| Part Ⅰ.Controlled study of conventional MR sequences, T2-mapping,and FS-3D-SPACE-PDWI sequences of articular cartilageObjective To compare the effect of MR conventional 2D proton-weighted fat suppression sequence(FS-PDWI),T2-mapping sequence and FS-3D-SPACE-PDWI sequence on the display of articular cartilage,and to investigate the best sequence for displaying articular cartilage.Materials and methods Eighteen healthy volunteers were selected for MR examination of the knee,and 30 healthy knees were included in total.The T2-mapping sequence was post-processed by Siemens Syngo via software to generate pseudo-color maps and adjust the color gamut,the 3D-SPACE-PD-FS sequence was multi-planar reconstructed(MPR)by AW 4.6 workstation,and the conventional sequence and FS-3D-SPACE-PDWI sequence were adjusted to fit the observation.The qualitative indexes were based on the Likert scale 5-point scale,and two imaging physicians assigned scores to the three sequences to evaluate the articular cartilage and image artifacts.The quantitative indexes were SNR and CNR,and three regions of interest were set up in the articular cartilage,subchondral bone,and surrounding air,and were calculated based on the formulas SNR=SI tissue/SD background and CNR=|SI tissue1-SI tissue2|/SD background.The Kappa test was used to evaluate the agreement of the scores of the 2 imaging physicians.the Mann-Whitney U test was used to compare the qualitative indicators of the 3 sequences,and the one-way ANOVA was used to compare the quantitative indicators of the 3 sequences.Results The agreement between the 2 imaging physicians’ qualitative index assessments was good.Cartilage display assessment: both radiologists considered the3D-SPACE-PD-FS sequence superior to the conventional 2D sequence(imaging physician 1: P=0.046;imaging physician 2: P=0.004)and the conventional 2D sequence superior to the T2-mapping sequence(P<0.001 for both imaging physicians).Artifact assessment: Both radiologists considered the 3D-SPACE-PD-FS sequence and the conventional 2D sequence to be of higher image quality than the T2-mapping sequence(P<0.001 for both).1 imaging physician considered the conventional 2D sequence to have less image artifact than the 3D-SPACE sequence(P=0.001),and the other imaging physician considered the 3D sequence to be of higher image quality than the 2D sequence.There was no statistical difference between 3D and 2D sequence image quality(P=0.226).Quantitative metrics analysis: 3D-SPACE-PD-FS sequences showed better signal-to-noise and contrast-to-noise ratios for cartilage than conventional 2D sequences,both of which were superior to T2-mapping sequences(F=86.847,P<0.001).Conclusion The 3D-SPACE-PD-FS sequence is the best sequence for displaying cartilage and has good consistency in assessment by different physicians.Motion artifacts may exist due to the long image acquisition time,but they do not have a significant effect on cartilage display.Part Ⅱ Study on the application of T2-mapping and FS-3D-SPACE-PDWI sequences to assess articular cartilage changes in knee gouty arthritisObjective To investigate the performance and value of quantitative parameters of the T2-mapping sequence in articular cartilage changes in gouty arthritis of the knee according to the results of the first part,applying the FS-3D-SPACE-PDWI sequence as a standard.The FS-3D-SPACE-PDWI sequence was applied to analyze the differences of cartilage in different sub-regions of the knee joint involved in gout,and to investigate the correlation between the degree of articular cartilage damage and clinical and laboratory indices.Materials and methods Twenty-one patients with clinically confirmed gouty arthritis of the knee from January 2022 to March 2023 with a total of 32 knees were selected as the gout group,and 18 healthy volunteers with age and sex matching the gout group with a total of 30 knees were selected as the control group.All subjects underwent knee MRI T2-mapping,FS-3D-SPACE-PDWI sequences.the T2-mapping sequence images were generated by post-processing software to generate pseudo-color images,outline the whole articular cartilage in six sub-regions(patella,femoral talus,medial and lateral femoral condyles,medial and lateral tibial plateau),and measure T2 values.the FS-3D-SPACE-PDWI sequence images were taken by two patients with gout.PDWI sequences were reviewed by two imaging physicians,and according to the International Cartilage Repair Society diagnostic grading(ICRS grading)criteria(grade 0: normal cartilage,no abnormalities in cartilage morphology,structure and signal;grade 1: intact articular cartilage surface,fair structural continuity,uneven internal cartilage signal;grade2: partial interruption of articular cartilage continuity,defect depth not exceeding 50% of the whole layer;grade 3 Grade 4: cartilage defect involving the whole layer,exposing the subchondral bone,with or without bone signal changes).The T2 values of cartilage in different sub-regions of the gout group were compared with those of the control group,and the T2 values of cartilage with different degrees of damage in the gout group were compared by one-way ANOVA,and the differences were compared by the LSD method.the ROC curve was used to assess the value of the T2 values for diagnosing the presence of cartilage damage and identifying mild and severe cartilage damage,and the AUC values of the area under the ROC curve were calculated.The Kruskal-Wallis test was used to compare the differences in the degree of cartilage damage in different sub-regions of the knee joint in gout patients;the Spearman correlation test was used to analyze the correlation between the degree of cartilage damage and clinical and laboratory indices.Results There was no statistically significant difference in age between the gout group and the healthy control group(t=-0.51,P=0.61),and there was no difference in the T2 values of articular cartilage in each subzone between the gout group and the control group(F=1.28,P=0.27 in the gout group;F=2.14,P=0.06 in the control group).The T2 values of articular cartilage in all six subregions were higher in the gout group than in the control group,and the differences were statistically significant(all P < 0.01).As the degree of cartilage damage increased,T2 values increased(F=60.87,P<0.01),and T2 values can quantitatively assess gout cartilage damage and the degree of damage,with high diagnostic efficacy(AUC 0.87,0.85,respectively).The degree of patellofemoral cartilage damage was higher in the gout group than in other subregions except the talus,and the difference was statistically significant(P < 0.05).Spearman correlation analysis showed that the degree of cartilage damage in gout patients was mildly and positively correlated with the disease duration(R = 0.248,P = 0.001),and there was no significant correlation with laboratory indexes such as uric acid and blood sedimentation.Conclusion The T2 value of articular cartilage in patients with knee gouty arthritis was higher than that of normal knee cartilage,and the T2 value increased with the degree of damage;the T2-mapping sequence can quantitatively diagnose the presence and degree of gouty cartilage damage in the knee joint,and has good diagnostic efficacy.The degree of patellar cartilage damage was higher in gout patients than in other subregions,suggesting that gouty arthritis often involves this area.The degree of cartilage damage in gout patients is positively correlated with the disease duration,and patients with long disease duration should be alert to gout-induced cartilage damage. |
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