遗传性出血性毛细血管扩张症

来自：双语学影像；病例选自《Mayo Clinic Body MRI Case Review》

History

55-year-old woman with epistaxis

55岁女性，鼻出血

Fig 2.15.1

Fig 2.15.2 

Fig 2.15.3 

Fig 2.15.4

Imaging Findings

Axial fat-suppressed T2-weighted FSE image (Figure 2.15.1)

demonstrates subtle, ill-defined areas of intermediate increased signal throughout the liver that are more easily visualized on DWI (b=600 s/mm2) (Figure 2.15.2). Axial arterial, portal venous, equilibrium phase, and delayed hepatobiliaryphase 3D SPGR images (Figure 2.15.3) demonstrate heterogeneous nodular hyperenhancement in the arterial phase with prominent early filling hepatic veins. There is persistent hyperenhancement of a few nodular lesions on the hepatobiliary phase image. Subvolume reformatted axial (Figure2.15.4A) and coronal (Figure 2.15.4B) arterial phase MIP images emphasize the extensive nodular hyperenhancement throughout the liver, as well as the enlarged hepatic artery and hepatic veins, which are also depicted in the VR image (Figure 2.15.4C). A hepatobiliary contrast agent (Multihance) was used; note the contrast in the hepatic duct on the hepatobiliary phase image.

横断位T2WI-FS序列 (Figure 2.15.1)示肝内多发稍高密度区，边界不清，于DWI(b=600 s/mm2)序列(Figure 2.15.2)显示较清。

肝胆特异性对比剂Multihance增强扫描动脉期、门脉期、平衡期及肝胆相位图(Figure 2.15.3)示动脉期病灶不均匀强化，并可见肝内静脉早期充盈。肝胆相位图示肝内部分结节可见持续性强化。

横断位和冠状位MIP(Figure2.15.4A、Figure 2.15.4B)更加清晰显示肝内多发强化的结节，同时可以看到扩张的肝内动脉和静脉，VR图像(Figure 2.15.4C)可以更加直观地显示。

本病例采用的肝胆特异对比剂Multihance，可以看到肝胆相位期强化的肝内胆管。

Diagnosis

Hereditary hemorrhagic telangiectasia

遗传性出血性毛细血管扩张症

Comment

HHT is an autosomal dominant hereditary disorder characterized by multiple small telangiectasias of skin, mucous membranes, the gastrointestinal tract, and other organs. Recurrent epistaxis is the dominant clinical symptom in most patients; however, more serious consequences, including cyanosis, hemoptysis, and paradoxical emboli, usually result from pulmonary arteriovenous malformations. Mutations in at least 2 different genes have been associated with HHT and are thought to be involved in regulation of angiogenesis.

HHT是一种常染色体显性遗传病，典型表现为皮肤、粘膜、胃肠道及其他组织的多发毛细血管扩张。大多数患者最常见的症状是反复鼻出血，但肺动静脉畸形引起的紫绀、咯血、反常的肺栓塞等表现则更为严重。HHT与至少两种基因突变有关，引起血管生长调节异常。

Hepatic involvement in HHT has stimulated much interest in recent years. Early investigations concluded that hepatic involvement was relatively infrequent; however, more recentstudies using multidetector CT and MRI have demonstrated hepatic manifestations in as many as 85% of patients. Although most patients with hepatic involvement are asymptomatic,3 clinical syndromes have been described: high-output cardiac failure resulting from intrahepatic shunts; portal hypertension developing in the clinical setting of arterial portal shunting;and biliary necrosis, also thought to occur as a result of arterial-venous shunting and consequent reduced blood supply to the biliary tree.

肝脏的HHT最近几年较多受关注，早期的研究认为肝脏HHT很少见，但近期使用多排螺旋CT和MR的研究指出高达85%的患者可见肝脏HHT。大部分患者无明显症状，文献认为临床症状包括三种：肝内分流引起的高输出心力衰竭、肝脏动脉-门静脉分流引起的门静脉高压、

动静脉分流引起胆管树缺血所致的胆道坏死。

Several characteristic findings have been described in HHT patients with hepatic involvement.Enlargement of the hepatic artery (to >6 mm in diameter) has been reported in theUSliterature as a sensitive and specific finding for HHT and can easily be seen with MRI.Focal arterial aneurysms may also occur, although these are relatively uncommon.Vascular shunts are seen in a majority of patients; hepatic artery–hepatic vein shunting occurs most frequently, in 50% to 65% of patients, and when severe, it may be responsible for high-output cardiac failure. This finding is seen in this patient as rapid filling of mildly dilated hepatic veins on the arterial phase postgadolinium acquisition. Arterioportal and portohepatic venous shunts occur somewhat less frequently but are nevertheless fairly common findings.

文献报道中，肝脏HHT有一定的典型的影像学表现。超声的文献报道肝内动脉扩张（直径大于6mm）对诊断HHT有较高的敏感性和特异性，而这一征象在MR也很容易观察。局限性动脉瘤较少见，但也有报道。

大多数患者可见血管分流，约50%-65%的患者可见肝动脉-静脉分流，严重者可引起高输出心力衰竭。这一表现见于增强扫描动脉期，扩张的肝静脉早期充盈。肝动脉-门静脉分流和门静脉-肝静脉分流相对少见，但仍然很普遍发生。

Telangiectasias are a near-universal finding. They appear as small, hyperenhancing nodules of less than 1 cm on arterial phase images and usually become isointense to hepatic parenchyma on portal venous and equilibrium phase images. These show mild-to-moderate increased signal intensity on T2-weighted images. Less discrete geographic perfusion abnormalities are also commonly seen on arterial and portal venous phase images.

毛细血管扩张症是一种近乎普遍的表现，增强扫描动脉期表现为略强化的小结节，直径小于1cm，门脉期及平衡期与周围肝实质呈等信号。动脉期及门静脉期小片状灌注异常也很常见。

Both nodular regenerative hyperplasia and FNH have been described in HHT patients, and the pathologic and imaging distinctions between the 2 entities are not entirely clear. The classic findings of FNH are isointense to mildly hyperintense signal intensity on T2-weightedimages, uniform arterial phase hyperenhancement, and isointensity to adjacentliver onportal venous and equilibrium phase images, with mild-to-moderate hyperenhancement on hepatobiliary phase images if a hepatobiliary contrast agent is used. These findings can also be seen with regenerative nodules, although a prominent central scar should suggest the diagnosis of FNH. Several authors have described an increased incidence (1%-3%) of FNH in HHT patients; however, 1 study with limited pathologic correlation reported an incidence of 47%.Since both entities are thought to be related to regeneration of normal hepatic tissue in response to increased perfusion and both are benign, a clear distinction between the 2 entities at MRI is probably not very important. It is worth remembering, however, that extensive nodular regeneration can occur without parenchymal fibrosis, and therefore a diagnosis of cirrhosis should be made with caution in these patients.

肝脏HHT需要和结节性再生性增生、FNH相鉴别，但无论从影像或病理都有一定难度。FNH典型表现为T2WI等或略高信号，动脉期均匀强化，门脉期及平衡期呈等信号，肝胆特异对比剂增强肝胆相位期呈略高信号。RN也可有类似表现，但如果出现中央瘢痕，则首先考虑FNH。部分作者认为HHT患者的FNH发病率增高，但一个与病理相关性研究的文献报道发病率为47%。结节性再生性增生、FNH的灌注增加认为与肝组织的退变有关，但都是良性病变，所以鉴别诊断相对并不十分重要。需要注意的是，广泛的结节性再生可能发生于没有肝纤维化背景的基础上，所以这些患者诊断肝硬化需要格外谨慎。

Fig 2.15.5

Two years later, the patient had a follow-up MRI with the hepatobiliary contrast agent Eovist. Axial postgadolinium early (Figure 2.15.5A) and late (Figure 2.15.5B) arterial, portal venous (Figure 2.15.5C), and hepatobiliary phase(Figure2.15.5D)images demonstrate extensive geographic perfusion abnormalities, as well as more numerous hyperenhancing noduleson the hepatobiliary phase image, consistent with regenerative nodules or FNH.

2年后，该患者行Eovist增强MR复查。动脉早期(Figure 2.15.5A)和动脉晚期(Figure 2.15.5B)、门脉期(Figure 2.15.5C)及肝胆相位期(Figure 2.15.5D)示广泛地图样灌注异常，肝胆相位期见多发强化结节，考虑RN或FNH.