重症肌无力患者正常和淋巴滤泡增生胸腺CT对比研究

重症肌无力患者正常和淋巴滤泡增生胸腺CT对比研究

Comparative study of computed tomography of normal and lymphoid follicular hyperplasia thymus in myasthenia gravis patients

图1.胸腺CT值与年龄的相关性（r=−0.779；P<0.05）。

Figure 1. Correlation of the thymus CT attenuation with the age of the patients (r=−0.779; P<0.05). CT, computed tomography.

图2. 男性重症肌无力患者（年龄18岁）淋巴滤泡增生的非增强CT图像。胸腺呈三角形，很容易与邻近组织区分开。

Figure 2. Unenhanced computed tomography image of a male myasthenia gravis patient (age, 18 years) with lymphoid follicular hyperplasia. The thymus is triangular in shape and may be easily distinguished from adjacent tissue.

图3. 女性重症肌无力患者（年龄26岁）伴淋巴滤泡增生。胸腺双侧叶之间可见间隔。

Figure 3. Female myasthenia gravis patient (age, 26 years) with lymphoid follicular hyperplasia. The septum between the two lobes is visible.

图4. 女性重症肌无力患者（年龄36岁），淋巴滤泡增生。胸腺呈四边形，胸腺区的CT值与脂肪组织和肌肉不同。

Figure 4. Female myasthenia gravis patient (age, 36 years) with lymphoid follicular hyperplasia. The thymus is quadrilateral and the computed tomography attenuation in the thymus region is different from that of the adipose tissue and musculature.

图5. 女性重症肌无力患者（年龄45岁）伴淋巴滤泡增生。胸腺呈四边形，脂肪浸润区可见结节。

Figure 5. Female myasthenia gravis patient (age, 45 years) with lymphoid follicular hyperplasia. The thymus is quadrilateral in shape and nodules are visible in the fat-infiltrated thymus region.

图6. 一例女性重症肌无力患者（年龄50岁）淋巴滤泡增生的增强CT图像。胸腺呈三角形，很容易与邻近组织，特别是脂肪组织区分开来。

Figure 6. Contrast-enhanced computed tomography image of a female myasthenia gravis patient (age, 50 years) with lymphoid follicular hyperplasia. The thymus is triangular in shape and can be easily distinguished from adjacent tissue, particularly adipose tissue.

图7. 女性重症肌无力患者（年龄，54岁）伴LFH。胸腺呈三角形，可见结节，病理证实为LFH。淋巴滤泡增生。

Figure 7. Female myasthenia gravis patient (age, 54 years) with LFH. The thymus is triangular in shape and a nodule is apparent, which was later pathologically confirmed as LFH. LFH, lymphoid follicular hyperplasia.

 

图8.女性重症肌无力患者（年龄58岁）淋巴滤泡增生的CT增强扫描。胸腺呈三角形，胸腺区可见结节。

Figure 8. Contrast-enhanced computed tomography image of a female myasthenia gravis patient (age, 58 years) with lymphoid follicular hyperplasia. The thymus is triangular in shape and nodules are apparent in the thymus region.

图9. 一例男性重症肌无力和淋巴滤泡增生患者（年龄67岁）的CT平扫图像。胸腺呈四边形，某些结节可与脂肪组织区分开。

Figure 9. Unenhanced computed tomography image of a male patient (age, 67 years) with myasthenia gravis and lymphoid follicular hyperplasia. The thymus is quadrilateral in shape and certain nodules may be distinguished from adipose tissue.

图11. 男性重症肌无力患者（年龄59岁）正常胸腺（退化）的CT平扫图像。胸腺呈四边形，CT值均匀。

Figure 11. Unenhanced CT image of a male myasthenia gravis patient (age, 59 years) with normal (involuted) thymus. The thymus is quadrilateral in shape and homogeneous regarding CT attenuation. CT, computed tomography.

图12.一例胸腺正常的男性重症肌无力患者（年龄72岁）的CT平扫图像。胸腺呈四边形，CT值均匀。

Figure 12. Unenhanced CT image of a male myasthenia gravis patient (age, 72 years) with normal thymus. The thymus is quadrilateral in shape and homogeneous regarding CT attenuation. CT, computed tomography.

The aim of the present study was to evaluate the thymuses of non-thymomatous myasthenia gravis (MG) patients by computed tomography (CT) for differentiating lymphoid follicular hyperplasia (LFH) thymus from normal/involuted thymus in order to assist surgeons in determining whether a non-thymomatous MG patient requires an operation. In the present retrospective review over 10 years, 80 patients who received CT scan and thymectomy at the Affiliated General Hospital of Tianjin Medial University (Tianjin, China) were included. According to the pathological records, 54 of the cases initially detected on CT were confirmed as LFH thymus. Thymic measurements, including anteroposterior and transverse dimensions, width (the longest axis of the lobe on a transverse scan) and thickness (the largest dimension perpendicular to the long axis of the lobe) and CT attenuation of the thymus region, adipose tissue and chest wall musculature in each CT slice were included to assess differences between the LFH group and the normal/involuted thymus group. Although a negative association between patient age and the CT attenuation of the thymus region was identified (r=-0.779, P<0.05, Pearson's correlation test), the LFH thymus group featured nodular changes on CT, while no such changes were observed in the normal/involuted thymus group. The mean age of disease onset in the LFH thymus group was significantly lower than that in the normal thymus group (40.2±17.3 vs. 59.2±9.3 years). Furthermore, significant differences in CT attenuation were identified between the LFH group and the normal/involuted thymus group [-41.21±54.42 vs. -108.23±8.72 Hounsfield units (HU) on unenhanced CT; -25.57±58.65 vs.-117.40±6.22 HU on contrast-enhanced CT]. In the LFH group, the difference in mean CT attenuation between the thymus region and adipose tissue was significant, while no significant difference was observed in the normal/involuted thymus group. In conclusion, CT may be used to distinguish LFH thymus from normal/involuted thymus in MG patients.