The Evaluation Of Knee Osteoarthritis Using Diffusion Tensor Imaging

Part Ⅰ:The study of correlationship between DTI and knee osteoarthritis Objective:This study was to investigate the anisotropic and diffusion characteristics of knee joint cartilage of normal adult and different classification of osteoarthritis (OA) via diffusion tensor imaging (DTI) and diffusion weighted imaging (DWI) and to describe the correlationship between the anisotropy (FA) and the mean diffusivity (ADC) with the different classification standard.Materials and methods:The control group consisted of10healthy volunteers (aged19to43years and mean29years,6males and4females) without the history of knee joint trauma and discomfort and the case group was with osteoarthritis, including60patients (aged23to64years,40years on average,33males and27females). Patients with OA in the cohort had to fulfill the clinincal criteria for the diagnosis of knee OA or confirmed by arthroscopy surgery. The case group also was subdivided mild, moderate and severe three grades according clinic syndromes and X-ray signs, in addition, the0grade was defined with a little effusion in intra-articular, the0grade also including subtle inhomogeneous signal intensity of knee joint cartilage.All volunteers and patients underwent MR imaging at Nanfang Hospital with a3.0-T MR system (Achieva3.0T; Philips Medical Systems) between October2012and February2013. A concentional knee MR protocol was as follows:T1W SE and T2WI FSE image, PDW-FS axial planes; DWI and DTI were obtained by3D-SE Echo-planar imaging (EPI) in axial planes.ADC mapping was performed with b-factors of400sec/mm2.The femoral cartilages were subdivided three parts, including medial and lateral parts representing weight bearing areas and no-weight bearing areas, respectively. ADC and FA values in the superficial, middle and deep zones of each part were measured, respectively. In addition, ADC and FA values of anterior cruciate ligaments and posterior cruciate ligaments were calculatedStatistical analysis:Statistical analyses were conducted using SPSS15.0software. ADC and FA values of differet groups and levels were recorded and used for statistic analyses. A one-way analysis of variance (ANOVA) was employed to compare among differet groups and levels. Levene test for equality of variances was used to test homogeneity of variances among groups and under an equal condition, the significance of differences were tested using ANOVA with LSD as a post hoc test, otherwise a Dnnett T3test was used. P≤0.05was considered as significance.Result:1. FA values were not statistically significantly different between control group and0grade, but the differences among other grades were obvious and significant.ADC values were statistically significantly different when comparing between severe grade with0grade and mild grade, respectively.2. The FA、ADC value comparison between the three cartilage layer zones:ADC value comparison:ADC values at different positions of the three cartilage layer zones comparison:the surface and middle layer, middle and deep layer without statistical significance, other pairs was statistically significant comparative between the three cartilage layer zones.FA value comparison:FA values at different positions of the three cartilage layer zones comparison:the surface and middle layer, middle and deep layer without statistical significance, other pairs was statistically significant comparative between the three cartilage layer zones.Both FA and ADC values were statistically significant between superficial zone and deep zone. In the superficial zone FA values was the lowest, on the contrary, ADC values was the highest.3. FA values were not statically significantly different among three parts, but ADC values were different. At no-weight bearing areas the ADC values were higher and at the lateral femoral condyle the values were lower.FA and ADC varied among different structures and different groups in adult knee cartilage. The correlation of ront fork and rear fork ligament’s FA/ADC between groups did not reach statistical Signifieance(P>0.05), while ADC showed a descending tendency.Conclusion:DWI and DTI could reflect changes in knee catilage composition, with comparably high spatial resolution, and can be potentially used as a clinical tool to detect early cartilage degeneration and longitudinal followup. The method can create a reliable quantitantive scale.Part Ⅱ:Diffusion-tensor imaging of rabbit osteoarthritis modelObjective:(1) To develop rabbit osteoarthritis model by intra-articular injecting papain and simulate the cartilage change in the early,middle and late periods as the basis of evaluating the pathological.(2) To determine whether DTI and DWI can evaluate the cartilage degeneration of rabbits.Materials and methods:24New Zealand adult rabbits were divided into A, B, C, D three groups randomly. In every group,0.3ml (2%) papain solution with different doses were injected into the left knee joints and establish articular cartilage degeneration animal model in early middle and late periods,D group as the control group.The rabbits in group A were scanned in24hours after the first injection, the rabbits in group B were scanned in24hours after the third injection, and the rabbits in group C were scanned in one month after the third injection.Results:The cartilage differences of anisotropy and diffusion characteristic s between cases and controls (p<0.05) were statistically significant.The ADC values comparison between the different groups:(1) levels Ⅲ osteoarthritis group<Ⅱ osteoarthritis group=contrast group=0level The differences between groups were statistically significant (P<0.05).(2) The FA values Contrast group=level0>Ⅰ>Ⅱ>Ⅲ stage osteoarthritis group. The differences between different groups were statistically significant (P<0.05).Conclusion:The main contents and results including:(1) the anisotropy and diffusion characteristics of different degree of cartilage lesion and normal group were statistically significant. DTI have high clinical value in the diagnosis of early articular cartilageosteoarthritis.(2)3.0T DTI could excellently display anatomical structure of knee joint cartilage, for accurate positioning and quantitative analysis in the study of the microstructure changes of knee joint degeneration.(3)The ADC and FA value can response ligament microstructure changes.