Hepatobiliary contrast agents: differential diagnosis of focal hepatic lesions, pitfalls and other indications

Is there added value of the hepatobiliary phase of MRI with hepatobiliary contrast agents for hepatocellular carcinoma diagnosis? A meta-analysis

Purpose

So far, there have been published several meta-analyses which focused on hepatocellular carcinoma (HCC) detection with hepatobiliary phase (HBP) contrast agents. However, only a few of them aimed at establishing whether there is any added value of the HBP itself for HCC diagnosis. To answer the question, we performed a systematic literature search with the time limit going back to 2010.

Material and methods

True positive, false positive, false negative, and true negative values with and without the HBP were extracted from the included studies. Pooled sensitivities and specificities with and without the HBP were calculated and summary receiver operating characteristics curves were drawn to assess the diagnostic performance of the studies with and without the HBP.

Results

A total of 13 studies were included involving 1184 HCC lesions. In 13 studies without the HBP, the pooled sensitivity, specificity, and area under the curve (AUC) were 0.83, 0.89 and 0.94 respectively. In 13 studies with the HBP, the pooled sensitivity, specificity and AUC were 0.91, 0.85 and 0.98 respectively.

Conclusions

We found no statistically significant differences in sensitivities between studies with and without the HBP (p = 0.1651).

Better 90 Minutes Late than Never: Differential Diagnosis on MRI Scanning in a Case of Hepatic Angiosarcoma

Primary hepatic angiosarcoma (PHA) is a rare liver malignancy with few studies describing its radiological characteristics. This article aims to assess the imaging features of each of the multiple delayed contrast-enhanced magnetic resonance imaging (MRI) scans, in addition to the conventional MRI protocol, in a patient with PHA. Standard MRI sequences and a liver protocol were used in the examination of a 71 year-old male with pathologically proven PHA after current imaging evaluation. In addition, the patient underwent transversal and coronal MRI T1-weighted scans at 10 min, 20 min and 90 min after intravenous (IV) administration of gadobenatedimeglumine (Gd-BOPTA). The PHA revealed a variable appearance on MRI, with classic imaging being insufficient in making a reliable diagnosis. Lesions have increased vascularity, which translates into increased IV contrast uptake in the MRI arterial phase, showing progressive and globular enhancement in the portal and parenchymatous phases. On delayed scans, at 10 min after IV administration, the lesions maintained no washout, but slightly began to washout at 20 min post-contrast. However, in the hepatobiliary phase (90 min post-contrast injection), on an MRI T1-weighted sequence, PHA lesions were hypointense, suggesting the absence of hepatocytes, thus indicating high-grade malignancy. This approach proved the conclusion that in a patient with PHA, an extra MRI T1-weighted scan at 90 min post-gadobenatedimeglumine injection can provide helpful information in differential diagnosis.

Imaging Diagnosis of Hepatocellular Carcinoma: A State-of-the-Art Review

Hepatocellular carcinoma (HCC) remains not only a cause of a considerable part of oncologic mortality, but also a diagnostic and therapeutic challenge for healthcare systems worldwide. Early detection of the disease and consequential adequate therapy are imperative to increase patients' quality of life and survival. Imaging plays, therefore, a crucial role in the surveillance of patients at risk, the detection and diagnosis of HCC nodules, as well as in the follow-up post-treatment. The unique imaging characteristics of HCC lesions, deriving mainly from the assessment of their vascularity on contrast-enhanced computed tomography (CT), magnetic resonance (MR) or contrast-enhanced ultrasound (CEUS), allow for a more accurate, noninvasive diagnosis and staging. The role of imaging in the management of HCC has further expanded beyond the plain confirmation of a suspected diagnosis due to the introduction of ultrasound and hepatobiliary MRI contrast agents, which allow for the detection of hepatocarcinogenesis even at an early stage. Moreover, the recent technological advancements in artificial intelligence (AI) in radiology contribute an important tool for the diagnostic prediction, prognosis and evaluation of treatment response in the clinical course of the disease. This review presents current imaging modalities and their central role in the management of patients at risk and with HCC.

Manganese(II) EOB-Pyclen Diacetate for Liver-Specific MRI

MRI is increasingly utilized for the diagnosis of liver disease and focal liver lesions. Although liver-targeted gadolinium-based contrast agents (GBCAs) have high efficacy, there continue to be safety concerns regarding release of toxic Gd(III) ions. Herein, Mn(EOB-PC2A) is synthesized as a nongadolinium alternative for liver-specific MRI. Mn(EOB-PC2A) has an r₁ relaxivity of 2.8 mM^-1 s^-1 in Dulbecco's phosphate-buffered saline (DPBS) and 5.9 mM^-1 s^-1 in saline containing human serum albumin at 1.5 T. It has a strong uptake in hepatocytes with minimal toxicity and demonstrated robust liver-specific enhancement at a dose of 60 μmol/kg. Mn(EOB-PC2A) is a promising liver-specific contrast agent for liver MRI.

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.

Use of diffusion-weighted imaging in the noninvasive diagnostic of obstructed biliary ducts

OBJECTIVE

This study sought to evaluate the role of diffusion-weighted imaging (DWI) in differentiation between obstructed and unobstructed bile ducts in patients undergoing magnetic resonance imaging (MRI).

METHODS

Eighty-four patients, 40 males and 44 females (mean age: 56.4 ± 15.1 years), undergoing MRI with DWI (0-50-500-700) were evaluated and divided into two groups: 58 with abnormal laboratory tests (obstructed group) and 26 with normal laboratory values (unobstructed group). Laboratory tests were total bilirubin, alkaline phosphatase, and gamma-glutamyltransferase. Median ADC values were calculated and correlated with laboratory tests and degree of bile-duct dilatation (absent, moderate, or severe). The persistence of signal on DWI (b500 and b700) in the biliary tract was evaluated. Bilirubin values were tested for correlation with bile-duct ADC values and persistence of b700 signal. For statistical analysis, Student t test, chi-square test and Wilcoxon-Mann-Whitney test were used. ADC maps were plotted for three levels of the biliary tree, and a receiver operating characteristic (ROC) curve was calculated.

RESULTS

In the obstructed group, 15 patients had severe dilatation, 24 had moderate dilatation, and 19 had no appreciable dilatation; 38 patients had persistent signal on b700 images. In the unobstructed group, 23 patients had no dilatation and 3 had moderate dilatation; 4 patients had persistent signal on b700 images. Correlation was found between degree of bile-duct dilatation, bilirubin levels, persistence of b700 signal, and ADC map values. The calculated ADC map cutoff value (353 10^-6 mm²/s) was able to differentiate the obstructed and unobstructed groups with 92.3% sensitivity, 81% specificity, and 91.9% accuracy.

CONCLUSIONS

DWI is able to distinguish patients with obstructed versus unobstructed bile ducts, regardless of the degree of dilatation, correlating with clinical and laboratory findings.

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.

Can gadoxetic acid–enhanced magnetic resonance imaging be used to avoid liver biopsy in patients with nonalcoholic fatty liver disease?

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a major cause of liver disease worldwide. The diagnosis of nonalcoholic steatohepatitis (NASH), the most severe form of NAFLD, is crucial and has prognostic and therapeutic implications. However, currently this diagnosis is based on liver biopsy and has several limitations.

AIM

To evaluate the performance of gadoxetic acid–enhanced magnetic resonance imaging (GA-MRI) in differentiating isolated steatosis from NASH in patients with NAFLD.

METHODS

In this prospective study, 56 patients with NAFLD (18 with isolated steatosis and 38 with NASH) underwent GA-MRI. The contrast enhancement index (CEI) was calculated as the rate of increase of the liver-to-muscle signal intensity ratio from before and 20 min after intravenous GA administration. Between-group differences in mean CEI were examined using Student's t test. The area under the receiver operator characteristic curve and the diagnostic performance of gadoxetic acid–enhanced magnetic resonance imaging were evaluated.

RESULTS

The mean CEI for all subjects was 1.82 ± 0.19. The mean CEI was significantly lower in patients with NASH than in those with isolated steatosis (P = 0.008). Two CEI cut-off points were used: < 1.66 (94% specificity) to characterize NASH and > 2.00 (89% sensitivity) to characterize isolated steatosis. CEI values between 1.66 and 2.00 indicated liver biopsy, and the procedure could be avoided in 40% of patients with NAFLD.

CONCLUSION

GA-MRI is an effective noninvasive method that may be useful for the differentiation of NASH from isolated steatosis, and could help to avoid liver biopsy in patients with NAFLD.

Atypical Enhancement of Gd-BOPTA on the Hepatobiliary Phase in Hepatic Metastasis from Carcinoid Tumor - Case Report

Patient: Female, 65-year-old

Final Diagnosis: Carcinoid tumor

Symptoms: Abdominal pain

Medication: —

Clinical Procedure: —

Specialty: Radiology

Spectrum of Pitfalls, Pseudolesions, and Potential Misdiagnoses in Cirrhosis

OBJECTIVE

The purposes of this article are to review a variety of pitfalls in liver imaging that can lead to the inaccurate diagnosis of focal hepatic lesions in cirrhosis, to describe the pathophysiologic processes of these pitfalls, and to provide specific clues for achieving the correct diagnoses.

CONCLUSION

Cirrhosis complicates liver imaging. The distortion and replacement of normal liver parenchyma by fibrous and regenerative tissue can change the typical appearance of many benign lesions, causing them to be misinterpreted as malignancy. In addition, the high incidence and prevalence of hepatocellular carcinoma among patients with cirrhosis put radiologists on high alert for any suspicious findings, especially because not all hepatocellular carcinomas have a typical imaging appearance.

Ascites relative enhancement during hepatobiliary phase after Gd-BOPTA administration: a new promising tool for characterising abdominal free fluid of unknown origin

OBJECTIVES

To correlate the degree of ascites enhancement during hepatobiliary phase after gadobenate dimeglumine (Gd-BOPTA) administration with ascites aetiology.

METHODS

IRB-approved retrospective study, need for informed consent was waived. We included 74 consecutive ascitic patients who underwent Gd-BOPTA-enhanced liver MRI including hepatobiliary phase (HBP) images between January 2014 and December 2017. Ascites appearance on unenhanced and HBP images was classified as hypo-, iso- or hyperintense in comparison to paraspinal muscles. Ascites signal intensity on unenhanced and HBP images was measured using round ROIs and was normalised to paraspinal muscles (NSI). Normalised relative enhancement (NRE) between native phase and HBP was calculated. The results were related to ascites aetiology using Wilcoxon and Mann-Whitney tests.

RESULTS

On native images, ascites appeared hypointense in 95.9% of the cases and isointense in 4.1%, whereas on HBP images, it appeared hyperintense in 59.4% of the cases, isointense in 36.5% and hypointense in 4.1%. Mean ascites NSI was 0.52 on unenhanced images and 1.50 on HBP ones (p < 0.0001). Mean ascites NRE was 201 ± 133%. Ascites of non-malignant aetiology showed mean NRE of 210 ± 134%, whereas malignant ascites showed mean NRE of 92 ± 20% (p = 0.001). ROC analysis showed that a NRE < 112.5% correlates with malignant aetiology with 100% sensitivity and 83.4% specificity (LR = 5.667). NRE did not show any significant correlation with ascites thickness, eGFR and time interval between contrast administration and HBP acquisition (p > 0.05).

CONCLUSIONS

Ascites NRE in HBP after Gd-BOPTA administration is significantly lower in patients with ascites secondary to peritoneal carcinomatosis than in patients with non-malignant ascites.

KEY POINTS

• Ascites enhancement in the hepatobiliary phase after Gd-BOPTA administration may determine false positive findings when looking for biliary leaks. • Ascites enhancement in the hepatobiliary phase after Gd-BOPTA administration is lower in patients with peritoneal carcinomatosis than in patients with portal hypertension or congestive heart failure. • None of the patients with peritoneal carcinomatosis showed an ascites enhancement of more than 112% as compared with unenhanced images.

Liver metastases: Detection and staging

The liver is more often involved with metastatic disease than primary liver tumors. The accurate detection and characterization of liver metastases are crucial since patient management depends on it. The imaging options, mainly consisting of contrast-enhanced ultrasound (CEUS), multidetector computed tomography (CT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI), extra-cellular contrast media and liver-specific contrast media as well as positron emission tomography/computed tomography (PET/CT), are constantly evolving. PET/MRI is a more recent hybrid method and a topic of major interest concerning liver metastases detection and characterization. This review gives a brief overview about the spectrum of imaging findings and focus on an update about the performance, advantages and potential limitations of each modality as well as current developments and innovations.

Magnetic resonance imaging of the cirrhotic liver: diagnosis of hepatocellular carcinoma and evaluation of response to treatment - Part 2

In the second part of this review, we will describe the ancillary imaging features of hepatocellular carcinoma (HCC) that can be seen on standard magnetic resonance imaging (MRI) protocol, and on novel and emerging protocols such as diffusion weighted imaging and utilization of hepatocyte-specific/hepatobiliary contrast agent. We will also describe the morphologic sub-types of HCC, and give a simplified non-invasive diagnostic algorithm for HCC, followed by a brief description of the liver imaging reporting and data system (LI-RADS), and MRI assessment of tumor response following locoregional therapy.

Acquired portosystemic collaterals: anatomy and imaging

Portosystemic shunts are enlarged vessels that form collateral pathological pathways between the splanchnic circulation and the systemic circulation. Although their causes are multifactorial, portosystemic shunts all have one mechanism in common-increased portal venous pressure, which diverts the blood flow from the gastrointestinal tract to the systemic circulation. Congenital and acquired collateral pathways have both been described in the literature. The aim of this pictorial essay was to discuss the distinct anatomic and imaging features of portosystemic shunts, as well as to provide a robust method of differentiating between acquired portosystemic shunts and similar pathologies, through the use of illustrations and schematic drawings. Imaging of portosystemic shunts provides subclinical markers of increased portal venous pressure. Therefore, radiologists play a crucial role in the identification of portosystemic shunts. Early detection of portosystemic shunts can allow ample time to perform endovascular shunt operations, which can relieve portal hypertension and prevent acute or chronic complications in at-risk patient populations.