MR Quantitative Indicators Of Infrapatellar Fat Pad,Quadriceps Femoral Fat Pad And Prefemorl Fat Pad In Relation To Knee Osteoarthritis

Part Ⅰ Quantitative MR imaging of the subpatellar fat pad in the evaluation of knee osteoarthritisObjective:To investigate the feasibility of fat fraction(FF),T2*relaxation time(T2*)and water diffusion coefficient(D)as imaging biomarkers for evaluating the subpatellar fat pad,and to evaluate the role of FF,T2*and D in evaluating the severity of knee osteoarthritis in the elderly.Methods and Materials:A total of 35 subjects(15 males,20 females;Age range:51 to 70 years,mean age:64 years),a total of 60 knee joints,Were enrolled.According to the KLG(KellgrenLawrence Grading)score of knee X-ray film,they were divided into 3 groups(no OA group[KLG 0-1],mild OA group[KLG 2]and severe OA group[KLG 3-4])with 20 knees in each group.Each group was matched with gender,age and body mass index.Knee pain was assessed using the WOMAC Index questionnaire.The degree of articular cartilage defect,subchondral bone marrow lesion and synovitis was evaluated by PDWSPAIR sequence.FF and T2*values were measured on mDIXON and D values were measured on IVIM.The quantitative characteristics of IPFP were evaluated by F(perfusion fraction)and D*(blood flow related pseudodiffusion coefficient)values.SPSS 23.0 software was used for statistical analysis.Spearman correlation analysis was used to evaluate the correlation between MR quantitative parameters and knee cartilage defect,bone marrow lesion,Hoffa synovitis,exudative synovitis and KLG grade.Oneway ANOVA was used for multi-group comparison and Bonferroni method was used for pairwise comparison.P<0.05 was considered statistically significant.Receiver operating characteristic curve(ROC curve)was used to analyze diagnostic performance.Results:The FF and T2*values of IPFP in the severe OA group were lower than those in the non-OA group and the mild OA group,and the D value(water molecular diffusion coefficient)was higher than that in the non-OA group and the mild OA group.There were significant differences in the quantitative parameter values among the three groups(all P<0.05).FF and T2*of IPFP were significantly negatively correlated with KLG,D was significantly positively correlated with KLG,and F and D*were not significantly correlated with KLG.The sensitivity,specificity and AUC value of FF value of IPFP were 77.5%,100.0%and 0.929 respectively,while the sensitivity,specificity and AUC value of T2*value were 75.0%,90.0%and 0.861 respectively.The sensitivity,specificity and AUC of D value in the diagnosis of knee osteoarthritis were 62.5%,95.0%and 0.814 respectivelyConclusion:FF,T2*and D values of IPFP can performance the severity of knee osteoarthritis well,and FF has high sensitivity and specificity in the diagnosis of KOA.The FF value of IPFP can be used as an important imaging biomarker to predict the occurrence and development of knee osteoarthritisPart Ⅱ Morphology and signal characteristics of quadriceps femoral fat pad and Prefemorl fat pad in relation to knee osteoarthritisObjective:To describe the associations between the morphology and signal characteristics of Quadriceps fat pad(QFP)and Prefemorl fat pad(PFP)and the structural changes of Radiographic osteoarthritis(ROA)of the knee..Materials and Methods:40 subjects(13 males,27 females,age range 46～74 years,mean age 56 years)who underwent simultaneous X-ray and 3.0T MRI were included in the study,with a total of 60 knee joints.Based on KLG grading criteria,the patients were divided into nonROA group(KLG grade 0 and 1)and ROA group(KLG grade 2,3 and 4),with 30 knees in each group.The high signal of quadriceps fat pad(QFP),the mass effect of QFP and the high signal of PFP interpatellofemoral fat were evaluated and measured on PDW-SPAIR sequence images.2)To evaluate the grade of upper cartilage defect,subchondral bone marrow lesion,Hoffa synovitis and exudative synovitis in the 5 subdivisions of patella,medial femoral condyle,lateral femoral condyle,medial tibial plateau and lateral tibial plateau;3)Measure the front and back diameter,head and tail diameter,oblique diameter and area of quadriceps fat pad(QFP);4)Measure the maximum thickness of the prefemoral fat pad(PFP).SPSS 23.0 software was used for statistical analysis.Independent sample T test was used for comparison between continuous variable groups,and X2 test was used for comparison between categorical variable groups.Spearman correlation analysis was performed between QFP and PFP and KLG grade,Hoffa synovitis,exudative synovitis,articular cartilage defect and subchondral bone marrow lesion.P<0.05 was considered statistically significant.Result:There were statistically significant differences between ROA group and non-ROA group in the head-to-tail diameter of QFP,high signal,mass effect,high signal between patellofemoral PFP and the maximum thickness of PFP(P<0.05).There was a slight positive correlation between high QFP signal and high PFP interpatellar signal and KLG(r=0.260,0.397,P<0.05),and a moderate negative correlation between the maximum thickness of PFP and KLG(R=-0.423,P<0.05).There was a slight positive correlation between the high QFP signal and Hoffa synovitis(r=0.328,P<0.05),and there was a slight negative correlation between the occupying effect of QFP and the maximum thickness of PFP and Hoffa synovitis(r=-0.285,-0.436,P<0.05).The maximum thickness of PFP was negatively correlated with exudative synovitis(r=-0.557,P<0.05).The high signal of PFP interpatellofemoral fat was positively correlated with cartilage defects in different subareas(r was 0.286-0.406,P<0.05),while QFP mass effect and maximum thickness of PFP were negatively correlated with cartilage defects in different subareas(R was-0.291-0.500,P<0.05).There was a slight negative correlation between the anterior and posterior diameter of QFP and the defect of medial tibial cartilage,and the maximum thickness of PFP was negatively correlated with the defect of medial tibial cartilage(r was-0.273-0.305,P<0.05).There was a slight and moderate positive correlation between the high PFP interpatellofemoral signal and the defect of medial tibial cartilage(R was 0.281,0.408,P<0.05).There was a slight negative correlation between the anterior and posterior diameter of QFP and the bone marrow lesion of medial and lateral tibia(r:-0.273,-0.277,P<0.05),and a moderate and mild positive correlation between PFP patellofemoral high signal and the bone marrow lesion of medial and lateral tibia(R:0.408,0.281,P<0.05).There was a slight negative correlation between the maximum thickness of PFP and the medial subchondral bone marrow of tibia(R=-0.305,P<0.05).Conclusion:The morphology and signal characteristics of quadricep fat pad and anterior femoral fat pad are correlated with radiological osteoarthritis of the knee(K-L grade)and MR synovitis,cartilage defect and bone marrow lesions,which may be the potential influencing factors for the development of osteoarthritis of the knee.