Nontumorous arterioportal shunt mimicking hypervascular tumor in cirrhotic liver: two-phase spiral CT findings

Transhepatic ultrasound guided embolization as a successful novel technique in treatment of pediatric complex intrahepatic arterioportal fistula: a case report and review of the literature

INTRODUCTION

Intrahepatic vascular shunts "IHVS" are abnormal communications between intra-hepatic vasculature involving the arterial, portal, or hepatic venous system. Arterio-portal fistula "APF" is an intrahepatic communication between the hepatic arterial system and the portal venous system without any communication with the systemic venous circulation. APF is considered a rare cause of portal hypertension and gastrointestinal bleeding in infancy.

CASE PRESENTATION

A 3-month-old Mediterranean female with known cardiac congenital anomalies presented to us with abdominal distension and diarrhea. Ultrasonography revealed massive ascites and computerized tomography (CT) abdomen with intravenous (IV) contrast revealed a left hepatic lesion. On further evaluation, an intrahepatic arterio-portal vascular malformation was detected. Attempted trans arterial embolization failed and radiology team successfully carried out direct trans hepatic ultrasound guided coiling of the aneurysmal venous sac followed by successful resection of segment 4 of the liver with the vascular malformation avoiding life threatening intra operative bleeding.

CONCLUSION

Any child with recurrent gastrointestinal bleeding, failure to thrive, vomiting, diarrhea, steatorrhea, splenomegaly, or ascites should be investigated for intrahepatic arterio-portal fistula "IAPF". Our novel technique of direct trans hepatic ultrasound guided coiling is an alternative method if trans arterial embolization "TAE" failed.

Lesion or Pseudolesion? A Comprehensive Description of Perfusion-Based Liver Alterations on Contrast-Enhanced Computed Tomography and Literature Review

ABSTRACT

Pseudolesions on contrast-enhanced computed tomography represent a diagnostic challenge for radiologists because they could be difficult to distinguish from true space-occupying lesions. This article aims to provide a detailed overview of these entities based on radiological criteria (hyperattenuation or hypoattenuation, localization, morphology), as well as a brief review of the hepatic vascular anatomy and pathophysiological process. Relevant examples from hospital case series are reported as helpful hints to assist radiologists in recognizing and correctly diagnosing these abnormalities.

Diagnostic performance of dual-energy computed tomography for HCC after transarterial chemoembolization: Utility of virtual unenhanced and low keV virtual monochromatic images

The purpose of this study is to evaluate the usefulness of virtual unenhanced (VUE) and low keV virtual monochromatic images (VMI) for diagnosing viable hepatocellular carcinomas (HCC) after transarterial chemoembolization (TACE). This retrospective study included 53 patients with suspected viable HCC after TACE who underwent multiphasic liver computed tomography including true unenhanced (TUE) phase and conventional (CV) enhanced phases on a dual-energy scanner. VUE images, 40 keV and 55 keV VMIs of enhanced phases were reconstructed using dual-energy computed tomography data. For every patient, six combination image sets (TUE-CV; TUE-55; TUE-40; VUE-CV; VUE-55; VUE-40) were evaluated by two readers and compared with the reference standard.There was no statistically significant difference (P > .05) in sensitivity or specificity among all image combinations. In most combinations, interobserver agreements were almost perfect. The diagnostic odds ratio showed a higher trend in combinations with conventional images. Currently, with regards to diagnostic performance, liver computed tomography including TUE and CV enhanced phases is recommended for tumor surveillance after TACE because VUE and VMIs do not have a distinct advantage compared to conventional images.

Transcatheter arterial embolization of iatrogenic massive arterioportal fistula in the liver

BACKGROUND

Massive arterioportal fistula (APF) is naturally irreversible and can induce portal hypertension and portal vein thrombosis (PVT), worsening survival outcomes.

PURPOSE

To evaluate the clinical course and details of transarterial embolization (TAE) procedures for massive APF.

MATERIAL AND METHODS

This retrospective single-center observational study evaluated the time until embolization after puncture, imaging, embolization methods, and laboratory data of 10 consecutive patients who were diagnosed with massive APF after puncture and underwent TAE at our hospital from 1 April 2012 to 30 September 2019.

RESULTS

Out of 10 cases, eight demonstrated a simple type and the other two cases a complex network type on the digital subtraction angiography pattern of massive APF. In two simple-type cases for which re-embolization was required, other subsegmental branches were embolized. The two cases showing a complex network type had been embolized via not only the subsegmental branch, but also the extrahepatic and multiple subsegmental branches. Child-Pugh scores were improved in eight of the ten cases. PVT was seen in six cases before embolization, but disappeared after embolization in all cases, despite the fact that three cases had not received anticoagulant therapy. Six cases had digestive varices before embolization, suggesting portal hypertension, and two of the six cases with esophageal varices and one with gastric varices decreased after embolization.

CONCLUSION

TAE for massive APF contributed to the improvement of hepatic reserve, the disappearance of PVT, and the improvement of portal hypertension; however, embolization of multiple branches may still be required in some cases.

Morphological, dynamic and functional characteristics of liver pseudolesions and benign lesions

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related deaths worldwide and one of the most common causes of death among patients with cirrhosis, developing in 1-8% of them every year, regardless of their cirrhotic stage. The radiological features of HCC are almost always sufficient for reaching the diagnosis; thus, histological confirmation is rarely needed. However, the study of cirrhotic livers remains a challenge for radiologists due to the developing of fibrous and regenerative tissue that cause the distortion of normal liver parenchyma, changing the typical appearances of benign lesions and pseudolesions, which therefore may be misinterpreted as malignancies. In addition, a correct distinction between pseudolesions and malignancy is crucial to allow appropriate targeted therapy and avoid treatment delays.The present review encompasses technical pitfalls and describes focal benign lesions and pseudolesions that may be misinterpreted as HCC in cirrhotic livers, providing the imaging features of regenerative nodules, large regenerative nodules, siderotic nodules, hepatic hemangiomas (including rapidly filling and sclerosed hemangiomas), segmental hyperplasia, arterioportal shunts, focal confluent fibrosis and focal fatty changes. Lastly, the present review explores the most promising new imaging techniques that are emerging and that could help radiologists differentiate benign lesions and pseudolesions from overt HCC.

Imaging Diagnosis of HCC: Future directions with special emphasis on hepatobiliary MRI and contrast-enhanced ultrasound

Hepatocellular carcinoma (HCC) is a unique cancer entity that can be noninvasively diagnosed using imaging modalities without pathologic confirmation. In 2018, several major guidelines for HCC were updated to include hepatobiliary contrast agent magnetic resonance imaging (HBA-MRI) and contrast-enhanced ultrasound (CEUS) as major imaging modalities for HCC diagnosis. HBA-MRI enables the achievement of high sensitivity in HCC detection using the hepatobiliary phase (HBP). CEUS is another imaging modality with real-time imaging capability, and it is reported to be useful as a second-line modality to increase sensitivity without losing specificity for HCC diagnosis. However, until now, there is an unsolved discrepancy among guidelines on whether to accept “HBP hypointensity” as a definite diagnostic criterion for HCC or include CEUS in the diagnostic algorithm for HCC diagnosis. Furthermore, there is variability in terminology and inconsistencies in the definition of imaging findings among guidelines; therefore, there is an unmet need for the development of a standardized lexicon. In this article, we review the performance and limitations of HBA-MRI and CEUS after guideline updates in 2018 and briefly introduce some future aspects of imaging-based HCC diagnosis.

Simultaneous embolization of a spontaneous porto-systemic shunt and intrahepatic arterioportal fistula: A case report

BACKGROUND

Hepatic encephalopathy (HE) is a frequent and debilitating complication of chronic liver disease. Recurrent HE is strongly linked with spontaneous portosystemic shunts (SPSSs). Intrahepatic arterioportal fistulas (IAPFs) occur rarely but pose a major clinical challenge and may lead to or worsen portal hypertension. Herein, we present a rare case of recurrent HE secondary to a SPSS combined with an IAPF.

CASE SUMMARY

A 63-year-old female with primary biliary cirrhosis presented with recurrent disturbance of consciousness for 4 mo. SPSS communicating the superior mesenteric vein with the inferior vena cava and IAPF linking the intrahepatic artery with the portal vein were found on contrast-enhanced abdominal computed tomography. The patient did not respond well to medical treatment. Therefore, simultaneous embolization of SPSS and IAPF was scheduled. After embolization, the symptoms of HE showed obvious resolution.

CONCLUSION

The presence of liver vascular disorders should not be neglected in patients with chronic liver disease, and interventional therapy is a reasonable choice in such patients.

Value of precontrast and portal venous phases for evaluating atypical hepatocellular carcinoma mimicking arterioportal shunt

PURPOSE

To evaluate the value of precontrast phase (PP) and portal venous phase (PVP) for differentiation of small hypervascular hepatocellular carcinomas (HCCs) without delayed washout from arterioportal (AP) shunts in high-risk patients of HCC.

METHODS

A total of 122 lesions (73 AP shunts and 49 HCCs) detected on quadriphasic CT in 101 patients with chronic liver disease were analyzed. All lesions (≤2 cm) showed arterial enhancement and isodensity on delayed phase (DP) with exclusion of typical features of AP shunts. Lesion morphologic features (size, location, shape, margin) on biphasic CT (arterial phase and DP), Alpha-fetoprotein (AFP) values and coexistent HCC were evaluated. The qualitative and quantitative analyses of lesion attenuation on quadriphasic CT were performed. Diagnostic performances for prediction of AP shunts over HCC were compared among the biphasic CT, triphasic CT (adding PP or PVP) and quadriphasic CT.

RESULTS

In multivariate analysis, the presence of concomitant HCC (p = 0.0005, odds ratio [OR] = 0.11), visual hypodensity on PP (p = 0.0004, OR = 17.72) and visual hyperdensity on PVP (p = 0.0003, OR = 0.051) were independent predictors for HCCs rather than AP shunts. Additional review of PP and PVP revealed significantly improved diagnostic performance yielding the highest diagnostic performance.

CONCLUSIONS

Hypodensity on PP and hyperdensity on PVP are significant predictive features in differentiating atypical small hypervascular HCC from AP shunts in patients with high-risk of HCC. Careful evaluation of the PP and PVP may reduce underdiagnosis and lead to earlier diagnosis of atypical small HCCs.

Imaging Features at the Periphery: Hemodynamics, Pathophysiology, and Effect on LI-RADS Categorization

Liver lesions have different enhancement patterns at dynamic contrast-enhanced imaging. The Liver Imaging Reporting and Data System (LI-RADS) applies the enhancement kinetic of liver observations in its algorithms for imaging-based diagnosis of hepatocellular carcinoma (HCC) in at-risk populations. Therefore, careful analysis of the spatial and temporal features of these enhancement patterns is necessary to increase the accuracy of liver mass characterization. The authors focus on enhancement patterns that are found at or around the margins of liver observations-many of which are recognized and defined by LI-RADS, such as targetoid appearance, rim arterial phase hyperenhancement, peripheral washout, peripheral discontinuous nodular enhancement, enhancing capsule appearance, nonenhancing capsule appearance, corona enhancement, and periobservational arterioportal shunts-as well as peripheral and periobservational enhancement in the setting of posttreatment changes. Many of these are considered major or ancillary features of HCC, ancillary features of malignancy in general, features of non-HCC malignancy, features associated with benign entities, or features related to treatment response. Distinction between these different patterns of enhancement can help with achieving a more specific diagnosis of HCC and better assessment of response to local-regional therapy. ^©RSNA, 2021.

Imaging-based diagnosis of benign lesions and pseudolesions in the cirrhotic liver

Liver cirrhosis is a leading cause of death worldwide, with 1-year mortality rates of up to 57% in decompensated patients. Hepatocellular carcinoma (HCC) is the most common primary tumor in cirrhotic livers and the second leading cause of cancer-related mortality worldwide. Annually, up to 8% of patients with cirrhosis develop HCC. The diagnosis of HCC rarely requires histological confirmation: in fact, according to the most recent guidelines, the imaging features of HCC are almost always sufficient for a certain diagnosis. Thus, the role of the radiologist is pivotal because the accurate detection and characterization of focal liver lesions in patients with cirrhosis are essential in improving clinical outcomes. Despite recent technical innovations in liver imaging, several issues remain for radiologists regarding the differentiation of HCC from other hepatic lesions, particularly benign lesions and pseudolesions. It is important to avoid misdiagnosis of benign liver lesions as HCC (false-positive cases) because this diagnostic misinterpretation may lead to ineligibility of a patient for potentially curative treatments or inappropriate assignment of high priority scores to patients on waiting lists for liver transplantation. This review presents a pocket guide that could be useful for the radiologist in the diagnosis of benign lesions and pseudolesions in cirrhotic livers, highlighting the imaging features that help in making the correct diagnosis of macroregenerative nodules; siderotic nodules; arterioportal shunts; hemangiomas, including fast-filling hemangiomas, hemangiomas with pseudowashout, and sclerosed hemangiomas; confluent fibrosis; pseudomasses in chronic portal vein thrombosis; and focal fatty changes.

Atypical Appearance of Hepatocellular Carcinoma and Its Mimickers: How to Solve Challenging Cases Using Gadoxetic Acid-Enhanced Liver Magnetic Resonance Imaging

Hepatocellular carcinoma (HCC) can be diagnosed noninvasively with contrast-enhanced dynamic computed tomography, magnetic resonance imaging, or ultrasonography on the basis of its hallmark imaging features of arterial phase hyperenhancement and washout on portal or delayed phase images. However, approximately 40% of HCCs show atypical imaging features, posing a significant diagnostic challenge for radiologists. Another challenge for radiologists in clinical practice is the presentation of many HCC mimickers such as intrahepatic cholangiocarcinoma, combined HCC-cholangiocarcinoma, arterioportal shunt, and hemangioma in the cirrhotic liver. The differentiation of HCCs from these mimickers on preoperative imaging studies is of critical importance. Hence, we will review the typical and atypical imaging features of HCCs and the imaging features of its common mimickers. In addition, we will discuss how to solve these challenges in practice.

Iatrogenic Arterioportal Fistula Caused by Radiofrequency Ablation of Hepatocellular Carcinoma: Clinical Course and Treatment Outcomes

PURPOSE

To analyze the clinical course and treatment outcomes of patients with iatrogenic arterioportal fistula (APF) caused by radiofrequency (RF) ablation of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Among the 1,620 hepatocellular carcinoma patients treated by RF ablation between January 2012 and August 2017, 99 who developed APF after RF ablation were included in this retrospective study. Depending on the extent of portal vein enhancement on arterial phase images, APF was classified as massive or nonmassive. The patients' clinical course was investigated and statistically evaluated by univariable and multivariable analyses.

RESULTS

Thrombocytopenia (odds ratio [OR] = 3.939; 95% confidence interval [CI], 1.141-13.598) was the only risk factor for developing massive APF. Eleven patients underwent embolotherapy (technical success rate, 90.9%) and no patients experienced serious adverse events within 30 days of the procedure. Patients with massive APF (66.7%) had a significantly higher chance of a Child-Pugh score increase than did the patients with nonmassive APF (13.6%) (P < .001). Massive APF had a significantly lower chance of natural regression than did nonmassive APF (P < .001). Child-Pugh B (OR = 17.739; 95% confidence interval, 2.361-133.279) and massive APF without treatment (OR = 11.061; 95% confidence interval, 1.257-97.341) were independent risk factors for liver failure that led to death of liver transplant within 1 year after RF ablation.

CONCLUSIONS

Massive APF caused by RF ablation is mostly irreversible and significantly worsens patients' outcomes, but may be effectively treated with embolotherapy.

Sonographic Appearances of Portal Vein Abnormalities

Portal venous system evaluation is required in many clinical circumstances, as substantial morbidity and mortality can be associated with a spectrum of portal vein abnormalities. Portal venous system pathologies can be congenital or acquired, and the knowledge of their imaging appearances will allow for a confident diagnosis and appropriate treatment options. In addition, a firm understanding of anatomical variants is important for planning surgical procedures and percutaneous interventions of the liver. This article will review various imaging appearances of portal venous systems abnormalities.

Contrast-Enhanced Ultrasound Features of Hepatic Reactive Lymphoid Hyperplasia: Correlation With Histopathologic Findings

OBJECTIVES

To find certain specifics of hepatic reactive lymphoid hyperplasia (HRLH) on contrast-enhanced ultrasound (CEUS) imaging as diagnostic imaging clues by retrospectively analyzing its enhancement features.

METHODS

From June 2010 to June 2017, 18 histopathologically confirmed HRLH lesions in 18 patients were included in this retrospective study. The lesion's location, maximum diameter, shape, margin, echogenicity, and color flow signal on conventional ultrasound (US) imaging and enhancement pattern, presence of a feeding artery, and donutlike enhancement on CEUS imaging were observed and recorded. The lesion size on CEUS imaging at peak enhancement and that on conventional US imaging were compared and recorded.

RESULTS

All of the lesions showed homogeneous hypoechogenicity with a regular well-defined margin on conventional US imaging, with a mean diameter ± SD of 14.3 ± 4.6 mm (range, 8-24 mm). On CEUS imaging, all of the lesions showed "quick-wash-in and quick-wash-out," which showed complete homogeneous hyperenhancement in the arterial phase and wash-out in the second half of the arterial phase or first half of the portal phase. In 83.3% (15 of 18) of the lesions, the lesion size that was enhanced at peak was enlarged compared with the hypoechoic area on conventional US imaging, and transient donutlike enhancement appeared when the lesion showed wash-out. In 55.6% (10 of 18) of cases, the feeding artery was detected.

CONCLUSIONS

Enlarged complete homogeneous hyperenhancement in the arterial phase, consequently followed by quick wash-out of the lesion and the appearance of donutlike enhancement, may be the CEUS features of HRLH.

Cone-Beam CT-Guided Chemoembolization in Patients with Complete Response after Previous Chemoembolization but Subsequent Elevated α-Fetoprotein without Overt Hepatocellular Carcinoma

PURPOSE

To evaluate the performance of C-arm computed tomography (CT)-guided chemoembolization in patients with hepatocellular carcinoma (HCC) with serum α-fetoprotein (AFP) level > 20 ng/mL but with no overt tumor on CT and/or magnetic resonance imaging.

MATERIALS AND METHODS

From May 2010 to May 2017, 34 patients with HCC (25 men and 9 women; mean age, 59.7 y) who had elevated serum AFP levels (> 20 ng/mL) but no overt tumor on 6-mo imaging studies and had shown complete response (CR) after previous chemoembolization underwent C-arm CT-guided conventional chemoembolization. Three radiologists retrospectively reviewed the imaging studies (preprocedural images, C-arm CT scans, and follow-up images) in consensus, and clinical data including AFP levels were retrospectively obtained. Tumor detection by C-arm CT and treatment response after chemoembolization were assessed.

RESULTS

HCC was imaged at the time of chemoembolization in 24 of 34 patients (70.6%). C-arm CT detected tumors in 25 patients (73.5%); 23 detections were true positives, 2 were false positives, and 1 was a false negative (diaphragm metastasis). Among the 23 patients with true-positive results, the first follow-up enhanced imaging studies showed CR (n = 17), partial response (n = 1), progressive disease (n = 4), and indeterminate status (n = 1; treated by percutaneous ethanol injection).

CONCLUSIONS

C-arm CT-guided chemoembolization may help to detect and treat recurrent tumors in patients who have shown CR after previous chemoembolization but subsequently, during follow-up surveillance, had serum AFP levels > 20 ng/mL without an overt tumor evident on imaging studies.

CT and MRI imaging and interpretation of hepatic arterioportal shunts

Hepatic arterioportal shunts (HAPS) occur due to organic or functional fistulization of blood flow between arterial hepatic vasculature and venous portal systems. It is a type of hemodynamic abnormality of the liver being observed increasingly with the use of temporal imaging modalities. HAPS occur due to other underlying hepatic abnormalities including the presence of an underlying tumor or malignancy. When a HAPS is present, the appearance of these abnormalities on imaging studies suggests an underlying abnormality, must be considered atypical even if asymptomatic, and warrants careful evaluation. Over time, and as a function of degree of fistulae, symptoms and potential life-threatening complications may arise from the HAPS. These systemic complications may include the development of portal hypertension, splenomegaly, as well as accelerated metastasis in patients with malignant tumors. This manuscript reviews common underlying conditions associated with HAPS and their radiologic interpretation.

Contrast-enhanced ultrasound of hepatocellular carcinoma: where do we stand?

Contrast-enhanced ultrasound (CEUS) represents a significant breakthrough in ultrasonography (US), and it is being increasingly used for the evaluation of focal liver lesions (FLLs). CEUS is unique in that it allows non-invasive assessment of liver perfusion in real time throughout the vascular phase, which has led to dramatic improvements in the diagnostic accuracy of US in the detection and characterization of FLLs, the choice of therapeutic procedures, and the evaluation of response. Currently, CEUS is included as a part of the suggested diagnostic work-up of FLLs, including in cirrhotic patients with hepatocellular carcinoma, resulting in better patient management and cost-effective delivery of therapy.

Contrast-enhanced ultrasound (CEUS) liver imaging reporting and data system (LI-RADS) 2017 - a review of important differences compared to the CT/MRI system

Medical imaging plays an important role in the diagnosis and management of hepatocellular carcinoma (HCC). The Liver Imaging Reporting and Data System (LI-RADS) was initially created to standardize the reporting and data collection of CT and MR imaging for patients at risk for HCC. As contrast-enhanced ultrasound (CEUS) has been widely used in clinical practice, it has recently been added to the LI-RADS. While CEUS LI-RADS shares fundamental concepts with CT/MRI LI-RADS, there are key differences between the modalities reflecting dissimilarities in the underlying methods of image acquisition and types of contrast material. This review introduces a recent update of CEUS LI-RADS and explains the key differences from CT/MRI LI-RADS.

Utility of percutaneous radiofrequency ablation alone or combined with transarterial chemoembolization for early hepatocellular carcinoma

Percutaneous radiofrequency ablation (RFA) combined with transarterial chemoembolization (TACE) is an effective, standard therapy against small hepatocellular carcinoma (HCC). However, there is debate regarding the effectiveness of RFA combined with TACE (RFA/TACE) compared with RFA alone. These two approaches were compared for the treatment of early HCC. The present study examined 83 HCC tumors in 83 patients treated with RFA between April 2007 and August 2014 at three medical institutions. All HCCs were single hypervascular tumors, with a median diameter of 16 mm (range, 6-30 mm). The overall survival (OS) rate of all patients (n=83) was 97.5% at 1 year, 82.8% at 3 years and 48.6% at 5 years, and the local recurrence rate of all patients was 14.3% at 1 year, 32.3% at 3 years and 36.5% at 5 years. The tumor-free survival (TFS) rate of all patients was 95.1% at 1 year, 56.3% at 3 years and 23.4% at 5 years. Compared with RFA alone, RFA/TACE significantly improved OS (P<0.001), intrahepatic distant recurrence (IDR; P=0.038) and TFS (P=0.010). A univariate analysis of prognostic indicators revealed that age <70 years (P=0.008), aspartate transaminase <40 IU/l (P=0.003), alanine aminotransferase <40 IU/l (P=0.006) and platelet count >10×10⁴/µl (P=0.05) were associated with a high survival rate. Multivariate analysis identified RFA/TACE [hazard ratio (HR), 0.108; P=0.001] as an independent prognostic indicator. RFA/TACE was identified as the only independent indicator of IDR (HR: 0.467; P=0.042) and TFS (HR: 0.452; P=0.012). RFA/TACE improved OS rate, IDR and TFS compared with RFA alone. The data suggested that RFA/TACE should be considered for the treatment of single hypervascular HCC.

Integration of Contrast-enhanced US into a Multimodality Approach to Imaging of Nodules in a Cirrhotic Liver: How I Do It

Accurate characterization of cirrhotic nodules and early diagnosis of hepatocellular carcinoma (HCC) are of vital importance. Currently, computed tomography (CT) and magnetic resonance (MR) imaging are standard modalities for the investigation of new nodules found at surveillance ultrasonography (US). This article describes the successful integration of contrast material-enhanced US into a multimodality approach for diagnosis of HCC and its benefits in this population. The application of contrast-enhanced US immediately following surveillance US allows for prompt dynamic contrast-enhanced evaluation, removing the need for further imaging of benign lesions. Contrast-enhanced US also provides dynamic real-time assessment of tumor vascularity so that contrast enhancement can be identified regardless of its timing or duration, allowing for detection of arterial hypervascularity and portal venous washout. The purely intravascular nature of US contrast agents is valuable as the rapid washout of nonhepatocyte malignancies is highly contributory to their differentiation from HCC. The authors believe contrast-enhanced US provides complementary information to CT and MR imaging in the characterization of nodules in high-risk patients. ^© RSNA, 2017 Online supplemental material is available for this article.

Comprehensive Comparison of Multiple-Detector Computed Tomography and Dynamic Magnetic Resonance Imaging in the Diagnosis of Hepatocellular Carcinoma with Varying Degrees of Fibrosis

Background & Aims

Liver computed tomography and dynamic magnetic resonance imaging play an important role in the early detection of hepatocellular carcinoma. However, the American Association for the Study of Liver Diseases (AASLD) recommend the use of applied imaging studies for HCC diagnosis only in cirrhotic patients. This study aimed to comprehensively compare liver CT and dynamic MRI for HCC diagnosis before surgical resection over years in clinical practice, and also to compare the diagnostic differences between liver CT and dynamic MRI in HCCs with varying degrees of fibrosis.

Methods

841 patients with liver tumor who had liver CT or dynamic MRI examinations followed by surgical resection were included in the study. We defined typical HCC imaging characteristics as early enhancement in the artery phase and early washout in the venous phase. The tumor size was recorded based on pathological examination after surgery. The pathologic fibrosis score was verified by the METAVIR scoring classification.

Results

Among the 841 patients, 756 underwent liver CT and 204 underwent dynamic liver MRI before surgery. The etiologies of chronic liver disease included hepatitis B virus, hepatitis C virus, hepatitis B and C virus, and non-hepatitis B or C virus. The sensitivity and accuracy of liver CT or MRI for HCC diagnosis was approximately 80%~90%. Liver CT had a diagnostic accuracy for HCC similar to that of dynamic MRI, and liver fibrosis stage did not influence their diagnostic efficacies.

Conclusions

The application of 4-phase dynamic CT and MRI exhibit similar diagnostic accuracy for hepatocellular carcinoma, in tumors of sizes 1 to 2 cm and >2 cm. Liver fibrosis status did not affect the diagnostic accuracy of liver CT or MRI for HCC. The AASLD and EASL restrictions of dynamic imaging studies for HCC diagnosis to cirrhotic patients alone are unnecessary.

Arterio-portal shunts in the cirrhotic liver: perfusion computed tomography for distinction of arterialized pseudolesions from hepatocellular carcinoma

OBJECTIVES

To determine perfusion computed tomography (P-CT) findings for distinction of arterial pseudolesions (APL) from hepatocellular carcinoma (HCC) in the cirrhotic liver.

METHODS

32 APL and 21 HCC in 20 cirrhotic patients (15 men; 65 ± 10 years), who underwent P-CT for evaluation of HCC pre- (N = 9) or post- (N = 11) transarterial chemoembolization, were retrospectively included using CT follow-up as the standard of reference. All 53 lesions were qualitatively (visual) and quantitatively (perfusion parameters) analysed according to their shape (wedge, irregular, nodular), location (not-/adjunct to a fistula), arterial liver perfusion (ALP), portal venous liver perfusion (PLP), hepatic perfusion index (HPI). Accuracy for diagnosis of HCC was determined using receiver operating characteristics.

RESULTS

18/32 (56 %) APL were wedge shaped, 10/32 (31 %) irregular and 4/32 (12 %) nodular, while 11/21 (52 %) HCC were nodular or 10/21 (48 %) irregular, but never wedge shaped. Significant difference between APL and HCC was seen for lesion shape in pretreated lesions (P < 0.001), and for PLP and HPI in both pre- and post-treated lesions (all, P < 0.001). Diagnostic accuracy for HCC was best for combined assessment of lesion configuration and PLP showing an area under the curve of 0.901.

CONCLUSION

Combined assessment of lesion configuration and portal venous perfusion derived from P-CT allows best to discriminate APL from HCC with high diagnostic accuracy.

KEY POINTS

• Arterio-portal shunting is common in the cirrhotic liver, especially after local treatment. • Arterial pseudolesions (APL) due to shunting might mimic hepatocellular carcinoma (HCC). • Perfusion-CT allows for qualitative and quantitative assessment of liver lesions. • Lesion configuration fails to discriminate APL from HCC in locally treated patients. • Integration of quantitative perfusion analysis improves accuracy for diagnosis of HCC.

Imaging findings of mimickers of hepatocellular carcinoma

Radiological imaging plays a crucial role in the diagnosis of hepatocellular carcinoma (HCC) as the noninvasive diagnosis of HCC in high-risk patients by typical imaging findings alone is widely adopted in major practice guidelines for HCC. While imaging techniques have markedly improved in detecting small liver lesions, they often detect incidental benign liver lesions and non-hepatocellular malignancy that can be misdiagnosed as HCC. The most common mimicker of HCC in cirrhotic liver is nontumorous arterioportal shunts that are seen as focal hypervascular liver lesions on dynamic contrast-enhanced cross-sectional imaging. Rapidly enhancing hemangiomas can be easily misdiagnosed as HCC especially on MR imaging with liver-specific contrast agent. Focal inflammatory liver lesions mimic HCC by demonstrating arterial-phase hypervascularity and subsequent washout on dynamic contrast-enhanced imaging. It is important to recognize the suggestive imaging findings for intrahepatic cholangiocarcinoma (CC) as the management of CC is largely different from that of HCC. There are other benign mimickers of HCC such as angiomyolipomas and focal nodular hyperplasia-like nodules. Recognition of their typical imaging findings can reduce false-positive HCC diagnosis.

CT Appearance of Hepatocellular Carcinoma after Locoregional Treatments: A Comprehensive Review

Hepatocellular carcinoma (HCC) is a major health problem worldwide, affecting more than 600,000 new patients per year. Curative treatments are available in a small percentage of patients, while most of them present in stages requiring locoregional treatments such as thermoablation, transarterial chemoembolization, and/or radioembolization. These therapies result in specific imaging features that the general radiologist has to be aware of in order to assess the response to treatment and to correctly manage the follow-up of treated patients. Multiphasic helical computed tomography has become a popular imaging modality for detecting hypervascular tumors and characterizing liver lesions. On this basis, many staging and diagnostic systems have been proposed for evaluating response to all different existing strategies. Radiofrequencies and microwaves generate thermoablation of tumors, and transarterial chemoembolization exploits the double effect of the locoregional administration of drugs and embolizing particles. Eventually radioembolization uses a beta-emitting isotope to induce necrosis. Therefore, the aim of this comprehensive review is to analyze and compare CT imaging appearance of HCC after various locoregional treatments, with regard to specific indications for all possible procedures.

Parametric response mapping of dynamic CT for predicting intrahepatic recurrence of hepatocellular carcinoma after conventional transcatheter arterial chemoembolization

OBJECTIVES

The aim of our study was to determine the diagnostic value of a novel image analysis method called parametric response mapping (PRM) for prediction of intrahepatic recurrence of hepatocellular carcinoma (HCC) treated with conventional transcatheter arterial chemoembolization (TACE).

METHODS

This retrospective study was approved by the IRB. We recruited 55 HCC patients who achieved complete remission (CR) after TACE and received longitudinal multiphasic liver computed tomography (CT). The patients fell into two groups: the recurrent tumour group (n = 29) and the non-recurrent tumour group (n = 26). We applied the PRM analysis to see if this technique could distinguish between the two groups. The results of the PRM analysis were incorporated into a prediction algorithm. We retrospectively removed data from the last time point and attempted to predict the response to therapy of the removed data.

RESULTS

The PRM analysis was able to distinguish between the non-recurrent and recurrent groups successfully. The prediction algorithm detected response to therapy with an area under the curve (AUC) of 0.76, while the manual approach had AUC 0.64.

CONCLUSIONS

Adopting PRM analysis can potentially distinguish between recurrent and non-recurrent HCCs and allow for prediction of response to therapy after TACE.

KEY POINTS

Parametric response mapping (PRM) could help assess patients with recurrent HCCs after TACE. Parametric response mapping could direct patients to individualized therapy. Longitudinal CT images were analyzed with advanced image analysis method.

The validation of the 2010 American Association for the Study of Liver Diseases guideline for the diagnosis of hepatocellular carcinoma in an endemic area

BACKGROUND AND AIM

Hepatocellular carcinoma (HCC) diagnosis could be made with one typical imaging study in a cirrhotic liver by the guideline of the American Association for the Study of Liver Diseases (AASLD) in 2010. Patients with hepatitis B who may not have fully developed cirrhosis could be applied. We aim to retrospectively analyze and validate the diagnostic power of the 2010 guideline in an HCC endemic area (Taiwan).

METHODS

From January 2006 to December 2010, a total of 648 patients with liver tumor post-surgical resection were reviewed. The fibrotic scores were verified by METAVIR score 4. Among the 648 patients, 569 (87.8%) were HCC patients. Hepatitis B accounts for 54.5%, hepatitis C 21.9%, hepatitis B + C 2.8%, and non-hepatitis B or C 20.7% of patients. Two hundred eighty-eight of 648 (44%) patients were with cirrhotic liver.

RESULTS

The diagnostic sensitivity, specificity, positive predictive value (PPV), negative predictive value, and accuracy of the 2010 AASLD guideline f are 99.1%, 36.7%, 91.9%, 85.3%, and 91.5%, respectively. Cirrhotic liver exhibited a higher PPV (P < 0.001) but lower specificity (P = 0.0479) than non-cirrhotic liver. In both cirrhotic and non-cirrhotic condition, no difference existed in patients with hepatitis B or hepatitis C (P > 0.05).

CONCLUSIONS

Similar sensitivity of HCC diagnosis existed between cirrhotic and non-cirrhotic liver, and across different fibrotic stages. But cirrhotic liver exhibited a higher PPV. Hepatitis B or C has no decisive effect in HCC diagnosis.

[Osler's disease]

Osler's disease, also known as hereditary hemorrhagic telangiectasia (HHT) and Osler-Weber-Rendu syndrome, is an autosomal dominant disorder leading to abnormal blood vessel formation in the skin, mucous membranes and often in organs, such as the lungs, liver and brain (arteriovenous malformations AVM). Various types are known. Patients may present with epistaxis. Teleangiectasia can be identified by visual inspection during physical examination of the skin or oral cavity or by endoscopy. Diagnosis is made after clinical examination and genetic testing based on the Curacao criteria. Modern imaging modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI) have become more important as they can depict the AVMs. Pulmonary AVMs can be depicted in CT imaging even without the use of a contrast agent while other locations including the central nervous system (CNS) usually require administration of contrast agents. Knowledge of possible clinical manifestations in various organs, possible complications and typical radiological presentation is mandatory to enable adequate therapy of these patients. Interventional procedures are becoming increasingly more important in the treatment of HHT patients.

Characterization of 1-to 2-cm liver nodules detected on hcc surveillance ultrasound according to the criteria of the American Association for the Study of Liver Disease: is quadriphasic CT necessary?

OBJECTIVE

The purpose of this study was to identify the essential number of phases from multiphasic CT for 1- to 2-cm hepatocellular carcinoma (HCC) on surveillance ultrasound and to compare the results with the American Association for the Study of Liver Disease (AASLD) standard (arterial phase hypervascularity and portal venous phase [PVP] or delayed phase hypovascularity).

MATERIALS AND METHODS

The study included 110 newly detected nodules (1-2 cm; 36 HCC, 74 benign) in 96 patients detected in an HCC surveillance program. Three radiologists prospectively evaluated the attenuation of each nodule relative to the liver on each phase of quadriphasic CT. Univariate and multivariate logistic regression analyses were used to identify parameters associated with HCC. Multiple combinations of phases were compared with the AASLD standard.

RESULTS

Only arterial phase hypervascularity and delayed phase hypovascularity were significantly associated with HCC both on univariate (odds ratio, arterial phase 7.51 [95% CI, 2.79-20.20]; delayed phase, 2.80 [1.14-6.90]) and multivariate analyses (arterial phase, 11.30 [4.30-29.68]; delayed phase, 4.39 [1.20-16.13]). The combination of arterial phase and delayed phase yielded the highest specificity (99%) and sensitivity (57%). There was no significant difference between AASLD standard (sensitivity, 57%; specificity, 98%) versus biphasic (arterial phase hypervascularity and delayed phase hypovascularity: sensitivity, 57%; p = 1 and specificity, 99%; p = 0.32), triphasic (arterial phase hypervascularity and unenhanced or PVP hypovascularity: sensitivity, 53%; p = 0.325 and specificity, 97%; p = 0.32), or quadriphasic combination (arterial phase hypervascularity and unenhanced, PVP or delayed phase hypovascularity: sensitivity, 57%; specificity, 97%), whereas the sensitivity of biphasic arterial phase and PVP was significantly lower (39% vs 57%, p = 0.022).

CONCLUSION

For diagnosing 1- to 2-cm HCC detected on surveillance ultrasound, arterial phase and delayed phase are two essential phases, providing higher sensitivity than the combination of arterial phase and PVP, and equal performance with triphasic and quadriphasic combinations. The biphasic combination of arterial phase and delayed phase may replace quadriphasic CT recommended by AASLD.

Detection of recurrent hepatocellular carcinoma in cirrhotic liver after transcatheter arterial chemoembolization: value of quantitative color mapping of the arterial enhancement fraction of the liver

Objective

To investigate the additional diagnostic value of color mapping of the hepatic arterial enhancement fraction (AEF) for detecting recurrent or residual hepatocellular carcinoma (HCC) in patients treated with transcatheter arterial chemoembolization (TACE).

Materials and Methods

Seventy-six patients with 126 HCCs, all of whom had undergone previous TACE, and subsequently, underwent follow-up multiphasic liver CT scans, were included in this study. Quantitative color maps of the AEF of the whole liver were created, by using prototype software with non-rigid registration. The AEF was defined as the ratio of the attenuation increment during the arterial phase to the attenuation increment during the portal phase. Two radiologists independently analyzed the two image sets at a two-week interval, i.e., the multiphasic CT image set and the second image set of the AEF color maps and the CT images. The additional diagnostic value of the AEF color mapping was determined, by the use of the jackknife-alternative free-response receiver-operating-characteristic analysis. The sensitivity and positive predictive values for detecting HCCs of each image set were also evaluated and compared.

Results

The reader-averaged figures of merit were 0.699 on the initial interpretation of the MDCT image set, and 0.831 on the second interpretation of the combined image set; the difference between the two interpretations was significant (p value < 0.001). The mean sensitivity for residual or recurrent HCC detection increased from 62.7% on the initial analysis to 82.1% on the second analysis using the AEF color maps (p value < 0.001). The mean positive predictive value for HCC detection was 74.5% on the initial analysis using MDCT, and 71.6% on the second analysis using AEF color mapping.

Conclusion

Quantitative color mapping of the hepatic AEF may have the possibility to increase the diagnostic performance of MDCT for the detection of recurrent or residual HCC without the potential risk of radiation-related hazards.

Perfusion and parenchymal changes related to vascular alterations of the liver

Imaging plays a significant role in the diagnosis of vascular abnormalities of the liver and sometimes provides the only clue to the correct diagnosis. With advances of imaging techniques and multiphasic acquisition of liver imaging, various perfusion changes are frequently encountered. Correct imaging diagnosis of significant vascular diseases can prompt appropriate work-up and timely management. Accurate differentiation of clinically insignificant perfusion phenomena from clinically significant findings including neoplastic conditions and in the setting of post-transplantation is essential. This pictorial essay illustrates various perfusion and parenchymal changes associated with portal venous inflow, hepatic venous outflow, and non-portal venous third inflow and describes brief background pathophysiology and differential points.

Hepatic arteriovenous fistulae: role of interventional radiology

INTRODUCTION

Hepatic arterial venous fistulae are abnormal communications between the hepatic artery and portal or hepatic vein and commonly occur either secondary to iatrogenic causes like liver biopsy, transhepatic biliary drainage, transhepatic cholangiogram and surgery, or following mechanical insult like blunt or penetrating trauma. Congenital fistulae are rare. Treatment is warranted as an emergency management or in the development of portal hypertension/heart failure in chronic cases. Both surgical and endovascular occlusion of the fistula can be attempted with the latter carrying low intra and post-procedure morbidity. Endovascular treatment has thus currently emerged as a minimally invasive reliable treatment option in such individuals.

METHODS AND RESULTS

We describe a short series consisting of four cases of acquired hepatic arterioportal/venous fistulae, which were referred to interventional radiology for endovascular management over the last 2 years. Three patients had arterio-portal communication and one patient had communication between the hepatic artery and middle hepatic vein. Successful embolization through the transarterial route was achieved in all four patients. A brief discussion of these cases is presented along with a relevant review of literature.

CONCLUSIONS

Endovascular techniques currently form less invasive and first line treatment options in arterioportal/venous fistulae, surgery being reserved only for unsuccessful embolizations/complex fistulae.

Transient Hepatic Parenchymal Enhancement detected at dynamic imaging: a short instruction manual for the clinician

Basic knowledge in the interpretation of hepatic imaging is essential for the clinical hepatologist. In recent years, the availability of dynamic imaging studies of the liver using computed tomography or magnetic resonance has led to appreciate the importance of early changes in arterial perfusion for the interpretation of hepatic lesions. Transient Hepatic Parenchymal Enhancement (THPE) is defined as a normal area of liver parenchyma that enhances after injection of contrast agent during the arterial phase of perfusion. Appearance of this sign is mostly associated with a reduction in portal perfusion or with inflammation, and appears in different morphologic patterns. THPE should not be considered a radiological artefact, and its interpretation is essential to avoid misclassification of hepatic lesions that may have clinical significance, such as hepatocellular carcinoma or hepatic metastases. In this short review we provide essential information on the causes, pathophysiology and morphology of THPE, and discuss the relevance of these findings in a clinical perspective.

Imaging assessment of congenital and acquired abnormalities of the portal venous system

Abnormalities of the portal venous system are a heterogeneous group of conditions that can cause substantial morbidity and mortality and may lead to complications during surgery or percutaneous interventions involving the portal venous system. High-resolution computed tomography, ultrasonography, and magnetic resonance imaging permit a comprehensive, noninvasive evaluation of the portal venous system, enabling the detection of both structural and functional abnormalities. However, an understanding of the embryologic development of the normal portal venous anatomy and anatomic variants is essential to accurately interpret the imaging findings. Knowledge of the characteristic appearances of abnormalities of the portal venous system allows a more confident diagnosis, permitting timely treatment and more informed guidance of surgical procedures and percutaneous interventions, which may lead to an improved outcome.

Pictorial review. Hepatic vascular shunts: embryology and imaging appearances

The purpose of this pictorial review is to understand the embryological basis of the development of congenital hepatic vascular shunts and to review the multimodality imaging appearances of congenital and acquired hepatic vascular shunts. Hepatic vascular shunts are commonly seen in imaging. Familiarity with their characteristic appearances is important in order to accurately characterise these shunts and diagnose the underlying disorders.

Intra-hepatic arterioportal shunt mimicking a metastatic liver tumor: report of a case

The differential diagnosis of an arterioportal shunt (APS) is difficult and important. We report a case of an intra-hepatic APS mimicking a metastatic liver tumor on imaging scans in a patient without hepatic cirrhosis. The patient was a 64-year-old woman, who had undergone low anterior resection of the rectum for advanced rectal cancer, followed 2 months later by right hemihepatectomy, including the middle hepatic vein, for a synchronous metastatic liver tumor. About 2 years after the hepatectomy, a follow-up CT scan showed a new mass in the remnant liver, suggestive of a metastatic liver tumor, the assumption of which was further supported by an elevated serum carcinoembryonic antigen (CEA) level. However, the findings of magnetic resonance imaging were not consistent with a malignant tumor, and Doppler ultrasonography showed a low echoic area connected with the portal vein branch and the hepatic artery branch. Thus, we diagnosed intra-hepatic APS. The patient remains well without signs of growth of the hepatic lesion, although with fluctuating serum CEA levels.

Hepatocellular carcinoma in cirrhotic patients at multidetector CT: hepatic venous phase versus delayed phase for the detection of tumour washout

OBJECTIVES

Our aim was to compare retrospectively hepatic venous and delayed phase images for the detection of tumour washout during multiphasic multidetector row CT (MDCT) of the liver in patients with hepatocellular carcinoma (HCC).

METHODS

30 cirrhotic patients underwent multiphasic MDCT in the 90 days before liver transplantation. MDCT was performed before contrast medium administration and during hepatic arterial hepatic venous and delayed phases, images were obtained at 12, 55 and 120 s after trigger threshold. Two radiologists qualitatively evaluated images for lesion attenuation. Tumour washout was evaluated subjectively and objectively. Tumour-to-liver contrast (TLC) was measured for all pathologically proven HCCs.

RESULTS

48 HCCs were detected at MDCT. 46 of the 48 tumours (96%) appeared as either hyper- or isoattenuating during the hepatic arterial phase subjective washout was present in 15 HCCs (33%) during the hepatic venous phase and in 35 (76%) during the delayed phase (p<0.001, McNemar's test). Objective washout was present in 30 of the 46 HCCs (65%) during the hepatic venous phase and in 42 of the HCCs (91%) during the delayed phase (p=0.001). The delayed phase yielded significantly higher mean TLC absolute values compared with the hepatic venous phase (-16.1±10.8 HU vs -10.5±10.2 HU; p<0.001).

CONCLUSIONS

The delayed phase is superior to the hepatic venous phase for detection of tumour washout of pathologically proven HCC in cirrhotic patients.

Outcome of small liver nodules detected by computed tomographic angiography in patients with hepatocellular carcinoma

PURPOSE

Hepatic lesions identified by computed tomography (CT) during arterial portography (CTAP) or CT hepatic arteriography (CTHA) in hepatocellular carcinoma (HCC) patients are sometimes too small to be diagnosed as HCC. We undertook this cohort study to assess whether these small lesions are actually HCC, and to clarify the effectiveness of these imaging examinations in a clinical setting.

METHODS

We assessed the characteristics of 74 tiny lesions detected by CTAP and/or CTHA, but not by CT in 67 patients.

RESULTS

Seven out of 10 nodules were histologically confirmed as HCC and 18 out of 64 lesions increased in size and showed typical findings of HCC during the follow-up period. Multivariate analysis revealed that the size of the main tumor (>30 mm in diameter) was associated with the presence of tiny additional HCC lesions (P = 0.002).

CONCLUSIONS

These findings indicate that CTAP and CTHA are recommended for determining the stage of HCC, especially when the HCC nodule is larger than 30 mm in diameter.

Gadoxetic acid-enhanced magnetic resonance imaging for differentiating small hepatocellular carcinomas (< or =2 cm in diameter) from arterial enhancing pseudolesions: special emphasis on hepatobiliary phase imaging

OBJECTIVES

To determine the characteristic enhancing features of hepatocellular carcinoma (HCC) and arterial-enhancing pseudolesion (AEP) on gadoxetic acid (Primovist)-enhanced magnetic resonance imaging (MRI) and to assess its performance compared with that of multirow detector computed tomography (MDCT) for differentiating small HCC (< or =2 cm in diameter) from AEP in cirrhotic liver.

MATERIALS AND METHODS

A total of 69 patients with 97 small, arterial enhancing hepatic lesions (0.5-2 cm in diameter), ie, 44 HCCs and 53 AEPs, detected on gadoxetic acid-enhanced MRI, were included in this study. HCCs were diagnosed either through histopathology confirmation (n = 16) or by a combination of liver computed tomography (CT), angiographic findings, lipiodol CT, and AFP levels (n = 28). AEPs were diagnosed either through histopathology confirmation (n = 2) or were based on the angiographic findings, liver CT, and follow-up imaging (n = 51). Two radiologists jointly analyzed the morphologic features and the enhancement characteristics on the gadoxetic acid-enhanced MRI. Of the 69 study patients, 42 patients with 60 arterial enhancing lesions underwent quadruple-phase CT in addition to their MRI examination within 4 weeks before or after the MRI, and 2 other radiologists who were blinded to the final diagnosis independently reviewed the MRI and CT images in random order, at an interval of 2 weeks. Diagnostic performance was evaluated using receiver operating characteristics. The Kappa test was used to evaluate interobserver agreement.

RESULTS

Among 44 HCCs, 42 (95.4%) demonstrated low signal intensity (SI) and only 2 showed iso- or high SI on the hepatobiliary phase of gadoxetic acid-enhanced MRI. Alternatively, most AEPs showed iso SI on the hepatobiliary (n = 50, 94.3%) phase, and only 2 AEPs showed low SI. Compared with the diagnostic performance of the 2 imaging modalities, the mean areas under the receiver-operator characteristic curves on MR imaging were 0.975 for reviewer 1 and 0.966 for reviewer 2, whereas those of CT imaging were 0.892 for reviewer 1 and 0.888 for reviewer 2 (P = 0.069 and P = 0.106, respectively). The sensitivity for each reviewer with MR imaging (93.9% and 90.9%, respectively) was significantly higher than that with multiphasic CT (54.5%, in both) (P = 0.001 and 0.0018, respectively).

CONCLUSION

HCCs and AEPs show different enhancing features on the delayed dynamic and hepatobiliary phases of gadoxetic acid-enhanced MRI. Gadoxetic acid-enhanced MRI may, therefore, help to differentiate between HCC and AEP.

Contrast-enhanced ultrasound in the detection and characterization of liver tumors

Contrast-enhanced ultrasound (CEUS) has unique advantages over contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) in the characterization of hepatic tumors. These include the capability of real-time dynamic imaging depicting the enhancement pattern of tumors regardless of its rapidity, purely intravascular properties of the microbubble contrast agents more consistently demonstrating washout of malignancy, and capability of repetitive observation of tumor vascularity with multiple injections of microbubbles with an excellent safety profile and no nephrotoxicity. For an indeterminate mass detected on an ultrasound scan, an immediate benign diagnosis reduces the necessity of costly further imaging as well as patients’ anxiety and an immediate malignant diagnosis prompts the proper work-up and management. CEUS is often served as a problem-solving tool for indeterminate lesions on prior CT or MRI scans, obviating further invasive steps. CEUS offers excellent visualization of peripheral nodular enhancement in even flash-filling or very slow-filling hemangiomas. Careful observation of early arterial filling pattern is helpful in the differentiation of focal nodular hyperplasia versus adenoma. Hepatocellular carcinoma is typically characterized by arterial hypervascularity and often late, partial washout. Metastasis shows brief arterial hypervascularity and complete rapid washout, which can improve its detection during a portal phase survey. The washout phenomenon of malignant tumors in general is useful to differentiate them from benign lesions.