Abstract：
BACKGROUND: Pathological alterations of lateral pterygoid muscle (LPM) are implicated in temporomandibular joint anterior disk displacement (ADD). However, quantification of the fatty infiltration of LPM and its correlation with ADD have rarely been reported. The aim of this study was to evaluate the fatty infiltration, morphological features and texture features of LPM in patients with ADD using T1-weighted Dixon sequence.
METHODS: This retrospective study included patients who underwent temporomandibular joint MRI with T1-weighted Dixon sequence between December 2018 and August 2020. The temporomandibular joints of the included patients were divided into three groups according to the position of disk: Normal position disk (NP) group, Anterior disk displacement with reduction (ADDWR) group and Anterior disk displacement without reduction (ADDWOR) group. Fat fraction, morphological features (Length; Width; Thickness), and texture features (Angular second moment; Contrast; Correlation; Inverse different moment; Entropy) extracted from in-phase image of LPM were evaluated. One-way ANOVA, Welch\'s ANOVA, Kruskal-Wallis test, Spearman and Pearson correlation analysis were performed. Intra-class correlation coefficient was used to evaluate the reproducibility.
RESULTS: A total of 53 patients with 106 temporomandibular joints were evaluated. Anterior disk displacement without reduction group showed higher fat fraction than normal position disk group (P = 0.024). Length of LPM was negatively correlated with fat fraction (r = -0.22, P = 0.026). Angular second moment (ρ = -0.32, P < 0.001), correlation (ρ = -0.28, P = 0.003) and inverse different moment (ρ = -0.27, P = 0.005) were negatively correlated with fat fraction, while positive correlation was found between entropy and fat fraction (ρ = 0.31, P = 0.001). The intra-class correlation coefficients for all values were ranged from 0.80 to 0.97.
CONCLUSIONS: Patients with ADDWOR present more fatty infiltration in the LPM compared to NP or ADDWR patients. Fatty infiltration of LPM was associated with more atrophic and higher intramuscular heterogeneity in patients with ADD. Fat fraction of LPM quantitatively and noninvasively evaluated by Dixon sequence may has utility as an imaging-based marker of the structural severity of ADD disease process, which could be clinical helpful for the early diagnose of ADD and predication of disease progression.
METHODS: This retrospective study included patients who underwent temporomandibular joint MRI with T1-weighted Dixon sequence between December 2018 and August 2020. The temporomandibular joints of the included patients were divided into three groups according to the position of disk: Normal position disk (NP) group, Anterior disk displacement with reduction (ADDWR) group and Anterior disk displacement without reduction (ADDWOR) group. Fat fraction, morphological features (Length; Width; Thickness), and texture features (Angular second moment; Contrast; Correlation; Inverse different moment; Entropy) extracted from in-phase image of LPM were evaluated. One-way ANOVA, Welch\'s ANOVA, Kruskal-Wallis test, Spearman and Pearson correlation analysis were performed. Intra-class correlation coefficient was used to evaluate the reproducibility.
RESULTS: A total of 53 patients with 106 temporomandibular joints were evaluated. Anterior disk displacement without reduction group showed higher fat fraction than normal position disk group (P = 0.024). Length of LPM was negatively correlated with fat fraction (r = -0.22, P = 0.026). Angular second moment (ρ = -0.32, P < 0.001), correlation (ρ = -0.28, P = 0.003) and inverse different moment (ρ = -0.27, P = 0.005) were negatively correlated with fat fraction, while positive correlation was found between entropy and fat fraction (ρ = 0.31, P = 0.001). The intra-class correlation coefficients for all values were ranged from 0.80 to 0.97.
CONCLUSIONS: Patients with ADDWOR present more fatty infiltration in the LPM compared to NP or ADDWR patients. Fatty infiltration of LPM was associated with more atrophic and higher intramuscular heterogeneity in patients with ADD. Fat fraction of LPM quantitatively and noninvasively evaluated by Dixon sequence may has utility as an imaging-based marker of the structural severity of ADD disease process, which could be clinical helpful for the early diagnose of ADD and predication of disease progression.
摘要：
背景：翼外肌（LPM）的病理变化与颞下颌关节前盘移位（ADD）有关。然而,LPM脂肪浸润的定量及其与ADD的相关性很少有报道。这项研究的目的是评估脂肪浸润，使用T1加权Dixon序列对ADD患者LPM的形态学特征和纹理特征进行分析。
方法：这项回顾性研究包括2018年12月至2020年8月接受颞下颌关节MRIT1加权Dixon序列的患者。将纳入患者的颞下颌关节按椎间盘位置分为三组:正常位置椎间盘(NP)组,前盘位移带复位(ADDWR)组和前盘位移不复位(ADDWOR)组。脂肪分数，形态特征(长度;宽度;厚度),从LPM的同相图像中提取的纹理特征（角二阶矩；对比度；相关性；逆不同矩；熵）进行了评估。单向方差分析,韦尔奇的方差分析，Kruskal-Wallis测试,进行Spearman和Pearson相关分析。使用类内相关系数来评估再现性。
结果：共评估了53例患者的106个颞下颌关节。前盘位移不减少组脂肪含量高于正常位置盘组(P=0.024)。LPM长度与脂肪含量呈负相关(r=-0.22,P=0.026)。角二阶矩(ρ=-0.32,P<0.001),相关(ρ=-0.28,P=0.003)和反差矩(ρ=-0.27,P=0.005)与脂肪分数呈负相关,熵与脂肪分数呈正相关(ρ=0.31,P=0.001)。所有值的类内相关系数范围为0.80至0.97。
结论：与NP或ADDWR患者相比，ADDWOR患者在LPM中表现出更多的脂肪浸润。在ADD患者中，LPM的脂肪浸润与更多的萎缩和更高的肌内异质性相关。通过Dixon序列定量和非侵入性评估的LPM的脂肪分数可能具有作为ADD疾病过程的结构严重程度的基于成像的标志物的实用性。临床上对ADD的早期诊断和疾病进展的预测有帮助。
方法：这项回顾性研究包括2018年12月至2020年8月接受颞下颌关节MRIT1加权Dixon序列的患者。将纳入患者的颞下颌关节按椎间盘位置分为三组:正常位置椎间盘(NP)组,前盘位移带复位(ADDWR)组和前盘位移不复位(ADDWOR)组。脂肪分数，形态特征(长度;宽度;厚度),从LPM的同相图像中提取的纹理特征（角二阶矩；对比度；相关性；逆不同矩；熵）进行了评估。单向方差分析,韦尔奇的方差分析，Kruskal-Wallis测试,进行Spearman和Pearson相关分析。使用类内相关系数来评估再现性。
结果：共评估了53例患者的106个颞下颌关节。前盘位移不减少组脂肪含量高于正常位置盘组(P=0.024)。LPM长度与脂肪含量呈负相关(r=-0.22,P=0.026)。角二阶矩(ρ=-0.32,P<0.001),相关(ρ=-0.28,P=0.003)和反差矩(ρ=-0.27,P=0.005)与脂肪分数呈负相关,熵与脂肪分数呈正相关(ρ=0.31,P=0.001)。所有值的类内相关系数范围为0.80至0.97。
结论：与NP或ADDWR患者相比，ADDWOR患者在LPM中表现出更多的脂肪浸润。在ADD患者中，LPM的脂肪浸润与更多的萎缩和更高的肌内异质性相关。通过Dixon序列定量和非侵入性评估的LPM的脂肪分数可能具有作为ADD疾病过程的结构严重程度的基于成像的标志物的实用性。临床上对ADD的早期诊断和疾病进展的预测有帮助。
