常规超声与其他肿瘤无异,可表现为低回声、高回声或混合回声病灶,多无声晕。彩色多普勒超声显示病灶内丰富的彩色动脉血流,血流流速高而阻力系数低,部分病灶可见中央粗大的动脉并向周围放射状分支。近年低机械指数超声造影技术的应用,能实时连续显示肝局灶性病变的血流灌注特点,显著提高肝内良恶性肿瘤诊断的敏感性和特异性,敏感性从78%提高到100%,特异性从23%提高到92%。FNH超声造影表现为病灶早期动脉相呈中央辐射状增强,整个病灶迅速均匀强化,延迟相病灶呈等增强或稍高增强,多数病灶可显示特征性的中央星状疤痕。
FNH CT平扫呈均匀等密度或低密度,较大病灶可显示中央疤痕结构呈更低密度。动态增强呈“快进慢出”表现:动脉早期显著均匀强化,部分病灶可显示供血动脉位于病灶中心或周边,粗大而扭曲,病灶中纤维瘢痕无早期增强而呈低密度;门脉期呈持续高密度强化,或呈等低密度;延迟期病灶为等密度或略低密度,与周围正常肝组织分界不清,中心瘢痕延迟强化为其特征(图1)。
Figure1 CT scan and surgical specimen of Focal Nodular Hyperplasia (FNH): a. non-enhanced CT scan showing a well-circumscribed hypodense lesion; b. arterial phase scan demonstrates fast-enhanced lesion with a un-enhanced central scar; c. portal phase scan showing a lesion with similar density to the surrounding normal liver tissue; d. the cutoff surface of the specimen showing the lesion with a similar color to the surrounding normal liver tissue, which is well-circumscribed with a clear central scar.
而MRI检查对FNH的敏感性和特异性高于CT,其敏感性达70%,特异性达98%。FNH在MRI的表现为稍长或等T1及