轴位 MRT2＊m apping 对腰椎小关节和椎间盘的定量研究

Quantitative assessment of lumber facet joints and intervertebral discs with axial MR T_2 star mapping

目的：探讨轴位腰椎小关节和椎间盘M R T2＊mapping成像的可行性，明确T2＊mapping定量成像技术对小关节和椎间盘早期退变的评估价值。方法收集慢性下腰痛患者22名作为病例组，性别和年龄匹配的健康志愿者20名为正常对照组，采用3．0T M RI对两组行T2＊mapping及常规T2 WI成像，根据Weishaupt分级法、Pfirrmann分级法分别对L2～ S1各节段小关节和椎间盘进行形态学分级，并测量小关节和椎间盘的 T2＊值，进行对比分析。结果不同Weishaupt分级小关节的T2＊值差异无统计学意义（ P＞0.05）。不同Pfirrmann分级椎间盘髓核的T2＊值差异有统计学意义（ P ＜0．05）。小关节与后纤维环的T 2＊值呈弱相关性（ r‐0．3874）。病例组与对照组小关节的 T 2＊值很相近，而髓核的T2＊值差异有统计学意义（ P ＜0．05）。在小关节评价的组间一致性方面，T2＊值的一致性很好（ r ＝0．835，P ＜0.05）；形态学Weishaupt分级一致性较差（kappa＝0．327）。结论此研究表明T2＊ mapping可用于软骨的定量研究，且轴位的腰椎小关节和椎间盘T2＊mapping联合成像是可行的。

Objective To value the feasibility of MR T2 star mapping of lumbar facet joints and intervertebral discs ,and to evaluate the diagnostic value of T 2 star mapping in early‐stage degeneration of lumbar facet joints and intervertebral discs .Methods 22 patients with low back pain and 20 age‐and sex‐matched volunteers were examined .T2 star mapping and fast spin echo T2WI of lumber facet joints and intervertebral discs were evaluated with a 3 .0 T MR imaging spectrom‐eter in 42 subjects .The Weishaupt grading was used for L2 ~S1 facet joints and the pfirrmann score was used for morpho‐logical disc grading .T2 star value in the facet joints and the intervertebral discs were measured respectively in T 2 star map‐ping imaging ,and the correlation of them and variance in different grading groups were analyzed .Results There was no significant difference in mean T2 star values between facet joints in different Weishaupt grading groups （ P〉0 .05） .There was significont difference in mean T2 star values between nueleus pulposus in different Pfirrmann scores （ P〈0 .05） .Fac‐et joint T2 star values showed a weak correlation with T 2 values of the posterior annulus （ r‐0 .3874） .The results showed similar facet joint T2 star values in patients and healthy volunteers ,but the difference of the average T2 star relaxation time of nucleus pulposus between the two teams had statistical significance （ P 〈0 .05） .The inter‐rater agreement was excel‐lent for the facet joint T2 star evaluation （ r=0 .835 ,P〈0 .05） ,and fair for the morphological Weishaupt grading （kappa=0 .327） .The results showed similar facet joint T2 star values in segments with normal and abnormal Pfirrmann scores , and the difference had no statistical significance （ P〉0 .05） .Conclusion This study demonstrates T2 star measurement is a quantitative tool for researching the cartilage based on T 2 star mapping ,and demonstrates the feasibility of a combined ax‐ial T2 star mapping approach for the facet joints and intervertebral discs .