MRI对肝硬化伴肝癌和非典型性结节诊断的敏感性观察

 目的探讨MRI对肝硬化伴肝癌和非典型性结节的敏感性.方法74例肝硬化患者肝移植前90d内行MRI检查,并同肝移植术后病理切片作对照.所有患者检查前均不知其有无肝癌,FLASH/T1WI、TSE/T2WI序列、动态3期增强扫描被获得.结果病理发现13例患者共21处肝脏有恶性病变,MRI发现其中12/21个恶性病变,敏感性为57.1%,其中发现87.5%(7/8)≥2cm的病变,44.4%(4/9)1～2cm的病变,25.0%(1/4)＜1 cm的病变;对≥2cm和＜2cm组的恶性病变的差异有统计学意义(P＜0.05).病理检查发现14例患者(14/74)共47个DN,MRI诊断9/47个DN病变,敏感性仅19.1%.结论MRI对肝硬化伴＞2cm的肝癌敏感性较好,但对＜2cm的肝癌及非典型性结节敏感性较差.     

The multistep process of hepatocarcinogenesis in cirrhosis with imaging correlation

Hepatocarcinogenesis in the cirrhotic liver has recently become a subject of intense investigation. The development of hepatocellular nodules demonstrating varying degrees of cellular and architectural atypia suggests that these nodular lesions represent a pathway of carcinogenesis in cirrhosis of different etiologies. This pathway involves processes, such as capillarization and neoangiogenesis, leading to a gradual change in blood supply from portal to arterial, as a dysplastic nodule becomes hepatocellular carcinoma. These changes in intranodular blood supply create different enhancement patterns in the two phases of liver circulation after an intravenous contrast injection on multi-phase helical CT or dynamic gadolinium-enhanced MRI. This article reviews the current concepts regarding the vascular changes occurring in dysplastic nodules in the multistep process of hepatocarcinogenesis, along with the associated imaging manifestations. Some practical issues and dilemmas regarding the follow-up and biopsy of these lesions are also discussed.     

Hyperintense nodules on non-enhanced T1-weighted gradient-echo magnetic resonance imaging of cirrhotic liver: fate and clinical implications

PURPOSE: To investigate the fate of hyperintense hepatic nodules on nonenhanced T1-weighted (T1w) gradient-echo (GRE) magnetic resonance (MR) images in cirrhotic patients. MATERIALS AND METHODS: A total of 79 cirrhotic patients with hyperintense nodules (>5 mm) on precontrast opposed-phase (repetition time (TR)/echo time (TE) = 140/2.7 msec) GRE images from initial MRI without T2-weighted (T2w) hyperintensity or arterial hypervascularity were subjected to analysis of subsequent MR images obtained at intervals of 12-56 months (mean = 24.5 months). Multiplicity of hyperintense nodules (group A, up to 8; group B, >8) was correlated with follow-up changes. RESULTS: Group B patients were younger (P = 0.003) than group A patients (mean = 47.5 and 56.2 years, respectively). In 66 group A patients, 39 out of 143 lesions (27%) were enlarged, including 20 malignantly transformed or borderline lesions. Of the 104 lesions (the eight largest lesions in each patient) in 13 group B patients, only three (2.9%) were enlarged. The results of best- and worst-case analyses showed that overall the lesions were benign in 91% and 82% of patients, respectively. CONCLUSION: T1w hyperintense nodules without T2w hyperintensity or arterial hypervascularity in the cirrhotic liver are benign in most cases. In younger patients with numerous macronodules, almost all of these lesions follow a benign course.     

Detection of hepatocellular carcinoma by ferumoxides-enhanced MR imaging in cirrhosis: Incremental value of dynamic gadolinium-enhancement

PURPOSE: To investigate the incremental value of dynamic gadolinium-enhancement performed immediately after ferumoxides-enhanced magnetic resonance (MR) imaging on the detection of hepatocellular carcinoma in patients with cirrhosis. MATERIALS AND METHODS: We retrospectively reviewed MR scans of 62 cirrhotic patients over a two-year period. Sequences included ferumoxides-enhanced T2-weighted fast spin echo followed by dynamic gadolinium-enhanced T1-weighted spoiled gradient echo. Two readers independently documented the presence of hepatocellular carcinoma on a three-point confidence scale, without and with gadolinium-enhanced images. The presence or absence of hepatocellular carcinoma was established by histopathology (58 patients) or follow-up imaging (four patients) over a mean period of nine months. RESULTS: A total of 71 hepatocellular carcinomas were found in 42 patients. There was no statistically significant difference in sensitivity for the diagnosis of hepatocellular carcinoma without vs. with gadolinium-enhanced images (68% vs. 74% for reader 1 and 62% vs. 73% for reader 2, respectively, P > 1.3). However, both readers showed a lower mean confidence for tumor detection without vs. with gadolinium-enhanced images (2.3 vs. 2.7 for reader 1, 2.3 vs. 2.9 for reader 2, P < 0.01). CONCLUSION: In our study, the addition of dynamic gadolinium-enhancement to ferumoxides-enhanced MR imaging did not improve hepatocellular carcinoma detection, but the addition of gadolinium-enhancement is recommended if ferumoxides-enhanced imaging is used because it increased reader confidence.     

Three-dimensional dynamic liver MR imaging using sensitivity encoding for detection of hepatocellular carcinomas: comparison with superparamagnetic iron oxide-enhanced mr imaging

PURPOSE: To assess the diagnostic performance of three-dimensional dynamic liver imaging with sensitivity encoding (SENSE), including double arterial phase images and increased resolution, by comparing it to superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging for the detection of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty-seven consecutive patients with 50 HCCs underwent Gd-BOPTA-enhanced dynamic imaging using SENSE and SPIO-enhanced MR imaging with at least a 24-hour interval between examinations. Using a three-dimensional gradient-echo technique applying SENSE, dynamic imaging consisting of double arterial phase-, portal phase- and delayed phase-images, was obtained. Using T2-weighted turbo spin-echo and T2*-weighted fast imaging with steady-state precession sequence, SPIO-enhanced MR imaging was obtained. For qualitative analysis, the diagnostic accuracy of both MR examinations for detecting the 50 HCCs was evaluated using the alternative free-response receiver operating characteristic method. Sensitivity and positive predictive value were also evaluated. RESULTS: The mean sensitivity and positive predictive value of three-dimensional dynamic imaging with SENSE were 91.3% and 89.2%, respectively, and those of SPIO-enhanced imaging were 77.3% and 92.6 %, respectively. There was a significant difference in sensitivity between the two images (P <0.05). The mean Az value of three-dimensional dynamic imaging with SENSE (0.97 +/- 0.01) was significantly higher than that of SPIO-enhanced imaging (0.90 +/- 0.02) (P=0.00). CONCLUSION: Three-dimensional dynamic liver MR imaging using SENSE for acquiring double arterial phase images is more efficient than SPIO-enhanced MR imaging for detecting HCCs.     

Stepwise carcinogenesis of hepatocellular carcinoma in the cirrhotic liver: demonstration on serial MR imaging

PURPOSE: To demonstrate imaging findings of stepwise carcinogenesis of hepatocellular carcinoma (HCC) in cirrhosis at serial state-of-the-art MR imaging exams. MATERIALS AND METHODS: In a retrospective search of the hospital archives, three patients were identified in which developing HCC was observed in serial MR examinations, with histopathology or alpha-fetoprotein (AFP) correlation. Image findings were assessed for signal intensity of the lesions at multiple sequences, including dynamic gadolinium-enhanced imaging. RESULTS: Initial findings in patient A showed a small nodule with fatty infiltration that developed in HCC in follow-up MRI, comprised of low-grade dysplastic nodule (DN; DN I), high-grade DN (DN II), and eventually classic HCC. In patient B, increased signal intensity on T2-weighted images in a single DN among numerous regenerative nodules was the only initial sign. Follow up MRI showed further increase in signal intensity and increased neovascularity, which suggested focal HCC in a DN II. Patient C demonstrated gradually increasing neovascularity as only initial sign, with development of classic HCC over time. CONCLUSION: MR imaging provides insight in various pathways of stepwise carcinogenesis of developing HCC in cirrhosis. This may further explain the genetic heterogeneity, and may facilitate early detection and better selection of patients for follow-up.     

Chronic hepatitis: role of diffusion-weighted imaging and diffusion tensor imaging for the diagnosis of liver fibrosis and inflammation

PURPOSE: To determine the diagnostic performance of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation. MATERIALS AND METHODS: Breathhold single-shot echo-planar imaging CDI and DTI with b-values of 0 and 500 second/mm(2) was performed in 31 patients with chronic liver disease and 13 normal volunteers. Liver biopsy was performed in all patients with liver disease with a median delay of two days from MRI. Fibrosis and inflammation were scored on a 5-point scale (0-4). Liver ADCs obtained with CDI and DTI were compared between patients stratified by fibrosis stage and inflammation grade. Receiver operating characteristic (ROC) curve analyses were conducted to evaluate the utility of the ADC measures for prediction of fibrosis and inflammation. RESULTS: Patients with liver fibrosis and inflammation had significantly lower liver ADC than subjects without fibrosis or inflammation with CDI and DTI. For prediction of fibrosis stage > or = 1 and stage > or = 2, area under the ROC curve (AUC) of 0.848 and 0.783, sensitivity of 88.5% to 73.7%, and specificity of 73.3% to 72.7% were obtained, for ADC < or =1.40 x 10(-3) mm(2)/second and < or =1.30 x 10(-3) mm(2)/second (using CDI), respectively. For prediction of inflammation grade > or = 1, AUC of 0.825, sensitivity of 75.0%, and specificity of 78.6% were obtained using ADC < or = 1.30 x 10(-3) mm(2)/second (using CDI). CDI performed better than DTI for diagnosis of fibrosis and inflammation. CONCLUSION: Liver ADC can be used to predict liver fibrosis and inflammation with acceptable sensitivity and specificity.     

肝硬化胆囊改变的影像学评估

胆囊改变是肝硬化较为常见的肝外影像征象,近年来研究表明其与肝硬化临床Child-Pugh分级、肝纤维化等存在相关性,对于肝硬化的临床诊断、指导治疗、疗效评估及预后有着一定的价值。从肝硬化病人胆囊的位置、形态、功能及结石形成等多方面综述述其发病机制、影像学评估及其临床意义。     

Improving detection of siderotic nodules in cirrhotic liver with a multi-breath-hold susceptibility-weighted imaging technique

Purpose:

To evaluate the role of abdominal susceptibility‐weighted imaging (SWI) in the detection of siderotic nodules in cirrhotic liver.

Materials and Methods:

Forty patients with pathologically identified liver cirrhosis and 40 age/sex‐matched normal controls underwent T1‐, T2‐, T2*‐weighted imaging and SWI at 3T. Two radiologists prospectively analyzed all magnetic resonance imaging (MRI) studies. Siderotic nodules detected by each imaging technique were counted for comparison. The conspicuity of siderotic nodules was assessed using a scale from 1 to 3 (1, weak; 2, moderate; 3, prominent).

Results:

The number of siderotic nodules detected by SWI (3863) was significantly greater than that of T1‐weighted imaging (262, P < 0.001), T2‐weighted imaging (842, P < 0.001), and T2*‐weighted imaging (2475, P < 0.001). No suspected siderotic nodules were detected in normal controls by any imaging technique.

Conclusion:

SWI appears to provide the most sensitive method to detect siderotic nodules in cirrhotic liver. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

DWI联合增强MRI对肝硬化背景下小肝癌诊断价值的Meta分析

目的 应用Meta分析评价磁共振弥散加权成像（DWI）联合增强MRI对肝硬化背景下小肝癌的诊断价值。 方法 检索PubMed、Web of Science、中国学术期刊网全文数据库、万方数据库、中文科技期刊数据库（VIP）,按纳入和排除标准收集2000年1月至2017年12月的文献。采用诊断性试验质量评价表（QUADAS）进行诊断性试验的评价。使用Meta-Disc 1.4及Stata 12.0软件进行统计学分析,采用χ2检验对各研究的诊断比值比（DOR）进行异质性检验,用I2评估异质性的大小。通过综合受试者工作特征（SROC）曲线及Spearman相关系数检验纳入文献是否存在阈值效应,根据异质性检测结果选择合适的效应模型,通过计算合并灵敏度、特异度、阳性似然比、阴性似然比、DOR、SROC曲线下面积评价DWI联合增强MRI对肝硬化背景下小肝癌的诊断准确率。 结果 共纳入文献7篇,均为英文文献,包含836例患者,共计1112个病灶。异质性I2=76.6%,这表明纳入的文献有高度异质性,Spearman检验r=−0.14（P=0.76）,这说明不存在由阈值效应导致的异质性。DWI联合增强MRI对肝硬化背景下小肝癌的诊断价值的合并灵敏度、特异度、阳性似然比、阴性似然比、DOR分别为0.90（95%CI：0.88～0.92）、0.90（95% CI：0.86～0.93）、7.09（95%CI：3.40～14.80）、0.13（95% CI：0.08～0.21）、64.15（95% CI：24.22～169.88）。SROC曲线下面积为0.95。 结论 DWI联合增强MRI对肝硬化背景下小肝癌的诊断具有较高的灵敏度和特异度,可为肝硬化背景下小肝癌的早期诊断及早期治疗提供重要的依据。     

MR imaging of hepatocellular carcinoma: relationship between lesion size and imaging findings, including signal intensity and dynamic enhancement patterns

PURPOSE: To assess the relationship between lesion size and MR imaging findings of pathologically-proven hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In a retrospective, single-center study, 37 consecutive patients were identified between 1999 and 2005 that underwent preoperative MRI and surgical resection of HCC. A total of 47 lesions (mean size = 6.85 cm, range = 1-25 cm) were assessed for signal intensity (SI), enhancement patterns, and secondary morphologic features. Interobserver rating, percentage enhancement, and contrast-to-noise-ratio (CNR) were determined. Lesions were assessed for combinations of typical MRI features. Regression analysis was used to assess relations between MRI findings and tumor size. RESULTS: On fat-suppressed T2-weighted (T2w) fast-spin-echo, smaller lesions had lower SI compared to larger lesions (P < 0.05). In the arterial phase, smaller lesions showed significantly higher percentage enhancement compared to larger lesions (P < 0.05). In the delayed phase, smaller lesions showed less pronounced washout (P < 0.05). Heterogeneity of the lesions, including fatty infiltration, internal nodules, or mosaic pattern, was observed significantly more frequently in larger lesions (P < 0.001). The classic combination of high T2w signal, strong arterial enhancement, and delayed phase washout was present in 23 of 44 lesions (52%). CONCLUSION: Smaller HCC often showed lower SI on T2w, more intense arterial enhancement, and less pronounced delayed washout compared to larger HCC.     

Enhancement of liver parenchyma after injection of hepatocyte‐specific MRI contrast media: A comparison of gadoxetic acid and gadobenate dimeglumine

Purpose:

To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte‐specific contrast media.

Materials and Methods:

Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1‐weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs).

Results:

The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed‐imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46–2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%).

Conclusion:

In the delayed, hepatocyte‐specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine. J. Magn. Reson. Imaging 2010; 31: 356–364. © 2010 Wiley‐Liss, Inc.

     

Small nodules (1-2 cm) in liver cirrhosis: characterization with contrast-enhanced ultrasound

Objective

To determine the diagnostic efficacy of arterial phase contrast-enhanced ultrasound (CEUS) for characterizing small hepatic nodules (1-2 cm) in patients with high-risk for hepatocellular carcinoma (HCC).

Materials and methods

Over 12 months, CEUS was performed in 59 patients at high-risk for HCC with small hepatic nodules (1-2 cm; mean, 1.5 cm). Based only on arterial phase (<45 s) vascular intensity and pattern, lesions were prospectively diagnosed as HCC if there was hypervascularity without known features of hemangioma. The diagnosis of HCC was made regardless of the presence or absence of washout. Verification of diagnosis was made by liver transplantation (n = 13), biopsy (n = 12), resection (n = 3) or clinical and imaging follow-up for at least 12 months (n = 31).

Results

At of the time of CEUS, the 59 nodules were diagnosed as HCC in 26 and benign lesions in 33, including 20 regenerative/dysplastic nodules (RN/DN), 11 hemangiomas, and 2 focal fat sparing. All 26 nodules with arterial phase hypervascularity without hemangioma-like features were HCC. However, CEUS misdiagnosed HCC as RN/DN in 4 cases with arterial iso- (n = 3) or hypovascularity (n = 1). CEUS correctly diagnosed all 11 hemangiomas. The sensitivity, specificity, and accuracy of CEUS for diagnosing HCC were 86.7, 100, and 93.2%.

Conclusions

Arterial phase vascular intensity and pattern of CEUS are highly accurate for the diagnosis of small (1-2 cm) HCC and hemangioma in liver cirrhosis. On CEUS, arterial phase hypervascularity without a hemangioma-pattern alone may be sufficient for diagnosis of small HCC. Infrequent iso/hypovascular HCC may erroneously suggest RN/DN necessitating biopsy or close follow-up.     

Value of delayed hypointensity and delayed enhancing rim in magnetic resonance imaging diagnosis of small hepatocellular carcinoma in the cirrhotic liver

Purpose:

To determine the diagnostic utility of delayed hypointensity and delayed enhancing rim on magnetic resonance imaging (MRI) as indicators of hepatocellular carcinoma (HCC) in arterially enhancing nodules ≤5 cm in the cirrhotic liver and determine the features that best predict HCC.

Materials and Methods:

Gadolinium‐enhanced MRI studies performed from January 2001 to December 2004 in patients with cirrhosis were evaluated for arterially enhancing nodules measuring ≤5 cm. Verification was via explant correlation, biopsy, or imaging follow‐up. Sensitivity and specificity of diagnostic features of HCC were calculated. Features predictive of HCC were determined using the Generalized Estimating Equation approach.

Results:

In all, 116 arterially enhancing nodules were identified in 80 patients (<2 cm: n = 79, 2–5 cm n = 37). Sensitivity and specificity of delayed hypointensity for HCC measuring ≤5 cm, 2–5 cm, and <2 cm were 0.54 (40 of 74) and 0.86 (36 of 42); 0.72 (23 of 32) and 0.80 (4 of 5); and 0.41 (17 of 42) and 0.87 (32 of 37). For the delayed enhancing rim sensitivity and specificity were 0.64 (47 of 74) and 0.86 (36 of 42); 0.75 (24 of 32) and 1.0 (5 of 5); and 0.55 (23 of 42) and 0.83 (31 of 37), respectively. Lesion size (≥2 cm) and delayed enhancing rim, as main features and their interaction, were the most significant predictors of HCC.

Conclusion:

Delayed hypointensity and enhancing rim improve the specificity of diagnosis of HCC of all sizes but are seen less frequently in small (<2 cm) HCC. Nodule size (≥2 cm) and delayed enhancing rim are the strongest predictors of HCC. J. Magn. Reson. Imaging 2010;32:360–366. © 2010 Wiley‐Liss, Inc.     

Added value of breathhold diffusion‐weighted MRI in detection of small hepatocellular carcinoma lesions compared with dynamic contrast‐enhanced MRI alone using receiver operating characteristic curve analysis

Purpose

To evaluate the added value of single‐breathhold diffusion‐weighted MRI (DWI) in detection of small hepatocellular carcinoma (HCC) lesions (≤2 cm) in patients with chronic liver disease, by comparing the detection sensitivity of combined DWI/conventional dynamic contrast‐enhanced (DCE)‐MRI to that of conventional DCE‐MRI alone.

Materials and Methods

A total of 37 patients with chronic liver diseases underwent abdominal MRI at 1.5T, including T1‐weighted imaging (T1WI), T2‐weighted imaging (T2WI), and 2D conventional DCE. For each patient study, axial DWI was performed with a single‐shot echo‐planar imaging (EPI) sequence using a modified sensitivity‐encoding (mSENSE) technique with b‐value of 500 seconds/mm². A total of 20–24 slices were obtained during a 15–17‐second breathhold. Two observers independently interpreted the combined DWI/conventional DCE‐MRI images and the conventional DCE‐MRI images alone in random order. For all small HCC lesions, the diagnostic performance using each imaging set was evaluated by receiver operating characteristic (ROC) curve analysis. Sensitivity and positive predictive values were also calculated and analyzed.

Results

A total of 47 small HCCs were confirmed as final result. The area under the ROC curve (Az) of combined DWI/conventional DCE‐MRI images (observer 1, 0.922; observer 2, 0.918) were statistically higher than those of conventional DCE‐MRI alone (observer 1, 0.809; observer 2, 0.778) for all small HCC lesions (P < 0.01). The lesion detection sensitivities using the combined technique for both observers were significantly higher than those using conventional DCE‐MRI alone (P < 0.01). The sensitivity values for two observers using the combined technique were 97.87% and those using conventional DCE‐MRI alone were 85.11% to 82.98%. The positive predictive values for two observers using the combined imaging technique (97.87%) were slightly higher than those using conventional DCE‐MRI alone (92.86–93.02%), but there was no significant difference between the two imaging sets.

Conclusion

Combined use of breathhold DWI with conventional DCE‐MRI helped to provide higher sensitivities than conventional DCE‐MRI alone in the detection of small HCC lesions in patients with chronic liver disease. J. Magn. Reson. Imaging 2009;29:341–349. © 2009 Wiley‐Liss, Inc.