背景：β2-微球蛋白是多发性骨髓瘤（MM）患者的血清标志物，但并不总能准确反映肿瘤负荷。相反，全身（WB）MRI对于检测骨病变具有高度敏感性。目的：开发和验证一种半定量的新诊断MM的WB MRI评分系统，并将其与国际分期系统（ISS）和修订的ISS（R-ISS）进行比较。材料和方法：本研究包括三组患有新诊断MM的患者（组1，2015年7月至2021年9月；组2，2020年2月至2021年9月；组3，2021年10月至2022年2月）。在组1中使用脊柱MRI扫描开发了一种新的MM评分系统，在组2中使用WB MRI扫描整合了三个特征：（a）骨髓背景模式，（b）局限性骨病变数量，（c）伴发性或骨髓旁病变的存在。总分范围从零到九。使用Fleiss或Cohen加权κ评估了每个特征的观察者间一致性。使用双向方差分析比较了组3中的WB MRI总分与ISS和R-ISS分期之间的关系。结果：组1、组2和组3分别包括103例患者（平均年龄62.1岁±9.1 [SD]；男性60例）、36例患者（平均年龄65.4岁±11.3 [SD]；女性19例）和39位参与者（平均年龄62.0岁±11.7 [SD]；男性20例）。评分系统的三个特征的观察者间一致性较高（κ范围为0.69-0.80）。WB MRI总分随ISS分期的增加而增加（ISS 1、2和3的平均分别为2.2、4.2和5.8；P = .009），随R-ISS分期的增加而增加（R-ISS 1、2和3的平均分别为2.1、3.8和5.9；P = .005）。结论：为MM开发的WB MRI评分系统显示出较高的观察者一致性，并与ISS和R-ISS分期良好对应。© RSNA，2023。该文章有补充资料可供参考。另请参阅本期Dragan和Messiou的编辑评论。

Background In patients with multiple myeloma (MM), the serum marker β2-microglobulin does not always accurately reflect tumor load. In contrast, whole-body (WB) MRI has shown high sensitivity for detecting bone lesions. Purpose To develop and validate a semiquantitative WB MRI scoring system for newly diagnosed MM and to compare it with the International Staging System (ISS) and Revised ISS (R-ISS). Materials and Methods This study included two retrospective groups (group 1, July 2015 to September 2021; group 2, February 2020 to September 2021) and one prospective group (group 3, October 2021 to February 2022) of patients with newly diagnosed MM. A new scoring system for MM was developed using spine MRI scans in group 1 and WB MRI scans in group 2 that integrated three features: (a) background marrow pattern, (b) number of focal bone lesions, and (c) presence of extramedullary or paramedullary lesions. The summed total score ranged from zero to nine. The interobserver agreement for each feature was assessed using Fleiss or Cohen weighted κ. WB MRI total scores in group 3 were compared across ISS and R-ISS stages using two-way analysis of variance. Results Groups 1, 2, and 3 included 103 patients (mean age, 62.1 years ± 9.1 [SD]; 60 men), 36 patients (mean age 65.4 years ± 11.3 [SD]; 19 women), and 39 participants (mean age, 62.0 years ± 11.7 [SD]; 20 men), respectively. The interobserver agreements for the three features composing the scoring system were substantial (κ range, 0.69-0.80). WB MRI total score increased with increasing ISS stage (mean score for ISS 1, 2, and 3 was 2.2, 4.2, and 5.8, respectively; P = .009) and R-ISS stage (mean score for R-ISS 1, 2, and 3 was 2.1, 3.8, and 5.9, respectively; P = .005). Conclusion The developed WB MRI scoring system for MM demonstrated substantial observer agreement and corresponded well with ISS and R-ISS stages. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Dragan and Messiou in this issue.