Abstract:

Objective To summarize the characteristics of fatty infiltration and edema of muscle MRI in Duchenne muscular dystrophy (DMD) patients. Methods A total of 70 DMD patients underwent Clinical Functional Scale and muscle MRI of the pelvic (gluteus maximus, gluteus medius, gluteus minimus, iliopsoas, piriformis, obturator internus, obturator externus, tensor fasciae latae, pectineus, erector spinae, psoas major muscle, iliacus), thigh (adductor magnus, gracilis, adductor longus, sartorius, rectus femoris, vastus intermedius, vastus medialis, vastus lateralis, biceps femoris, semitendinosus, semimembranosus) and leg (gastrocnemius, soleus, peroneus longus, tibialis posterior, tibialis anterior, flexor hallucis longus, extensor hallucis longus, extensor digitorum longus). T₁WI fatty infiltration grade and fat suppression T₂WI edema grade were performed to analyze the imaging features of fatty infiltration and edema. Results In 31 muscles, 30 muscles (96.77% ) presented fatty infiltration and 23 (74.19% ) presented edema. The occurrence rate of fatty infiltration was higher than that of edema. A total of 21 muscles including gluteus maximus, were found T₁WI fatty infiltration grades greater than 2, and 10 muscles including tibialis posterior, were less than 1. Five muscles including soleus were found fat suppression T₂WI edema grade 3. Spearman rank correlation analysis showed positive correlations between T₁WI fatty infiltration grade and Clinical Functional Scale in 7 pelvic muscles [gluteus maximus (r_s = 0.518, P = 0.016), gluteus medius (r_s = 0.528, P = 0.014), gluteus minimus (r_s = 0.528, P = 0.014), iliopsoas (r_s = 0.695, P = 0.000), piriformis (r_s = 0.451, P = 0.040), pectineus (r_s = 0.567, P = 0.009), erector spinae (r_s = 0.499, P = 0.025)], 7 thigh muscles [adductor magnus (r_s = 0.607, P = 0.005), adductor longus (r_s = 0.547, P = 0.013), rectus femoris (r_s = 0.614, P = 0.004), vastus intermedius (r_s = 0.566, P = 0.009), vastus medialis (r_s = 0.522, P = 0.018), vastus lateralis (r_s = 0.503, P = 0.024), biceps femoris (r_s = 0.508, P = 0.022)] and 3 leg muscles [gastrocnemius (r_s = 0.715, P = 0.001), peroneus longus (r_s = 0.571, P = 0.017), tibialis posterior (r_s = 0.514, P = 0.035)]. There was no correlation between T₁WI fatty infiltration grade and Clinical Functional Scale in other muscles (P > 0.05, for all). There was no correlation between fat suppression T₂WI edema grade and Clinical Functional Scale in all muscles (P > 0.05, for all). Conclusions Fatty infiltration grade can be well used to assess the severity of DMD. The role of muscle edema on assessing clinical severity should be analyzed according to individual muscle characteristics.

Key words: Muscular dystrophy, Duchenne, Magnetic resonance imaging, Adipose tissue, Edema

摘要：

目的 总结Duchenne 型肌营养不良症肌肉MRI 脂肪浸润和水肿特点。方法 共70 例诊断明确的Duchenne 型肌营养不良症患者均行临床严重程度分级，以及臀部（包括臀大肌、臀中肌、臀小肌、髂腰肌、梨状肌、闭孔内肌、闭孔外肌、阔筋膜张肌、耻骨肌、竖脊肌、腰大肌、髂肌）、大腿（包括大收肌、股薄肌、长收肌、缝匠肌、股直肌、股中间肌、股内侧肌、股外侧肌、股二头肌、半腱肌、半膜肌）和小腿（包括腓肠肌、比目鱼肌、腓骨长肌、胫骨后肌、胫骨前肌、长屈肌、长伸肌、趾长伸肌）共计31 块肌肉MRI 检查，并采用T₁WI 脂肪浸润分级和T₂WI 抑脂成像水肿分级评价肌肉脂肪浸润和水肿程度。结果 31 块肌肉中30 块（96.77%）出现脂肪浸润，23 块（74.19%）出现水肿，肌肉脂肪浸润比例高于水肿比例。臀大肌等21 块肌肉T₁WI脂肪浸润分级≥ 2 级，胫骨后肌等10 块肌肉T₁WI脂肪浸润分级≤ 1 级；比目鱼肌等5 块肌肉T₂WI 抑脂成像水肿分级3 级。Spearman 秩相关分析显示，盆带肌群中臀大肌（r_s = 0.518，P = 0.016）、臀中肌（r_s = 0.528，P = 0.014）、臀小肌（r_s = 0.528，P = 0.014）、髂腰肌（r_s = 0.695，P = 0.000）、梨状肌（r_s = 0.451，P = 0.040）、耻骨肌（r_s = 0.567，P = 0.009）、竖脊肌（r_s = 0.499，P = 0.025），大腿肌群中大收肌（r_s = 0.607，P = 0.005）、长收肌（r_s = 0.547，P = 0.013）、股直肌（r_s = 0.614，P = 0.004）、股中间肌（r_s = 0.566，P = 0.009）、股内侧肌（r_s = 0.522，P = 0.018）、股外侧肌（r_s = 0.503，P = 0.024）、股二头肌（r_s = 0.508，P =0.022），小腿肌群中腓肠肌（r_s = 0.715，P = 0.001）、腓骨长肌（r_s = 0.571，P = 0.017）、胫骨后肌（r_s = 0.514，P = 0.035）T₁WI 脂肪浸润分级与临床严重程度分级呈正相关，其余肌肉T₁WI 脂肪浸润分级与临床严重程度分级无关联性（均P > 0.05）；31 块肌肉T₂WI 抑脂成像水肿分级与临床严重程度分级均无关联性（P > 0.05）。结论 Duchenne 型肌营养不良症肌肉脂肪浸润与临床严重程度一致性较好，是反映临床严重程度的理想指标，而水肿对临床严重程度的影响需根据肌肉特点个体化分析。

关键词: 肌营养不良, 杜氏, 磁共振成像, 脂肪组织, 水肿