HBV相关肝硬化结节演变的多模态MRI研究

目的:通过与病理结果进行对照分析,总结肝硬化再生结节多步演变的多模态MRI影像特征,探讨肝硬化再生结节的早期诊断及鉴别诊断价值.方法:搜集乙肝肝硬化患者50例(85个结节),回顾性分析其MRI平扫及增强扫描资料,对病理证实的多步演变结果与对应的MRI影像表现进行对照研究.结果:MRI检出82个结节,检出率为96.5％,T2 WI和动态增强扫描是检测再生结节较敏感的序列,检出率分别为93.9％和96.3％,磁敏感成像(SWI)的检出率稍低(69.5％);再生结节(RN)与低级不典型增生结节(LGDN)(x2=8.348,P=0.004)、高级不典型增生结节(HGDN)与肝细胞癌(HCC)(x2=4.612,P=0.032)的MRI诊断符合率差异均有统计学意义.T1WI图像上LGDN的信噪比(SNR)值与RN、HGDN、HCC比较差异均有统计学意义(P值均＜0.05);T2 WI图像上HCC的SNR值与RN、LGDN、HGDN比较差异均有统计学意义(P值均＜0.05).结论:MRI是目前检测肝硬化结节最敏感的无创性检查方法,通过MRI与病理的对照分析,多模态序列从不同角度反映了肝硬化再生结节的影像学特征及演变规律,对肝硬化再生结节的诊断及鉴别诊断具有一定价值.     

3D T1WI/TFE序列在肝硬化增生结节诊断中的应用

目的：探讨MRI中三维T1加权成像梯度回波(3DT1WI／TFE)序列在肝硬化结节诊断中的价值。方法：对临床疑肝硬化和／或经Cr及超声检查后诊断为肝硬化33例进行MRI3DT1WI／TFE序列扫描检查，分析肝硬化结节在该序列中的特点。结果：33例中，无增生结节的肝硬化7例，肝硬化合并增生结节6例，肝硬化并肝癌20例。肝硬化结节在3DT1WI／TFE上呈高信号，在T2WI上呈低信号，在静脉动态增强中肝硬化结节与正常肝实质同步强化。而肝硬化并肝癌在3DT1WI／TFE上呈低信号，在T2WI上呈高信号，在静脉动态增强中表现为“快进快出”的特性。结论：MRI中3DT1WI／TFE序列在肝硬化检查中，能很好的显示肝内增生结节，并且可与结节性肝癌进行鉴别。图像质量高，能够满足临床的诊断需要。     

钆塞酸二钠磁共振增强成像对肝硬化结节及小肝癌的诊断评价

目的探讨钆塞酸二钠(Gd-EOB-DTPA)增强肝胆期对肝硬化结节及小肝癌的诊断价值。方法对75例(89个病灶)经病理学或临床证实的肝硬化伴肝内结节病变患者行GD-EOB-DTPA增强检查,将全部患者图像分为无肝胆期组和有肝胆期组即在无肝胆期组基础上增加肝胆期图像,对比肝硬化结节与小肝癌的信号及强化类型特点。结果 89个病灶中(21个肝硬化结节、68个小肝癌),有肝胆期组诊断的灵敏度、特异度、阴性预测值、阳性预测值以及诊断符合率分别为98.53%、90.48%、97.10%、95.00%以及96.63%,其灵敏度、阴性预测值和诊断符合率均明显高于无肝胆期组(P0.05)。结论 Gd-EOB-DTPA磁共振增强肝胆期对肝硬化结节及小肝癌的检出及定性有一定优越性,有较高的诊断价值。     

钆塞酸二钠增强MRI检查在小肝癌临床诊断中的应用价值

目的 评价Gd-EOB-DTPA MRI检查中肝胆管期对定期复查肝硬化患者检出小肝癌的临床诊断价值.方法 33例肝硬化患者分别进行超声增强检查、Gd-EOB-DTPA增强MRI检查和64排螺旋CT检查共检测出48枚肝脏小结节(直径为10～30 mm),全程使用盲法,以2005年美国肝脏病研究协会标准为诊断标准.结果 48枚肝脏小结节中,38枚(79.2％)被诊断为肝细胞癌,MRI检查中30枚(78.9％)符合典型血管强化征象(快进快出),CT检查有22枚(57.9％),增强超声检查有17枚(44.7％).所有38枚肝细胞癌和3枚良性结节在肝胆管期显示低信号(敏感性100％,特异性70％,阳性预测值93％,阴性预测值100％,阳性似然比3.33,阴性似然比0).38枚肝细胞癌结节中,有7枚在各影像学检查中均不显示典型血管强化征象,有8枚(21.1％)显示为门静脉期廓清,MR肝胆管期低信号征象,此征象未见于良性病变中.结论 Gd-EOB-DTPA MRI检查能提高定期复查的肝硬化患者小肝癌检出的敏感性.门静脉期/静脉期低信号,肝胆管期低信号可以作为MRI最新诊断征象,特别是对乏血供肝细胞癌的检出.     

乙型肝炎肝硬化背景下小肝癌的CT平扫、增强扫描与MRI平扫、DWI表现分析

目的 :分析乙型肝炎肝硬化背景下小肝癌的CT平扫、增强扫描与MRI平扫、DWI的表现。方法 :选取经组织病理学确诊的乙肝肝硬化背景下的小肝癌65例共74个肿瘤病灶,比较CT平扫、CT增强扫描、MRI平扫、DWI对小肝癌总的检出率、不同直径小肝癌的检出率及包膜显示率。结果:CT平扫对病灶检出率为64.86%;CT增强扫描动脉期、门静脉期、延迟期对病灶检出率分别为85.14%、68.92%、72.97%;MRI平扫对病灶检出率为86.49%;DWI为93.24%。各种方法对小肝癌病灶检出率的差异有统计学意义(P0.001)。CT平扫、CT增强扫描、MRI平扫、DWI对包膜的显示率分别为40.54%、59.46%、71.62%、97.30%,差异有统计学意义(P0.001)。CT增强扫描动脉期、门静脉期、延迟期对直径≤1 cm的小肝癌检出率均低于对直径1~3 cm小肝癌的检出率(均P0.05)。结论:DWI对小肝癌的检出率和包膜显示率最高,且CT增强扫描更易检出直径1~3 cm的病灶。     

肝硬化合并肝癌与肝硬化再生结节螺旋CT双期扫描影像分析

目的:分析肝硬化合并肝癌与肝硬化再生结节螺旋CT双期扫描的影像表现并评价其诊断价值.方法:回顾性分析30例肝硬化合并小肝癌,28例肝硬化再生结节螺旋CT平扫、动脉期、门脉期的CT征象.扫描层厚5～10 mm,对比剂为60%的有机碘水溶液,用高压注射器静脉团注,注射流率3 ml/s,总量80～100 ml.动脉期扫描为注射开始后25～30 s,门静脉期为60～70 s.结果:小肝癌平扫多数为低密度,少数为等密度,动脉期全瘤范围强化,其强化密度高于肝但低于同层主动脉,门脉期肿瘤密度从高于肝迅速降至低于肝,同时也低于同层主动脉密度.肝硬化再生结节表现为平扫一般为等密度或稍高密度,动脉期大多数再生结节不强化或呈低密度,极少有轻度强化,门静脉期再生结节多数为均匀强化,少数为低密度.结论:螺旋CT增强双期扫描对肝硬化合并小肝癌具有诊断意义,特别是与肝硬化再生结节的鉴别诊断具有重要意义.     

1.5T磁共振成像在肝脏小结节性病变定性诊断中的价值简

肝内小结节是指单个病灶最大直径＜3 cm,或2个结节最大径之和＜3 cm的病变,最常见的为在乙型肝炎肝硬化基础上形成的增生性肝内结节,继而恶变形成的小肝癌,少部分为良性再生性结节和少见的肿瘤类型,如原发肝脏的淋巴瘤,胆管细胞癌及纤维板层细胞癌等,如何早期发现并鉴别诊断增生性结节和肝脏恶性肿瘤,是提高肝癌生存率的主要方法,高场强磁共振成像（MRI）在肝内结节定性诊断中明显优于其他影像学检查,本文运用1．5T MRI平扫及动态增强对40例肝内小结节性占位病变进行分析,并与病理结果对比,评价1．5T MRI 在肝脏小结节性病变定性诊断中的价值。     

肝硬化相关结节的MRI研究与进展

肝硬化结节癌变经历再生结节、低级别不典型增生结节、高级别不典型增生结节到小肝癌,是一个多步骤的过程,其演变过程中重要的特征是血流动力学的改变.早期诊断和鉴别这些不同性质的肝硬化结节非常重要,MRI作为无创性的影像学方法,在肝硬化相关结节的诊断中起着重要作用,就肝硬化相关结节的MRI的研究进展予以综述.     

肝硬化再生结节和退变结节的MRI表现：初步研究结果

目的研究肝硬化再生结节和退变结节的MRI表现.资料与方法前瞻性地研究26例肝硬化再生结节和退变结节的MRI表现,其中合并肝癌8例.26例中有12例行CT平扫,6例行CT增强扫描;26例均行MRI平扫,18例行Gd-DTPA增强MRI,10例行超顺磁性氧化铁(菲立磁)增强MVI.临床实验室检查中,除8例合并有肝癌的患者甲胎蛋白显著增高外,其余18例甲胎蛋白均正常.结果26例中12例结节灶直径＜1 cm，8例在1～3 cm，6例＞3 cm.MRI表现：12例直径＜1 cm的结节灶在T1WI呈等信号，T2WI呈低信号，Gd-DTPA和菲立磁增强与正常肝实质呈同步强化，在CT上呈高密度改变.结节灶直径1～3 cm的8例中,5例结节在T1WI呈高信号,T2WI呈低信号,强化同前;另3例在T1WI呈低信号的结节,在T2WI呈高信号,其强化与正常肝实质不同步,在菲立磁增强扫描中呈高信号;CT平扫均呈等密度.6例直径＞3 cm的结节中2例在T1WI、T2WI均呈等高信号,菲立磁增强扫描呈高信号,Gd-DTPA增强MRI示巨大结节较周围邻近正常肝组织信号高;4例在T1WI呈高信号,在T2WI呈低信号，菲立磁增强扫描呈低信号,Gd-DTPA增强扫描巨大结节无强化，较周围邻近正常肝组织信号低,有时可见血管经过巨大结节表面.CT显示6例呈等或稍高密度.在MRI上可见1例“结中结”征.结论肝硬化再生结节在MRI上能较好地与肝细胞癌鉴别,但较难与退变结节鉴别.退变结节在T2WI不呈高信号,而肝细胞癌呈高信号,以此可作区别.此外,良性退变结节菲立磁增强T2WI呈低信号.     

磁敏感加权成像在肝硬化结节多步癌变中的临床应用

目的探讨磁敏感加权成像在肝硬化结节多步癌变中的临床应用,旨在能够更早发现癌前病变、小肝癌。方法回顾性分析经病理、手术证实的45例肝硬化患者结节的MRI平扫、增强及DWI、SWI图像,分析不同性质结节的信号变化。结果所有序列共检出结节76个,其中43个RN(SWI呈低信号43个),21个DN(SWI呈低信号15个、呈高信号6个),12个s HCC(SWI呈高信号11个、呈低信号1个)。结论 SWI可以从不同性质结节内铁含量变化的角度进行评价,为癌前病变与小肝癌的进一步鉴别诊断提供新的影像依据。     

Benign versus malignant hepatic nodules: MR imaging findings with pathologic correlation.

According to the currently used nomenclature, there are only two types of hepatocellular nodular lesions: regenerative lesions and dysplastic or neoplastic lesions. Regenerative nodules include monoacinar regenerative nodules, multiacinar regenerative nodules, cirrhotic nodules, segmental or lobar hyperplasia, and focal nodular hyperplasia. Dysplastic or neoplastic nodules include hepatocellular adenoma, dysplastic foci, dysplastic nodules, and hepatocellular carcinoma (HCC). Many of these types of hepatic nodules play a role in the de novo and stepwise carcinogenesis of HCC, which comprises the following steps: regenerative nodule, low-grade dysplastic nodule, high-grade dysplastic nodule, small HCC, and large HCC. State-of-the-art magnetic resonance (MR) imaging facilitates detection and characterization in most cases of hepatic nodules. State-of-the-art MR imaging includes single-shot fast spin-echo imaging, in-phase and opposed-phase T1-weighted gradient-echo imaging, T2-weighted fast spin-echo imaging with fat saturation, and two-dimensional or three-dimensional dynamic multiphase contrast material-enhanced imaging.     

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.     

Hepatocellular carcinoma in the cirrhotic liver with helical CT and MRI: imaging spectrum and pitfalls of cirrhosis-related nodules

OBJECTIVE: This article reviews the imaging spectrum of cirrhosis-related nodules on CT and MRI and differentiates between hepatocellular carcinoma (HCC) and common focal lesions that can simulate HCC in the cirrhotic liver. CONCLUSION: Knowledge of cirrhotic nodules and focal lesions and how they mimic HCC will improve the diagnosis and characterization of focal lesions in cirrhotic liver on CT and MRI.     

Method for simultaneous voxel-based morphometry of the brain and cervical spinal cord area measurements using 3D-MDEFT

Purpose:

To develop a quantitative multiparametric PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) magnetic resonance imaging (MRI) approach and its application in a diethylnitrosamine (DEN) chemically induced rodent model of hepatocarcinogenesis for lesion characterization.

Materials and Methods:

In nine rats with 33 cirrhosis‐associated hepatic nodules including regenerative nodule (RN), dysplastic nodule (DN), hepatocellular carcinoma (HCC), and cyst, multiparametric PROPELLER MRI (diffusion‐weighted, T2/M0 (proton density) mapping and T1‐weighted) were performed. Apparent diffusion coefficient (ADC) maps, T2 and M0 maps of each tumor were generated. We compared ADC, T2, and M0 measurements for each type of hepatic nodule, confirmed at histopathology.

Results:

PROPELLER images and resultant parametric maps were inherently coregistered without image distortion or motion artifacts. All types of hepatic nodules demonstrated complex imaging characteristics within conventional T1‐ and T2‐weighted images. Quantitatively, cysts were distinguished from RN, DN, and HCC with significantly higher ADC and T2; however, there was no significant difference of ADC and T2 between HCC, DN, and RN. Mean tumor M0 values of HCC were significantly higher than those of DN, RN, and cysts.

Conclusion:

This study exploited quantitative PROPELLER MRI and multidimensional analysis approaches in an attempt to differentiate hepatic nodules in the DEN rodent model of hepatocarcinogenesis. This method offers great potential for parallel parameterization during noninvasive interrogation of hepatic tissue properties. J. Magn. Reson. Imaging 2010;31:1242–1251. © 2010 Wiley‐Liss, Inc.     

Invited. Hepatitis,cirrhosis, and hepatoma

Virus hepatitis and liver cirrhosis are found at high incidence in Asia, and they require not only biochemical examination of blood but also subsequent imaging, because they are often complicated by hepatocellular carcinoma (HCC). It is, therefore, very important to know the specific appearances of hepatitis, liver cirrhosis, and HCC when we diagnose these diffuse liver diseases. Liver necrosis due to severe hepatitis is seen as high intensity on T2-weighted spin echo images. Regeneration is seen as low intensity on T2-weighted images. Morphologic and pathologic changes of cirrhotic liver are well demonstrated by MR imaging techniques. Fibrotic septum with inflammatory cell infiltration or rich pseudo bile duct show high intensity on T2-weighted images, and regenerating nodules shows low intensity. Gradient echo images show regenerating nodules with iron deposition as low-intensity nodules due to susceptibility artifact. MRI also has the potential to evaluate function of diffuse liver disease, cirrhosis, and hepatitis. MRI can visualize and diagnose HCC objectively. Dynamic MRI is very useful for diagnosing HCC. It is also applied for evaluation of effect after transcatheter arterial chemoembolization, because it shows enhancement only in the viable region at an arterial phase. MRI is less invasive and is thus an extremely important form of liver imaging.     

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.     

Arterial enhancing‐only nodules less than 2 cm in diameter in patients with liver cirrhosis: Predictors of hepatocellular carcinoma diagnosis on gadobenate dimeglumine‐enhanced mr imaging

Purpose:

To assess whether gadobenate dimeglumine (Gd‐BOPTA)‐enhanced MR imaging could predict hepatocellular carcinoma (HCC) diagnosis in small arterial enhancing‐only nodules detected by contrast‐enhanced computed tomography (CT) in patients with liver cirrhosis.

Materials and Methods:

We prospectively recruited 125 cirrhotic patients (67 males, and 58 females; age: 68 ± 12.36 years) with 151 small (<2 cm in diameter) arterial enhancing‐only nodules identified by contrast‐enhanced CT. All patients were scanned by MR imaging before and after Gd‐BOPTA injection during the hepatic arterial phase (HAP), portal venous phase (PVP), equilibrium phase (EP), and hepatobiliary phase (HP). Nodule characterization was based on reference imaging criteria (n = 29 nodules), follow‐up (n = 105), or histology (n = 17). Two radiologists (5 and 10 years experience) analyzed the MR images, and logistic regression was conducted to assess how well MR imaging findings could predict HCC diagnosis.

Results:

Final diagnoses included 115 benign nodules and 36 HCCs. Nodule T2 hyperintensity, T1 hypointensity, PVP‐EP hypointensity, and HP hypointensity were the best predictors of HCC on univariate analysis. Nodule T2 hyperintensity, T1 hypointensity, and HP hypointensity, were independent predictors of HCC on multivariate analysis.

Conclusion:

Gd‐BOPTA‐enhanced MR imaging provides imaging findings which may predict a diagnosis of HCC in small arterial enhancing‐only nodules in cirrhotic patients. J. Magn. Reson. Imaging 2013;37:892–902. © 2012 Wiley Periodicals, Inc.     

MR Imaging of hepatocellular carcinoma in the cirrhotic liver: challenges and controversies

The incidence of hepatocellular carcinoma (HCC) is expected to increase in the next 2 decades, largely due to hepatitis C infection and secondary cirrhosis. HCC is being detected at an earlier stage owing to the implementation of screening programs. Biopsy is no longer required prior to treatment, and diagnosis of HCC is heavily dependent on imaging characteristics. The most recent recommendations by the American Association for the Study of Liver Diseases (AASLD) state that a diagnosis of HCC can be made if a mass larger than 2 cm shows typical features of HCC (hypervascularity in the arterial phase and washout in the venous phase) at contrast material-enhanced computed tomography or magnetic resonance (MR) imaging or if a mass measuring 1-2 cm shows these features at both modalities. There is an ever-increasing demand on radiologists to detect smaller tumors, when curative therapies are most effective. However, the major difficulty in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. The authors present a review of the MR imaging and pathologic features of regenerative nodules and dysplastic nodules and focus on HCC in the cirrhotic liver, with particular reference to small tumors and lesions that may mimic HCC. The authors also review the sensitivity of MR imaging for the detection of these tumors and discuss the staging of HCC and the treatment options in the context of the guidelines of the AASLD and the imaging criteria required by the United Network for Organ Sharing for transplantation. MR findings following ablation and chemoembolization are also reviewed.     

Siderotic nodules at MR imaging: regenerative or dysplastic?

OBJECTIVE: To determine if iron containing "siderotic" nodules detected at magnetic resonance (MR) imaging are regenerative (RN) or dysplastic (DN) and to attempt to identify features that may distinguish them. MATERIAL AND METHODS: MR imaging (1.5 T) was performed on 77 cirrhotic patients who underwent orthotopic liver transplantation within 0-117 days (mean 30 days) of MR imaging. Two readers retrospectively evaluated breath-hold gradient-echo pulse sequences (echo time > or =9.0 ms, flip angle < or =45 degrees) for the presence of hypointense nodules, which were classified as micronodular (< or =3 mm), macronodular (>3 mm), or mixed. Nodule distribution was classified as focal (<5), scattered (5-20), or diffuse (>20) per slice. Thin section pathologic correlation was available in all cases, and Prussian blue iron stains were performed. RESULTS: Of 35 patients with pathologically proven siderotic nodules, 10 (29%) had at least 2 siderotic DN. MR detected siderotic nodules in 10 of 10 (100%) patients with siderotic DN and RN, and in 18 of 25 patients (72%) with siderotic RN only. CONCLUSION: Siderotic RN cannot be reliably distinguished from siderotic DN with MR imaging, and therefore the widely used term "siderotic regenerative nodule" should be avoided and replaced by "siderotic nodule."