Hepatocellular adenoma: diagnostic difficulties and novel imaging techniques

Hepatic adenomatosis: spectrum of imaging findings

OBJECTIVE

This pictorial essay reviews the imaging appearance and differential diagnosis of hepatic adenomatosis.

CONCLUSION

In addition to such entities as multifocal hepatocellular carcinoma, metastases, and multiple focal nodular hyperplasia, hepatic adenomatosis should also be considered when confronted with multiple hypervascular liver lesions. Certain CT and MRI features can strongly suggest the diagnosis of adenomatosis.

Novel functional magnetic resonance imaging biomarkers for assessing response to therapy in hepatocellular carcinoma

The established and adapted image biomarkers based on size for tumor burden measurement continue to be applied to hepatocellular carcinoma (HCC) as size measurement can easily be used in clinical practice. However, in the setting of novel targeted therapies and liver directed treatments, simple tumor anatomical changes can be less informative and usually appear later than biological changes. Functional magnetic resonance imaging (MRI) has a potential to be a promising technique for assessment of HCC response to therapy. In this review, we discuss various functional MRI biomarkers that play an increasingly important role in evaluation of HCC response after treatment.

Beta-catenin-activated hepatocellular adenoma showing hyperintensity on hepatobiliary-phase gadoxetic-enhanced magnetic resonance imaging and overexpression of OATP8

We report a male case of beta-catenin-activated hepatocellular adenoma (HCA) focusing on findings of gadoxetic-acid-enhanced magnetic resonance imaging (EOB-MRI) and discussing the molecular background and possible clinical significance. The patient was a 31-year-old man in whom computed tomography (CT) showed a large nodule of 14 cm in diameter in the right liver lobe. On dynamic contrast-enhanced CT, heterogeneous and slight to moderate enhancement was observed during the early phase, with washout in the late phase. Focal fat deposits and a scar-like portion in the lesion were also seen. Most of the lesion was slightly hyperintense compared with the background liver on the hepatobiliary phase of EOB-MRI. After operation, this patient was confirmed pathologically as having beta-catenin-activated HCA with a portion suggestive of malignant transformation. In addition, intense organic anion transporter polypeptide 8 expression was observed throughout the tumor by immunohistochemical staining.

Liver-specific contrast agent-enhanced magnetic resonance and ¹⁸F-fluorodeoxyglucose positron emission tomography findings of hepatocellular adenoma: report of a case

We report a case of hepatocellular adenoma, focusing on the findings of liver-specific contrast agent-enhanced magnetic resonance imaging (MRI) and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET). The patient was a 37-year-old woman, referred to us after contrast-enhanced computed tomography showed a homogeneous, poorly enhanced liver tumor, 2.8 cm in diameter. Magnetic resonance imaging showed a liver mass with significant fatty change. The tumor increased in size to 3.3 cm over 9 months of follow-up. Gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid-enhanced MRI revealed spotty enhancement in the hypointense tumor in the hepatobiliary phase. Subsequent FDG-PET showed increased uptake of FDG (maximum standardized uptake value 5.0), which suggested the possibility of malignancy. The patient underwent partial hepatectomy, and histological examination of the resected specimen revealed a tumor composed of hepatocyte-like cells with minimal cellular atypia and significant diffuse fatty change. Based on these findings, we diagnosed hepatocellular adenoma.

A comparison of 31P magnetic resonance spectroscopy and microbubble-enhanced ultrasound for characterizing hepatitis c-related liver disease

We compared in vivo hepatic (31) P magnetic resonance spectroscopy ((31) P MRS) and hepatic vein transit times (HVTT) using contrast-enhanced ultrasound with a microbubble agent to assess the severity of hepatitis C virus (HCV)-related liver disease. Forty-six patients with biopsy-proven HCV-related liver disease and nine healthy volunteers had (31) P MRS and HVTT performed on the same day. (31) P MR spectra were obtained at 1.5 T. Peak areas were calculated for metabolites, including phosphomonoesters (PME) and phosphodiesters (PDE). Patients also had the microbubble ultrasound contrast agent, Levovist (2 g), injected into an antecubital vein, and time-intensity Doppler ultrasound signals of the right and middle hepatic veins were measured. The HVTT was calculated as the time from injection to a sustained rise in Doppler signal 10% greater than baseline. The shortest times were used for analysis. Based on Ishak histological scoring, there were 15 patients with mild hepatitis, 20 with moderate/severe hepatitis and 11 with cirrhosis. With increasing severity of disease, the PME/PDE ratio was steadily elevated, while the HVTT showed a monotonic decrease. Both imaging modalities could separate patients with cirrhosis from the mild and moderate/severe hepatitis groups. No statistical difference was observed in the accuracy of each test to denote mild, moderate/severe hepatitis and cirrhosis (Fisher's exact test P =1.00). (31) P MRS and HVTT show much promise as noninvasive imaging tests for assessing the severity of chronic liver disease. Both are equally effective and highly sensitive in detecting cirrhosis.

Detection Of Focal Liver Lesions In Cirrhotic Liver Using Contrast-Enhanced Ultrasound

Patients with liver cirrhosis are at increased risk of hepatocellular carcinoma (HCC). Conventional or baseline ultrasound (BUS) is often used as the first-line tool for HCC surveillance or detection, but the accuracy of BUS in HCC detection or differentiation from other focal liver lesions (FLLs) is limited. Contrast-enhanced ultrasound (CEUS) represents a recent revolution in the field of ultrasonography and it has become increasingly important in the detection and evaluation of FLLs. In CEUS, HCC typically exhibits arterial hyper-enhancement and portal-venous washout represented by hypo-enhanced lesions in the portal venous and late phases. The detection rate of HCC was significantly higher with CEUS compared with BUS. Even regenerative or some dysplastic nodules may exhibit arterial hyper-enhancement as they are differentiated from HCC by its iso-enhancing pattern in portal and late phases. The contrast-enhancement patterns of other different types of benign and malignant FLLs, as well as their detection rates with CEUS, were also discussed.

Adrenal masses: characterization with in vivo proton MR spectroscopy--initial experience

PURPOSE

To prospectively determine the accuracy of in vivo proton ((1)H) magnetic resonance (MR) spectroscopy in distinguishing adrenal adenomas, pheochromocytomas, adrenocortical carcinomas, and metastases, with histologic or computed tomographic findings and follow-up data as the reference standards.

MATERIALS AND METHODS

This study was approved by the institutional ethics committee, and informed consent was obtained. Sixty consecutive patients (24 male and 36 female patients; mean age, 53 years) harboring adrenal tumors larger than 2 cm in diameter (mean diameter, 4.6 cm +/- 3.4 [standard deviation]) entered the study and were examined with a 1.5-T MR imaging system and point-resolved multivoxel (1)H MR spectroscopy. Thirty-eight patients had adenomas; 10, pheochromocytomas; five, carcinomas; and seven, metastases. Amplitude values for choline, creatine, lipid, and a metabolite peak at precession frequency of 4.0-4.3 ppm were measured. Metabolite ratios (choline-creatine, choline-lipid, lipid-creatine, and 4.0-4.3 ppm/creatine) and cutoff values (obtained by using receiver operating characteristic analyses) were obtained and compared for each type of adrenal mass, which was identified previously on the basis of clinical, hormonal, and pathologic evidence. Results were evaluated with chi(2) and Student t tests. Significance was inferred at P < .05.

RESULTS

Cutoff values of 1.20 for the choline-creatine ratio (92% sensitivity, 96% specificity; P < .01), 0.38 for the choline-lipid ratio (92% sensitivity, 90% specificity; P < .01), and 2.10 for the lipid-creatine ratio (45% sensitivity, 100% specificity) enabled adenomas and pheochromocytomas to be distinguished from carcinomas and metastases. A 4.0-4.3 ppm/creatine ratio greater than 1.50 enabled distinction of pheochromocytomas and carcinomas from adenomas and metastases (87% sensitivity, 98% specificity; P < .01). The best distinction was obtained by comparing choline-creatine and 4.0-4.3 ppm/creatine ratios.

CONCLUSION

(1)H MR spectroscopy can be used to characterize adrenal masses on the basis of spectral findings for benign adenomas, carcinomas, pheochromocytomas, and metastases.

The role of contrast-enhanced ultrasound for focal liver lesion detection: an overview

The development of new ultrasound (US) contrast agents and sonographic techniques has considerably improved the possibilities of ultrasound in the assessment of liver tumors. An overview is given on diagnostic potential of contrast-enhanced US (CEUS) and real-time low mechanical index technique in the detection of various focal liver lesions compared with computed tomography, magnetic resonance imaging or intraoperative US. In two of our own studies that included 100 patients each we showed an increase of correct findings in CEUS compared with B-mode US from 64% to 87% and from 67% to 84% as confirmed by intraoperative evaluation of the liver. Especially after chemotherapy and in the case of small metastases, significantly more metastases were correctly detected by CEUS compared with B-mode US. These results and clinical study results in the literature show that CEUS allows tumor detection and direct visualization of the tumor vascularity and put contrast-enhanced sonography among recommended noninvasive imaging methods for focal liver lesions with improvements in diagnostic strategy.

Focal liver lesions: sinusoidal phase of CEUS

Ultrasound examination is the first imaging modality for hepatic study in neoplastic and chronic liver diseases. Focal liver lesions frequently cause diagnostic problems in terms of characterization, especially when small and hypoechoic to the rest of the parenchyma. Contrast--enhanced ultrasonography (CEUS) has shown its value in the characterization of focal liver lesions. This study assessed the value of the sinusoidal phase of CEUS with a second-generation contrast agent in the characterization of focal liver lesions to distinguish benign from malignant. Two hundred hepatic lesions with suspicious features at baseline ultrasound were prospectively studied with CEUS. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy of the sinusoidal phase in the characterization of benign versus malignant liver lesions were evaluated. Hypoechogenicity of the focal liver lesion, during the sinusoidal phase of CEUS, allowed the diagnosis of malignancy with a sensitivity of 85%, specificity of 88%, positive predictive value of 92%, negative predictive value of 77%, and diagnostic accuracy of 86%. The diagnostic confidence in the diagnosis of malignancy significantly increased, with receiver operating characteristic curve areas from 0.536 for baseline ultrasound to 0.902 for the sinusoidal phase of CEUS.

In vivo detection of metabolic changes by 1H-MRS in the DEN-induced hepatocellular carcinoma in Wistar rat

PURPOSE

To investigate the serial changes of the hepatic metabolites in a chemical-induced rat model of hepatocellular carcinoma (HCC) in vivo by a clinical 1.5 T MR scanner.

METHODS

Diethyl nitrosamine (DEN) induced HCC model rats (n=60) and control rats (n=20) were included. From week 7 to week 20 after DEN administration, every other week 10-12 animals (8-9 treated and 2-3 controls) were randomly scanned before being sacrificed. According to the pathologic changes, the whole process of tumorigenesis was divided into early and late periods (week 7-13 and week 14-20, respectively). The serial hepatic changes were tested by both routine MRI and single voxel 1H-MRS and compared with pathological results. Point resolved spectroscopy sequence (PRESS) was used for the location in MRS. The integrations of lipid- and choline-containing metabolites were calculated and analyzed.

RESULTS

All of the listed tests were fully finished in 66 rats (48 treated and 18 controls). Of the MRS curves, 65.2% (43/66) could be analyzed (mainly with resistant baseline with peaks appearing at right positions). From those qualified MRS curves, there were up to seven peaks which could be identified. The peaks of methylene lipids and methyl lipids were combined together in most cases and became the most notable component. The relative integrals of the combined lipid peak and that of the choline-containing compounds in different groups and stages were measured. Comparing with that of the controls of the same stage, the lipid of treated rats decreased in the late stage, and the choline-containing compounds increased in the same stage. Statistically significant differences were found (P<0.05) for the integrals of the lipid and the choline-containing metabolites between treated and controls in the late stage.

CONCLUSIONS

Our initial studies for the integrals of the lipid compounds and the choline-containing metabolites might be useful for a better understanding of the metabolic activity of this DEN-induced rat HCC model.

Proton and phosphorus-31 nuclear magnetic resonance spectroscopy of human bile in hepatopancreaticobiliary cancer

OBJECTIVE

Hepatopancreaticobiliary cancers can be difficult to diagnose. Nuclear magnetic resonance (NMR) spectroscopy provides non-invasive information on phospholipid metabolism, and previous studies of liver tissue have highlighted changes in phospholipids in malignancy. We hypothesised that in-vitro NMR spectroscopy of human bile may provide independent diagnostic indices in cancer management through an assessment of the phospholipid content.

DESIGN AND METHODS

Bile samples from 24 patients were collected at endoscopic retrograde cholangiopancreatography and from one subject at cholecystectomy. Thirteen patients had cancer: pancreatic carcinoma (eight), cholangiocarcinoma (three) and metastatic liver disease (two). The remaining 12 patients had non-malignant pathology. In-vitro proton (H) and phosphorus-31 (P) NMR spectra were obtained from all samples using an 11.7 Tesla NMR spectroscopy system.

RESULTS

Complementary information was obtained from the H and P NMR spectra. Signals were assigned to phosphatidylcholine in both H and P NMR spectra. Phosphatidylcholine levels were significantly reduced in the bile from cancer patients when compared with bile from non-cancer patients (P=0.007).

CONCLUSION

These preliminary studies suggest that H and P NMR spectroscopy of bile may be used to detect differences in phospholipid content between cancer and non-cancer patients. This may have implications for the development of novel diagnostic strategies in hepatopancreaticobiliary cancers. Further larger-scale studies are warranted.

The diagnosis and management of benign hepatic tumors

Benign hepatic tumors include a broad spectrum of regenerative and true neoplastic processes. Because of advances in imaging studies such as computed tomography (CT) and magnetic resonance imaging (MRI) as well as progress in immunohistochemistry, accurate diagnosis can now be made in a large percentage of patients without surgical laparotomy or resection. This article will focus on the pathogenesis, diagnosis, and management of focal benign lesions of the liver. Many of these tumors present with typical features in various imaging studies. On occasions, biopsies are required and/or surgical removal is needed. The most common benign hepatic tumors include cavernous hemangioma, focal nodular hyperplasia, hepatic adenoma, and nodular regenerative hyperplasia. In the majority of cases of benign hepatic tumors, patients are asymptomatic, and no treatment is indicated. The main indication for treatment is the presence of significant clinical symptoms or suspicion of malignancy or fear of malignant transformation.

In vivo and in vitro nuclear magnetic resonance spectroscopy as a tool for investigating hepatobiliary disease: a review of H and P MRS applications

Nuclear magnetic resonance (NMR) spectroscopy is a non-invasive technique, which allows the study of cellular biochemistry and metabolism. It is a diverse research tool, widely used by biochemists to investigate pathophysiological processes in vitro and, more recently, by physicians to determine disease abnormalities in vivo. This article reviews the basics of the NMR phenomenon and summarises previous research on the hepatobiliary system using both laboratory-based and clinical methodologies. The role of proton and phosphorus-31 ((31)P) NMR spectroscopy in the study of malignant and non-malignant liver disease and studies of bile composition are discussed. In vivo techniques (magnetic resonance spectroscopy, MRS) can be performed as an adjunct to standard MR examination of the liver. Although still primarily a research tool, the in vivo technique provides non-invasive biochemical information on disease severity and holds promise in its use to gauge response to treatment regimens.

Real-time imaging with the sonographic contrast agent SonoVue: differentiation between benign and malignant hepatic lesions

OBJECTIVE

We investigated the ability of contrast-enhanced sonography with SonoVue (Altana Pharma, Konstanz, Germany), a sulfur hexafluoride microbubble contrast agent, to reveal differences between benign and malignant focal hepatic lesions.

METHODS

One hundred twenty-six lesions in 124 patients with focal hepatic lesions detected by B-mode sonography (hepatocellular carcinoma, n = 36; metastasis, n = 25; cholangiocellular carcinoma, n = 1; lymphoma, n = 2; focal nodular hyperplasia, n = 9; adenoma, n = 4; regenerative cirrhotic nodule, n = 13; hemangioma, n = 29; and focal hyposteatosis, n = 7) were examined in a prospective study. After intravenous injection of 2.4 mL of SonoVue, the liver was examined continuously for 3 minutes by low-mechanical index pulse inversion sonography.

RESULTS

For the discrimination of malignant versus benign liver lesions, SonoVue-enhanced sonography improved sensitivity from 78% to 100% and specificity from 23% to 92% compared with baseline sonography. Receiver operating characteristic analysis revealed a significant improvement in this discrimination (area under the receiver operating characteristic curve, 0.510 +/- 0.054 [SD] at baseline sonography, 0.998 +/- 0.003 with SonoVue-enhanced sonography; P < .001). The following flow patterns in the early phase were diagnosis specific: early central starlike pattern for focal nodular hyperplasia, peripheral globular-nodular pattern for hemangioma, and diffuse arterial enhancement for malignant lesions. Homogeneous enhancement in the late phase was predictive for benign lesions (P < .001). Conversely, 93% of patients without contrast enhancement in the late phase had malignant lesions (P < .001).

CONCLUSIONS

SonoVue-enhanced sonography has greater specificity and sensitivity than baseline sonography for the differentiation of benign and malignant liver lesions.

Hepatocellular carcinoma - issues in imaging

The imaging diagnosis of hepatocellular carcinoma is challenging as benign hypervascular lesions and arterioportal shunts (pseudolesions) often mimic it. There is also overlap in the imaging appearance from dysplastic and regenerating nodules. This article addresses the above imaging problems, examines proposed non-invasive imaging criteria for the diagnosis of hepatoma and discusses the optimal imaging modality.

In vivo proton magnetic resonance spectroscopy of large focal hepatic lesions and metabolite change of hepatocellular carcinoma before and after transcatheter arterial chemoembolization using 3.0-T MR scanner

PURPOSE

To investigate the value of in vivo proton magnetic resonance spectroscopy (MRS) in the assessment of large focal hepatic lesions and to measure the metabolite change of hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) using 3.0-T scanner.

MATERIALS AND METHODS

In this prospective study, 43 consecutive patients with large (not less than 3 cm in diameter) hepatic tumors and eight normal volunteer were included. MRS of the lesions in addition to uninvolved liver parenchyma was carried out using a whole-body 3.0-T scanner. Among the patients with proven HCC, eight lesions were evaluated before and two to five days after TACE. The choline-to-lipid (cho/lipid) ratio was measured by dividing the peak area of choline at 3.2 ppm by the peak area of lipid at 1.3 ppm. The sensitivity and specificity profiles of MRS in the diagnosis of malignant hepatic tumors were determined by plotting empirical receiver operating characteristic (ROC) curve. The mean cho/lipid ratios in different groups before and after TACE were also measured.

RESULTS

The technical success rate for MRS was 90% (53/59). The ROC curve showed proton MRS has moderate discriminating ability in diagnosing malignant hepatic tumors, although the sensitivity was less than 50% while 1-specificity was less than 20%. The area under the curve was 0.71 (P < 0.05). The mean +/- 1 standard error (SE) of cho/lipid ratios for uninvolved liver (N = 8), benign tumor (N = 8), and malignant tumor (N = 21; 19 HCC, one angiosarcoma, and one lymphoma) were 0.06 +/- 0.02, 0.02 +/- 0.02, and 0.17 +/- 0.05, respectively. A significantly statistical difference (ANOVA planned contrast test, P = 0.01 and Games-Howell procedure, P = 0.03) was achieved in the mean cho/lipid ratio between malignant and benign tumors. The mean cho/lipid ratios were significantly decreased from 0.23 +/- 0.11 before TACE to 0.01 +/- 0.00 after the treatment (t = 2.01, P < 0.05, one-tail paired t-test; z = -2.37, P < 0.05, Wilcoxon Signed Ranks Test).

CONCLUSION

In vivo proton MRS is technically feasible for the evaluation of focal hepatic lesions. The technique has potential in the detection of early metabolite change in malignant liver tumors after TACE but limitation still exists in clear differentiation between normal liver and benign and malignant tumor.