The imaging diagnosis of hepatic focal nodular hyperplasia]

Focal nodular hyperplasia (FNH) is a rare benign hepatocellular tumor occurring in noncirrhotic patients, mostly females, 20-50 years of age. It is usually asymptomatic. The authors took the lead from 5 cases of FNH studied over last year to analyze the different patterns exhibited by the condition on the various imaging techniques currently available. At scintigraphy with 99mTc DISIDA or with TcSC, FNH can be hyper, normal, or hypocaptating. On US scans, the lesion is often homogeneous and isoechoic, but it can also be hyper/hypoechoic. With Doppler US, high-flow signals can be observed. On unenhanced CT scans the lesion is solid, well-demarcated, isodense or slightly hyperdense; sometimes it shows a central hypodense area corresponding to fibrovascular scar. On postcontrast scans it appears hyper/isodense. At dynamic CT the lesion density, which is high during the arterial phase, decreases quickly in the parenchymal and the venous phases and reaches equal/inferior values to surrounding liver parenchyma. On liver angio-CT it is sometimes possible to visualize the bile ducts in the central scar. At angiography, FNH is hypervascular and homogeneous. On MR scans, in T1-weighted SE sequences, the condition is isointense or slightly hypointense, whereas on T2-weighted pulse sequences it is slightly hyperintense; the central scar is hypointense on T1, and hyperintense on T2, weighted scans. As we have no pathognomonic patterns but only orientative ones, a reliable differential diagnosis with hepatocellular adenoma (HA) and fibrolamellar hepatocellular carcinoma (FL-HCC) must be based on biopsy or cytology or, even better, histology. The differential diagnosis is nevertheless necessary because, while FNH does not usually require a surgical approach but only a radiological follow-up, both HA (due to possible bleeding and degeneration) and FL-HCC require surgery.     

"Scar sign" on computed tomography and sonography in fibrolamellar hepatocellular carcinoma

Demonstration by computed tomography of a central linear or stellate low-attenuation region within a focal liver mass has been reported to be suggestive of focal nodular hyperplasia in appropriate clinical settings. We present a case of a focal liver mass with typical central scarring in which the ultimate diagnosis was fibrolamellar hepatocellular carcinoma.     

MR imaging of hepatic focal nodular hyperplasia: characterization and distinction from primary malignant hepatic tumors

Spin-echo MR imaging at 0.35 T was used to image hepatic focal nodular hyperplasia (FNH) and to attempt to distinguish it from primary malignant hepatic tumors. There were six FNH and 10 malignant tumors including seven hepatocellular carcinomas, two cholangiocarcinomas, and one hepatoblastoma. Our results show that FNH has a fairly consistent appearance, dissimilar from that of malignant primary hepatic tumors. Four of six FNH lesions were isointense (except for a central scar in three) and indistinguishable from normal hepatic parenchyma on all pulse sequences, whereas two of six were homogeneous but slightly hyperintense on T2-weighted sequences. Furthermore, a central hyperintense scar was seen in three of six lesions on T2-weighted sequences. In contrast, each of the malignant primary hepatic tumors was hyperintense on T2-weighted sequences and seven of 10 were hypointense on T1-weighted sequences; in nine of 10, heterogeneous areas of intensity were noted. In two fibrolamellar hepatocellular carcinomas a central scar was seen that was hypointense on all pulse sequences. By using quantitative data, the best characterization was obtained by using lesion/normal-liver intensity ratios from a T2-weighted sequence; all FNH had a ratio less than 1.33, while in nine of 10 primary malignant tumors it was greater than 1.41. We conclude that focal nodular hyperplasia may have a consistent appearance on spin-echo MR imaging and probably can be distinguished from primary malignant lesions in most instances.     

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。     

Contrast-enhanced ultrasonographic spoke-wheel sign in hepatic focal nodular hyperplasia

BACKGROUND: To determine the utility of contrast-enhanced ultrasonography (CEUS) in assessing hepatic tumors with central feeding arteries found by color/power Doppler ultrasonograophy (CDUS/PDUS). METHODS: We prospectively studied 37 hepatic tumors (34 patients), with a mean size of 2.9cm and each having a central feeding artery, by CDUS/PDUS. The CEUS was performed with a galactose-based microbubble contrast agent. The detection of a spoke-wheel sign was interpreted as evidence of focal nodular hyperplasia (FNH). All patients underwent tumor biopsies or surgical resection. RESULTS: CEUS showed a central feeding artery with a spoke-wheel sign in 36 tumors, including 34 FNHs and 2 hepatocellular carcinomas. The remaining tumor was demonstrated to be FNH despite the absence of a spoke-wheel sign as detected by CEUS. The sensitivity of the spoke-wheel sign or central scar for FNH was 97.1% (34/35), 40% (14/35), 28.6% (10/35), 50% (8/16) and 0% (0/15) for CEUS, CDUS/PDUS, dynamic computed tomography (CT) or magnetic resonance imaging (MRI), hepatic angiography and liver scintigraphy, respectively. The two hepatocellular carcinomas showed scirrhous changes histologically. CONCLUSIONS: CEUS is more sensitive than CDUS/PDUS, dynamic CT, MRI, hepatic angiography and liver scintigraphy in the detection of the spoke-wheel sign or central scar in FNH. Scirrhous hepatocellular carcinoma should be included in the differential diagnosis for liver tumors with spoke-wheel sign detected by CEUS.     

Radiologists' performance in the diagnosis of liver tumors with central scars by using specific CT criteria

PURPOSE: To determine the performance of radiologists with differing levels of expertise in the diagnosis of the most common types of liver tumors with central scars (ie, focal nodular hyperplasia [FNH], fibrolamellar hepatocellular carcinoma [HCC], and large hepatic hemangioma) by using specific computed tomographic (CT) findings. MATERIALS AND METHODS: Review of medical records at the University of Pittsburgh Medical Center identified patients with a total of 64 liver tumors that had central scars-including 29 cases of FNH, 20 fibrolamellar HCCs, and 15 large (>3.5 cm in diameter) hemangiomas-and with CT scans available for review. Retrospective review of these scans was performed individually by six radiologists who were blinded to the diagnosis, including two faculty abdominal radiologists, one abdominal imaging fellow, and three radiology residents. Individual performance was evaluated by means of receiver operating characteristic analysis, and interobserver agreement was measured by using the Cronbach alpha. Individual CT findings that may allow differentiation of tumor types were identified with the Kruskal-Wallis test. RESULTS: CT allowed good to excellent interobserver agreement in the diagnosis of tumor type and in recognition of differential findings among the three types. The individual accuracy of diagnosis was very good, with the average area under the receiver operating characteristic curve ranging from 0.81 to 0.90. Although the faculty radiologists performed the best, the differences in performance between the subgroups of readers and the levels of confidence in diagnosis were not statistically significant. The diagnosis of fibrolamellar HCC was the most accurate and had the highest sensitivity, followed by FNH and large hemangioma. Clinical and CT findings that were found to be statistically significant in differentiating tumor types were patient age and sex, tumor size larger than 10 cm, width of tumor scars, invasion of vessels, nodular centripetal enhancement, marked hyperattenuation on arterial phase images, lymphadenopathy, heterogeneity, extrahepatic metastases, surface lobulation, calcification, and isoattenuation with liver tissue on portal venous phase images. CONCLUSION: CT allows accurate differentiation of the most common types of liver tumors with central scars, including FNH, fibrolamellar HCC, and large hemangioma.     

Fibrolamellar hepatocellular carcinoma with biliary tumor thrombus: an unreported association

Fibrolamellar hepatocellular carcinoma (FHCC) is a rare malignant tumor of hepatocyte origin occurring earlier in life than typical hepatocellular carcinoma (HCC). We describe a distinctive case of FHCC with biliary tumor thrombus (BTT) in a 25-year-old Caucasian patient, pointing out the imaging features supported by histopathology.     

肝脏多发局灶性结节性增生的MRI诊断

目的 评估MR诊断肝脏多发局灶性结节性增生(focal nodular hyperplasia,FNH)的价值.方法 回顾性分析经病理证实的9例多发FNH的MR表现,并与部分病灶病理所见对照.结果 9例诊断均考虑到FNH的可能性,5例第一诊断考虑为FNH,3例第一诊断考虑为肝腺瘤,1例第一诊断考虑为纤维板层型肝癌.9例共31个病灶,T2WI 19个呈稍高信号、12个呈等信号;T1WI上12个呈稍低信号、7个呈等信号、12个呈高信号;反相位成像1个病灶局部信号略有减低.注射Gd-DTPA后,动脉期18个病灶轻度至明显不均匀强化、11个病灶显著均匀强化、1个病灶中度不均匀环形强化、1个病灶未见异常强化;门静脉期和延迟期31个病灶均逐渐呈等信号或稍高信号.共16个病灶出现中央瘢痕,瘢痕延迟期强化.结论 多发FNH有特征性表现,大部分病例MR能正确诊断.     

Fibrolamellar hepatocellular carcinoma: imaging and pathologic findings in 31 recent cases.

PURPOSE: To review characteristic findings of fibrolamellar hepatocellular carcinoma (HCC) at computed tomography (CT) and magnetic resonance (MR) imaging. MATERIALS AND METHODS: The authors retrospectively reviewed the clinical, pathologic, and preoperative imaging findings in 31 patients with histologically proved fibrolamellar HCC. Dynamic contrast material-enhanced CT of the liver was performed in 31 patients, helical multiphase CT in 21, and MR imaging in 11. Complete resection was performed in 17 patients, and imaging-pathologic correlation was performed. RESULTS: Large tumors (mean diameter, 13 cm) were depicted at CT and MR in all cases. At CT, the margins of the tumors were well defined in 24 (77%) of 31 cases calcifications were depicted in 21 (68%), a central scar in 22 (71%), and abdominal lymphadenopathy in 20 (65%). In 20 (80%) of 25 cases with hepatic arterial phase CT images, all tumors were heterogeneous and depicted areas of hypervascularity. At MR imaging, tumors were hypointense to liver on T1-weighted images (n = 11) and hyperintense to liver on T2-weighted images (n = 10). Calcification was not depicted on MR images, but a central scar was depicted as hypointense to surrounding tumor in nine cases. CONCLUSION: CT and MR images demonstrate characteristic features that may allow confident diagnosis of fibrolamellar HCC.     

Focal nodular hyperplasia of the liver: arterial angio-CT and microangiography.

To differentiate focal nodular hyperplasia (FNH) from other hepatic tumors, especially hepatocellular carcinoma, we evaluated the hemodynamics of histologically proved FNH in three patients, two by arterial angio-CT and one by microangiography of the resected specimen. These studies demonstrated the centrifugal blood supply of FNH (early filling of central tumor vessels radiating to periphery, and lobulated tumor stains with central low density area in the late phase), which could not be demonstrated by dynamic CT or hepatic angiography. Arterial angio-CT is useful as a further study, when differential diagnosis of FNH is uncertain by other imaging techniques.     

Hepatic neoplasia: Selected clinical aspects

Benign liver tumors are relatively uncommon and, even when large enough to be symptomatic, they usually remain undiagnosed prior to exploratory laparotomy. Hemangiomas constitute the majority of benign hepatic neoplasms and are 9 times as frequent in females as in males. Most are asymptomatic but abdominal swelling, a mass, or symptoms due to compression of adjacent organs may occur and abdominal hemorrhage is reported in 4.5% of patients. Hepatic hemangioma may produce a large arteriovenous communication serious enough to cause heart failure. Recently an increased frequency of liver tumors, mostly adenomas, has been noted in women taking oral contraceptives (OCs); the cause has been attributed to estrogens. The exact incidence is unknown but believed to be low. It is most common in women in their late 20s who have been on OCs for 7 years or more. The tumor occasionally completely regresses on withdrawal of the OCs. The tumor may be discovered incidentally at laparotomy or may manifest inself by pain, a palpable mass, or catastrophic hemoperitoneum. Hepatic adenoma is usually a solitary lesion and infrequently degenerates into malignancy. Differential diagnosis includes chronic gall bladder disease and peptic ulcer. Focal nodular hyperplasia (FNH) is apparently much less frequently related to OC use and is less likely to bleed seriously than adenoma. Hepatic chemistry is usually normal in adenoma and FNH, but slight increases in serum bilirubin, serum alkaline phosphatase, and serum transaminase may occur. Primary liver cancer (hepatocellular carcinoma or hepatoma) is mostly a disease of males and in the US and Western Europe seldom develops before age 40. Fibrolamellar carcinoma, which characteristically develops in adolescents and young adults, occurs with equal sex incidence. Doubt has been expressed about its relationship to OCs. In the US about 75% of primary hepatocellular carcinomas are associated with cirrhosis, and about 5% of cirrhosis cases develop primary liver cancer. Clinical manifestations of hepatoma have been divided into 5 groups: frank cancer (62.7%), acute abdominal cancer (8%), febrile cancer (8%), occult cancer (16%), and metastatic cancer (5%). Detection of large amounts of alpha fetoprotein has proven useful in diagnosis of hepatocellular carcinoma, but values may be negative in OC users. It has been estimated that 1/3 to 1/2 of all malignant tumors eventually metastasize to the liver.     

Unusual Primary Neoplasms of the Adult Liver: Review of Imaging Appearances and Differential Diagnosis

The radiological appearance of common primary hepatic tumors such as hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) is widely recognized. Hepatic masses with unusual histology are occasionally encountered, but seldom suspected on imaging. However, many possess characteristic imaging findings, which when assessed along with the clinical and demographic background and serum tumor markers, may enable a prospective diagnosis. This review attempts to familiarize the reader with the clinicopathological characteristics, imaging manifestations, and differential diagnosis of these unusual liver tumors in adults.Biphenotypic primary liver carcinoma is suspected in masses showing distinct areas of HCC and CCA-type enhancement pattern in cirrhotic livers. Fibrolamellar carcinoma occurs in young individuals without underlying chronic liver disease and shows a characteristic T2-hypointense scar frequently showing calcification. Perivascular epithelioid cell tumors are differentials for any arterial hyperenhancing mass in the noncirrhotic liver, particularly in patients with tuberous sclerosis. Multifocal subcapsular tumors showing target-like morphology, capsular retraction and “lollipop” sign are suspicious for epithelioid hemangioendothelioma. On the other hand, multiple hemorrhagic lesions showing patchy areas of bizarre-shaped arterial phase hyperenhancement are suspicious for angiosarcoma. Primary hepatic lymphoma (PHL) is suspected when patients with immunosuppression present with solitary or multifocal masses that insinuate around vessels and bile ducts without causing luminal narrowing. Intense diffusion restriction and low-level homogeneous or target-like enhancement are also ancillary features of PHL. Primary hepatic neuroendocrine tumor shows uptake on Ga-68 DOTANOC PET/CT. Although a straightforward diagnosis may be difficult in these cases, awareness of the characteristic imaging appearances is helpful in suspecting the diagnosis.     

肝局灶性结节增生的MRI表现

目的 对肝局灶性结节增生(FNH)的MRI表现进行分析和总结，以提高对FNH MRI表现的认识。资料与方法 经手术病理证实的FNH18例，24个病灶，均作快速多层面扰相梯度回波(FMPSPGR)动态增强，11例作SET1WI、PDWI及T2WI，7例作SET1WI及FSET2WI。结果 24个病灶中，2个有典型中心瘢痕，9个有不典型中心瘢痕；动脉期明显强化23个；门脉期7个明显强化，15个中度强化，中心线样或点状强化6个；平衡期16个病灶中度强化，8个轻度强化，中心线样或点状强化2个；延迟期17个病灶，12个轻度强化，5个与肝实质等信号，4个有中心线样或点状强化。结论 MRI可对多数FNH(83．3％)作出正确诊断，对不典型FNH应结合病史及SPIO或Gd-EOB-DTPA动态扫描综合判断。     

Hepatocellular carcinoma with a prominent vascular scar in the center: MR imaging findings

We report herein a case of hepatocellular carcinoma (HCC) with a prominent central scar. Dynamic CT and MRI studies revealed a hypervascular liver mass and a washout of contrast material in the delayed phase. The tumor center showed particular hyperintensity on T2-weighted images and delayed or prolonged enhancement. The surgical specimen revealed moderately differentiated HCC with a central scar. The central scar consisted of prominent vascular channels and loose fibrous tissue, indicative of a vascular scar. We should understand MR imaging findings of this type of central scar in the HCC. This article was presented at a meeting of the Kyushu district chapter of the Japan Radiological Society in February 2005.     

肝脏局灶性结节增生CT诊断

目的:提高对肝脏局灶性结节增生(FNH)CT表现的认识和术前诊断准确性。方法:回顾性分析6例经手术病理确诊FNH病例的典型和不典型CT表现。结果:6例FNH病例中,4例具有较典型的CT表现:如显示中心疤痕(3例);增强早期明显均匀强化(除外疤痕)(4例);增粗与扭曲的供血动脉(3例)等。另外2例,增强早期明显不均匀强化;疤痕区不明显等,术前被误诊为肝细胞肝癌。结论:通过对典型和不典型FNH病例的平扫和增强CT分析,有助于提高对FNH的CT征象的认识,从而提高FNH术前诊断的准确性。     

Focal nodular hyperplasia: CT findings with emphasis on multiphasic helical CT in 78 patients

PURPOSE: To evaluate features of focal nodular hyperplasia (FNH) at multiphasic helical computed tomography (CT). MATERIALS AND METHODS: Clinical, pathologic, and preoperative imaging findings were retrospectively reviewed in 78 patients. Conventional liver CT was performed in nine patients; helical multiphasic CT, in 69. Diagnosis was based on complete resection (n = 20), biopsy (n = 42), or clinical and imaging follow-up for a minimum of 6 months (n = 16). Number, size, location, margins, surface, homogeneity of enhancement, and presence of a central scar, mass effect, exophytic growth, calcification, pseudocapsule, or vessels feeding or draining the lesion were evaluated. RESULTS: CT depicted 124 tumors (mean diameter, 4.1 cm; range, 1-11 cm); 62 were small (< or =3 cm). FNHs were hypervascular and hyperattenuating to liver on 106 of 106 arterial phase scans and were isoattenuating to liver on 82 of 89 delayed scans. Of the 124 tumors, 111 enhanced homogeneously, 109 had a smooth surface, 101 were subcapsular, 89 had ill-defined margins, and 62 had a central scar that was observed more often in large lesions (40 of 62 lesions) than in small lesions (22 of 62 lesions). FNHs less frequently exerted a mass effect (43 lesions), had vessels around or within the lesion (42 lesions), demonstrated exophytic growth (40 lesions), or showed a pseudocapsule (10 lesions). Only one FNH had calcification. CONCLUSION: Helical CT demonstrates characteristic features that may allow confident diagnosis of FNH. In typical cases, neither biopsy nor further imaging is necessary.     

肝局灶性结节增生的多种影像学表现分析

目的分析肝局灶性结节增生(FNH)的CT、DSA及18FDG正电子发射体层摄影术(PET)的影像表现,认识FNH的多种影像学特征.资料与方法 10例FNH经手术病理证实,回顾分析其多种影像学表现.10例均行CT平扫及动态增强扫描,其中4例行DSA肝动脉造影,2例行18FDG PET显像.结果 10例FNH均为单发性结节,位于肝右叶8例,肝左叶2例.肿瘤直径1.1～9.3 cm,平均5.1 cm.CT检查10例,平扫均为低密度,其中8例病灶(直径均＞3.0 cm)中央区有星芒状的更低密度区;增强扫描,动脉期9个结节明显强化,1个中等强化,病灶中央更低密度区无强化,2个病灶中央或周边见增粗迂曲血管,其中1个尚可见动脉-门脉、动脉-静脉分流现象;门脉期病灶密度稍有下降,8个高于或等于肝实质,2个低于肝实质;延迟期7个等于或略高于肝实质,3个低于肝实质,5个病灶中央更低密度有强化.血管造影:4例FNH的供血动脉均来自肝动脉系统,供血动脉增粗、扭曲, 1例血管分支放射状分布,周围呈环绕状聚集染色,中央局限性缺损,另3个分支血管紊乱并呈抱球征,1个尚见动脉-门脉、动脉-静脉分流.2例18FDG PET显像均未见异常放射性浓聚.结论 FNH CT平扫为低密度,增强扫描以"快进慢出"为主要特征,而血管造影显示肝动脉供血为主,表现为供血动脉增粗、扭曲,呈轮辐状向周围发散.这些影像特征有利于FNH的定性诊断.     

Differential diagnosis of focal nodular hyperplasia with quantitative parametric analysis in contrast-enhanced sonography

OBJECTIVES: We investigated the potential of quantitative parametric analysis in the differential diagnosis of focal nodular hyperplasia (FNH) from other hypervascularized liver focal lesions. MATERIALS AND METHODS: Eighty-five focal liver lesions (in 83 patients) were explored using contrast-enhanced ultrasound (SonoVue and Cadence Contrast Pulse Sequencing) consisting of typical FNH (n=52), hepatocellular carcinoma (n=11), hemangioma with high flow (n=8), hypervascular metastases (n=10), and hepatocellular adenoma (n=4). QontraXt software (AMID, Italy) was used here to estimate the following parameters: maximum peak value, Tr (time corresponding to time for obtaining 63% of the plateau), beta parameter corresponding to the exponential factor, and slope corresponding to the tangent value of the first phase of enhancement. These parameters were obtained from the time-intensity curves derived from the enhancement observed in 2 regions of interest corresponding, respectively, to the whole lesion and the central region only. RESULTS: A significant statistical difference (P<0.05) was found in the values of Tr, beta, and slope between FNH and other hypervascularized lesions on both the whole lesion and central region. Among these parameters, slope appeared as the most valuable whatever the region of interest, ie, central or whole lesion (P<0.01). Central region was more accurate in the differentiation of FNH and concordant with visual characterization. CONCLUSION: Quantitative parametric curve analysis of the different hypervascularized lesions confirms the depiction of the central artery in FNH and thus could help in differentiating this specific focal liver lesion from the others.     

Hypervascular hepatic focal lesions: spectrum of imaging features

Detection and characterization of liver lesions often present a diagnostic challenge to the radiologists. Liver lesions may be classified as hypovascular and hypervascular based on degree of hepatic arterial blood supply. Common hypervascular liver lesions include hemangioma, focal nodular hyperplasia, hepatocellular adenoma, hepatocellular carcinoma, fibrolamellar carcinoma, and metastases from primary tumors such as islet cell tumor, carcinoid, renal cell carcinoma, melanoma, and thyroid carcinoma. In this review article, we discuss the spectrum of imaging features of hypervascular liver lesions.