Uterine leiomyoma：MRI findings and histopathology<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

第二军医大学长海医院放射科，上海 200433

Ning SONG, Jian-ping LU, Xin-hong HE, Fei WANG, Qi LIU, Li WANG     (Department of Radiology, Changhai Hospital, The Second Military Medical University, Shanghai 200433)

Abstract

Objective：To discuss the MR imaging findings of uterine leiomyoma and contrast with histopathology, and evaluate its diagnostic value.

Methods：MRI scanning was performed for 30 patients with suspected uterine leiomyomas by Ultrasound (US). Ability of detecting of uterine leiomyomas were calculated and compared with US. Comparative analysis between MRI finding and pathology results was done.

Results：There were 64 lesions in 30 cases. The difference between the number of lesions detected by two modalities had statistical significance (90.6% for MRI vs 68.8% for ultrasound,χ²=14.57, P<0.05). MRI diagnosis in all cases was consistent with the results given by surgery and pathology, except 1 being diagnosed hydatidiform mole. The diagnostic accuracy of MRI was 96.7%. The accuracy of ultrasound was 86.7%. T₂WI could manifest the structure of the uterus clearly .The sagittal plane could show the uterine position and relationship with uterine cavity. Almost all the leiomyoma showed slight hypointensity or isointensity on T₁-weigthed images. Most ordinary leiomyomas displayed hypointensity on T₂-weigthed images. Most cellular and degenerated leiomyomas manifested as hyperintensity on T₂-weigthed images. Most ordinary leiomyoma showed homogenously enhancement, but lower than the myometrium. Most cellular and degenerated leiomyomas presented homogenously enhancement and mild enhancement respectively.

Conclusion：MRI is a highly sensitive method for the evaluation of uterine leiomyoma. The signal intensity on MRI has bearing on the histopathology. Certain characteristic features on MRI were different in leiomyomas with different pathological subtype.

Key words：Uterine neoplasms; Leiomyoma; Magnetic resonance imaging; Pathology

二、结  果<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

2.1病理学表现

本组30例共64个病灶，直径0.5cm～26cm,平均4.5cm。多发病灶26例，单发4例。肌壁间肌瘤 37个（57.8％），浆膜下肌瘤22个（34.4％），粘膜下肌瘤5个（7.8％）。普通型肌瘤38个（59.4%），细胞型肌瘤7个(10.9%)，退变型肌瘤19个(29.7%)。

2.2 肌瘤MRI表现

MRI检出58个病灶，其中普通型35个(图1-3)，细胞型7个（图4-6），退变型16个（图7-8）。55个肌瘤T₁WI上表现为均匀低信号或稍低信号；2个囊性变及1个钙化病灶T₁WI表现为等信号病灶中央出现囊状或斑片状更低信号区，信号不规则，欠均匀。T₂WI上，35个普通型肌瘤病灶中28个病灶表现为低信号，5个病灶表现为等信号，2个病灶表现为稍高信号，除1个病灶信号欠均匀外，其余病灶信号规则、均匀。7个细胞型肌瘤中除1个病灶T₂WI表现为均匀高信号为，其余病灶呈均匀稍高信号。16个退变型病灶中，12个玻璃样变性病灶及1个红色样变性病灶T₂WI上呈均匀稍高信号，2例囊性变病灶呈囊性高信号，1例钙化病灶呈低信号。增强扫描，35个普通型肌瘤呈均匀强化，强化程度低于正常子宫肌层；7个细胞型肌瘤亦呈均匀强化，强化程度高于正常子宫肌层；16个退变型肌瘤中，12个玻璃样变性病灶呈不规则强化，强化程度低于正常子宫肌层，红色样变性病灶、囊性病灶及钙化病灶呈周边轻度、不规则强化。

2.4 肌瘤周围MRI表现

子宫局限性或弥漫性增大，表面不规则、结节状突起，子宫体受压、形态不规则，宫腔变形，甚至闭塞，粘膜受压移位，本组27例见此征象，与肌瘤大小、位置有关。肌瘤呈圆形或椭圆形，压迫周围组织形成假包膜而与周围组织界限鲜明，T₂WI上可见肌瘤周边一圈高信号带或肿瘤边缘断续线样高信号影，本组19例见此征象。

2.5 MRI与超声检查结果比较

本组30例病人同时行术前超声检查。B超确诊26例，1例误诊为卵巢肿瘤，1例误诊为子宫腺肌症，2例未做出诊断，其诊断准确率为86.7％。30例病人行术前MRI检查，除1例（左侧阔韧带肌瘤）因在怀孕期，且病灶位于子宫体外并体积巨大，其内可见多发囊状T₂WI高信号影，而被误诊为葡萄胎外，其余29例均作出正确诊断，准确率为96.7％。术后病理证实共64个病灶，MRI检出58个，病灶检出率为90.6％，B超检出44个，病灶检出率为68.8%,两者统计学处理（χ²检验）有显著性差异，χ²＝14.57，P<0.05。另本组30例中3例合并子宫腺肌症，2例合并附件内膜异位囊肿，5例合并卵巢黄体血肿或滤泡囊肿，1例合并双侧卵巢浆液性囊腺瘤，1例合并左侧卵巢黏液性囊腺瘤，术前MRI均明确诊断。

3  讨  论

3.1 MRI检查技术

由于盆腔MRI检查受呼吸运动影响较小，采用TSE高分辨、多次采集成像，

可获得良好的图像质量。矢状面T₂WI序列是显示子宫的最佳层面，能够较好的显示子宫的形态和内部结构，包括肌层、结合带及内膜，且易于观察宫颈前后唇及子宫峡部，同时可观察宫体、宫腔与膀胱、直肠的关系。而T₂-STIR序列则可以更好的显示病变的轮廓，结合横断面和冠状面能全面显示病灶的形态、数量、大小及部位。T₁WI、脂肪抑制T₁WI和T₂WI相结合对病灶的变性（如脂肪变性、红色变性等）的诊断更具有特异性。因此将上述扫描序列及扫描位置相结合，可以提高病变的检出率和诊断的准确率，有利于病灶的空间定位及发现并发疾病，为临床治疗提供更多的信息。

子宫肌瘤与其他疾病的鉴别诊断<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

巨大的子宫肌瘤应与子宫平滑肌肉瘤鉴别：后者瘤体内不规则坏死和出血

T₂WI显示为不规则高低混杂信号，T₁WI出血为高信号，动态增强早期即显示明显增强效应，迅速增强，迅速消退，同时伴有低信号的坏死区。子宫肌瘤显示为弱的强化，且增强后消退时间较长。

子宫肌瘤与子宫腺肌症：单发的子宫肌瘤主要与局限性腺肌病鉴别，巨大子宫平滑肌瘤需与弥漫性腺肌病鉴别。子宫腺肌症为异位的子宫内膜向肌层浸润性生长所致的一种良性病变，弥散性者表现为子宫均匀性增大，轮廓光滑，结合带弥漫性均匀或不均匀增厚；局限性者在T₁WI和T₂WI上表现为等或低信号占位，其内可见散在点状高信号影。

浆膜下肌瘤应注意与卵巢肿瘤鉴别：起源于浆膜下特别是子宫阔韧带的肌瘤，偏离中线，与子宫关系不密切时，与附件肿瘤区别较困难。

子宫颈肌瘤和粘膜下肌瘤脱出应注意与子宫粘膜息肉鉴别:典型的粘膜息肉在T₂WI上呈网织状不均匀高信号。MRI可以清楚显示肌瘤的解剖和组织结构。

总之，MRI是诊断子宫肌瘤的优越的无创性检查方法，矢状面TSE-T₂WI序列可以很好的显示子宫的各层解剖结构，而STIR－T₂WI序列更利于病变的显示；脂肪抑制T₁WI可以清楚显示子宫与周围组织的解剖关系，并能鉴别肌瘤红色变性与脂肪变性。MRI对于子宫肌瘤的特征性表现，使其在显示肌瘤大小、位置、数目及与宫腔关系上有较高的诊断价值，可作为B超及CT检查的重要补充手段。

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