Focal lesions in cirrhotic liver: what else beyond hepatocellular carcinoma?

Detection and characterization of focal lesions in the cirrhotic liver may pose a diagnostic dilemma. Several benign and malignant lesions may be found in a cirrhotic liver along with hepatocellular carcinoma (HCC), and may exhibit typical or atypical imaging features. In this pictorial essay, we illustrate computed tomography and magnetic resonance imaging findings of lesions such as simple bile duct cysts, hemangioma, focal nodular hyperplasia-like nodules, peribiliary cysts, intrahepatic cholangiocarcinoma, lymphoma, and metastases, all of which occur in cirrhotic livers with varying prevalences. Pseudolesions, such as perfusion anomalies, focal confluent fibrosis, and segmental hyperplasia, will also be discussed. Imaging characterization of non-HCC lesions in cirrhosis is important in formulating an accurate diagnosis and triaging the patient towards the most appropriate management.The detection and characterization of focal lesions in a cirrhotic liver on computed tomography (CT) and magnetic resonance imaging (MRI) is a challenging task due to the marked changes in the organ architecture. Although hepatocellular carcinoma (HCC) is the most frequent primary tumor arising in a cirrhotic liver, several other benign and malignant lesions may be encountered in this setting (1, 2). It is thus not surprising that CT and MRI have limited specificity for the diagnosis of HCC in cirrhosis.Imaging characterization of focal lesions in cirrhosis is of the utmost importance for appropriate patient management. The radiologist’s primary task is to maximize tumor detection (i.e., minimize false negatives), because missing the diagnosis of HCC may preclude potentially curative therapies, such as hepatic resection, percutaneous ablation procedures, and, in selected patients, liver transplantation. However, it is equally important to avoid the misdiagnosis of benign liver lesions as HCC (i.e., minimize false positives) because this diagnostic interpretation may incorrectly increase the tumor burden. This may also result in the ineligibility of the patient for potentially curative treatments or the inappropriate assignment of increased priority scores for patients on the waiting list for liver transplantation. In this paper, we discuss and illustrate CT and MRI features of both common and uncommon non-HCC liver lesions occurring in cirrhotic patients.     

Rationale Schnittbildgebung des hepatozellulären Karzinoms

Clinical/methodical issue

Both computed tomography (CT) and magnetic resonance imaging (MRI) constitute the gold standard in radiological imaging of hepatocellular carcinoma (HCC). In cases of typical contrast behavior each modality as a single dynamic technique allows the diagnosis of HCC. There is still a challenge in detection of small HCCs <?2 cm, in differentiating HCC and high-grade dysplasia from other benign liver lesions as well as the evaluation of hypovascular liver lesions in the cirrhotic liver.

Performance

Nowadays, both modalities achieve high detection rates of 90–100?% for lesions >?2 cm. Regarding lesions between 1 and 2 cm there is a higher sensitivity for MRI ranging between 80 and 90?% compared to 60–75?% with CT. Besides the multimodal diagnostic criteria, MRI provides significant benefits with the use of hepatobiliary contrast. Especially in combination with diffusion- weighted imaging (DWI) increased sensitivity and diagnostic accuracy compared to CT has been described for lesions sized <?2 cm. Regarding the differentiation from other hepatic nodules in the cirrhotic liver there is strong evidence that the coexistence of arterial enhancement and hypointensity on hepatobiliary imaging is specific for HCC. Moreover, hypointensity on hepatobiliary imaging is associated with a high positive predictive value (PPV) of up to 100?% for the presence of high-grade dysplasia and HCC.

Achievements

The use of MRI including hepatobiliary imaging and DWI has to be regarded as the best non-invasive imaging modality for the detection of HCC and for the characterization of nodules in patients with liver cirrhosis. In comparison to CT there are benefits regarding detection of small lesions <?2 cm and evaluation of hypovascular liver lesions in the context of the hepatocarcinogenesis including prognostic values of premalignant lesions.

Practical recommendations

Both MRI and CT provide a high diagnostic performance in evaluation of HCC in liver cirrhosis. With MRI there are considerable advantages regarding the detection rate and specificity. For daily clinical routine, CT offers a fast, reliable and easy available modality with benefits for patients in reduced general state of health and restricted compliance.     

Benign and malignant mimickers of infiltrative hepatocellular carcinoma: tips and tricks for differential diagnosis on CT and MRI

Hepatocellular carcinoma (HCC) may have an infiltrative appearance in about 8–20% of cases. Infiltrative HCC can be a challenging diagnosis and it is associated with the worst overall survival among HCC patients. Infiltrative HCC is characterized by the spread of multiple minute nodules throughout the liver, without a dominant one, ultimately resulting into macrovascular invasion. On CT and MRI, infiltrative HCC appears as an ill-defined, large mass, with variable degree of enhancement, and satellite neoplastic nodules in up to 52% of patients. On MRI, it may show restriction on diffusion weighted imaging, hyperintensity on T2- and hypointensity on T1-weighted images, and, if hepatobiliary agent is used, hypointensity on hepatobiliary phase. Infiltrative HCC must be differentiated from other liver diseases, such as focal confluent fibrosis, steatosis, amyloidosis, vascular disorders of the liver, cholangiocarcinoma, and diffuse metastatic disease. In cirrhotic patients, the identification of vascular tumor invasion of the portal vein and its differentiation from bland thrombosis is of utmost importance for patient management. On contrast enhanced CT and MRI, portal vein tumor thrombosis appears as an enhancing thrombus within the portal vein, close to the main tumor and results into vein enlargement. The aim of this pictorial review is to show CT and MRI features that allow the diagnosis of infiltrative HCC and portal vein tumor thrombosis. A particular point of interest includes the tips and tricks for differential diagnosis with potential mimickers of infiltrative HCC.     

How to detect hepatocellular carcinoma in cirrhosis

Cirrhosis predisposes to hepatocellular carcinoma (HCC) which develops by sequential steps of de-differentiation of hepatocytes from regenerative nodules via borderline (dysplastic) nodules to frankly malignant HCC. Effective treatment depends on early recognition of HCC, so the key tasks for imaging are firstly recognising the presence of a suspicious lesion, and secondly differentiating between benign, borderline and malignant nodules. Screening of high-risk cirrhotic patients with sonography and measurement of alpha fetoprotein (AFP) is helpful but will not reliably differentiate small HCC from benign or dysplastic nodules. Large HCCs can usually be recognised by their characteristic morphology on imaging, but the appearances of smaller benign and malignant nodules show considerable overlap on unenhanced sonography, CT and MRI. Increasing degrees of histological malignancy are associated with increasing arterialisation and loss of portal blood supply, so the recognition of HCC requires the use of dynamic imaging with contrast-enhanced CT or T1-weighted MRI with gadolinium enhancement. Sonography with microbubble contrast media now offers another method for detecting arterialised nodules; however, some non-malignant nodules show arterial hypervascularity and a minority of HCCs are hypovascular, so the assessment of perfusion does not conclusively distinguish benign from malignant lesions. Kupffer cell function is another attribute of liver tissue which can be explored using MRI with superparamagnetic iron oxide particles (SPIO). Experience thus far suggests that uptake of SPIO is an effective discriminator between benign and malignant nodules. The combination of SPIO with gadolinium-enhanced MRI offers the opportunity for imaging characterisation of cirrhotic nodules by cellular function as well as by blood supply, and this approach is now proposed as the examination of choice for detecting HCC in cirrhosis.     

Focal lesions in cirrhosis: Not always HCC

Even though most hepatocellular carcinomas (HCC) develop in the setting of cirrhosis, numerous other focal liver lesions and pseudolesions may be encountered. The role of the radiologist is therefore to differentiate these lesions from HCC to avoid under- and overdiagnosis. There are several ways of classifying these lesions: those which predate the development of fibrosis and cirrhosis (cystic lesions, hemangioma), those related to or a consequence of cirrhosis (regenerative nodules, dysplastic nodules, focal fibrosis, peribiliary cysts, shunts, or even cholangiocarcinoma), and those related to the underlying cause of chronic liver disease (lymphoma). Finally, some may develop independently (liver metastases). From an imaging point of view, it is important to remember that the imaging features of pre-existing lesions are not dramatically changed by cirrhosis. Differentiating non-HCC from HCC requires not only an understanding of the multi-step process of hepatocarcinogenesis, but also the importance of medical history, and of complimentary imaging modalities, namely computed tomography (CT) and magnetic resonance imaging (MRI). This review article gives an overview of the imaging features of benign and malignant non-HCC focal liver lesions in the setting of cirrhosis, with a focus on CT and MR imaging.     

螺旋CT三期增强扫描误诊漏诊肝细胞癌20例分析

目的：探讨螺旋CT三期增强扫描误诊或漏诊的20例肝细胞性肝癌（HCC）的原因,以进一步提高HCC的诊断准确性。方法：20例HCC患者行平扫及三期增强扫描,对比剂注射流率为3.0ml/s,然后开始动脉期、门脉期和延迟期的扫描,观察病灶的强化方式和部位。结果：漏诊的5个病灶均〈1cm,其中2个病灶在三期扫描中均未能发现,其余3个病灶因观察分析不仔细而漏诊。16个病灶误诊为其它肝脏病变,肝血管瘤（5个）,肝脓肿（4个）,肝硬化结节（3个）,局灶性结节增生（2个）,肝炎性假瘤（2个）。结论：HCC在三期增强扫描中强化方式不典型是误诊的主要原因,而这种不典型强化方式是HCC的病理基础和生长方式所造成的。了解HCC的病理基础和生长方式及仔细阅片和分析可进一步提高HCC的诊断准确性。     

肝硬化结节与小肝癌的CT、MRI诊断

在肝硬化结节及小肝癌的早期诊断方面,CT、MRI仍是目前临床工作中最重要的方法,本文阐述肝硬化结节演变为肝癌过程中的几个重要环节的CT、MRI表现及国内、外对此的研究现状,这几个环节包括肝硬化再生结节、发育不良性结节(低、中、高级)、小肝癌及肝癌,它们在CT、MRI表现上各有特征,但相互间也有影像学表现上的重叠,故多数较典型者可以通过CT密度值、MRI信号值及增强表现判断其性质,少部分诊断有困难的病灶可以通过双动脉期扫描、MR菲立磁增强及灌注成像等方法提供更多的诊断信息。     

Infarcted regenerative nodules in cirrhosis: CT and MR imaging findings with pathologic correlation

OBJECTIVE. The purpose of this article is to present the imaging findings and correlative pathologic findings of infarcted regenerative nodules in the cirrhotic liver. CONCLUSION. Infarcted regenerative nodules exhibit a spectrum of imaging appearances in the cirrhotic liver and can resemble hypovascular hepatocellular carcinoma or other neoplasms on CT and MR imaging. Although uncommon, this abnormality must be included in the differential diagnosis of focal liver lesions in patients with cirrhosis, particularly in patients with a history of substantial gastrointestinal bleeding. Serial imaging may help differentiate these lesions from malignant tumors.     

Evaluation of the usefulness of ultrasonics in the diagnosis of cancerous cirrhosis. Comparison with CT

Cirrhotic liver hepatocellular carcinoma (HCC) was evaluated with both US and CT. In a group of 600 cirrhotic patients 64 had HCC, which was confirmed at histology in 24 cases, and by disease evolution in the other 40; single focal degeneration was proven in 40 patients, multiple (2, 3 focal lesions), or diffuse degeneration (more than 3 focal lesions) in the remaining 24. Sixteen patients had associated portal thrombosis. US recognized 38/40 single HCC, 22/24 multiple or diffuse lesions, and 11/16 portal vein thromboses. Degeneration was most frequently hypo/isoechoic in small tumors, hyperechoic and mixed in large lesions. When small lesions are hyperechoic their differentiation from both hemangiomas and regeneration noduli is extremely difficult. In such cases CT is mandatory. US diagnostic accuracy is by far superior to that of CT: 95% vs 85% in single lesions and 91.6% vs 87.5% in diffuse forms. Overall accuracy is 93.7% for US and 85.9% for CT. The authors believe that US should be performed every 6 months on cirrhotic patients, so as to allow HCC to be detected in time for radical surgery, while CT should be performed only when doubts persist.     

Pretransplantation diagnosis and staging of hepatocellular carcinoma in patients with cirrhosis: value of dual-phase helical CT

OBJECTIVE: The objective of our study was to prospectively evaluate the results of helical CT in the detection of hepatocellular carcinoma (HCC) in patients with cirrhosis undergoing orthotopic liver transplantation. SUBJECTS AND METHODS. Eighty-five patients with cirrhosis were studied preoperatively with biphasic helical CT. Arterial, portal, and equilibrium phase images were obtained after injection of 170 mL of contrast material at 5 mL/sec. The prospective CT interpretation was compared with pathologic results on a lesion-by-lesion basis. RESULTS: Pathologic examination found 85 cases of HCC in 51 patients. Helical CT enabled a correct diagnosis of HCC in 67 of 85 lesions for a sensitivity of 78.8%. HCC nodules were hypervascular in the arterial phase and hypovascular in the equilibrium phase in 63.5% (54/85) of patients. The false-negative rate was 21% (n = 18), and the positive predictive value was 88%. We had nine false-positive findings (11.8%) related to hemangiomas, transient hepatic attenuation differences, and regenerative nodules. Helical CT detected 61% (23/38) of lesions smaller than 2 cm and 93.6% (44/47) of lesions 2 cm or larger. CONCLUSION: Helical CT is a useful preoperative imaging technique in cirrhotic patients who are candidates for orthotopic liver transplantation, although it is relatively insensitive for detection of small lesions (< 2 cm).     

Pseudotumoral presentation of nodular regenerative hyperplasia of the liver: Imaging in five patients including MR imaging

Nodular regenerative hyperplasia (NRH) of the liver is a condition characterized by multiple monoacinar regenerative nodules in the absence of fibrous septa. When these nodules become confluent they may be seen with sonography or CT. The appearance of these pseudotumoral pattern of NRH has been scarcely described with MRI. We present the imaging findings of five patients with NRH and a pseudotumoral form at sonography. Sonography depicted hyperechoic lesions in four patients and hypoechoic lesions in another. Computed tomography showed hypodense lesions with little contrast enhancement in two patients. Three patients showed subtle focal liver lesions on MRI: isointense in one, mildly hypointense in another, and minimally hyperintense in a patient with siderosis. The dynamic behavior at MRI was similar to the normal liver parenchyma. Hyperechoic lesions on sonography or hypodense lesions on CT, barely or not seen on MRI, can be indicative of NRH in an appropriate clinical setting.     

Hepatocellular carcinoma in cirrhotic patients: prospective comparison of US, CT and MR imaging

Objectives

To prospectively compare the diagnostic performance of ultrasound (US), multidetector computed tomography (MDCT) and contrast-enhanced magnetic resonance imaging (MRI) in cirrhotic patients who were candidates for liver transplantation.

Methods

One hundred and forty consecutive patients with 163 hepatocellular carcinoma (HCC) nodules underwent US, MRI and MDCT. Diagnosis of HCC was based on pathological findings or substantial growth at 12-month follow-up. Four different image datasets were evaluated: US, MDCT, MRI unenhanced and dynamic phases, MRI unenhanced dynamic and hepatobiliary phase. Diagnostic accuracy, sensitivity, specificity, PPV and NPV, with corresponding 95 % confidence intervals, were determined. Statistical analysis was performed for all lesions and for three lesion subgroups (<1 cm, 1-2 cm, >2 cm).

Results

Significantly higher diagnostic accuracy, sensitivity and NPV was achieved on dynamic + hepatobiliary phase MRI compared with US, MDCT and dynamic phase MRI alone. The specificity and PPV of US was significantly lower than that of MDCT, dynamic phase MRI and dynamic + hepatobiliary phase MRI. Similar results were obtained for all sub-group analyses, with particular benefit for the diagnosis of smaller lesions between 1 and 2 cm.

Conclusions

Dynamic + hepatobiliary phase MRI improved detection and characterisation of HCC in cirrhotic patients. The greatest benefit is for diagnosing lesions between 1 and 2 cm.

Key Points

? US, CT and MRI can all identify HCC in cirrhotic patients ? US has good sensitivity but suffers from false-positive findings ? Dynamic CT and MR have similar diagnostic performance for diagnosing HCC ? Dynamic + hepatobiliary phase MRI significantly improves detection and characterisation of HCC ? The greatest benefit is for the diagnosis of lesions between 1 and 2 cm     

Small nodule detection in cirrhotic livers: evaluation with US, spiral CT, and MRI and correlation with pathologic examination of explanted liver

PURPOSE: The purpose of this work was to evaluate the detection and characterization of nodules > or = 8 mm and small hepatocellular carcinomas (HCCs) in liver cirrhosis. METHOD: Pathologic examination and results of US, helical CT, and dynamic MRI with gadolinium were compared after orthotopic liver transplantation (OLT) of 43 cirrhotic patients. Nodules were classified as macroregenerative nodules (MRNs), borderline nodules (BNs), and HCC. RESULTS: Pathologic examination classified 69 nodules: 50 MRNs, 6 BNs, and 13 HCCs. Sensitivities of MRN, BN, and HCC detection were, respectively, for US imaging 2% (1/50), 33.3% (2/6), and 46.2% (6/13); for helical CT 2% (1/50), 50% (3/6), and 53.8% (7/13); and for MRI 42% (21/50), 50% (3/6), and 76.9% (10/13). MRI detected 21 MRNs. They presented on T1/T2-weighted images as hyperintense/hypointense (n = 8), hyperintense/isointense (n = 7), hypointense/hypointense (n = 4), hypointense/isointense (n = 1), and hypointense depicted only on echo planar imaging (n = 1). The three detected BNs were hyperintense/hypointense nodules. The 10 detected HCCs appeared hyperintense/isointense (n = 7), hyperintense/hypointense (n = 2), and hypointense/isointense (n = 1). None of the MRNs but eight HCCs and one BN were enhanced after gadolinium injection. CONCLUSION: Contrast-enhanced MRI is the most sensitive technique for detecting liver nodules. No MR signal intensity pattern characteristic of small HCCs enables differentiation from benign nodules, however. Gadolinium enhancement is the most sensitive and specific characteristic of HCC.     

Progression to hypervascular hepatocellular carcinoma: correlation with intranodular blood supply evaluated with CT during intraarterial injection of contrast material

PURPOSE: To analyze the correlation between intranodular blood supply of borderline lesions (ie, dysplastic nodules or hypovascular well-differentiated hepatocellular carcinoma [HCC] nodules) and their progression to hypervascular classic HCC in cirrhotic livers. MATERIALS AND METHODS: One hundred seventy-six borderline lesions seen at computed tomography (CT) during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) were evaluated in 49 patients with cirrhosis who underwent repeated CTAP and/or CTHA but no therapy. On the basis of CTAP findings, nodules were categorized as group A (showing almost the same portal venous supply as the surrounding liver), group B (showing decreased portal venous supply) or group C (showing partially absent portal venous supply); on the basis of CTHA findings, nodules were categorized as group I (showing almost the same arterial supply as the liver), group II (showing decreased arterial supply), or group III (showing partially increased arterial supply). RESULTS: Progression to classic HCC was observed in 29.4% of group A nodules, 53.9% of group B nodules, and 87.9% of group C nodules within 1,000 days; in 58.6% of group I nodules, 12.9% of group II nodules, and 92.2% of group III nodules within 730 days; and in 0% of nodules in group A and I, 28% of nodules in group B and/or II, and 88.7% of nodules in group C and/or III within 730 days. CONCLUSION: Evaluation of intranodular blood supply was valuable in predicting the prognosis in borderline lesions, except when only arterial blood supply was evaluated.     

超顺磁性氧化铁在肝脏局灶性病变中的定性研究

目的 探讨超顺磁性氧化铁（SPIO）增强MRI在肝脏局灶性病变的定性能力。材料与方法 43例怀疑肝占位者经常规MRI和Gd-DTPA增强后1－7后,行SPIO增强检查。其中31例经手术病理证实,12例经随访、实验室生化检查及临床资料证实。分析平扫MRI及SPIO增强后病灶的信号变化,并与Gd-DTPA动态增强结果相对照。结果 43例共12种病变、单发病灶21例,多病灶22例。包括原发性肝细胞肝癌22例,血管瘤5例,囊肿4例,转移性肝癌5例,肝硬化结节4例,局灶性结节增生（FNH）5例,其他病变6例。22例多发病灶中有8例合并1或2种病变。SPIO增强后,肝细胞肝癌T1WI为等或略高信号,T2WI为较高信号;血管瘤T1WI为较高信号,T2WI信号同平扫为高信号;囊肿T1WI、T2WI信号无改变;肝硬化结节T2WI为等信号同正常肝实质;FNH T2WI信号明显下降。其余病变的诊断SPIO增强不具有特征性,须与Gd-DTPA动态增强相结合。结论 SPIO具有一定的定性能力Gd-DTPA增强相结合,可帮助提高肝局灶性病变诊断和鉴别诊断的准确性。     

MRI对比噪声比对肝占位性病变微血管评估的价值

目的:研究肝良恶性病变微血管密度(MVD)与动态增强MRI对比噪声比(CNR)之间的联系,以建立通过MRl评估微血管分布的理论基础,为临床诊断治疗HCC提供依据.方法:115例肝细胞癌(HCC),6例肝细胞胆管细胞混合癌,14例胆管细胞癌,3例局灶性结节增生(FNH),2例肝腺瘤,4例坏死肝癌,3例慢性肝脓肿,3例凝固坏死,4例腺瘤样增生,2例血管平滑肌脂肪瘤,6例炎性假瘤,1例纤维炎性坏死结节,1例嗜酸性肉芽肿及1例神经纤维瘤.MRI检查后手术切除全部病灶,切除标本经CD34单克隆抗体免疫组化染色,计数MVD.测量痛灶信号强度SI灶,肝实质信号强度SI肝和背景噪声信号强度SI噪,分别计算各时相CNR=(SI灶-SI肝)/SI噪.按病灶直径＜3cm,＞3cm分组分别计算动态增强各时相病灶的对比噪声比(CNR),按病理诊断分组分别对动脉期、门脉期和平衡期CNR与病灶MVD计数行Pearson相关分析.HCC组按病灶最大径＜3cm和＞3cm分为两组.结果:两组HCC各时相CNR与MVD计数均有显著相关性(P＜0.05),但其余病变未显示明显相关.结论:MRI对比噪声比可用于评估HCC微血管密度,动态增强MRI对于显示HCC病灶具有重要作用.     

Double-contrast MRI (DC-MRI) in the study of the cirrhotic liver: utility of administering Gd-DTPA as a complement to examinations in which SPIO liver uptake and distribution alterations (SPIO-LUDA) are present and in the identification and characterisation of focal lesions

PURPOSE: The aim of this study was to compare the performance of double-contrast magnetic resonance imaging (DC-MRI) with the sequential use of superparamagnetic iron oxide (SPIO) and gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) contrast agents compared with unenhanced MRI and SPIO-enhanced MRI (SPIO-MRI) in the study of the cirrhotic liver. Special attention was paid to cases in which alterations of liver uptake and distribution of the SPIO contrast medium [SPIO-liver uptake and distribution alterations (SPIO-LUDA)] could lead to diagnostic errors at SPIO-MRI. MATERIALS AND METHODS: We used DC-MRI to study 67 patients suffering from hepatic cirrhosis and on a waiting list for liver transplant. The study was performed with a 1.5-Tesla device and characterised by three phases: the first phase without contrast material (unenhanced MRI), the second after the administration of ferumoxides (SPIO-MRI), and the third, a double-contrast study following the injection of a bolus of paramagnetic contrast material (DC-MRI). The sensitivity of unenhanced MRI, SPIO-MRI and DC-MRI in identifying and characterising hepatic focal lesions was assessed, together with the diagnostic increment of one technique with respect to the others. The gold standard was histological confirmation in 38 cases and clinical-radiological follow-up in all cases. Liver function, kidney function, blood tests and urinalysis were performed in all patients 24-48 h before and after the MRI examination. RESULTS: In 14/67 cases (20.8%), SPIO-LUDA were present, which posed a limitation to the SPIO-MRI examination. Focal lesions were absent in 44 patients, and the action of the ferumoxides was reduced by the presence of SPIO-LUDA in nine cases. There were five cases of confluent fibrosis, two of decompensated cirrhosis, one of vascular thrombosis, and one of scarring in a patient who had undergone hepatic resection for hepatocellular carcinoma (HCC). In all these cases, completion of the MR examination with the DC technique clarified the MR picture, confirming the absence of focal lesions. Twenty-three patients had a total of 68 lesions, which consisted of 37 dysplastic nodules (DN), 19 HCC nodules, two relapses of HCC following chemoembolisation, two HCC associated with portal thrombosis, one cancer-cirrhosis, two angiomas and five small cysts. SPIO-LUDA were present in five patients, thus limiting the identification, characterisation or assessment of the real size of the lesions. SPIO-LUDA were the result of vascular thrombosis in one case and fibrosis in four cases. In all of these cases, DC-MRI proved useful for diagnosis. The sensitivity of unenhanced MRI, SPIO-MRI and DC-MRI for lesion detection was 57.3%, 67.6% and 75%, respectively. The results obtained in the characterisation of the lesions were 20.5%, 63.2% and 73.5% for unenhanced MRI, SPIO-MRI and DC-MRI, respectively. The diagnostic increment of SPIO-MRI over unenhanced MRI for lesion identification and characterisation was 9% and 42.7%, respectively, whereas the diagnostic increment of DC-MRI over SPIO-MRI was 7.4% and 10.3%, respectively. CONCLUSIONS: In our study, the combined use of two contrast agents, negative and positive, provided greater diagnostic confidence and caused no side effects in the patients.     

菲立磁增强MRI检测肝脏占位病变与三期动态增强CT扫描的比较研究

目的　比较菲立磁增强MRI和增强CT扫描在肝脏实性占位病变检测中的应用价值。方法　对 18例肝内局灶性占位患者行MR平扫及菲立磁增强扫描。观察肝脏与病灶信号强度变化 ,形态及数目 ,比较增强前后T2 WI病灶及肝脏的信噪比 (SNR)及对比噪声比 (CNR) ,做出MRI定性诊断 ,并与增强CT扫描诊断进行比较。其中肝细胞肝癌 4例 ,复发性肝癌 4例 ,转移瘤 4例 ,肝血管瘤 6例。结果　菲立磁增强明显降低正常肝组织信号强度 ,而恶性肿瘤的信号强度无强化 ,病灶—肝脏信噪比增加可清晰显示病变 ,并发现新病灶。肝血管瘤的血池效应与增强CT扫描比较有鉴别诊断意义。结论　做为增强CT扫描和Gd -DTPAMR增强的补充方法 ,SPIO增强MRI对肝脏占位病变的显示 ,小病灶发现和定性诊断中有重要的临床意义     

Cirrhosis: CT and MR imaging evaluation

In this article, we present the CT and MR imaging characteristics of the cirrhotic liver. We describe the altered liver morphology in different forms of viral, alcoholic and autoimmune end-stage liver disease. We present the spectrum of imaging findings in portal hypertension, such as splenomegaly, ascites and varices. We describe the patchy and lacelike patterns of fibrosis, along with the focal confluent form. The process of hepatocarcinogenesis is detailed, from regenerative to dysplastic nodules to overt hepatocellular carcinoma. Different types of non-neoplastic focal liver lesions occurring in the cirrhotic liver are discussed, including arterially enhancing nodules, hemangiomas and peribiliary cysts. We show different conditions causing liver morphology changes that can mimic cirrhosis, such as congenital hepatic fibrosis, "pseudo-cirrhosis" due to breast metastases treated with chemotherapy, Budd-Chiari syndrome, sarcoidosis and cavernous transformation of the portal vein.     

Focal lesions in the cirrhotic liver: high resolution ex vivo MRI with pathologic correlation

Cirrhosis is a progressive, diffuse process of liver fibrosis that is characterized by architectural distortion and the development of a spectrum of nodules ranging from benign regenerative nodules to premalignant dysplastic nodules to overtly malignant hepatocellular carcinoma. The purpose of this essay is to demonstrate the ex vivo MR and pathology findings of these nodules as well as other masses that can be seen in the cirrhotic liver. The optimal conditions under which ex vivo imaging can be performed allow greater spatial resolution than that achieved with in vivo imaging, without artifacts that may degrade image quality. Clearly, contrast-enhanced MRI is essential for both the diagnosis and the characterization of focal lesions in the cirrhotic liver. However, the use of ex vivo imaging precludes the evaluation of these important in vivo pulse sequences.