1 Department of Radiology, Seoul National University College of Medicine, 101 Daehak-ro Jongno-gu, Seoul 110-744, Korea.
2 Division of Rheumatology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
AJR Am J Roentgenol. 2016 Feb;206(2):378-84. doi: 10.2214/AJR.15.14774.
The purpose of this study is to describe MRI findings of muscle involvement in patients with polyarteritis nodosa (PAN), with an emphasis on the contrast enhancement characteristics.
MRI studies of eight patients with PAN were retrospectively reviewed (four male and four female patients; mean age at presentation, 34.3 years; age range, 7-64 years). MR images were evaluated focusing on the following features: affected structures (muscle, fascia, or periosteum), lesion signal intensity and characteristics on T1-and T2-weighted images, and contrast enhancement patterns.
Seven patients had lower leg involvement, and one had thigh involvement. In the seven patients with lower leg involvement, the main lesions were within the muscles, whereas in one patient with thigh involvement, the investing fascia was mainly involved. In the seven patients with predominantly muscle involvement, T2-weighted images showed either diffuse (n = 3) or patchy (n = 4) hyperintensity of the affected muscles. On contrast-enhanced images, small fluffy enhancing lesions centered on vessels (i.e., the "cotton-wool appearance") were noted within the affected muscles in six patients. In the one patient with mainly fascial lesions, the investing fascia showed diffuse enhancement. Periosteal enhancement was found along the tibial cortex in 50% (4/8) of our patients.
PAN should be considered a differential diagnosis in cases where MR images show patchy or diffuse muscle signal changes. Muscle involvement in PAN may show fluffy enhancing lesions centered on vessels on contrast-enhanced images and may accompany fascial or periosteal enhancement.
本研究旨在描述结节性多动脉炎（PAN）患者肌肉受累的 MRI 表现，重点介绍对比增强特征。
回顾性分析 8 例 PAN 患者的 MRI 资料（男 4 例，女 4 例；发病时平均年龄 34.3 岁；年龄范围 7-64 岁）。重点评估以下特征：受累结构（肌肉、筋膜或骨膜）、T1 加权像和 T2 加权像上的病变信号强度和特征、以及对比增强模式。
7 例患者下肢受累，1 例大腿受累。在 7 例下肢受累患者中，主要病变位于肌肉内，而在 1 例大腿受累患者中，主要受累的是筋膜。在 7 例以肌肉受累为主的患者中，T2 加权像显示受累肌肉弥漫性（n=3）或斑片状（n=4）高信号。在增强图像上，6 例患者在受累肌肉内可见以血管为中心的小而絮状增强病变（即“棉絮状外观”）。在 1 例主要筋膜病变患者中，筋膜呈弥漫性增强。50%（4/8）的患者胫骨皮质可见骨膜增强。
当 MRI 图像显示斑片状或弥漫性肌肉信号改变时，应考虑 PAN 作为鉴别诊断。PAN 肌肉受累在增强图像上可能表现为以血管为中心的絮状增强病变，并可能伴有筋膜或骨膜增强。
