Department of Diagnostic Imaging, Akershus University Hospital, Lørenskog, Norway.
Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
Eur Radiol Exp. 2022 Jul 20;6(1):38. doi: 10.1186/s41747-022-00284-y.
Fatty infiltration of the paraspinal muscles may play a role in pain and disability in lumbar spinal stenosis. We assessed the reliability and association with clinical symptoms of a method for assessing fatty infiltration, a simplified muscle fat index (MFI).
Preoperative axial T2-weighted magnetic resonance imaging (MRI) scans of 243 patients aged 66.6 ± 8.5 years (mean ± standard deviation), 119 females (49%), with symptomatic lumbar spinal stenosis were assessed. Fatty infiltration was assessed using both the MFI and the Goutallier classification system (GCS). The MFI was calculated as the signal intensity of the psoas muscle divided by that of the multifidus and erector spinae. Observer reliability was assessed in 102 consecutive patients for three independent investigators by intraclass correlation coefficient (ICC) and 95% limits of agreement (LoA) for continuous variables and Gwet's agreement coefficient (AC1) for categorical variables. Associations with patient-reported pain and disability were assessed using univariate and multivariate regression analyses.
Interobserver reliability was good for the MFI (ICC 0.79) and fair for the GCS (AC1 0.33). Intraobserver reliability was good or excellent for the MFI (ICC range 0.86-0.91) and moderate to almost perfect for the GCS (AC1 range 0.55-0.92). Mean interobserver differences of MFI measurements ranged from -0.09 to -0.04 (LoA -0.32 to 0.18). Adjusted for potential confounders, none of the disability or pain parameters was significantly associated with MFI or GCS.
The proposed MFI demonstrated high observer reliability but was not associated with preoperative pain or disability.
腰部脊柱狭窄症患者的脊柱旁肌肉脂肪浸润可能与疼痛和残疾有关。我们评估了一种评估脂肪浸润的方法，即简化的肌肉脂肪指数（MFI）的可靠性及其与临床症状的相关性。
对 243 名年龄为 66.6±8.5 岁（平均值±标准差）的有症状的腰椎脊柱狭窄症患者的术前轴向 T2 加权磁共振成像（MRI）扫描进行评估。使用 MFI 和 Goutallier 分级系统（GCS）评估脂肪浸润。MFI 的计算方法是将竖脊肌和多裂肌的信号强度除以腰大肌的信号强度。通过组内相关系数（ICC）和连续变量的 95%置信区间（LoA）以及分类变量的 Gwet 一致性系数（AC1），评估了 102 名连续患者的三位独立观察者的观察者可靠性。使用单变量和多变量回归分析评估与患者报告的疼痛和残疾的相关性。
MFI 的观察者间可靠性良好（ICC 0.79），GCS 的观察者间可靠性一般（AC1 0.33）。MFI 的观察者内可靠性良好或优秀（ICC 范围 0.86-0.91），GCS 的观察者内可靠性中等至几乎完美（AC1 范围 0.55-0.92）。MFI 测量值的平均观察者间差异范围为-0.09 至-0.04（LoA -0.32 至 0.18）。在调整了潜在混杂因素后，MFI 或 GCS 与任何残疾或疼痛参数均无显著相关性。
提出的 MFI 具有较高的观察者可靠性，但与术前疼痛或残疾无关。
