Study of clinical application of hepatic-biliary specific MR contrast agent (Gd-EOB-DTPA) in the diagnosis of focal hepatic lesions

目的:探讨Gd-EOB-DTPA MRI增强扫描时肝局灶性病变的表现及此新型对比剂的诊断效能,提高对肝脏局灶性病变的诊断准确性.方法:已知或怀疑为肝脏局灶性病变的34例患者共90个病灶,病灶性质依次为肝囊肿20个、肝细胞肝癌16个、胆管细胞癌1个、肝脏转移性肿瘤37个、肝血管瘤9个、退变结节1个、肝脏局灶性结节增生1个、肝细胞腺瘤1个、肝脏炎性病变3个及肝脏淋巴上皮瘤样癌1个.所有患者依次行MRI平扫(抑脂TSE T2 WI、抑脂3DVIBE、2D GRE T1 WI)、Gd-EOB-DTPA三期(动脉期、门脉期和平衡期)增强扫描(抑脂3D VIBE)及延迟20min肝实质期扫描(抑脂2D GRET1WI、抑脂TSE T2 WI、抑脂3D VIBE).测量并分析Gd-EOB-DTPA增强前后肝脏和病灶信号变化、病灶-肝脏对比噪声比绝对值(|CNR|)变化情况;并观察病灶Gd-EOB-DTPA增强扫描表现和特征.结果:Gd-EOB-DTPA增强后各期肝实质信号及病灶肝脏|CNR|均显著增加(P＜0.001).动脉期、门脉期和平衡期所有病灶符合应用常规含钆(Gd)对比剂时的强化表现和特征;延迟20min肝实质期扫描时,肝脏局灶性结节增生呈等信号—高信号.1个肝细胞肝癌呈相对高信号,其余肝囊肿、肝细胞肝癌、胆管细胞癌、肝脏转移性肿瘤、淋巴上皮瘤样癌、退变结节、肝细胞腺瘤、肝血管瘤和肝脏炎性假瘤等均呈相对低信号.结论:Gd-EOB-DTPA动态增强扫描与延迟肝实质期扫描联合应用,可以提供病变形态、血供、细胞来源及功能等更多相关信息,从而提高诊断信心及诊断准确性.     

肝胆特异性磁共振对比剂Gd-EOB-DTPA在肝脏局灶性病变诊断中的应用研究

目的:探讨Gd-EOB-DTPA MRI增强扫描时肝局灶性病变的表现及此新型对比剂的诊断效能,提高对肝脏局灶性病变的诊断准确性。方法:已知或怀疑为肝脏局灶性病变的34例患者共90个病灶,病灶性质依次为肝囊肿20个、肝细胞肝癌16个、胆管细胞癌1个、肝脏转移性肿瘤37个、肝血管瘤9个、退变结节1个、肝脏局灶性结节增生1个、肝细胞腺瘤1个、肝脏炎性病变3个及肝脏淋巴上皮瘤样癌1个。所有患者依次行MRI平扫(抑脂TSE T2WI、抑脂3DVIBE、2DGRE T1WI)、Gd-EOB-DTPA三期(动脉期、门脉期和平衡期)增强扫描(抑脂3DVIBE)及延迟20min肝实质期扫描(抑脂2DGRE T1WI、抑脂TSE T2WI、抑脂3DVIBE)。测量并分析Gd-EOB-DTPA增强前后肝脏和病灶信号变化、病灶-肝脏对比噪声比绝对值(|CNR|)变化情况,并观察病灶Gd-EOB-DTPA增强扫描表现和特征。结果:Gd-EOB-DT-PA增强后各期肝实质信号及病灶-肝脏|CNR|均显著增加(P<0.001)。动脉期、门脉期和平衡期所有病灶符合应用常规含钆(Gd)对比剂时的强化表现和特征;延迟20min肝实质期扫描时,肝脏局灶性结节增生呈等信号-高信号,1个肝细胞肝癌呈相对高信号,其余肝囊肿、肝细胞肝癌、胆管细胞癌、肝脏转移性肿瘤、淋巴上皮瘤样癌、退变结节、肝细胞腺瘤、肝血管瘤和肝脏炎性假瘤等均呈相对低信号。结论:Gd-EOB-DTPA动态增强扫描与延迟肝实质期扫描联合应用,可以提供病变形态、血供、细胞来源及功能等更多相关信息,从而提高诊断信心及诊断准确性。     

三维多期动态增强MRI在肝脏局灶性病变中的诊断价值

目的:评价Propeller LAVA序列三维容积多期动态增强MRI检查对肝脏局灶性病变的诊断价值.方法:回顾性分析83例行Propeller LAVA序列三维容积多期动态增强MRI检查的肝脏局灶性病变的血供特点、强化表现,从而推断其组织学特点,并与最终病理诊断或临床诊断相比较.结果:有1例患者图像质量不能满足诊断要求而未能纳入本研究.余82例患者共检出富血供病变65例,包括肝细胞癌31例,肝血管瘤29例,局灶结节增生4例,肾癌肝转移瘤1例.低血供病变17例,其中结节型肝细胞癌2例,肝转移瘤10例,肝内胆管细胞癌3例,炎性假瘤2例.富血供病变在肝动脉期明显强化,除4例局灶结节增生在门静脉期和延迟期与邻近肝实质信号强度近似外,余61例富血供结节在门静脉期和延迟期均表现为明显的低信号强度;低血供病变在肝动脉期强化不显著,除1例炎性假瘤在延迟期与邻近肝实质信号相等外,余16例低血供病变在门静脉期和延迟期均低于邻近肝实质信号强度.结论:Propeller LAVA序列动态增强MRI检查能够准确显示肝脏局灶性病变的血供特点,清晰显示病变的形态、边缘及强化表现,从而准确判定其组织学性质.     

肝局灶性结节性增生的影像诊断及病理对照研究

目的探讨肝局灶性结节性增生(focal nodu lar hyperp lasia,FNH)的影像学表现特点。方法经手术切除病理证实为肝局灶性结节性增生17例病例,术前均行螺旋CT平扫及动态增强扫描,其中10例又行MR平扫及动态增强扫描,分别进行影像学及病理学对照分析。结果17例FNH病灶均呈孤立结节或分叶状肿块,多数直径2~5 cm。平扫呈等或略低密度及信号,T2W I为略高信号。动态增强扫描,动脉期病灶均为明显的均质的强化,静脉期及延迟期12例仍略高于肝实质,6例略低于或等于肝实质。11例病灶内显示瘢痕,其中8例呈延迟强化。4例静脉期出现包膜样强化。病理观察:17例FNH均无包膜,增生的肝细胞形成肝板被纤维间隔分割呈结节状,瘢痕区域由纤维结缔组织及厚壁畸形血管组成。结论典型的FNH影像学可明确诊断,不典型的FNH应与肝细胞腺瘤、肝细胞癌、肝血管瘤相鉴别。     

造影剂Sono Vue和对比脉冲序列成像技术诊断肝脏局灶性病变的价值

目的探讨新型造影剂SonoVue和对比脉冲序列(CPS)成像技术对肝脏局灶性病变(FLL)的诊断价值.材料和方法对126例(142个病灶)FLL患者进行超声造影检查,103例经手术或穿刺病理证实,余23例经CT、MRI增强检查和临床综合资料证实(肝细胞性肝癌63个,肝内胆管细胞癌5个,转移性肝癌15个,肝血管瘤28个,肝局灶性结节性增生10个,肝炎性假瘤3个,肝腺瘤3个,局灶性脂肪肝7个,肝硬化结节8个).结果恶性组与良性组相比达峰时间、消退时间提前,持续时间缩短(P＜0.05);原发性肝癌比转移性肝癌消退时间提前(P＜0.05).在动脉相,41个(65%)中低分化肝细胞性肝癌(Hcc)病灶呈高增强,3个(5%)高分化HCC病灶在所有时相均呈等增强;3个肝内胆管细胞癌和8个转移性肝癌病灶在动脉相呈环状增强.18个(18/28)血管瘤在动脉相,呈周边结节状增强,门脉相呈向心性填充;6个(6/10)肝局灶性结节性增生动脉相呈轮辐状增强;2个肝腺瘤动脉相呈高增强;2个炎性假瘤于3个时相均未见增强.所有的局灶性脂肪肝和肝硬化结节在3个时相呈等增强.结论超声造影是鉴别FLL的一种很有前途的影像手段,极大地提高了超声对FLL的诊断价值.     

左肾上腺巨大海绵状血管瘤1例CT评价及文献复习

目的研究肾上腺海绵状血管瘤CT表现的动态变化。方法 1例经手术病理证实的左侧肾上腺巨大海绵状血管瘤患者术前接受了CT三期动态增强扫描,对其CT表现结合文献复习进行了回顾性分析。结果 CT平扫显示左肾上腺区有一大小约12cm×11cm×9cm的等低混杂密度肿块,边界清楚,肿块内有斑片状及条带状钙化影。增强扫描后,肿块呈明显不均匀强化,于动脉期肿块边缘有斑片状明显强化灶,于静脉期及延迟期强化灶逐渐向中心扩大。结论肾上腺海绵状血管瘤在三期动态增强扫描中具有特征性表现,有助于其明确诊断。     

螺旋CT强化方式在肝脏局灶性病变定性诊断中的价值

目的 探讨螺旋CT强化方式对肝脏局灶性病变的定性诊断价值. 方法 回顾性分析行肝脏螺旋CT多期增强扫描且发现局灶性病变的44例患者(54个病灶)的诊断结果,重点分析各类病灶的强化方式. 结果 (1)78%(14/18)的肝细胞癌表现为"快进快出"的强化方式,83%存在肝硬化背景,22%门脉可见癌栓;(2)9个肝血管瘤表现为"快进慢出",边缘明显强化逐渐向中心充填;(3)4例胆管细胞型肝癌表现为"慢进慢出",部分瘤灶内包埋胆管,周围可见扩张的肝内胆管;(4)14个肝转移瘤和5例肝脓肿表现为环形强化,肝转移瘤为周边程度不一的环形强化,肝脓肿则为单环或多环强化;(5)3例肝局灶性结节增生和1例肝细胞腺瘤表现为"快进慢出",2例局灶性结节增生存在中央瘢痕并延迟强化.结论螺旋CT强化方式能充分显示肝脏局灶性病变的血供特点,对定性诊断有较高的临床价值.     

动态增强容积内插序列在肝脏占位性病变的临床应用价值

目的:评价MRI三维动态增强容积内插序列在肝脏局灶性病变的临床应用价值.方法:91例肝脏占位性病变患者进行常规MR T1WI和T2WI扫描后,采用三维扰相梯度序列行屏气全肝3期动态增强扫描并进行图像重组,观察病灶的增强特点,并对肝动脉的显示程度进行分级.结果:91例中原发性肝癌17例,肝血管瘤24例,肝转移性肿瘤16例,局灶性结节增生2例,肝脓肿11例,肝囊肿21例.肝动脉显示为2级86例94.5%,1级3例3.3%,0级2例2.2%.结论:MR 动态增强容积内插技术可以获得高质量的图像(尤其是动脉期),有利于肝脏局灶性病变的定性、定位诊断和指导临床治疗.     

肝腺瘤的综合影像诊断

目的：描述肝腺瘤的超声（US），CT和MRI表现与病理基础，探讨综合影像对肝腺瘤的诊断价值。方法：回顾性分析经手术切除，病理症实的6例肝腺瘤的US，CT和MRI表现，并与病理所见对照。结果：6例肝腺瘤均为单发肿块，1例术前综合影像诊断为肝腺瘤，4例误诊为肝癌，例误诊为肝局灶结节性增生。US：6例呈稍低或低回声，4例有低回声晕，彩色多普勒显示6例肿块内有较丰富的门脉样血流和低速动脉样血流，CT：6例为稍低或低密度，4例有假包膜，4例动脉期，门脉期均轻度强化，1例动脉期中度强化，门脉期轻度强化，MRI：T1WI和T2WI上，6例表现为以高信号为主的混杂信号，用脂肪抑制后T1WI上的高信号无变化；2例动脉期显著强化，门脉期和延迟期轻度强化，3例动脉期，门脉期和延迟基匀轻度强化。6例均有假包膜，且在门脉期或延迟期现轻度强化。结论：肝腺瘤的综合影像表现缺乏特性性。对有假包膜和混杂高信号（用脂肪抑制后T1WI上的高信号无变化）的多血供肿块应考虑到肝腺瘤的诊断。     

肝局灶性结节性增生的CT表现及其诊断价值

目的：探讨肝局灶性增生的CT表现特点及其价值。资料与方法：搜集本院从1996年1月至2004年6月行CT扫描，经穿刺活检或行手术证实为肝局灶性结节性增生的病例10例，所有病例均行CT平扫和增强扫描结果：6例平扫为稍低或等密度，增强时动脉期明显强化．且3例肿块内可见“星状瘢痕征”，CT作出了准确的诊断．4例增强动脉期强化不是十分显著，未见“星状瘢痕征”．CT诊断为肝癌可能性大，最后手术证实为肝局灶性结节性增生。结论：CT对肝局灶性结节性增生病灶的检出及定位具有重要的意义，可反映该病的许多病理特征，但无明显的特异性，而放射性核素扫描阳性具有特殊意义，穿刺活检或手术由最终的确诊依据。     

螺旋CT双期或三期扫描对肝脏占位性病变的诊断

目的：分析肝脏螺旋CT双期或三期扫描表现，探讨其对原发性肝癌、肝转移瘤、肝血管瘤的诊断及鉴别诊断的意义。方法：经临床证实25例，均作螺旋CT平扫、动脉期、门脉期及部分平衡期和延迟期扫描，并分析螺旋CT多期扫描表现。结果：原发性肝癌动脉期明显强化而肝脏无强化，形成鲜明的对比，门脉期呈相对低密度或恢复到平扫时表现。肝血管瘤CT特征为动脉期呈边缘性环状、结节样强化，门脉期病灶边缘强化向中心强化并充满病灶呈高密度，平衡期呈等密度或低密度肝转移瘤表现多样化，周边强化或不均匀强化或不强化。结论：螺旋CT双期或三期扫描已作为对肝脏占位性病变的主要检查方法，并作为常规。     

肝脏局灶性结节性增生2例报告及文献复习

目的通过分析肝脏局灶性结节增生的影像表现，提高其诊断准确性。方法2例经手术病理证实的肝脏局灶性结节增生患者均接受超声、CT和MRI检查，其影像表现结合文献复习进行了分析。结果超声显示了2例的肝右叶实性占位性病变。1例CT平扫肝右叶病灶显示不清，增强扫描后，肝右叶前段有一直径约3．1cm的类圆形病灶呈均匀强化。MR平扫见2例的肝内结节病灶均呈等T1、等T2信号，增强扫描动脉期病灶明显强化，门脉期和延迟期病灶的强化程度逐渐下降。结论腹部超声可提示本病的诊断，而CT和MRI，尤其是增强扫描，可清晰显示病灶的血供特点和强化特征，为定性诊断提供重要依据。     

Fungal liver infection in immunocompromised patients: depiction with multiphasic contrast-enhanced helical CT

PURPOSE: To retrospectively assess multiphasic (nonenhanced, arterial phase, and portal venous phase) computed tomography (CT) of the liver for depiction of hepatic fungal infection in immunocompromised patients. MATERIALS AND METHODS: The institutional ethics review board approved the study and waived the requirement for informed consent. Sixty multiphasic hepatic CT examinations were performed in 39 immunocompromised patients who fulfilled the criteria for having probable or proved fungal liver infection. The detection and conspicuity of focal liver lesions were assessed on scans obtained during each CT phase. The lesion enhancement pattern was determined, and, accordingly, lesions were stratified into two groups: lesions suggestive of infection (with ring enhancement patterns or high attenuation) and nonspecific hypoattenuating lesions. Statistical analyses were performed by using logistic regression with generalized estimating equations. RESULTS: A total of 536 liver lesions detected at 36 CT examinations with results positive for fungal infection were assessed. All 36 (100%) examinations yielded positive results during the arterial phase, whereas 25 (69%) of them yielded positive results during the portal venous phase (P < .001). At lesion-by-lesion analysis, the arterial phase scans depicted significantly more lesions (483 of 536 [90%]) than the portal venous phase (329 of 536 [61%]) and nonenhanced (265 of 465 [57%]) scans (P < .001 for both comparisons). In addition, on arterial phase scans, 386 of 483 lesions, as compared with 134 of 329 lesions on portal venous phase scans (P < .001), were judged to have an enhancement pattern suggestive of infection. The CT phases did not differ significantly in terms of the conspicuity of detected lesions. CONCLUSION: In patients suspected of having hepatic fungal infection, arterial phase CT depicts significantly more hepatic lesions than does CT performed during the other phases, and it reveals more lesions with enhancement patterns suggestive of infection. Arterial phase CT should be performed in addition to portal venous phase CT in patients suspected of having hepatic fungal infection.     

Eosinophilic hepatic necrosis: magnetic resonance imaging and computed tomography comparison

OBJECTIVE: To compare the findings of magnetic resonance (MR) imaging with those of computed tomography (CT) of focal liver lesions related to peripheral eosinophilia. METHODS: For 12 patients with peripheral eosinophilia (>7%) examined with hepatic MR imaging and CT, 52 focal hepatic lesions larger than 0.5 cm, including 31 lesions simultaneously found on the 2 imaging modalities, were subjected to a comparative analysis of their imaging features. RESULTS: The total number of lesions distinguished from background liver was 39 (75%) on MR imaging and 44 (85%) on CT scans. On arterial phase images of 10 patients with comparable data, homogeneously hyperintense lesions were demonstrated more frequently (P = 0.006) on MR imaging (16 [50%] of 32 lesions) than on CT scans (4 [13%] of 32 lesions). Only 7 (22%) of the 32 hypoattenuating lesions on portal phase CT were depicted as hypointense lesions on portal phase MR images in 12 patients. On delayed phase images in 8 patients, the number of hyperintense lesions on MR images (9 [56%] of 16) was greater (P = 0.077) than that seen on the CT scans (4 [25%] of 16). CONCLUSIONS: For many focal hepatic lesions related to peripheral eosinophilia, dynamic MR imaging more easily demonstrates lesional enhancement on arterial and delayed phases than CT scans. Because of the higher degree of lesional enhancement of MR imaging compared with CT, the lesion-to-liver contrast may not be sufficient to distinguish the lesion from the background liver, resulting in decreased sensitivity of portal phase dynamic MR imaging.     

肝脏炎性假瘤的CT及MRI征象

目的:探讨肝脏炎性假瘤的CT和MRI表现。方法:8例经手术病理证实的肝脏炎性假瘤。男5例,女3例,年龄35~65岁,平均53岁。8例均作CT平扫及增强扫描,其中3例行MR对比检查。结果:CT表现为1 个病灶6 例,2个病灶2例,共发现病灶10个。平扫9个病灶表现为低密度,1 个病灶表现为稍高密度。动态增强扫描2 个病灶动脉期显著强化,门脉期及延迟期中度强化;8个病灶动脉期无明显强化,门脉期及延迟期有不同方式的强化,主要表现为周边完整或不完整的环形或结节状强化,中心核心样强化及线状或不规则分隔样强化。MRI表现为2 例病灶T1WI呈低信号,T2WI呈稍高信号,1例病灶T1WI及T2WI均为等信号,动态增强扫描与CT相仿。结论:肝脏炎性假瘤的CT及MRI表现因其病理阶段不同而表现各异,诊断需结合临床,确诊尚依靠病理检查。     

肝脏局灶性结节增生的螺旋CT和MRI诊断

目的 :分析肝脏局灶性结节增生 (FNH)平扫和动态增强的螺旋CT、MRI表现 ,提高FNH诊断符合率。方法 :对 13例经手术病理证实的FNH影像学表现进行回顾性分析。螺旋CT检查 8例 ,MRI检查 6例 ,其中 1例同时做CT和MRI检查。结果 :8例CT平扫病灶均呈低密度 ,均匀或不均匀。增强动脉期扫描除中心疤痕外 ,所有病灶均有明显均匀强化 ,其中 4例还可见到病灶中心或周边增粗、扭曲的动脉。门脉期和延迟期扫描 4例呈略高密度、4例病灶呈等密度或略低密度 ,4例伴有中心疤痕者均有延迟强化。MRI检查 6例 ,病灶均呈不均匀略长或等T1及T2 信号 ,增强动脉期呈明显强化 ,门脉期及延迟期呈等或略高强化 ,4例MRI平扫显示中央瘢痕者有延迟强化。结论 :平扫和动态增强螺旋CT、MRI能较全面显示FNH的病理特征和血供特点 ,明显地提高与其它富血管恶性肿瘤的鉴别诊断能力     

肝脏局灶结节性增生的CT特征

目的探讨肝脏局灶结节性增生(Focalnodularhyperplasia,FNH)这种较少见的肝细胞良性占位性病变的CT特征。材料和方法自1990年至1999年期间我院CT室诊为肝脏占位病变的900余例中,将有手术切除标本并经病理证实的肝脏FNH8例的临床及CT片逐例进行分析和归纳,重点讨论其鉴别要点。结果8例均为单发病灶。发生在肝左叶3例,肝右叶5例。其病灶大小在5cm以下者4例;5cm以上者4例(其中10cm以上者2例)。7例为类圆形,1例不规则形。平扫时7例为低密度,1例为等密度(有脂肪肝影响)。均行增强扫描,2例动脉期有显著增强,5例门静脉期扫描仍有显著增强,8例延迟3分钟后扫描为等密度。7例病灶内均可见裂隙或小片状密度减低影。1例为均匀密度影。结论利用CT扫描,尤其是多时相螺旋CT扫描,可以对肝脏局灶结节性增生(FNH)进行明确的术前诊断。     

肝脏血管平滑肌脂肪瘤的CT及MRI征象分析

目的 分析13例肝脏血管平滑肌脂肪瘤（AML）的CT及MRI表现,进一步提高诊断准确性。方法 所有病例均经手术病理证实。12例经CT检查,其中6例做过MRI检查,仅1例只做MRI检查。平扫后行增强动脉期和门脉期扫描,5例做了延迟期扫描。MRI检查行SE T1WI、快速自旋回波（FSE）T2WI和快速多层面干扰梯度回波（FMPSPGR）序列横断面动态多期增强扫描。结果 CT平扫11个病灶为低密度,1个为略高密度。动脉期所有病灶均有强化表现,8个病灶见到中心血管影。门脉期8个病灶有持续强化,有6个病灶见到中心血管影。MR T1WI上5个病灶为混杂信号,T2WI上所有病灶均为高信号,但信号强度各不相同。MR增强动脉期6个病灶有强化,1个病灶强化不明显。门脉期4个病灶有持续强化,3个为低信号。MR增强扫描中也有4个病灶显示中心血管影。结论 CT和MRI检查均可显示AML的特征,特别是病灶中脂肪成分和血管影高度提示AML的诊断。MR SE序列加脂肪抑制显示脂肪成分比CT更加敏感。CT和MR动态增强多期扫描可充分反映AML的强化特征,有助于提高AML的诊断准确性。     

Focal nodular hyperplasia and hepatocellular adenoma of the liver: differentiation with multiphasic helical CT

OBJECTIVE: Differences of attenuation and enhancement patterns in focal nodular hyperplasia and hepatocellular adenoma were evaluated and quantified using triphasic single-slice helical CT. MATERIALS AND METHODS: Forty-five histologically proven focal nodular hyperplasias in 27 patients and 18 hepatocellular adenomas in six patients were examined with helical CT. Quantitative evaluation included the following: attenuation of lesions, scar, and liver parenchyma during unenhanced, arterial (20 sec after injection), and portal venous phases (70 sec after injection); relative enhancement of lesions and liver (the ratio between attenuation in arterial phase and portal venous phase, respectively, and attenuation in unenhanced phase); and the prevalence of scar and its central vessel in focal nodular hyperplasia. RESULTS: The study showed no significant difference between mean attenuation values of focal nodular hyperplasia (mean +/- SD, 51.2 +/- 5.9 H) and hepatocellular adenoma (mean +/- SD, 56.3 +/- 7.8 H) in the unenhanced phase. In the arterial phase attenuation values were significantly higher in focal nodular hyperplasia (mean +/- SD, 117.9 +/- 15.1 H) than in hepatocellular adenoma (mean +/- SD, 80.1 +/- 10.5 H). In the portal venous phase no significant differences in attenuation values were detected between focal nodular hyperplasia (mean +/- SD, 112.1 +/- 20.4 H) and hepatocellular adenoma (mean +/- SD, 110.2 +/- 12.9 H). For enhancement parameter thresholds separating focal nodular hyperplasia from hepatocellular adenoma, the following were found: the relative enhancement was higher in 100% of the focal nodular hyperplasias and lower than or equal to 1.6 (accuracy, 96%) in 87% of the hepatocellular adenomas. CONCLUSION: Triphasic helical CT combined with quantitative evaluation of liver lesions offers the possibility of detecting differences in liver lesions that are visually similar on CT. The attenuation and relative enhancement in the arterial phase show significant differences that make accurate differentiation between focal nodular hyperplasia and hepatocellular adenoma possible.