55-76years)and 7 males(mean age,52.4years ± 7.8[standard deviation];age range,43-65 years).The DECT digital subtraction technique removes calcium to obtain VNCa images,the knee joint was then divided into 14 anatomical regions on the axial image,the distal femur and proximal tibia were divided into six regions respectively,the patella was divided into two regions.By two radiologist reading the imaging alone,Bone marrow were assessed using a four-grading system(Grade 4: very obvious lesions;Grade 3: relatively obvious lesions;Grade 2: mild or suspicious lesions;Grade 1: normal),Furthermore,CT values of bone marrow lesions on the VNCa images were measured.Using MRI as a reference standard,grade 3-4 bone marrow lesions were considered as a positive result,to assess VNCa image detecting performance of knee osteoarthritis associated with bone marrow lesions,and according to the CT value of bone marrow,the ROC curve was performed to analyse for VNCa images detecting bone marrow lesions related with knee osteoarthritis.Results: VNCa images and MRI showed good consistency(the knee: Kappa= 0.802;distal femur: Kappa= 0.756;proximal tibia: Kappa= 0.891;patella: Kappa= 0.651).When grade 3-4 bone marrow lesions were considered as positive results,the sensitivity,specificity,positive predictive value and negative predictive value of VNCa images detecting knee osteoarthritis associated with bone marrow lesions were 75.76%,98.72%,92.59%,95.06%,respectively;70.37%,98.52%,90.48%,94.33%,respectively,for the distal femur;88.33%,100%,100%,96.35%,respectively,for the proximal tibia;66.67%,95.56%,75%,93.48%,respectively,for the patella.The average CT value of the bone marrow positive area and negative area in knee joint were(-24.62 ± 47.80)HU and(-85.21 ± 33.73)HU respectively,and those were(-33.0 ± 53.89)HU in positive resions and(-86.0 ± 31.75)HU in negative resions for the distal femur,(-22.23 ± 40.22)HU in positive resions and(-86.90 ± 32.75)HU in negative resions for the proximal tibia,(-7.36 ± 52.05)HU in positive resions and(-77.92 ± 41.43)HU in negative resions for the patella(all p value < 0.001).The areas under the ROC curve of VNCa images for detecting osteoarthritis associated with bone marrow lesions were 0.776 in the distal femur,0.873 in the proximal tibia,0.842 in the patella.Conclusion: VNCa images of DECT showed good diagnostic performance in the assessing of bone marrow lesions of knee osteoarthritis,and it may become an importantly and commonly used method to detect bone marrow lesions in the future.