桥本脑病的MRI特点

The MRI characteristics of Hashimoto encephalopathy

目的探讨桥本脑病（HE）的MRI特点及其机制，以提高诊断及鉴别诊断能力。方法回顾性分析5例临床诊断为HE患者的临床和MRI资料。5例患者均行头颅常规MR扫描，并对其中常规MRI表现异常的3例患者行DWI、MRA和增强扫描。观察病变的分布和信号特点，测量病变处和对侧无病变区组织的ADC值。并通过分析2例有连续临床和MRI资料的患者，推测其机制。结果5例患者中有3例发现脑内异常改变，3例均表现为深部白质内斑点样异常信号，T1WI、DWI呈等信号，T2WI、液体衰减反转恢复（FLAIR）序列呈高信号，同时伴脑内其他部位多发斑片状病变，灰、白质均受累，主要累及基底节核团、海马和扣带回，发病初期T1WI呈等、低信号，T2WI、FLAIR、DWI呈高信号，病变区ADC值[（0．449±0．092）×10^-3mm^2／s]较对侧无病灶区[（0．838±0．062）×10^-3mm^2／s]均明显降低。所有患者均无MRA异常改变和强化表现。对2例经糖皮质激素治疗症状缓解的患者连续追踪，1例MRI表现为病灶明显缩小，T1WI呈高信号，T2WI、FLAIR呈等、高信号，DWI呈低信号，ADC值明显升高；另1例病灶完全消失。结论桥本脑病的MRI表现具有一定特点，可以作为HE诊断、鉴别诊断和疗效判断的手段之一，并可能成为活体研究HE病理机制的有效方法。

Objective To study the MRI findings of HE and the pathological mechanism and to improve the diagnosis and differential diagnosis of HE. Methods Five patients of HE diagnosed by clinical and laboratory examination were examined with conventional MRI scan. Additional DWI, MRA and enhancement MRI scan were performed on 3 patients in which abnormal findings was detected on the conventional MRI. The distribution of lesions and signal characteristics were analyzed. The ADC values of the lesions and of the contralateral non-lesion area were measured. Moreover, the possible pathological mechanisms of HE were discussed on the basis of changes of clinical and imaging manifestations in the two cases with serial clinical and MRI data. Results Of 5 patients, brain abnormalities were found in 3 cases, which showed scattered spotted supratentorial white matter lesions of isointensity on T1WI and DWI, and high signal intensity on T2WI and fluid-attenuated inversion recovery （FLAIR）. Meanwhile, multiple plaque-like lesions involving both white matter and gray matter were found, mainly located at the basal ganglia nuclei, hippocampus and cingulate cortex. The lesions demonstrated iso-or hypo-intensity on T1WI, and iso-or hyper-intensity on T2 WI, FLAIR and DWI at the initial stage. No enhancement was found in these lesions and MRA disclosed no remarkable findings. The ADC value of the lesions [ （0. 449 ± 0. 092） × 10^-3 mm^2/s] was decreased significantly compared with the contralateral noninvolved area [ （0. 838 ± 0. 062） × 10^-3 mm^2/s] at the early onset. In 2 cases with glucocorticoid therapy, together with symptom relief, MRI follow-up scan demonstrated the reduction of lesion volume, the signal change to hyperintensity on T1WI and hypo-intensity on DWI. The ADC of the lesions increased significantly. Conclusion The MRI could be one of the effective tools for diagnosis, differential diagnosis, and judging the prognosis and therapeutic results of HE. Meanwhile, it may be a non-invasive method to study the pathological mechanism of HE.