Diagnostic accuracy of MRI in differentiating hepatocellular adenoma from focal nodular hyperplasia: prospective study of the additional value of gadoxetate disodium. AJR Am J Roentgenol. 2012;199:26-34. [PMID: 22733890 DOI: 10.2214/ajr.11.7750]

Qualitative and quantitative assessment of gadoxetic acid MRI in distinguishing atypical focal nodular hyperplasia from hepatocellular adenoma subtypes

OBJECTIVE

To assess qualitative and quantitative imaging features, including lesion-to-liver contrast enhancement ratio (LLCER), on gadoxetic acid-enhanced MRI for differentiating atypical focal nodular hyperplasia (aFNH) from hepatocellular adenoma (HCA) subtypes.

MATERIALS AND METHODS

This retrospective study included patients with histopathologically-confirmed aFNH and HCA who underwent gadoxetic acid-enhanced MRI between January 2010 and December 2020. Two radiologists assessed qualitative imaging features and calculated LLCERs for quantitative evaluation of HBP enhancement. Statistical analyses included ROC curves, sensitivity, specificity, and a decision tree.

RESULTS

86 patients (41 ± 11 years; 64 women) had 29 aFNHs and 90 HCAs. HBP iso-/hyperintensity was observed in 72.4% (21/29) of aFNH compared to 28.8% (15/52) of U-HCA, 35% (7/20) of I-HCA, and 0% (0/11) of H-HCA. β-HCA showed 71.4% (5/7) iso-/hyperintensity, overlapping with aFNH (p = 0.17). Homogeneous iso-/hyperintensity and rim-like enhancement were present in 48.3% (14/29) and 20.7% (6/29) of aFNH but absent in β-HCA (p = 0.004). LLCER demonstrated high diagnostic performance, differentiating aFNH from U-HCA, H-HCA, and I-HCA(AUCs 0.91-0.99, sensitivities 82.8-96.6%, specificities 90.0-100%). For β-HCA, LLCER showed overlap with aFNH; AUCs (0.62-0.64) and specificities (57.1%). Among HCAs with HBP iso-/hyperintensity, 74.1% had negative LLCER values, while 25.9% (mostly β-HCA/U-HCA) showed positive values (true enhancement). Combined decision trees selected LLCER as the primary node, with downstream HBP features variably incorporated, except β-HCA, which solely used qualitative features.

CONCLUSION

HBP iso-/hyperintensity and LLCER reliably differentiated aFNH from most HCA subtypes, except β-HCA, validated by decision tree analyses. Homogeneous iso-/hyperintensity or rim-like enhancement was absent in β-HCA, aiding differentiation.

KEY POINTS

Question Variability in hepatobiliary phase (HBP) enhancement among hepatocellular adenoma (HCA) subtypes and atypical FNH (aFNH) poses diagnostic challenges. Findings Despite HBP enhancement overlap in aFNH/β-HCA, "homogeneous" and rim-like enhancement aided aFNH differentiation from HCAs. LLCER separated HCAs lacking true HBP uptake from aFNH. Clinical relevance This study explored challenges in differentiating aFNH from HCA subtypes, especially overlapping β-HCA, highlighting discriminatory qualitative markers and quantitative assessment to distinguish true HBP enhancement, an approach validated by decision tree analysis.

Gadoxetic acid-enhanced MRI in differentiating focal nodular hyperplasia from hepatocellular adenoma in children

OBJECTIVE

To investigate the diagnostic performance of gadoxetic acid (Gd-EOB)-enhanced MRI for distinguishing focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA) in children.

METHODS

Twenty-two patients (HCA, n = 6; FNH, n = 16) underwent MRI with Gd-EOB were retrospectively included in this study. The diagnosis was established by biopsy in eight patients and by imaging criteria and follow-up in 13 patients. After qualitative analyses of MRI, quantitative analyses were performed by calculating the relative signal intensity ratios (SIR) between lesion and liver parenchyma both on precontrast and hepatobiliary phase (HBP) images. Two equations, SIRpost-pre and liver-to-lesion contrast enhancement ratio (LLCER), using both SIRs of precontrast and HBP imaging together were also calculated.

RESULTS

The most distinguishing non-contrast-enhanced MRI feature of HCA was intralesional fat since all HCA contained fat but none of FNHs. All FNHs were iso- or hyperintense relative to the adjacent liver on HBP images, but all HCAs except one were hypointense. The mean SIRpost-pre and LLCER of FNH were significantly higher than that of HCA (P < .001). SIRpost-pre and LLCER provided sensitivity and specificity values of 100%.

CONCLUSION

Although intralesional fat is a strong discriminative feature for distinguishing between HCA and FNH, qualitative properties of these lesions may not be enough for confident diagnosis. Gd-EOB uptake in the HBP provides high diagnostic accuracy, but overlap can be seen. SIRpost-pre and LLCER overcome the difficulties and have the best sensitivity and specificity.

ADVANCES IN KNOWLEDGE

Gadoxetic acid-enhanced MRI is a valuable tool for differentiation of FNH and HCA in children.

Perinatal Management of Hepatic Adenomas

Importance

With a strong association between hepatic adenomas and estrogen established, understanding the risks, evaluation, and perinatal management of hepatic adenomas is necessary for obstetric clinicians.

Objective

The aim of this study is to review the preconception counseling, perinatal management, and postpartum care of hepatic adenomas.

Evidence Acquisition

A literature review identified relevant research, review articles, textbook chapters, databases, and societal guidelines.

Results

Hepatic adenomas require individualized recommendations based on their prepregnancy size and evolution over pregnancy. Hepatic adenomas measuring greater than 5 cm are associated with a significantly increased risk during pregnancy including rupture. Ideally, optimal management of hepatic adenoma includes accurate diagnosis, discontinuation of estrogen-containing contraception, and surgical resection of large masses prior to conception. Patients should undergo serial surveillance of the adenoma during the antenatal and postpartum periods, with surgical intervention as indicated with multidisciplinary planning.

Conclusions and Relevance

An individualized approach is necessary when managing hepatic adenomas in the patient who is pregnant or intends pregnancy. More contemporary data are required to guide management and patient counseling.

Contrast-Enhanced Ultrasound Compared With Hepatobiliary Agent MRI for Differentiation of Focal Nodular Hyperplasia and Hepatic Adenoma: A Prospective Trial

ABSTRACT

Magnetic resonance imaging (MRI) may be time-consuming, expensive, or poorly tolerated by patients with liver lesions. This is a prospective clinical trial designed to evaluate if contrast-enhanced ultrasound (CEUS) can be used to differentiate focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA) with similar accuracy compared with hepatobiliary agent MRI.Institutional review board approval was obtained (1805450097), and the trial was registered with ClinicalTrials.gov (NCT03652636). From 2018 through 2023, 40 patients who had lesions consistent with FNH or HCA on HBA-MRI underwent 1-time prospective CEUS of up to 2 hepatic lesions. Sonographic images obtained before and after intravenous administration of 2 mL sulfur hexafluoride lipid-type A microspheres (Lumason) per lesion totaling 59 lesions (27 FNHs/32 HCAs). Two blinded radiologists provided a diagnosis of FNH or HCA.Thirty-eight female and 2 male patients (age 36.7 ± 9.9) were scanned. Radiologists provided diagnosis of FNH or HCA with respective sensitivity (66.7/64.0%), specificity (71.9/90.6%), and accuracy (69.5/78.0%). For 38 lesions greater than or equal to 2 cm in size (17 FNHs/21 HCAs), readers had sensitivity (70.6/84.2%), specificity (70.6/84.2%), and accuracy (81.5/86.8%). Interobserver agreement for all lesions was fair (κ = 0.34), whereas agreement for lesions 2 cm or larger was substantial (κ = 0.67).Contrast-enhanced ultrasound can differentiate FNH from HCA with accuracy approaching that of hepatobiliary agent MRI for lesions 2 cm or greater. Interobserver agreement is improved with larger lesions. CEUS may have utility as an alternate diagnostic tool for FNH/HCA, especially in patients who cannot or do not desire to undergo MRI.

ACG Clinical Guideline: Focal Liver Lesions

Focal liver lesions (FLLs) have become an increasingly common finding on abdominal imaging, especially asymptomatic and incidental liver lesions. Gastroenterologists and hepatologists often see these patients in consultation and make recommendations for management of multiple types of liver lesions, including hepatocellular adenoma, focal nodular hyperplasia, hemangioma, and hepatic cystic lesions including polycystic liver disease. Malignancy is important to consider in the differential diagnosis of FLLs, and healthcare providers must be familiar with the diagnosis and management of FLLs. This American College of Gastroenterology practice guideline uses the best evidence available to make diagnosis and management recommendations for the most common FLLs.

Pedunculated Focal Nodular Hyperplasia: When in Doubt, Should We Cut It Out?

Focal nodular hyperplasia (FNH) is the second most common benign hepatic tumor and can rarely present as an exophytic solitary mass attached to the liver by a stalk. Most FNH cases are usually detected as incidental findings during surgery, imaging or physical examination and have a high female predominance. However, the pedunculated forms of FNH are particularly rare and commonly associated with severe complications and diagnostic challenges. Hence, our study aims to provide a comprehensive summary of the available data on the pedunculated FNH cases among adults and children. Furthermore, we will highlight the role of different therapeutic options in treating this clinical entity. The use of imaging techniques is considered a significant addition to the diagnostic toolbox. Regarding the optimal treatment strategy, the main indications for surgery were the presence of symptoms, diagnostic uncertainty and increased risk of complications, based on the current literature. Herein, we also propose a management algorithm for patients with suspected FNH lesions. Therefore, a high index of suspicion and awareness of this pathology and its life-threatening complications, as an uncommon etiology of acute abdomen, is of utmost importance in order to achieve better clinical outcomes.

Differentiation of focal nodular hyperplasia and hepatocellular adenoma using qualitative and quantitative imaging features and classification and regression tree analysis

PURPOSE

To assess qualitative and quantitative analysis of gadoxetate disodium-enhanced hepatobiliary phase MR imaging (MRI) and assess the performance of classification and regression tree analysis for the differentiation of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA).

MATERIALS AND METHODS

This retrospective study was approved by our local ethics committee. One hundred seventy patients suspected of having FNH or HCA underwent gadoxetate disodium-enhanced MRI. The reference standard was either pathology or follow-up imaging. Two readers reviewed images to identify qualitative imaging features and measure signal intensity on unenhanced, dynamic, and hepatobiliary phase images. For quantitative analysis, contrast enhancement ratio (CER), lesion-to-liver contrast (LLC), signal intensity ratio (SIR), and relative signal enhancement ratio (RSER) were calculated. A classification and regression tree (CART) analysis was developed.

RESULTS

Eighty-five patients met the inclusion criteria, with a total of 97 FNHs and 43 HCAs. For qualitative analysis, the T1 signal intensity on the hepatobiliary phase provided the highest overall classification performance (91.9% sensitivity, 90.1% specificity, and 90.9% accuracy). For quantitative analysis, RSER in the hepatobiliary phase with a threshold of 0.723 provided the highest classification performance (92.6% sensitivity and 89.4% specificity) to differentiate FNHs from HCAs. A CART model based on five qualitative imaging features provided an accuracy of 94.4% (95% confidence interval 90.0-98.9%).

CONCLUSION

Gadoxetate disodium-enhanced hepatobiliary phase provides high diagnostic performance as demonstrated in quantitative and qualitative analysis in differentiation of FNH and HCA, supported by a CART decision model.

Hepatic Adenoma Subtypes on Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI: Systematic Review and Meta-Analysis

BACKGROUND. Accumulating evidence indicates that hepatocellular adenoma (HCA) may have a higher frequency of hepatobiliary phase (HBP) iso- or hyperintensity than previously reported. OBJECTIVE. The purpose of this study was to evaluate the proportion of HCA that shows iso- or hyperintensity in the HBP of gadoxetic acid-enhanced MRI, stratified by HCA subtype (HNF1a-inactivated [H-HCA], inflammatory [I-HCA], β-catenin-activated [B-HCA], and unclassified [U-HCA] HCA), and to assess the diagnostic performance of HBP iso- or hyperintensity for differentiating focal nodular hyperplasia (FNH) from HCA. EVIDENCE ACQUISITION. PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched through February 14, 2022, for articles reporting HBP signal intensity on gadoxetic acid-enhanced MRI among pathologically proven HCAs, stratified by subtype. The pooled proportion of HBP iso- or hyperintensity was determined for each subtype and compared using metaregression. Diagnostic performance of HBP iso- or hyperintensity for differentiating FNH from all HCA subtypes combined and from B-HCA and U-HCA combined was assessed using bivariate modeling. EVIDENCE SYNTHESIS. Twenty-eight studies (12 original investigations, 16 case reports or case series) were included, yielding 364 patients with 410 HCAs (112 H-HCAs, 203 I-HCAs, 33 B-HCAs, 62 U-HCAs). Pooled proportion of HBP iso- or hyperintensity was 14% (95% CI, 4-26%) among all HCAs, 0% (95% CI, 0-2%) among H-HCAs, 11% (95% CI, 0-29%) among U-HCAs, 14% (95% CI, 2-31%) among I-HCAs, and 59% (95% CI, 26-88%) among B-HCAs; metaregression showed significant difference among subtypes (p < .001). In four studies reporting diagnostic performance information, HBP iso- or hyperintensity had sensitivity of 99% (95% CI, 57-100%) and specificity of 89% (95% CI, 82-94%) for differentiating FNH from all HCA subtypes and sensitivity of 99% (95% CI, 53-100%) and specificity of 65% (95% CI, 44-80%) for differentiating FNH from B-HCA or U-HCA. CONCLUSION. HCA subtypes other than H-HCA show proportions of HBP iso- or hyperintensity ranging from 11% (U-HCA) to 59% (B-HCA). Low prevalence of B-HCA has contributed to prior reports of high diagnostic performance of HBP iso- or hyperintensity for differentiating FNH from HCA. CLINICAL IMPACT. Radiologists should recognize the low specificity of HBP iso- or hyperintensity on gadoxetic acid-enhanced MRI for differentiating FNH from certain HCA subtypes.

Study protocol for a multicentre nationwide prospective cohort study to investigate the natural course and clinical outcome in benign liver tumours and cysts in the Netherlands: the BELIVER study

INTRODUCTION

Benign liver tumours and cysts (BLTCs) comprise a heterogeneous group of cystic and solid lesions, including hepatic haemangioma, focal nodular hyperplasia and hepatocellular adenoma. Some BLTCs, for example, (large) hepatocellular adenoma, are at risk of complications. Incidence of malignant degeneration or haemorrhage is low in most other BLTCs. Nevertheless, the diagnosis BLTC may carry a substantial burden and patients may be symptomatic, necessitating treatment. The indications for interventions remain matter of debate. The primary study aim is to investigate patient-reported outcomes (PROs) of patients with BLTCs, with special regards to the influence of invasive treatment as compared with the natural course of the disease.

METHODS AND ANALYSIS

A nationwide observational cohort study of patients with BLTC will be performed between October 2021 and October 2026, the minimal follow-up will be 2 years. During surveillance, a questionnaire regarding symptoms and their impact will be sent to participants on a biannual basis and more often in case of invasive intervention. The questionnaire was previously developed based on PROs considered relevant to patients with BLTCs and their caregivers. Most questionnaires will be administered by computerised adaptive testing through the Patient-Reported Outcomes Measurement Information System. Data, such as treatment outcomes, will be extracted from electronic patient files. Multivariable analysis will be performed to identify patient and tumour characteristics associated with significant improvement in PROs or a complicated postoperative course.

ETHICS AND DISSEMINATION

The study was assessed by the Medical Ethics Committee of the University Medical Center Groningen and the Amsterdam UMC. Local consultants will provide information and informed consent will be asked of all patients. Results will be published in a peer-reviewed journal.

STUDY REGISTRATION

NL8231-10 December 2019; Netherlands Trial Register.

Case Report: Rare Acute Abdomen: Focal Nodular Hyperplasia With Spontaneous Rupture

Focal nodular hyperplasia (FNH) of the liver is a benign lesion characterized by hypertrophic nodules with central star-shaped fibrous scars. The etiology and pathogenesis of FNH are not completely understood. A 43-year-old man was hospitalized because of acute abdominal pain. Emergency computed tomography(CT) showed hepatic tumor rupture and bleeding. The patient’s condition improved following arteriographic embolization to stop bleeding. Laparotomy confirmed spontaneous rupture and hemorrhage of focal hyperplasia and the patient remains asymptomatic after an uneventful recovery. FNH with spontaneous rupture and bleeding is extremely rare. Currently, there is no unified management standard for FNH and most previous studies recommend observation and follow-up. We recommend consideration of surgical treatment of cases with spontaneous rupture and bleeding.

Oxaliplatin related multiple focal nodular hyperplasia mimicking metastasis from a gastric cancer

Introduction

The FOLFOX6 scheme is a combination drug chemotherapy that contains calcium leucovorin (folinic acid), fluorouracil, and oxaliplatin, the chronic use of chemotherapy with oxaliplatin can progress to focal nodular hyperplasia (FNH), which is a benign hepatic lesion.

Case report

We present a case of a 26- year-old female diagnosed with an ovarian mixed germ cell tumor with extension to the peritoneum, treated with 12 cycles in 9 months with neoadjuvant chemotherapy FOLFOX 6 scheme and oophorectomy. A three-year follow-up CT showed three nodular and hypervascular hepatic lesions suspicious of metastatic disease; an MRI with liver-specific contrast confirmed the diagnosis of FNH.

Management and outcome

The patient continued her follow-up without other treatment and metastatic disease.

Discussion

While most multiple liver lesions in a patient with cancer will be suspicious of metastasis, a careful drug history should be obtained, as an oxaliplatin-related side effect to develop FNH has been reported. MRI with liver-specific contrast has a positive predictive value of 95% because of the biliary excretion through OATP1B3 transporter, expressed in functional hepatocytes and overexpressed in some liver tumors such as FNH, so it should be performed when FNH is suspected.

Diagnostic value of morphological enhancement patterns in the hepatobiliary phase of gadoxetic acid-enhanced MRI to distinguish focal nodular hyperplasia from hepatocellular adenoma

OBJECTIVES

To describe the different morphological enhancement patterns of focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI (Gd-EOB-DTPA MRI) and to determine their added value in their differential diagnosis.

METHODS

A retrospective analysis of imaging findings in 185 benign hepatocellular lesions (154 FNH; 31 HCA) in 108 patients who underwent Gd-EOB-DTPA MRI was performed by two independent reviewers. Six patterns on HBP were recorded: 1) homogeneous enhancement; 2) peripheral ring-like enhancement with hypointense central core; 3) peripheral ring-like enhancement with hyperintense central core; 4) central core enhancement with hypointense periphery; 5) heterogeneous enhancement; and 6) the absence of enhancement.

RESULTS

Peripheral ring-like enhancement with hypointense central core and peripheral ring-like enhancement with hyperintense central core showed the highest specificity for the diagnosis of FNH (100% and 96.8%, respectively). The absence of enhancement and central core enhancement with hypointense periphery were only present in 0.6% and 1.9% of FHN, respectively. All other patterns were observed with similar frequencies in FNH (22.1% to 26.6%). Six HCA showed contrast uptake on the HBP: homogeneous (6.5%), peripheral ring-like enhancement with hyperintense central core (3.2%) and heterogeneous (9.7%).

CONCLUSION

Both FNH and HCA may demonstrate enhancement in the HBP of Gd-EOB-DTPA MRI, limiting its specificity. A significant improvement in specificity can be achieved by the evaluation of morphological enhancement patterns: Peripheral ring-like enhancement with hypointense or hyperintense central core was highly specific for FNH diagnosis. On the other hand, the absence of HBP enhancement makes the diagnosis of FNH unlikely.

An MR-based radiomics model for differentiation between hepatocellular carcinoma and focal nodular hyperplasia in non-cirrhotic liver

PURPOSE

We aimed to develop and validate a radiomics model for differentiating hepatocellular carcinoma (HCC) from focal nodular hyperplasia (FNH) in non-cirrhotic livers using Gd-DTPA contrast-enhanced magnetic resonance imaging (MRI).

METHODS

We retrospectively enrolled 149 HCC and 75 FNH patients treated between May 2015 and May 2019 at our center. Patients were randomly allocated to a training (n=156) and validation set (n=68). In total, 2260 radiomics features were extracted from the arterial phase and portal venous phase of Gd-DTPA contrast-enhanced MRI. Using Max-Relevance and Min-Redundancy, random forest, least absolute shrinkage, and selection operator algorithm for dimensionality reduction, multivariable logistic regression was used to build the radiomics model. A clinical model and combined model were also established. The diagnostic performance of the models was compared.

RESULTS

Eight radiomics features were chosen for the radiomics model, and four clinical factors (age, sex, HbsAg, and enhancement pattern) were chosen for the clinical model. A combined model was built using the factors from the previous models. The classification accuracy of the combined model differentiated HCC from FNH in both the training and validation sets (0.956 and 0.941, respectively). The area under the receiver operating characteristic curve of the combined model was significantly better than that of the clinical model for both the training (0.984 vs. 0.937, p=0.002) and validation (0.972 vs. 0.903, p=0.032) sets.

CONCLUSIONS

The combined model provided a non-invasive quantitative method for differentiating HCC from FNH in non-cirrhotic liver with high accuracy. Our model may assist clinicians in the clinical decision-making process.

Value of discrepancy of the central scar-like structure between dynamic CT and gadoxetate disodium-enhanced MRI in differentiation of focal nodular hyperplasia and hepatocellular adenoma

PURPOSE

To identify the value of discrepancies in the central scar (CS)-like structure between dynamic CT and gadoxetate disodium-enhanced MRI for differentiating FNH from HCA.

METHODS

This retrospective study included 113 patients with pathologically-diagnosed FNH (n = 80) or HCA (n = 37). CS-like structures were evaluated on arterial phase (AP) CT and hepatobiliary phase (HBP) MRI. Presence of the CS-like structure, its discrepancy in visibility or size between AP CT and HBP MRI and between AP and HBP MRI, and features of non-scarred tumor portion were evaluated by two radiologists. Inter-observer agreement was evaluated by intraclass correlation coefficients (ICCs) and weighted kappa. Univariable and multivariable logistic regression and ROC analysis were performed to explore features differentiating FNH from HCA.

RESULTS

Inter-observer agreement was moderate-to-excellent (ICCs≥0.74, kappa≥0.65). On univariable analysis, presence of CS-like structures (P < 0.001), discrepancy of the CS-like structures between AP CT and HBP MRI (73.8 % in FNH; 16.2 % in HCA, P < 0.001) and between AP and HBP MRI (70.0 % in FNH; 16.2 % in HCA, P < 0.001), and the features of non-scarred tumor portion (P ≤ 0.011) were significantly different between FNH and HCA. On multivariable analysis, the discrepancy of CS-like structures between AP CT and HBP MRI, and the absence of low SI of the non-scarred tumor portion on HBP MRI, were suggestive of FNH (P = 0.036 and P < 0.001, respectively; area under the ROC curve, 0.96 [95 % CI, 0.93-0.99]).

CONCLUSION

Evaluation of discrepancy in the visibility or size of CS-like structures between dynamic CT and gadoxetate disodium-enhanced MRI may facilitate the differentiation of FNH from HCA.

Clinicopathological features and post-resection outcomes of hepatocellular adenoma

Backgrounds/Aims

Hepatocellular adenomas (HCA) are rare benign liver tumors with the potential of malignant transformation and risk of bleeding. We investigated the clinicopathological features and outcomes of HCA in 19 patients who underwent surgical resection.

Methods

This retrospective observational study included 19 patients who underwent hepatic resection during a 9-year period from 2011 to 2019.

Results

The incidence of HCA was 0.18% of all hepatic resection cases during the study period. The mean age of the patients was 34.3±9.6 years, and 12 patients (63.2%) were female. Abdominal pain was present as initial clinical manifestation in 5 patients and the other 14 patients had no specific symptoms. HCA was diagnosed in 7 out of 8 patients who underwent liver biopsy. R0 resection was performed in 18 patients (94.7%) and laparoscopic liver resection was performed in 11 patients (57.9%). The mean tumor size was 5.6±3.6 cm and 17 patients had a single tumor. Immunohistochemical analysis of the resected tumor specimens revealed hepatocyte-nuclear-factor-1α mutated HCA in 2 (10.5%), β-catenin-mutated HCA in 2 (10.5%), inflammatory HCA in 12 (63.2%) and unclassified HCA in 3 (15.8%). There were no pathognomonic findings in the preoperative liver imaging studies among these four groups. Currently, all patients are alive with a mean follow-up period of 40.1±26.3 months. One patient showed residual tumors after incomplete resection.

Conclusions

Surgical resection may be indicated if imaging studies show diagnostic ambiguity, growing tumor or symptomatic mass. Because of the risk of tumor recurrence and malignant transformation, long-term follow-up is necessary.

Spectrum of liver lesions hyperintense on hepatobiliary phase: an approach by clinical setting

Hepatobiliary MRI contrast agents are increasingly being used for liver imaging. In clinical practice, most focal liver lesions do not uptake hepatobiliary contrast agents. Less commonly, hepatic lesions may show variable signal characteristics on hepatobiliary phase. This pictorial essay reviews a broad spectrum of benign and malignant focal hepatic observations that may show hyperintensity on hepatobiliary phase in various clinical settings. In non-cirrhotic patients, focal hepatic observations that show hyperintensity in the hepatobiliary phase are usually benign and typically include focal nodular hyperplasia. In patients with primary or secondary vascular disorders, focal nodular hyperplasia-like lesions arise as a local hyperplastic response to vascular alterations and tend to be iso- or hyperintense in the hepatobiliary phase. In oncologic patients, metastases and cholangiocarcinoma are hypointense lesions in the hepatobiliary phase; however, occasionally they may show a diffuse, central and inhomogeneous hepatobiliary paradoxical uptake with peripheral rim hypointensity. Post-chemotherapy focal nodular hyperplasia-like lesions may be tricky, and their typical hyperintense rim in the hepatobiliary phase is very helpful for the differential diagnosis with metastases. In cirrhotic patients, hepatocellular carcinoma may occasionally appear hyperintense on hepatobiliary phase.

Steatohepatitic hepatocellular carcinoma: imaging findings with clinicopathological correlation

AIM

To evaluate the clinicopathological and computed tomography (CT) and magnetic resonance imaging (MRI) findings of steatohepatitic hepatocellular carcinoma (SH-HCC).

MATERIALS AND METHODS

Clinicopathological and radiological features were evaluated in 20 patients with SH-HCC. The diagnosis of SH-HCC was made histologically if the tumour had four of the following five characteristics: steatosis (>5% tumour cells), ballooning, Mallory-Denk bodies, interstitial fibrosis, and inflammation. All patients underwent dynamic CT and MRI. CT and MRI images were reviewed for morphological features including tumour size, presence, and distribution of fat, and patterns and degree of contrast enhancement.

RESULTS

Obesity, hypertension, and history of heavy alcohol intake were common clinical findings observed in 10 (50%), 13 (65%), and 11 (55%) of the 20 patients, respectively. Steatosis and steatohepatitis were pronounced in the background liver in 12 (60%) and 10 (50%) patients, respectively. SH-HCC was moderately differentiated in 18 patients (90%) and well differentiated in two (10%). Pathologically, steatohepatitic features were diffuse in 12 (60%) of the 20 tumours and focal in eight (40%). Tumour size and the percentage of intratumoural steatosis were not correlated (r=0.17, p=0.47). On CT, 16 (80%) patients showed arterial phase enhancement and delayed washout. On MRI, 16 (80%) of 20 tumours showed prominent fatty deposition (10 diffusely, six focally) with arterial phase enhancement.

CONCLUSIONS

SH-HCC is likely to show prominent fatty deposits with arterial phase enhancement on CT and MRI. A hypervascular lesion with prominent fatty change should raise the diagnostic suspicion of SH-HCC.

Surgical Management of Hepatic Benign Disease: Have the Number of Liver Resections Increased in the Era of Minimally Invasive Approach? Analysis from the I Go MILS (Italian Group of Minimally Invasive Liver Surgery) Registry

BACKGROUND

Increased expertise with minimally invasive liver surgery (MILS) could cause an unjustified extension of indications to resect liver benign disease (BD). The aim of this study was to evaluate the operative risk of MILS for BD and if implementation and diffusion of MILS have widened indications for BD resection.

METHODS

A prospective study including centers with > 6 MILS for BD, enrolled in the I Go MILS registry from January 2015 to October 2016. Cysts fenestrations were excluded.

RESULTS

Eight hundred eighteen MILS were performed in 15 centers. One hundred seventy-three of these (21.1%) were for BD: conversion rate was 6.9%, postoperative mortality and morbidity rates were 0 and 13.9%. During the same period, 3713 liver resections (open + MILS) were performed and 407 (11.0%) were for BD. A time-trend analysis showed that the total number of MILS and the number of MILS for malignant disease significantly increased, but this increasing trend was not documented for the number of MILS for BD, which remained stable during the study period of time. This trend was confirmed for the overall rate of resected BD (open + MILS) that remained stable.

DISCUSSION

BD represents a valid indication for MILS. For BD, 21.1% of MILS was performed, rate significantly lower than that previously reported in Italy. Although an evident growth of the use of MILS was observed during the time period analysis in Italy, this trend did not correspond to an increased number of MILS for BD, and the overall rate of resected BD was comparable to that reported in previous large open series.

New boundaries of liver imaging: from morphology to function

From an invisible organ to one of the most explored non-invasively, the liver is, today, one of the cornerstones for current cross-sectional imaging techniques and minimally invasive procedures. After the achievements of US, CT and, most recently, MRI in providing highly accurate morphological and structural information about the organ, a significant scientific development has gained momentum for the last decades, coupling morphology to liver function and contributing far most to what we know today as precision medicine. In fact, dedicated tailor-made investigations are now possible in order to detect and, most of all, quantify physiopathological processes with unprecedented certitude. It is the intention of this review to provide a better insight to the reader of several functional imaging techniques applied to liver imaging. Contrast enhanced imaging, diffusion weighted imaging, elastography, spectral computed tomography and fat and iron assessment techniques are commonly performed clinically. Diffusion kurtosis imaging, magnetic resonance spectroscopy, T1 relaxometry and radiomics remain largely limited to advanced clinical research. Each of them has its own value and place on the diagnostic armamentarium and provide unique qualitative and quantitative information regarding the pathophysiology of diseases, contributing at a large scale to model therapeutic decisions and patient follow-up. Therefore, state-of-the-art liver imaging acts today as a non-invasive surrogate biomarker of many focal and diffuse liver diseases.

Gd-EOB-DTPA MRI for focal nodular hyperplasia-like lesions in pediatric cancer survivors

OBJECTIVES

To investigate the hepatobiliary enhancement patterns of gadoxetic acid (Gd-EOB-DTPA) MRI and the temporal evolution of focal nodular hyperplasia (FNH)-like lesions in pediatric cancer survivors.

METHODS

We retrospectively included pediatric cancer survivors who had new liver lesions detected during surveillance imaging and who were diagnosed with FNH-like lesions by Gd-EOB-DTPA MRI without the aid of a hepatobiliary phase. The hepatobiliary enhancement patterns of FNH-like lesions were categorized as homogeneous hyperintense/isointense, heterogeneous hyperintense, and ring-like enhancement. Temporal changes in the FNH-like lesions were evaluated by follow-up Gd-EOB-DTPA MRI. Statistical analyses included one-way analysis of variance and Spearman's rank correlation test.

RESULTS

A total of 132 radiologically diagnosed FNH-like lesions in 18 patients showed the three different hepatobiliary enhancement patterns: homogeneous hyperintense/isointense (n = 65, 49%), heterogeneous hyperintense (n = 24, 18%), and ring-like enhancement (n = 43, 33%). A weak positive correlation was found between the lesion size and the hepatobiliary enhancement pattern (p = 0.015). Follow-up MRI showed alterations in the size and number of 55 FNHs in 8 patients, including stable size (n = 15, 27%), increased size (n = 17, 31%), decreased size (n = 11, 20%), disappearance (n = 12, 22%), and 74 new lesions (5 patients, 63%).

CONCLUSIONS

FNH-like lesions in pediatric cancer survivors showed three different hepatobiliary enhancement patterns and various temporal changes. Recognition of the radiological characteristics of FNH-like lesions may avoid unnecessary invasive procedures and reduce patients/parents' anxiety.

KEY POINTS

• FNH-like lesions in pediatric cancer survivors showed three different hepatobiliary enhancement patterns. The most common was homogeneous hyperintense/isointense, followed by heterogeneous hyperintense, and ring-like enhancement. • FNH-like lesions in pediatric cancer survivors can show various temporal changes during follow-up.

Benign Liver Tumors

Background

Due to the frequent use of medical imaging including ultrasonography, the incidence of benign liver tumors has increased. There is a large variety of different solid benign liver tumors, of which hemangioma, focal nodular hyperplasia (FNH), and hepatocellular adenoma (HCA) are the most frequent. Advanced imaging techniques allow precise diagnosis in most of the patients, which reduces the need for biopsies only to limited cases. Patients with benign liver tumors are mostly asymptomatic and do not need any kind of treatment. Symptoms can be abdominal pain and pressure effects on adjacent structures. The 2 most serious complications are bleeding and malignant transformation.

Summary

This review focuses on hepatic hemangioma (HH), FNH, and HCA, and provides an overview on clinical presentations, surgical and interventional treatment, as well as conservative management. Treatment options for HHs, if indicated, include liver resection, radiofrequency ablation, and transarterial catheter embolization, and should be carefully weighed against possible complications. FNH is the most frequent benign liver tumor without any risk of malignant transformation, and treatment should only be restricted to symptomatic patients. HCA is associated with the use of oral contraceptives or other steroid medications. Unlike other benign liver tumors, HCA may be complicated by malignant transformation. HCAs have been divided into 6 subtypes based on molecular and pathological features with different risk of complication.

Key Message

The vast majority of benign liver tumors remain asymptomatic, do not increase in size, and rarely need treatment. Biopsies are usually not needed as accurate diagnosis can be obtained using modern imaging techniques.

Focal Nodular Hyperplasia and Hepatic Adenoma: Evaluation and Management

Focal nodular hyperplasia and hepatocellular adenoma are benign liver lesions that occur most frequently in women and may be found as incidental findings on imaging. hepatocellular adenomas may be infrequently associated with malignant progression or risk of rupture and as such, require surveillance or definitive treatments based on their size threshold. It is important clinically to differentiate these lesions, and utilizing imaging modalities such as contrast enhanced ultrasound or magnetic resonance imaging can be helpful in diagnosis. Further molecular subtyping of hepatocellular adenoma lesions may be beneficial to describe risk factors and potential future clinical complications.

State-of-the-art MR Imaging of Fat-containing Focal Lesions of the Liver

BACKGROUND

Fat can be identified in numerous liver lesions, and usually is not a specific finding. Distinguishing between different kinds of fatty deposits is an important part of differential diagnosis. Magnetic Resonance Imaging (MRI) is superior to other imaging techniques because it allows distinguishing intracellular from macroscopic fat.

DISCUSSION

Intracellular lipid may be found in focal hepatic steatosis, hepatic adenoma, hepatocellular carcinoma and, less commonly, in focal nodular hyperplasia as well as regenerative and dysplastic nodules. Macroscopic fat is seen in angiomyolipoma, lipoma, metastases from fatcontaining neoplasms, primary or metastatic liposarcoma, hydatid cyst, pseudolipoma of the Glisson capsule, pericaval fat collection, lipopeliosis, hepatic teratoma, focal hepatic extramedullary haematopoiesis and adrenal rest tumour.

CONCLUSION

Liver nodules should be characterised with regard to underlying liver condition, MRI characteristics and contrast enhancement pattern, including hepatobiliary phase. In many cases, identification of fatty content may help narrowing the differential diagnosis.

MRI of the liver: choosing the right contrast agent

Contrast enhanced MRI of the liver provides valuable information in the evaluation of both chronic liver disease and focal liver lesions. Currently, two classes of MRI contrast agents are available for clinical use, namely the extracellular contrast agent (ECA) and the hepatobiliary agent (HBA). The use of appropriate contrast agents for liver MRI requires knowledge of the clinical situation and question to be answered. ECAs have been used for decades since their introduction into clinical practice and provide excellent dynamic phase information that is useful in characterizing focal liver lesions. In the last decade, HBAs, particularly Gadoxetate, have been found useful for characterizing lesions with functioning hepatocytes and more importantly in evaluating the biliary tree. Gadoxetate, however, provides less satisfactory dynamic phase images compared to ECAs, particularly during the arterial phase. In this perspective article, we will discuss the various intravenous contrast agents used for liver MRI and their ideal utilization.

A rare case of hepatocellular carcinoma arising from gadoxetate-retaining hepatic adenoma

Hepatocellular adenomas (HCAs) are benign lesions of the liver which can rarely undergo malignant transformation. We report a 26-year-old woman with no underlying liver disease found to have an incidental liver lesion on noncontrast CT during workup for gastric reflux. Follow up MRI revealed a 10 cm gadoxetate-retaining lesion within the right hepatic lobe with imaging features suggestive of HCA vs focal nodular hyperplasia . Within this lesion was a focus of arterial enhancement with venous washout suggestive of hepatocellular carcinoma (HCC) within HCA, later confirmed at surgical resection. Understanding the imaging characteristics of HCAs as well as their rare ability to undergo malignant transformation is useful in differentiating HCAs from focal nodular hyperplasia.

Performance of Contrast-Enhanced Sonography Versus MRI With a Liver-Specific Contrast Agent for Diagnosis of Hepatocellular Adenoma and Focal Nodular Hyperplasia

OBJECTIVE. The purpose of this article is to compare contrast-enhanced sonography (CEUS) with sulfur hexafluoride with MRI with the liver-specific contrast agent gadobenate dimeglumine in the diagnosis of hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH) in a cohort of consecutive patients. MATERIALS AND METHODS. Patients referred to a tertiary center for hepatobiliary disease who had suspected HCA or FNH on MRI performed with an extracellular gadolinium-based contrast agent underwent a prospective workup including CEUS and MRI with a liver-specific contrast agent. Diagnosis was definite when the findings of CEUS and MRI with a liver-specific contrast agent were concordant; histopathologic examination (HPE) was performed for cases with discordant findings. Descriptive statistics and the association between categoric variables were presented as numbers and percentages and were assessed using the Fisher exact test. The primary analysis was patient based. Sensitivity, specificity, and AUC and predictive values for the diagnosis of HCA and FNH were calculated separately for CEUS and MRI with a liver-specific contrast agent. RESULTS. A total of 181 patients were selected for the first analysis. Findings from CEUS and MRI with a liver-specific contrast agent were concordant for 132 patients (73%) and discordant for 49 (27%). HPE was performed for 26 of the 49 patients with discordant findings (53%), with findings indeterminate for two of these patients, the findings of MRI with a liver-specific contrast agent correct for 21 of the remaining 24 patients (87.5%), and the findings of CEUS correct for three of these 24 patients (12.5%) (p < 0.05). For further analysis, 156 patients with concordant findings or HPE-proven cases were included. For CEUS, the sensitivity and specificity for the diagnosis of HCA and FNH were 85% and 87%, respectively; the ROC AUC value was 0.856; and the positive predictive value and negative predictive value were 79% and 90%, respectively. For MRI with a liver-specific contrast agent, the sensitivity and specificity were 95% each, the ROC AUC value was 0.949, and the positive predictive value and negative predictive value were 92% and 97%, respectively, for the diagnosis of HCA and FNH. CONCLUSION. The findings of CEUS and MRI with a liver-specific contrast agent showed fair agreement for the diagnosis of HCA and FNH. MRI with a liver-specific contrast agent is diagnostically correct significantly more often than CEUS in cases with discordant findings that are HPE proven.

Hepatic disorders associated with exogenous sex steroids: MR imaging findings

OBJECTIVE

To describe the MRI findings of the effects of exogenous sex steroids on the liver.

FINDINGS

Estrogens, progesterone and synthetic testosterone are exogenous sex steroids that may result in a variety of liver diseases, including tumour formation and vascular disorders. These hormones are mainly administered in the form of the oral contraceptive pill (OCP) and anabolic steroids. Both are implicated in hepatic adenoma formation. The HNF-1α-mutated and inflammatory adenoma subgroups are more commonly seen in association with the OCP whereas there is an increased incidence of the β-catenin positive subtype with anabolic steroid use. Furthermore, anabolic steroids are associated with hepatocellular carcinoma resulting from malignant transformation of β-catenin positive adenomas. The oral contraceptive pill may also induce vascular disorders within the liver, some of which are related to the prothrombotic effect of the hormones, such as hepatic and portal vein thrombosis. Other hepatic vascular abnormalities resulting from exogenous sex steroids include veno-occlusive disease and peliosis hepatis.

MRI for characterization of benign hepatocellular tumors on hepatobiliary phase: the added value of in-phase imaging and lesion-to-liver visual signal intensity ratio

OBJECTIVES

To evaluate the lesion-to-liver visual signal intensity ratio (SIR) before and at the hepatobiliary phase MRI (HBP-MRI) after gadobenate dimeglumine (Gd-BOPTA) injection, using several T1-weighted images (T1-WI), for the characterization of benign hepatocellular lesions.

METHODS

Patients with histologically proven focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA), who underwent Gd-BOPTA-enhanced HBP-MRI from 2009 to 2017, were retrospectively identified. The lesion-to-liver SIR was visually assessed by two radiologists on HBP (post-HBP analysis) and compared with that of unenhanced sequences (pre/post-HBP analysis) on T1-WI in-phase (T1-IP), out-of-phase (T1-OP), and fat suppression (T1-FS). Lesions were classified as hyper-, iso-, or hypointense on post-HBP, and as decreasing, stable, or increasing SIR on pre/post-HBP analyses. The performance of the different T1-WI sequences for the diagnostic of FNH was evaluated on post-HBP analysis.

RESULTS

Twenty-nine FNHs and 33 HCAs were analyzed. On post-HBP analysis, FNHs appeared hyper-/isointense in 89.7% of all T1-WI. HCAs appeared hypointense in 93.9%, 63.6%, and 69.7% of T1-IP, T1-OP, and T1-FS, respectively. FNHs exhibited an increasing SIR in 55.2-58.6%, a stable SIR in 44.8-58.6%, and a decreasing SIR in 0%, whereas HCAs exhibited a decreasing SIR in 66.7-93.9%, a stable SIR in 6.1-33.3%, and an increasing SIR in 0% (p < 0.0001). The specificity of T1-IP was significantly higher than that of T1-OP (p = 0.015) and T1-FS (p = 0.042).

CONCLUSION

T1-IP is the most reliable sequence due to misleading tumor/liver signal ratio in the case of fatty liver when using T1-FS or T1-OP. The pre/post-HBP lesion-to-liver SIR is accurate to classify benign hepatocellular lesions and contributes to avoid biopsy.

KEY POINTS

•The T1-weighted images in-phase should be systematically included in the HBP-MRI protocol, as it is the most reliable sequence especially in the case of fatty liver. •The comparison between lesion-to-liver signal intensity ratios on unenhanced and at the hepatobiliary phase sequences is useful to classify benign hepatocellular lesions in three categories without misclassification: FNH (increasing signal intensity ratio), HCA (decreasing signal intensity ration), and indeterminate lesions (stable signal intensity ratio).

Differentiating focal nodular hyperplasia from hepatocellular adenoma: Is hepatobiliary phase MRI (HBP-MRI) using linear gadolinium chelates always useful?

PURPOSE

To assess the value of Hepatobiliary phase MRI (HPB-MRI) to differentiate FNH and HCA, and evaluate its impact on diagnostic accuracy, diagnostic confidence, inter-observer variability, and patient clinical management.

METHODS

Forty-nine patients referred for Gd-BOPTA-enhanced MRI were retrospectively included in this IRB-approved study, with a total of 119 lesions-90 FNH and 29 HCA. Two observers separately assessed in 2 distinct randomized reading sessions the performance of MRI with (HBP-MRI) or without (conventional MRI) the use of HBP images. Each lesion was ranked with a 5-point scale (from 1 Typical FNH to 5 Certainly not a FNH). Sensitivity, specificity, overall accuracy, and inter-observer agreement for the differentiation of FNH from HCA were calculated and compared between conventional and HBP-MRI.

RESULTS

Both sensitivity (respective values of 38.9% and 97.8%), overall accuracy (respective values of 53.8% and 98.3%), and inter-observer agreement (respective values of Kappa 0.56 and 0.88) were significantly higher using HBP-MRI than with conventional MRI, with unchanged specificity (100%). The sensitivity of conventional MRI for the diagnosis of FNH was significantly lower in lesions ≤ 3 cm (20% vs. 88%). Overall, HBP could have changed lesion management in 59/119 cases (49.5%), including 53 FNH and 6 HCA with no impact in 60/119 lesions (50.5%) including all 35 lesions classified as scores 1 and 2 for the diagnosis of FNH.

CONCLUSIONS

The clinical impact of HBP-MRI is mostly important for smaller than 3-cm FNH, and more limited in larger FNH lesions as well as for HCA diagnosis for which conventional MRI is already accurate. The use of extracellular contrast agents upfront could limit the required use of linear HBP contrast agents for benign hepatocellular lesion characterization. On HBP, all FNH appeared hypointense compared to adjacent liver while close to 97% of HCA appeared hypointense.

Quantitative correlation between uptake of Gd-BOPTA on hepatobiliary phase and tumor molecular features in patients with benign hepatocellular lesions

PURPOSE

The purpose of our study was to correlate the quantitative analysis of benign hepatocellular tumor uptake on delayed hepatobiliary phase (HBP) imaging with the quantitative level of OATP expression.

METHODS

This single-center retrospective study, which took place between September 2009 and March 2015, included 20 consecutive patients with a proven pathologic and immunohistochemical (IHC) diagnosis of FNH or HCA, including quantification of the OATP expression. The patients underwent Gd-BOPTA-enhancement MRI, including an HBP. The analysis of HBP uptake was performed using the liver-to-lesion contrast enhancement ratio (LLCER). Mean LLCER and OATP expressions were compared between FNH and HCA, and the expression of OATP was correlated with the LLCER value.

RESULTS

Of the 23 benign hepatocellular tumors, 9 (39%) were FNH and 14 (61%) were HCA, including 6 inflammatory, 2 HNF1a inactivated, 3 β-catenin-mutated and 3 unclassified HCAs. On HBP, 100% of the FNH appeared hyper- or isointense, and 79% of the adenomas appeared hypointense. The mean OATP expression of FNH (46.67 ± 26.58%) was significantly higher than that of HCA (22.14 ± 30.74%) (p = 0.0273), and the mean LLCER of FNH (10.66 ± 7.403%) was significantly higher than that of HCA (-13.5 ± 12.25%) (p < 0.0001). The mean LLCER of β-catenin-mutated HCA was significantly higher than that of other HCAs (p = 0.011). Significant correlation was found between the OATP expression and LLCER values (r = 0.661; p = 0.001).

CONCLUSION

In benign hepatocellular tumors, the quantitative analysis of hepatobiliary contrast agent uptake on HBP is correlated with the level of OATP expression and could be used as an imaging biomarker of the molecular background of HCA and FNH.

KEY POINTS

• Gd-BOPTA uptake on HBP correlates with the OATP level in benign hepatocellular tumors • FNH and β-catenin-mutated HCA showed an increased lesion-to-liver contrast enhancement ratio (LLCER) • Increased LLCER may be explained by activation of the Wnt β-catenin pathway.

Contrast enhanced ultrasound (CEUS) imaging of solid benign focal liver lesions

Ultrasound is well accepted worldwide for imaging of the liver. Absences of radiation exposure, low cost and large diffusion are some of the advantages that make this technique the first to be used in the assessment of focal liver lesions (FLL). Areas covered: Contrast enhanced ultrasound (CEUS) has been introduced more than twenty years ago, and its detection rate is comparable to that of contrast enhanced magnetic resonance imaging (CEMRI) and contrast enhanced computed tomography (CECT). In this narrative review, we discuss the main CEUS features of benign liver lesions and controversies in published results including the gold standard chosen and the quality and knowledge of the preferred techniques. Expert commentary: CEUS is safe and allows an immediate evaluation of the nature of FLL. CEUS permits differentiation between malignant and benign FLL in healthy liver parenchyma by analysing the arterial, portal venous and late phases. CEMRI and CECT are reliable to characterize FLL but higher costs, radiation exposure, nephrotoxicity (in particular for CECT) and absence of real time imaging limit the appropriate evaluation of FLL. Therefore CEUS can be preferred in most clinical situations, and when results are unclear or suggestive for malignant FLL, biopsy and histological examination can be directly initiated avoiding unnecessary additional imaging.

Contributions of Magnetic Resonance Imaging to Gastroenterological Practice: MRIs for GIs

MRI has transformed from the theoretical, investigative realm to mainstream clinical medicine over the past four decades and has become a core component of the diagnostic toolbox in the practice of gastroenterology (GI). Its success is attributable to exquisite contrast and the ability to isolate specific proton species through the use of different pulse sequences (i.e., T1-weighted, T2-weighted, diffusion-weighted) and exploiting extracellular and hepatobiliary contrast agents. Consequently, MRI has gained preeminence in various GI clinical applications: liver and pancreatic lesion evaluation and detection, liver transplantation evaluation, pancreatitis evaluation, Crohn's disease evaluation (using MR enterography) rectal cancer staging and perianal fistula evaluation. MR elastography, in concert with technical innovations allowing for fat and iron quantification, provides a noninvasive approach, or "MRI virtual liver biopsy" for diagnosis and management of chronic liver diseases. In the future, the arrival of ultra-high-field MR systems (7 T) and the ability to perform magnetic resonance spectroscopy in the abdomen promise even greater diagnostic insight into chronic liver disease.

A cost-effectiveness analysis of the diagnostic strategies for differentiating focal nodular hyperplasia from hepatocellular adenoma

OBJECTIVES

We evaluated the cost-effectiveness of a gadoxetic acid-enhanced MRI (EOB-MRI) strategy compared with conventional MRI strategy and biopsy to differentiate focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA).

METHODS

A decision tree model was constructed to compare the cost-effectiveness of EOB-MRI, conventional MRI with extracellular contrast agents, and biopsy as the initial diagnostic modality in patients with incidentally detected focal liver lesions suspected of being FNH or HCA. We analysed the cost and effectiveness, i.e. probability of successful diagnosis of each strategy. Costs were based on utilisation rates and Medicare reimbursements in the USA and South Korea.

RESULTS

In the base case analysis of our decision tree model, the effectiveness of the three strategies was similar. The cost of the EOB-MRI strategy ($1283 in USA, $813 in South Korea) was lowest compared with the biopsy strategy ($1725 in USA, $847 in South Korea) and the conventional MRI strategy ($1750 in USA, $962 in South Korea). One-way, two-way and probabilistic sensitivity analysis showed unchanged results over an acceptable range.

CONCLUSIONS

EOB-MRI strategy is the most cost-effective strategy for differentiating FNH from HCA in patients with incidentally detected focal liver lesions in a non-cirrhotic liver.

KEY POINTS

• The effectiveness of the three strategies was similar. • The cost of the EOB-MRI strategy was lowest. • EOB-MRI strategy is the most cost-effective for differentiating FNH from HCA.

Inflammatory hepatic adenomas: Characterization with hepatobiliary MRI contrast agents

PURPOSE

To characterize the MRI appearance of inflammatory hepatic adenomas using hepatobiliary contrast agents.

MATERIALS AND METHODS

MRI was performed using hepatobiliary contrast agents (3 with gadobenate dimeglumine and 24 with gadoxetic acid) in 27 patients with immunohistochemistry-confirmed diagnosis of inflammatory hepatic adenoma. The appearance of the lesions on T2 and diffusion-weighted images, pre-gadolinium T1-weighted images, dynamic post-gadolinium images, and hepatobiliary phase images was assessed.

RESULTS

Seven lesions (26%) showed predominant hyperenhancement on hepatobiliary phase images in comparison with adjacent hepatic parenchyma: 1 lesion showed diffuse, mildly heterogeneous hyperenhancement, and the remaining 6 lesions showed peripheral hyperenhancement and central hypoenhancement. Twenty lesions (74%) were predominantly hypoenhancing compared to adjacent liver on hepatobiliary phase images. Nine lesions showed a pattern of peripheral hyperenhancement and central hypoenhancement on hepatobiliary phase images; in 6 of these lesions a majority of the mass appeared hyperenhancing, while the remaining 3 lesions showed predominant hypoenhancement.

CONCLUSIONS

This investigation shows that a significant percentage of inflammatory hepatic adenomas appear isointense or hyperintense in comparison to adjacent normal liver on hepatobiliary phase images, and therefore this feature should not be used to distinguish hepatic adenomas from focal nodular hyperplasia without additional supporting evidence.

Multiple focal nodular hyperplasia: MRI features

PURPOSE

To describe MRI features of multiple Focal Nodular Hyperplasia (FNHs).

METHODS

40 consecutive subjects (37 females, mean age, 38.8years) were included. All studies were independently reviewed. This was an observational study to define the radiological features of multifocal FNH.

RESULTS

130 lesions were evaluated. The majority (88.5%), were peripheral in location. 92.3% lesions were lobulated. Marked enhancement was present in 94.6% lesions. In the portal venous and delayed phase, 46.2% and 47.7% lesions were mildly hyperintense. Central scar was present in 77% lesions.

CONCLUSIONS

Distinctive features included predominant subcapsular location and mild hyperintensity in the delayed phase, seen in nearly 50% of FNHs.

Inflammatory and multiple hepatocellular adenoma are associated with a higher BMI

AIM

To identify patient and lesion characteristics associated with the occurrence of single or multiple hepatocellular adenoma (HCA).

PATIENTS AND METHODS

Using a tertiary centre database, we retrospectively collected information on patient and lesion characteristics, management and follow-up of all patients with HCA included between 2001 and 2016. Patients were classified into three groups; patients with a single HCA, 2-9 HCA and at least 10 HCA.

RESULTS

A total of 458 patients were diagnosed with HCA, including 121 (26.4%) with single HCA, 235 (51.3%) with 2-9 HCA and 102 (22.3%) with at least 10 HCA. Significant differences in the mean BMI were found, with the highest BMI in patients with more than 10 HCA (P<0.05). The mean BMI was significantly higher in patients with inflammatory HCA compared with steatotic HCA (31 vs. 26, respectively, P<0.05). Steatotic HCA were more often single lesions (22/55, 40%), whereas patients with inflammatory HCA were often diagnosed with multiple lesions (122/166, 73%).

CONCLUSION

Our series show a significantly higher BMI and frequency of inflammatory HCA in patients with multiple HCA compared with single HCA.

Development and validation of a predictor of insufficient enhancement during the hepatobiliary phase of Gd-EOB-DTPA-enhanced magnetic resonance imaging

Background Insufficient enhancement of liver parenchyma negatively affects diagnostic accuracy of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). Currently, there is no reliable method for predicting insufficient enhancement during the hepatobiliary phase (HBP) in Gd-EOB-DTPA-enhanced MRI. Purpose To develop a predictor for insufficient enhancement of liver parenchyma during HBP in Gd-EOB-DTPA-enhanced MRI. Material and Methods In order to formulate a HBP enhancement test (HBP-ET), clinical factors associated with relative enhancement ratio (RER) of liver parenchyma were retrospectively determined from the datasets of 156 patients (Development group) who underwent Gd-EOB-DTPA-enhanced MRI between November 2012 and May 2015. The independent clinical factors were identified by Pearson's correlation and multiple stepwise regression analysis; the performance of HBP-ET was compared to Child-Pugh score (CPS), Model for End-stage Liver Disease score (MELD), and total bilirubin (TBIL) using receiver operating characteristic (ROC) curve analysis. The datasets of 52 patients (Validation group), which were examined between June 2015 and Oct 2015, were applied to validate the HBP-ET. Results Six biochemical parameters independently influenced RER and were used to develop HBP-ET. The mean HBP-ET score of patients with insufficient enhancement was significantly higher than that of patients with sufficient enhancement ( P < 0.001) in both the Development and Validation groups. HBP-ET (area under the curve [AUC] = 0.895) had better performance in predicting insufficient enhancement than CPS (AUC = 0.707), MELD (AUC = 0.798), and TBIL (AUC = 0.729). Conclusion The HBP-ET is more accurate than routine indicators in predicting insufficient enhancement during HBP, which is valuable to aid clinical decisions.

Diagnostic Value of Gadoxetic Acid-Enhanced MR Imaging to Distinguish HCA and Its Subtype from FNH: A Systematic Review

Objective: The purpose of this study was to systematically review the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI) for differentiation of hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH), as well as HCA classification by using the low signal intensity (SI) in the hepatobiliary phase (HBP). Methods: A systematic process was used to review all published data in MEDLINE database about Gd-EOB-DTPA-MRI applied to differentiation of HCA and FNH, and classification of HCA by using low SI in the HBP. The pooled sensitivity and specificity were calculated to assess the diagnostic value of low SI in the HBP. Results: A review of 45 articles identified 10 eligible studies with a total of 288 HCA lesions. The pooled proportion of low SI in the HBP of HCA were 91% (95% CI: 0.81-0.97). In specific, the subtypes of HCA were 75% (95% CI: 0.64-0.85) for I-HCA, 100% (95% CI: 0.95-1.00) for H-HCA, 92% (95% CI: 0.70-1.00) for U-HCA, and 59% (95% CI: 0.00-1.00) for b-HCA, respectively. The pooled specificity and sensitivity of low SI in the HBP for distinguishing FNH from HCA were 95% (95% CI: 0.92-0.98) and 92% (95% CI: 0.87-0.96), respectively. Conclusion: Low SI in the HBP of Gd-EOB-DTPA-MRI is associated with higher accuracy for distinguishing HCA from FNH. However, the diagnostic accuracy may be overvalued, especially for the diagnosis of subtypes of b-HCA and I-HCA. Therefore, the risk factors and conventional imaging findings should be take into account simultaneously.

Intravoxel incoherent motion and dynamic contrast-enhanced MRI for differentiation between hepatocellular adenoma and focal nodular hyperplasia

OBJECTIVE

To examine if intravoxel incoherent motion (IVIM) and dynamic contrast-enhanced MRI (DCE-MRI) can be used as new and supplemental MRI techniques to differentiate hepatocellular adenomas (HCAs) from focal nodular hyperplasias (FNHs) and analyse if diffusion parameter apparent diffusion coefficient (ADC) and IVIM parameter true diffusion coefficient (D) differ in doing so.

METHODS

This prospective study included 21 patients (8 HCAs and 13 FNHs) who underwent a specifically designed MRI scanning protocol, including series for analysis of IVIM (four b-values 0, 10, 150 and 800 s mm^-2) and DCE-MRI. On a dedicated workstation, identical regions of interest were placed in parametric maps of K^trans, V_e, D and ADC in each lesion for quantification. Diagnostic accuracy was assessed using receiver operating characteristics analysis. Time-intensity curves (TICs) were classified in different types.

RESULTS

HCAs had significantly lower values for K^trans (mean 1.45 vs 2.68 min^-1; p = 0.029) and D (mean 1.02 × 10^-3 vs 1.22 × 10^-3 mm² s^-1; p = 0.033). Both parameters showed good diagnostic accuracy of 76%. TIC analysis could not differentiate between HCAs and FNHs.

CONCLUSION

In this exploratory study, K^trans and D were able to differentiate HCAs from FNHs in most cases, whereas V_e, ADC and TIC analysis were not. Advances in knowledge: Histological differences between HCAs and FNHs can be quantified on MRI using K^trans and D.

Diagnostic Value of Gd-EOB-DTPA-MRI for Hepatocellular Adenoma: A Meta-Analysis

Objective: This study aimed to systematically review the gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI) findings of hepatocellular adenoma (HCA), especially focusing on the diagnostic value of low signal intensity (SI) in the hepatocyte-phase (HBP) for differentiating HCA from focal nodular hyperplasia (FNH).

Methods: A thorough literature search was conducted in PubMed, Excerpta Medica Database (EMBASE) and China National Knowledge Infrastructure databases (CNKI) to identify studies evaluating Gd-EOB-DTPA-MRI presentations of HCA. Published studies using pathological examinations as the gold standard were included. The pooled proportions of low SI in the HBP, arterial-phase, portal venous-phase (PVP) in HCA were calculated, as well as pooled proportions of bleeding, fatty degeneration, and central scar. Meta-analysis was used to evaluate the diagnostic value of low SI in the HBP for HCA.

Results: The search yielded 90 studies, with 8 assessing a total of 256 HCA cases included in this study, total of 229 lesions showed low signal in the HBP. Pooled proportions of low SI in the arterial-phase, PVP, and HBP were 2% (95% CI: 0.01-0.05), 39% (95% CI: 0.25-0.55), and 89% (95% CI: 0.80-0.94), respectively. Pooled proportions of bleeding, fatty degeneration, and central scar in HCA were 11% (95% CI: 0.03-0.19), 37% (95% CI: 0.27-0.49), and 10% (95% CI: 0.03-0.27), respectively. The meta-analysis revealed the following characteristics of low SI in the HBP for HCA diagnosis: 1) pooled sensitivity, 0.917 (95% CI: 0.86-0.96); 2) pooled specificity, 0.952 (95% CI: 0.91-0.98); 3) pooled positive likelihood ratio, 15.028 (95% CI: 7.10-31.82); 4) pooled negative likelihood ratio, 0.105 (95% CI: 0.07-0.17); 5) area under the ROC, 0.9802 (Q value of 0.9375), The sensitivity analysis showed that no single study was found to influence the overall pooled estimates significantly, which indicated the stability of the meta-analysis results were good.

Conclusions: Low SI on the HBP of Gd-EOB-DTPA-MRI was helpful for the diagnosis of HCA and differentiating from FNH, but it was overvalued, especially for some HCA pathological subtypes. Combining low SI in the HBP with routine MRI presentations and the risk factors of liver diseases could substantially improve its diagnosis value for HCA as well as differential diagnosis.

Ruptured focal nodular hyperplasia observed during follow-up: a case report

BACKGROUND

Focal nodular hyperplasia (FNH) is the second most common benign hepatic tumor and is very rarely complicated by hemorrhage or rupture. Although thought to be extremely rare, there have been several reports of hemorrhage caused by ruptured FNH. Herein, we report the case of a patient with ruptured FNH, who subsequently developed hemorrhage during follow-up.

CASE PRESENTATION

A 32-year-old man was admitted to our department for an asymptomatic hepatic tumor in segments 4 and 5 (S4/5), which measured 8 cm in diameter and observed to project from the liver. Imaging and pathologic examination of a biopsy specimen confirmed the diagnosis of FNH. Three years after the diagnosis, the patient was readmitted to our hospital because of sudden onset of upper abdominal pain. Dynamic abdominal computed tomography revealed ascites around the tumor with high-density areas that were considered to represent hematoma caused by ruptured FNH. Transcatheter arterial embolization (TAE) was performed to stop the hemorrhage. One month after TAE, S4/5 of the liver was resected; macroscopic findings revealed that a large part of the tumor was composed of necrotic tissue and hematoma. Pathological examination using hematoxylin-eosin staining and immunohistochemical examination indicated a final diagnosis of FNH rupture and hemorrhage.

CONCLUSION

Although a well-established diagnosis of FNH usually requires no treatment or surveillance, careful examination remains necessary when the FNH is large and projects from the liver because of the possibility of rupture and hemorrhage.

Impact of hepatobiliary phase liver MRI versus Contrast-Enhanced Ultrasound after an inconclusive extracellular gadolinium-based contrast-enhanced MRI for the diagnosis of benign hepatocellular tumors

PURPOSE

To compare the added values of hepatobiliary phase (HBP) MRI and contrast-enhanced ultrasound (CEUS) in addition to inconclusive extracellular gadolinium-based contrast-enhanced MRI (CE-MRI) to characterize benign hepatocellular tumors (BHT).

METHODS

Eighty-three BHT-46 focal nodular hyperplasia (FNH) and 37 hepatocellular adenomas (HCA)-with inconclusive CE-MRI in 54 patients (43 women and 11 men, mean age 42 years old ± 14.8) were retrospectively analyzed. All patients underwent both HBP-MRI and CEUS. Two radiologists independently reviewed 2 sets of images, SET-1: CE-MRI and HBP-MRI; SET-2: CE-MRI and CEUS, and classified lesions as "definite FNH," "possible FNH," or "definitely not FNH." Sensitivity (Se) and specificity (Spe) were compared between the two sets; subgroup analyses according to the lesion's size were performed.

RESULTS

Regardless of lesion size, the respective Se and Spe of both datasets were not statistically different (95.7 and 100% vs. 76.1 and 94.6% for set-1 and -2 respectively; p = 0.18). For lesions larger than 35 mm, although both sets had similar specificity (100%), sensitivity was higher for SET-1 (100% vs. 40%); p = 0.04. Tumor classifications using SET-1 and SET-2 could have changed patient management in 35/54 (64.8%) and 33/54 (61.1%) of all patients, respectively.

CONCLUSIONS

HBP-MRI or CEUS should be performed after an inconclusive CE-MRI. Both can change patient management by avoiding unnecessary biopsy or surveillance. The use of HBP-MRI should be advocated over CEUS in larger (>35 mm) lesions.

Hepatocellular adenoma: when and how to treat? Update of current evidence

Hepatocellular adenoma (HCA) is a rare, benign liver tumor. Discovery of this tumor is usually as an incidental finding, correlated with the use of oral contraceptives, or pregnancy. Treatment options have focused on conservative management for the straightforward, smaller lesions (<5 cm), with resection preferred for larger lesions (>5 cm) that pose a greater risk of hemorrhage or malignant progression. In recent years, a new molecular subclassification of HCA has been proposed, associated with characteristic morphological features and loss or increased expression of immunohistochemical markers. This subclassification could possibly provide considerable benefits in terms of patient stratification, and the selection of treatment options. In this review we discuss the decision-making processes and associated risk analyses that should be made based on lesion size, and subtype. The usefulness of this subclassification system in terms of the procedures instigated as part of the diagnostic work-up of a suspected HCA will be outlined, and suitable treatment schemes proposed.