Evaluation On Developmental Dysplasia Of The Hip Using Techniques Of MRI

Objective:Evaluation on the patients with developmental dysplasia of the hip?DDH?in various conditions,using functional and other techniques on MRI.1)To study whether the limbus in patients with DDH impedes the development of the cartilage of hips using T₂mapping and CUBE sequences.2)To utilize introvoxel incoherent motion?IVIM?DWI-MRI sequence to measure and compare the parameters reflecting perfusion and diffusion between DDH sides and normal sides of the epiphysis of femoral heads in patients with DDH after close reduction.3)Evaluating the labra injury of patients with DDH using ultrasound guided MR arthrography of the hips,and evaluate the sensitivity,specificity,positive predictive values and negative predictive values of the MR arthrography with the gold standard of operation.Methods:1)Patients with suspicious DDH were recruited in this study.All the patients were subdivided into three groups:the patients with DDH and limbi,the patients with DDH without limbi and the controls.Coronal T₂ mapping was utilized to calculate the T₂ values of the cartilage of the hips underlying the limbi in group 1and the labra in group 2 and group 3.Coronal T₂ CUBE was reconstructed and the maximal suprainferior,transversal and anteroposterior diameters of the limbi were measured.Statistics significant differences of T₂ values of cartilage of acetabula and femoral heads among the three groups were analyzed by ANOVA and LSD.The correlation of the volume of the limbus and T₂ values in patients in group 1 was analyzed by lineal regression analysis.2)The patients with DDH and performed close reductionwere enrolled in this study.The DDH sides of hips were treated as lesion group,and the normal sides as control group.The MR examinations were performed immediately after close reduction.The abduction angles of hips were measured and compared between the two groups,using Mann-Whitney U test.The IVIM data were acquired by a multi-b single shot SE-EPI pulse sequence.Region of interest was placed on the epiphysis of both femoral heads on the b=0 DWI image.The ADC_slow,ADC_fast,f,and ADC_fast×f were measured.The intraclass correlation coefficient was calculated to assess the variability of data for intro and inter-observers.A Mann-Whitney U test was performed to compare the values of ADC_slow,ADC_fast,f,and ADC_fast×f between the lesion group and the control group.Receiver operating characteristic curves were generated with respective cut-off values.The lesion sides were classified based on the IHDI classification,the ADC_slow,ADC_fast,f,and ADC_fast×f were compared among the groups.3)Totally 16 patients with DDH performed ultrasound guided MR arthrography of the hips.The diagnoses were made on the anterior,laterosuperior,posterior and the overall labra of the hips,the location and severity of the injury of the labra were recorded.Based on the operation,the sensitivity,specificity,positive predictive values?PPV?,and the negative predictive values?NPV?of the MR arthrography of the hips were calculated.Results:1)There were significant differences in the T₂ values of cartilage of acetabula among the 3 groups.The T₂ values in group 1 were higher than those in group 2?P=0.006?and group 3?P=0.000?,but there was no significant difference of T₂ values of cartilage of acetabula between group 2 and group 3?P=0.192?.The T2values in group 1 were higher than those in group 3?P=0.038?,and there was no significant difference of T₂ values of cartilage of femoral heads between group 1 and group 2?P=0.380?,and between group 2 and group 3?P=0.198?.As the volume of the limbus increased,the T₂ values of cartilage of acetabula and of femoral heads in group 1 increased respectively.2)The abduction angles of hips in both groups were in normal limits,and showed no differences?Z=-0.302,P=0.762?.The ICC of intro-observer of ADC_slow,ADC_fast,f,and ADC_fast×f was 0.997,0.991,0.985,0.988,respectively,the ICC of inter-observer of ADC_slow,ADC_fast,f,and ADC_fast×f was0.992,0.983,0.990,0.988.The values of ADCslow in the lesion group were significantly higher than that in the control group,the values of the ADC_fast,f and ADC_fast×f in the lesion group were significantly lower than that in the control group.The ADC_fast×f value was the most powerful parameter.The optimal cut-off value of ADC_fast×f was 0.023.ADC_fast was 0.0379,ADC_slow was 0.000312,f was0.545.The values in the lesion group of DDH patients with various IHDI grades showed significant differences?P=0.000⁰.044?.As the IHDI grades increased in the lesion group,ADC_fast,f,and ADC_fast×f decreased and ADC_slowlow increased.3)The sensitivity of the MR arthrography of the hips of the anterior labra was 85.7%,specificity was 100%,PPV was 100%,NPV was 90%;the sensitivity of the laterosuperior labra was 100%,specificity was 87.5%,PPV was 90%,NPV was100%;the sensitivity of the posterior labra was 50%,specificity was 100%,PPV was100%,NPV was 93.8%;Of the whole labra,the diagnostic sensitivity of the MR arthrography of the hips was 89.5%,specificity was 96.8%,PPV was 94.4%,NPV was 93.8%.Conclusions:The patients with DDH of various conditions can be made early,quantitative and accurate diagnosis before and after operations,using MR techniques,which can offer imaging aids for the treatments of surgeons.