CT and MRI of diffuse liver disease

Non-alcoholic fatty liver disease in patients with chylomicronemia syndromes

BACKGROUND

Chylomicronemia syndrome is a form of severe hypertriglyceridemia (HTG) caused by the familial chylomicronemia syndrome (FCS) or multifactorial chylomicronemia syndrome (MCS). Non-alcoholic fatty liver disease (NAFLD) has been associated with components of the metabolic syndrome and is more prevalent in subjects with elevated triglycerides.

OBJECTIVE

The primary objective was to compare the prevalence of hepatic steatosis assessed by conventional imaging between HTG groups (FSC, MCS and moderate HTG (mHTG)). The secondary objective was to determine the difference in the prevalence of liver fibrosis.

METHODS

This cross-sectional observational study was performed on adult patients from the lipid clinic of the Montreal Clinical Research Institute (IRCM). We retrospectively reviewed the imaging reports available in the patients' files for signs of NAFLD. We also used the FIB-4 index as a surrogate marker of liver fibrosis.

RESULTS

We reviewed the medical files of 300 patients; 22 with FCS, 82 with MCS and 196 with mHTG. There was significantly more hepatic steatosis in the MCS group compared to the mHTG and FCS groups (79%, 66% and 43% respectively p=0.02). There was a significantly higher prevalence of subjects within the "unlikely fibrosis" category in the mHTG group (91%) compared to the MCS (84%) and FCS groups (59%), p=0.0004.

CONCLUSION

We found that the prevalence of hepatic steatosis was 3-, 2.5-, and 2-fold higher in MCS, mHTG and FCS patients than in the general population. This suggests that patients with elevated triglycerides, regardless of the underlying etiology, are at higher risk of hepatic steatosis and NAFLD.

Quantification of Liver Iron Overload with MRI: Review and Guidelines from the ESGAR and SAR

Accumulation of excess iron in the body, or systemic iron overload, results from a variety of causes. The concentration of iron in the liver is linearly related to the total body iron stores and, for this reason, quantification of liver iron concentration (LIC) is widely regarded as the best surrogate to assess total body iron. Historically assessed using biopsy, there is a clear need for noninvasive quantitative imaging biomarkers of LIC. MRI is highly sensitive to the presence of tissue iron and has been increasingly adopted as a noninvasive alternative to biopsy for detection, severity grading, and treatment monitoring in patients with known or suspected iron overload. Multiple MRI strategies have been developed in the past 2 decades, based on both gradient-echo and spin-echo imaging, including signal intensity ratio and relaxometry strategies. However, there is a general lack of consensus regarding the appropriate use of these methods. The overall goal of this article is to summarize the current state of the art in the clinical use of MRI to quantify liver iron content and to assess the overall level of evidence of these various methods. Based on this summary, expert consensus panel recommendations on best practices for MRI-based quantification of liver iron are provided.

Fatty Liver Disease-Alcoholic and Non-Alcoholic: Similar but Different

In alcohol-induced liver disease (ALD) and in non-alcoholic fatty liver disease (NAFLD), there are abnormal accumulations of fat in the liver. This phenomenon may be related to excessive alcohol consumption, as well as the combination of alcohol consumption and medications. There is an evolution from simple steatosis to steatohepatitis, fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Hepatic pathology is very similar regarding non-alcoholic fatty liver disease (NAFLD) and ALD. Initially, there is lipid accumulation in parenchyma and progression to lobular inflammation. The morphological changes in the liver mitochondria, perivenular and perisinusoidal fibrosis, and hepatocellular ballooning, apoptosis and necrosis and accumulation of fibrosis may lead to the development of cirrhosis and HCC. Medical history of ethanol consumption, laboratory markers of chronic ethanol intake, AST/ALT ratio on the one hand and features of the metabolic syndrome on the other hand, may help in estimating the contribution of alcohol intake and the metabolic syndrome, respectively, to liver steatosis.

Non-alcoholic fatty liver disease (NAFLD): a review of pathophysiology, clinical management and effects of weight loss

Given the increasing prevalence of diabetes and obesity worldwide, the deleterious effects of non-alcoholic fatty liver disease (NAFLD) are becoming a growing challenge for public health. NAFLD is the most common chronic liver disease in the Western world. NAFLD is closely associated with metabolic disorders, including central obesity, dyslipidaemia, hypertension, hyperglycaemia and persistent abnormalities of liver function tests.In general NAFLD is a common denominer for a broad spectrum of damage to the liver, which can be due to hepatocyte injury, inflammatory processes and fibrosis. This is normally seen on liver biopsy and can range from milder forms (steatosis) to the more severe forms (non-alcoholic steatohepatitis (NASH), advanced fibrosis, cirrhosis and liver failure). In these patients, advanced fibrosis is the major predictor of morbidity and liver-related mortality, and an accurate diagnosis of NASH and NAFLD is mandatory. Histologic evaluation with liver biopsy remains the gold standard to diagnose NAFLD. Diagnosis of NAFLD is defined as presence of hepatic steatosis, ballooning and lobular inflammation with or without fibrosis. Weight loss, dietary modification, and the treatment of underlying metabolic syndrome remain the mainstays of therapy once the diagnosis is established. Dietary recommendations and lifestyle interventions, weight loss, and the treatment of underlying metabolic syndrome remain the mainstays of therapy once the diagnosis is established with promising results but are difficult to maintain. Pioglitazone and vitamin E are recommended by guidelines in selected patients. This review gives an overview of NAFLD and its treatment options.

Computed tomography (CT) and magnetic resonance imaging (MRI) of diffuse liver disease: a multiparametric predictive modelling algorithm can aid categorization of liver parenchyma

BACKGROUND

Liver steatosis is common and tracking disease evolution to steatohepatitis and cirrhosis is essential for risk stratification and resultant patient management. Consequently, diagnostic tools allowing categorization of liver parenchyma based on routine imaging are desirable. The study objective was to compare established mono-factorial, dynamic single parameter and iterative multiparametric routine computed tomography (CT) and magnetic resonance imaging (MRI) analyses to distinguish between liver steatosis, steatohepatitis, cirrhosis and normal liver parenchyma.

METHODS

A total of 285 multi-phase contrast enhanced CT and 122 MRI studies with histopathological correlation of underlying parenchymal condition were retrospectively included. Parenchymal conditions were characterized based on CT Hounsfield units (HU) or MRI signal intensity (SI) measurements and calculated HU or SI ratios between non-contrast and contrast enhanced imaging time points. First, the diagnostic accuracy of mono-factorial analyses using established, static non-contrast HU and in- to opposed phase SI change cut-offs to distinguish between parenchymal conditions was established. Second, single dynamic discriminator analyses, with optimized non-contrast and enhancement HU and SI ratio cut-off values derived from the data, employing receiver operating characteristic (ROC) curve areas under the curve (AUCs) and the Youden index for maximum accuracy, were used for disease diagnosis. Third, multifactorial analyses, employing multiple non-contrast and contrast enhanced HU and SI ratio cut-offs in a nested, predictive-modelling algorithm were performed to distinguish between normal parenchyma, liver steatosis, steatohepatitis and cirrhosis. CT and MRI analyses were performed separately.

RESULTS

No single CT or MRI parameter showed significant difference between all four parenchymal conditions (each P>0.05). Mono-factorial static-CT-discriminator analyses identified liver steatosis with 75% accuracy. Mono-factorial MRI analyses identified steatosis with 89% accuracy. Single-dynamic CT parameter analyses identified normal parenchyma with 72% accuracy and cirrhosis with 75% accuracy. Single-dynamic MRI parameter analyses identified fatty parenchyma with 90% accuracy. Multifactorial CT analyzes identified normal parenchyma with 84%, liver steatosis with 95%, steatohepatitis with 95% and cirrhosis with 80% accuracy. Multifactorial predictive modelling of MRI parameters identified normal parenchyma with 79%, liver steatosis with 89%, steatohepatitis with 92% and cirrhosis with 89% accuracy.

CONCLUSIONS

Multiparametric analyses of quantitative measurements derived from routine CT and MRI, utilizing a predictive modelling algorithm, can help to distinguish between normal liver parenchyma, liver steatosis, steatohepatitis and cirrhosis.

Evaluation of Adjuvant Chemotherapy-Associated Steatosis (CAS) in Colorectal Cancer

Chemotherapy-associated steatosis is poorly understood in the context of colorectal cancer. In this study, Stage II–III colorectal cancer patients were retrospectively selected to evaluate the frequency of chemotherapy-associated steatosis and to determine whether patients on statins throughout adjuvant chemotherapy develop chemotherapy-associated steatosis at a lower frequency. Baseline and incident steatosis for up to one year from chemotherapy start date was assessed based on radiology. Of 269 patients, 76 (28.3%) had steatosis at baseline. Of the remaining 193 cases, patients receiving adjuvant chemotherapy (n = 135) had 1.57 (95% confidence interval [CI], 0.89 to 2.79) times the adjusted risk of developing steatosis compared to patients not receiving chemotherapy (n = 58). Among patients who underwent chemotherapy, those using statins for pre-existing hyperlipidemia (n = 37) had 0.71 (95% CI, 0.10 to 2.75) times the risk of developing steatosis compared to patients who were not prevalent users of statins (n = 98). Chemotherapeutic treatment of Stage II–III colorectal cancer appears to be consistent with a moderately increased risk of steatosis, although larger studies are necessary to assess the significance of this observation. Prospective trials should be considered to further explore the potential for protective use of statins in this curative patient population.

Are Noninvasive Methods Comparable to Liver Biopsy in Postoperative Patients After Roux-en-Y Gastric Bypass?

INTRODUCTION

Transient tissue elastography (TTE) may estimate the degree of hepatic fibrosis in patients with obesity, but the method has restrictions that are mainly related to patients' BMI.

PURPOSE

To compare the results of the evaluation of hepatic fibrosis by biochemical methods and TTE with those determined by liver biopsy in patients after RYGB.

METHODS

This was a cross-sectional study involving patient data, TTE, and liver biopsy 1 year after RYGB.

RESULTS

Of the 94 selected patients, 33 underwent TTE and liver biopsy. The average weight of patients was 84.4 ± 15.4 kg. The mean APRI was 0.2 ± 0.1, and 36 patients (97.3%) were classified as F0-F1. The average NFS was - 2.0 ± 1.0, with 25 patients (67%) classified as F0-F1 and 12 patients (32.4%) classified as F2. The agreement rate between Fibroscan and liver biopsy was 80.0%. Histological analysis revealed regression of inflammatory changes in all patients: 26 patients (72.2%) had some degree of non-alcoholic steatohepatitis (NAS ≥ 5), and after surgery, no patient presented inflammation upon biopsy. Nine patients (24.3%) had fibrosis at surgery, and only two (5.4%) still had fibrosis 1 year later (p < 0.008).

CONCLUSIONS

The use of APRI and Fibroscan is promising, but more studies are needed to evaluate patients with an advanced degree of NAFLD and confirm the entire spectrum of the disease.

Noninvasive Evaluation for Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis

PURPOSE

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide and has the potential risk for progressing to nonalcoholic steatohepatitis (NASH), which is associated with a greater risk for complications of chronic liver disease. Noninvasive testing has been evaluated for diagnosis, risk stratification, disease progression, and assessing response to therapy. The purpose of this narrative review was to outline the current noninvasive testing modalities for the diagnostic evaluation of NAFLD and NASH, while discussing possible markers that could be used for monitoring response to therapies.

METHODS

The PubMed and Cochrane databases were searched for relevant articles that evaluated the diagnosis of NAFLD/NASH with serum biomarkers and/or imaging.

FINDINGS

Serum biomarkers, imaging modalities, and combinations/serial algorithms involved in the diagnosis of NAFLD and NASH are outlined. In addition, noninvasive modalities that have been used for assessing response to therapies in clinical trials are discussed.

IMPLICATIONS

Liver biopsy currently remains the gold standard for diagnosis and is often used in clinical trials to assess treatment response. However, developing safe and accessible noninvasive modalities for diagnosis and monitoring will have greater impact and relevance, as biopsy may not always be feasible in all clinical settings.

Typical imaging finding of hepatic infections: a pictorial essay

Hepatic infections are frequent in clinical practice. Although epidemiological, clinical and laboratory data may suggest hepatic infection in certain cases, imaging is nearly always necessary to confirm the diagnosis, assess disease extension and its complications, evaluate the response to treatment, and sometimes to make differential diagnoses such as malignancies. Ultrasound (US) is usually the first-line investigation, while computed tomography (CT) and magnetic resonance imaging (MRI) provide better characterization and a more precise assessment of local extension, especially biliary and vascular. The purpose of this article is to describe the typical features and main complications of common hepatic infections. Familiarity with the radiological features of this entity can help suggest the correct diagnosis and the need for further studies as well as determine appropriate and timely treatment.

Vanishing washout of hepatocellular carcinoma according to the presence of hepatic steatosis: diagnostic performance of CT and MRI

OBJECTIVES

To compare the presence of washout and the diagnostic performance of computed tomography (CT) and magnetic resonance imaging (MRI) for hepatocellular carcinoma (HCC) according to the presence of hepatic steatosis.

METHODS

This retrospective study included 566 patients with chronic liver disease who had undergone hepatic resection for hepatic tumors (482 HCCs and 84 non-HCCs) between January 2016 and June 2018 and had available multiphasic CT and MR images. Patients were allocated in the fatty liver (n = 141) or non-fatty liver (n = 425) group according to the presence of hepatic steatosis, defined as lipid droplets in at least 5% of hepatocytes on pathological examination. The presence of HCC washout and the diagnostic performance of CT and MRI for HCC were compared between the groups.

RESULTS

HCC washout was less frequently seen in the fatty liver group than in the non-fatty liver group on CT (61.5% vs. 88.9%, p < 0.001), whereas it was similarly present on MRI in both groups (77.0% vs. 74.4%, p = 0.565). For diagnosis of HCC, the sensitivity (53.3% vs. 80.0%, p < 0.001) and accuracy (53.9% vs. 80.9%, p < 0.001) of CT were lower in the fatty liver group than in the non-fatty liver group. However, for MRI, these values were not significantly different between the groups (p > 0.05).

CONCLUSIONS

Hepatic steatosis significantly decreased the performance of CT for the diagnosis of HCC, whereas it did not significantly alter the performance of MRI.

KEY POINTS

• Unlike MRI, there is vanishing HCC washout on CT caused by the background hepatic steatosis. • The diagnostic performance of CT for the diagnosis of HCC was significantly altered by hepatic steatosis. • The optimal cutoff HU value of the liver parenchyma for the vanishing washout of HCC was < 50 HU on unenhanced CT images.

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.

Iodine accumulation of the liver in patients treated with amiodarone can be unmasked using material decomposition from multiphase spectral-detector CT

Amiodarone accumulates in the liver, where it increases x-ray attenuation due to its iodine content. We evaluated liver attenuation in patients treated and not treated with amiodarone using true-non-contrast (TNC) and virtual-non-contrast (VNC) images acquired with spectral-detector-CT (SDCT). 142 patients, of which 21 have been treated with amiodarone, receiving SDCT-examinations (unenhanced-chest CT [TNC], CT-angiography of chest and abdomen [CTA-Chest, CTA-Abdomen]) were included. TNC, CTA-Chest, CTA-Abdomen, and corresponding VNC-images (VNC-Chest, VNC-Abdomen) were reconstructed. Liver-attenuation-index (LAI) was calculated as difference between liver- and spleen-attenuation. Liver-attenuation and LAI derived from TNC-images of patients receiving amiodarone were higher. Contrary to TNC, liver-attenuation and LAI were not higher in amiodarone patients in VNC-Chest and in VNC-Abdomen. To verify these initial results, a phantom scan was performed and an additional patient cohort included, both confirming that VNC is viable of accurately subtracting iodine of hepatic amiodarone-deposits. This might help to monitor liver-attenuation more accurately and thereby detect liver steatosis as a sign of liver damage earlier as well as to verify amiodarone accumulation in the liver.

Herpes Simplex Virus-2 Hepatitis: A Case Report and Review of the Literature

Herpes simplex virus (HSV) is a rare cause of hepatitis in pregnancy and the chronically immunosuppressed, with a high propensity to progress to acute liver failure (ALF) and death. Patients typically present with a nonspecific clinical picture that often delays diagnosis and treatment, contributing to the high mortality rate. We present a case of a young female on chronic prednisone and hydroxychloroquine for systemic lupus erythematosus (SLE) who was diagnosed with HSV-2 hepatitis after presenting with right-sided chest and abdominal discomfort. Despite early clinical deterioration, prompt initiation of therapy with intravenous acyclovir and methylprednisolone led to rapid improvement.

Beyond pyogenic liver abscess: a comprehensive review of liver infections in emergency settings

Hepatobiliary infections are commonly encountered in emergency settings ranging from common pathology such as pyogenic abscess to relatively uncommon and rare etiologies. Since extensive literature is already available on imaging of more common bacterial infections, for the sake of focused discussion, this review will discuss radiological appearance of less commonly encountered hepatic infections of fungal, parasitic, viral, and tubercular etiologies. Epidemiological and clinical information remain extremely important for obtaining more accurate presumptive diagnosis. In the era of diverse population migration, a modern-era radiologist must be well versed about the imaging spectrum of liver infections.

Evaluation of the liver with virtual non-contrast: single institution study in 149 patients undergoing TAVR planning

OBJECTIVE

To evaluate accuracy of virtual-non-contrast images (VNC) compared to true-unenhanced-images (TNC) for evaluation of liver attenuation acquired using spectral-detector CT (SDCT).

METHODS

149 patients who underwent multiphase transcatheter-aortic-valve-replacement (TAVR) SDCT-examinations [unenhanced-chest (TNC), CT-angiography chest (CTA-chest, early arterial-phase) and abdomen (CTA-abdomen, additional early arterial-phase after a second injection of contrast media)] were retrospectively included. VNC of CTA-chest (VNC-chest) and CTA-abdomen (VNC-abdomen) were reconstructed and compared to TNC. Region of interest-based measurement of mean attenuation (Hounsfield unit, HU) was applied in the following regions: liver, spleen, abdominal aorta and paraspinal muscle.

RESULTS

VNC accuracy was high in the liver, spleen, abdominal aorta and muscle for abdomen-scanning. For the liver, average attenuation was 59.0 ± 9.1 HU for TNC and 72.6 ± 9.5 HU for CTA-abdomen. Liver attenuation in VNC-abdomen (59.1 ± 6.4 HU) was not significantly different from attenuation in TNC (p > 0.05). In contrast, VNC was less accurate for chest-scanning: Due to the protocol, in CTA-chest no contrast media was present in the liver parenchyma as indicated by the same attenuation in TNC (59.0 ± 9.1 HU) and CTA-chest (58.8 ± 8.9 HU, p > 0.05). Liver attenuation in VNC-chest (56.2 ± 6.4 HU, p < 0.05) was, however, significantly lower than in TNC and CTA-chest implying an artificial reduction of attenuation.

CONCLUSION

VNC performed well in a large cohort of TAVR-examinations yielding equivalent mean attenuations to TNC; however, application of this technique might be limited when no or very little contrast media is present in parenchyma, more precisely in an early arterial-phase of the liver.

ADVANCES IN KNOWLEDGE

This study showed that VNC can be reliably applied in cardiac protocols when certain limitations are considered.

Infections of the Hepatobiliary System

Hepatobiliary infections account for a small but clinically important proportion of emergency department presentations. They present a clinical challenge due to the broad range of imaging characteristics on presentation. Recognition of complications is imperative to drive appropriate patient care and resource utilization to avoid diagnostic pitfalls and avert adverse patient outcomes. A thorough understanding of anatomy infectious pathology of hepatobiliary system is essential in the emergency setting to confidently diagnose and guide medical intervention. Many presentations of hepatobiliary infection have characteristic imaging features on individual imaging modalities with others requiring the assimilation of findings of multiple imaging modalities along with incorporating the clinical context and multispecialist consultation. Familiarity with the strengths of individual imaging modalities in the radiologists' arsenal is imperative to guide the appropriate utilization of resources, particularly in the emergent time sensitive setting. Accurate identification and diagnosis of hepatobiliary infections is vital for appropriate patient care and management stratification.

[11C]acetate PET as a tool for diagnosis of liver steatosis

Purpose

To investigate [¹¹C]acetate PET-surrogate parameter of fatty acid synthase activity—as suitable tool for diagnosis and monitoring of liver steatosis.

Methods

In this retrospective study, data were obtained from 83 prostatic carcinoma patients from 1/2008 to 1/2014. Mean HU was calculated from unenhanced CT of all patients from liver with liver HU less than 40 as threshold for liver steatosis. SUV_max of the liver and of the blood pool in thoracic aorta (as background for calculation of a liver/background ratio [SUV_l/b]) was measured. t test was used with a P < 0.05 considered as statistically significant difference and ROC analysis was used for calculating specificity and sensitivity.

Results

19/83 patients (20%) had diagnosis of hepatic steatosis according to CT. Uptake of [¹¹C]acetate was significantly higher in patients with hepatic steatosis as compared to control group (SUV_max 7.96 ± 2.0 vs. 5.48 ± 2.3 [P < 0.001]). There was also a significant correlation between both SUV_max (r = − 0.52, P < 0.001) and SUV_l/b (r = − 0.59, P < 0.001) with the density (HU) of the liver. In ROC analysis for detection of liver steatosis SUV_max (threshold: 5.86) had a sensitivity of 94% and specificity of 69% with an AUC of 0.81. Increasing body mass index is correlated with the severity of steatosis.

Conclusion

We showed for the first time that hepatic steatosis associates with increased [¹¹C]acetate uptake. Also, severity of steatosis correlates with [¹¹C]acetate uptake. [¹¹C]acetate uptake PET seems promising for the assessment of liver steatosis.

Electronic supplementary material

The online version of this article (10.1007/s00261-018-1558-4) contains supplementary material, which is available to authorized users.

When to Initiate Weight Loss Medications in the NAFLD Population

Nonalcoholic fatty liver disease (NAFLD) is characterized by histological evidence of hepatic steatosis, lobular inflammation, ballooning degeneration and hepatic fibrosis in the absence of significant alcohol use and other known causes of chronic liver diseases. NAFLD is subdivided into nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). NAFL is generally benign but can progress to NASH, which carries a higher risk of adverse outcomes including cirrhosis, end-stage liver disease, hepatocellular carcinoma and death if liver transplantation is not pursued in a timely fashion. Currently, lifestyle modifications including healthy diet and increased physical activity/exercise culminating in weight loss of 5% to >10% is the cornerstone of treatment intervention for patients with NAFLD. Patients with NAFLD who fail to obtain this goal despite the help of dietitians and regimented exercise programs are left in a purgatory state and remain at risk of developing NASH-related advance fibrosis. For such patients with NAFLD who are overweight and obese, healthcare providers should consider a trial of FDA-approved anti-obesity medications as adjunct therapy to provide further preventative and therapeutic options as an effort to reduce the risk of NAFLD-related disease progression.

Current status of imaging in nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common diffuse liver disease, with a worldwide prevalence of 20% to 46%. NAFLD can be subdivided into simple steatosis and nonalcoholic steatohepatitis. Most cases of simple steatosis are non-progressive, whereas nonalcoholic steatohepatitis may result in chronic liver injury and progressive fibrosis in a significant minority. Effective risk stratification and management of NAFLD requires evaluation of hepatic parenchymal fat, fibrosis, and inflammation. Liver biopsy remains the current gold standard; however, non-invasive imaging methods are rapidly evolving and may replace biopsy in some circumstances. These methods include well-established techniques, such as conventional ultrasonography, computed tomography, and magnetic resonance imaging and newer imaging technologies, such as ultrasound elastography, quantitative ultrasound techniques, magnetic resonance elastography, and magnetic resonance-based fat quantitation techniques. The aim of this article is to review the current status of imaging methods for NAFLD risk stratification and management, including their diagnostic accuracy, limitations, and practical applicability.

Analysis of computed tomography density of liver before and after amiodarone administration

PURPOSE

To evaluate CT density of liver changes between before and after amiodarone administration.

MATERIALS AND METHODS

Twenty-five patients underwent non-enhanced CT including the liver before and after amiodarone administration. We set regions of interest (ROIs) at liver S8, spleen, paraspinal muscle, and calculated average CT density in these ROIs, then compared CT density between liver and other organs. Statistical differences between CT density of liver and various ratios before and after administration were determined, along with correlations between cumulative dose of amiodarone and liver density after administration, density change of liver, and various ratios after administration.

RESULTS

Liver density, liver-to-spleen ratio, and liver-to-paraspinal muscle ratio differed significantly between before and after amiodarone administration. No significant correlations were found between cumulative doses of amiodarone and any of liver density after administration, density change of liver, or various ratios after administration.

CONCLUSION

CT density of liver after amiodarone administration was significantly higher than that before administration. No correlations were identified between cumulative dose of amiodarone and either liver density after administration or density change of liver. Amiodarone usage should be checked when radiologists identify high density of the liver on CT.

Using MRI to non-invasively and accurately quantify preoperative hepatic steatosis

BACKGROUND

The obesity epidemic has significantly increased the incidence and severity of hepatic steatosis in liver surgery patients and liver donors, potentially impacting postoperative liver regeneration and function. Development of a non-invasive means to quantify hepatic steatosis would facilitate selection of candidates for liver resection and transplant donation.

METHODS

An IRB-approved protocol prospectively enrolled 28 patients with liver tumors requiring hepatic resection. In all patients, fast dual-echo gradient-echo MR images were acquired using 2-Point Dixon technique in 2D and 3D. The degree of steatosis was quantified by percent fat fraction (%FF) from in- and out-of-phase, and water-only and fat-only images. The technique-specific %FFs were compared to intraoperative and histopathological findings.

RESULTS

For patients with >30% steatosis by histology, the mean %FF was 22% (SD ± 5.2%) compared to a mean %FF of 5.0% (SD ± 2.1%, p = 0.0001) in patients with <30% steatosis. Using scaled values for the MR-calculated %FF, all patients with >30% pathologic steatosis could be identified preoperatively.

CONCLUSIONS

Quantitative MRI identified patients with clinically-relevant steatosis with 100% accuracy. These findings could have significant impact on the management of liver resection patients and transplant donors.

Nonalcoholic fatty liver disease: What do we know and what will we have to learn?

The article reviews relevant data on the prevalence, natural history, pathogenesis, diagnosis, and treatment of nonalcoholic fatty liver disease and critically assesses the fixed notion of this disease.

Fibrosis Assessment in Nonalcoholic Fatty Liver Disease (NAFLD) in 2016

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of liver pathologies characterized by hepatic steatosis with a history of little to no alcohol consumption or secondary causes of hepatic steatosis. The prevalence of NAFLD is 20-25 % of the general population in the Western countries and is associated with metabolic risk factors such as obesity, diabetes mellitus, and dyslipidemia. The spectrum of disease ranges from simple steatosis to nonalcoholic steatohepatitis, fibrosis, and cirrhosis. Advanced fibrosis is the most significant predictor of mortality in NAFLD. It is crucial to assess for the presence and degree of hepatic fibrosis in order to make therapeutic decisions and predict clinical outcomes. Liver biopsy, the current gold standard to assess the liver fibrosis, has a number of drawbacks such as invasiveness, sampling error, cost, and inter-/intra-observer variability. There are currently available a number of noninvasive tests as an alternative to liver biopsy for fibrosis staging. These noninvasive fibrosis tests are increasingly used to rule out advanced fibrosis and help guide disease management. While these noninvasive tests perform relatively well for ruling out advanced fibrosis, they also have limitations. Understanding the strengths and limitations of liver biopsy and the noninvasive tests is necessary for deciding when to use the appropriate tests in the evaluation of patients with NAFLD.

Reoperation after mitral valve repair in viewpoints of kidney injury as well as hemolytic anemia

A 70-year-old woman developed anemia and kidney injury 10 months after mitral valve (MV) repair. Serological findings and Doppler echocardiography suggested hemolytic anemia due to mitral regurgitation jet collision with an annuloplasty ring (MRCR). Since kidney injury persisted even without exacerbation of anemia over 10 months, we performed an MV replacement. The anemia improved rapidly after the surgery; however, the renal function remained chronic kidney disease (CKD) after reoperation. Kidney injury was thought to be due to iron deposition and decreased renal perfusion that caused tubular injury. A comprehensive literature review shows that hemolysis due to MRCR in the early postoperative phase (within 3 postoperative months) can be often ameliorated with endothelialization without the need for reoperation; however, hemolysis in the late postoperative phase can persist even for a long period without reoperation. Chronic hemolysis can lead to kidney injury and progress to CKD even without clinical evidence of exacerbation of anemia. Therefore, in cases of late postoperative phase hemolysis, reoperation should be considered for better management of kidney injury and hemolytic anemia.

Non-alcoholic fatty liver disease: The diagnosis and management

Non-alcoholic fatty liver disease (NAFLD) is now the most frequent chronic liver disease that occurs across all age groups and is recognized to occur in 14%-30% of the general population, representing a serious and growing clinical problem due to the growing prevalence of obesity and overweight. Histologically, it resembles alcoholic liver injury but occurs in patients who deny significant alcohol consumption. NAFLD encompasses a spectrum of conditions, ranging from benign hepatocellular steatosis to inflammatory nonalcoholic steatohepatitis, fibrosis, and cirrhosis. The majority of hepatocellular lipids are stored as triglycerides, but other lipid metabolites, such as free fatty acids, cholesterol, and phospholipids, may also be present and play a role in disease progression. NAFLD is associated with obesity and insulin resistance and is considered the hepatic manifestation of the metabolic syndrome, a combination of medical conditions including type 2 diabetes mellitus, hypertension, hyperlipidemia, and visceral adiposity. Confirmation of the diagnosis of NAFLD can usually be achieved by imaging studies; however, staging the disease requires a liver biopsy. Current treatment relies on weight loss and exercise, although various insulin-sensitizing agents, antioxidants and medications appear promising. The aim of this review is to highlight the current information regarding epidemiology, diagnosis, and management of NAFLD as well as new information about pathogenesis, diagnosis and management of this disease.

Diagnostic accuracy of a noninvasive hepatic ultrasound score for non-alcoholic fatty liver disease (NAFLD) in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

CONTEXT AND OBJECTIVE

Noninvasive strategies for evaluating non-alcoholic fatty liver disease (NAFLD) have been investigated over the last few decades. Our aim was to evaluate the diagnostic accuracy of a new hepatic ultrasound score for NAFLD in the ELSA-Brasil study.

DESIGN AND SETTINGS

Diagnostic accuracy study conducted in the ELSA center, in the hospital of a public university.

METHODS

Among the 15,105 participants of the ELSA study who were evaluated for NAFLD, 195 individuals were included in this sub-study. Hepatic ultrasound was performed (deep beam attenuation, hepatorenal index and anteroposterior diameter of the right hepatic lobe) and compared with the hepatic steatosis findings from 64-channel high-resolution computed tomography (CT). We also evaluated two clinical indices relating to NAFLD: the fatty liver index (FLI) and the hepatic steatosis index (HSI).

RESULTS

Among the 195 participants, the NAFLD frequency was 34.4%. High body mass index, high waist circumference, diabetes and hypertriglyceridemia were associated with high hepatic attenuation and large anteroposterior diameter of the right hepatic lobe, but not with the hepatorenal index. The hepatic ultrasound score, based on hepatic attenuation and the anteroposterior diameter of the right hepatic lobe, presented the best performance for NAFLD screening at the cutoff point ≥ 1 point; sensitivity: 85.1%; specificity: 73.4%; accuracy: 79.3%; and area under the curve (AUC 0.85; 95% confidence interval, CI: 0.78-0.91)]. FLI and HSI presented lower performance (AUC 0.76; 95% CI: 0.69-0.83) than CT.

CONCLUSION

The hepatic ultrasound score based on hepatic attenuation and the anteroposterior diameter of the right hepatic lobe has good reproducibility and accuracy for NAFLD screening.

Quantification of liver iron with MRI: state of the art and remaining challenges

Liver iron overload is the histological hallmark of hereditary hemochromatosis and transfusional hemosiderosis, and can also occur in chronic hepatopathies. Iron overload can result in liver damage, with the eventual development of cirrhosis, liver failure, and hepatocellular carcinoma. Assessment of liver iron levels is necessary for detection and quantitative staging of iron overload and monitoring of iron-reducing treatments. This article discusses the need for noninvasive assessment of liver iron and reviews qualitative and quantitative methods with a particular emphasis on magnetic resonance imaging (MRI). Specific MRI methods for liver iron quantification include signal intensity ratio as well as R2 and R2* relaxometry techniques. Methods that are in clinical use, as well as their limitations, are described. Remaining challenges, unsolved problems, and emerging techniques to provide improved characterization of liver iron deposition are discussed.

Systematic review with meta-analysis: non-invasive assessment of non-alcoholic fatty liver disease--the role of transient elastography and plasma cytokeratin-18 fragments

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) affects 15-40% of the general population. Some patients have non-alcoholic steatohepatitis (NASH) and progressive fibrosis, and would be candidates for monitoring and treatment.

AIM

To review current literature on the use of non-invasive tests to assess the severity of NAFLD.

METHODS

Systematic literature searching identified studies evaluating non-invasive tests of NASH and fibrosis using liver biopsy as the reference standard. Meta-analysis was performed for areas with adequate number of publications.

RESULTS

Serum tests and physical measurements like transient elastography (TE) have high negative predictive value (NPV) in excluding advanced fibrosis in NAFLD patients. The NAFLD fibrosis score comprises of six routine clinical parameters and has been endorsed by current American guidelines as a screening test to exclude low-risk individuals. The pooled sensitivities and specificities for TE to diagnose F ≥ 2, F ≥ 3 and F4 disease were 79% and 75%, 85% and 85%, and 92% and 92% respectively. Liver stiffness measurement often fails in obese patients, but the success rate can be improved with the use of the XL probe. A number of biomarkers have been developed for the diagnosis of NASH, but few were independently validated. Serum/plasma cytokeratin-18 fragments have been most extensively evaluated and have a pooled sensitivity of 66% and specificity of 82% in diagnosing NASH.

CONCLUSIONS

Current non-invasive tests are accurate in excluding advanced fibrosis in NAFLD patients, and may be used for initial assessment. Further development and evaluation of NASH biomarkers are needed.

Statins for non-alcoholic fatty liver disease and non-alcoholic steatohepatitis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are common causes of elevated liver enzymes in the general population. NASH and to some extent NAFLD have been associated with increased liver-related and all-cause mortality. No effective treatment is yet available. Recent reports have shown that the use of hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) in patients with elevated plasma aminotransferases may result in normalisation of these liver enzymes. Whether this is a consistent effect or whether it can lead to improved clinical outcomes beyond normalisation of abnormal liver enzymes is not clear.

OBJECTIVES

To assess the beneficial and harmful effects of statins (that is, lovastatin, atorvastatin, simvastatin, pravastatin, rosuvastatin, and fluvastatin) on all-cause and liver-related mortality, adverse events, and histological, biochemical, and imaging responses in patients with NAFLD or NASH.

SEARCH METHODS

We performed a computerised literature search in the Cochrane Hepato-Biliary Group Controlled Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, and Science Citation Index Expanded up to March 2013. We did fully recursive searches from the reference lists of all retrieved relevant publications to ensure a complete and comprehensive search of the published literature. We did not apply any restrictions regarding language of publication or publication date.

SELECTION CRITERIA

All randomised clinical trials using statins as the primary treatment for NAFLD or NASH versus no treatment, placebo, or other hypolipidaemic agents.

DATA COLLECTION AND ANALYSIS

Data were extracted, and risk of bias of each trial was assessed independently by two or more review authors. Meta-analyses were performed whenever possible. Review Manager 5.2 was used.

MAIN RESULTS

When the described search method was used and the eligibility criteria of the search results were applied, 653 records were found. Only two of these were randomised clinical trials that were considered eligible for inclusion. We assessed both trials as trials with high risk of bias. One of the trials was a pilot trial in which 16 participants with biopsy-proven NASH were randomised to receive simvastatin 40 mg (n = 10) or placebo (n = 6) once daily for 12 months. No statistically significant improvement in the aminotransferase level was seen in the simvastatin group compared with the placebo group. Liver histology was not significantly affected by simvastatin.The other trial had three arms. The trial compared atorvastatin 20 mg daily (n = 63) versus fenofibrate 200 mg daily (n = 62) versus a group treated with a combination of the two interventions (n = 61). There were no statistically significant differences between any of the three intervention groups regarding the week 54 mean activity levels of aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, and alkaline phosphatase. The triglyceride levels seemed higher in the fenofibrate group compared with the atorvastatin group. Liver histology was not assessed in this trial. The presence of biochemical and ultrasonographic evidence of NAFLD seemed to be higher in the fenofibrate group compared with the atorvastatin group (58% versus 33%). Three patients discontinued treatment due to myalgia and elevated serum creatine kinase activity; one from the atorvastatin group and two from the combination group. Another patient from the atorvastatin group discontinued treatment due to alanine aminotransferase activity that was over three times the upper normal limit.No data for all-cause mortality and hepatic-related mortality were reported in the included trials.

AUTHORS' CONCLUSIONS

Based on the findings of this review, which included two trials with high risk of bias and a small numbers of participants, it seems possible that statins may improve serum aminotransferase levels as well as ultrasound findings. Neither of the trials reported on possible histological changes, liver-related morbidity or mortality. Trials with larger sample sizes and low risk of bias are necessary before we may suggest statins as an effective treatment for patients with NASH. However, as statins can improve the adverse outcomes of other conditions commonly associated with NASH (for example, hyperlipidaemia, diabetes mellitus, metabolic syndrome), their use in patients with non-alcoholic steatohepatitis may be justified.

Computed tomography findings for predicting severe acute hepatitis with prolonged cholestasis

AIM: To evaluate the significance of computed tomography (CT) findings in relation to liver chemistry and the clinical course of acute hepatitis.

METHODS: Four hundred and twelve patients with acute hepatitis who underwent enhanced CT scanning were enrolled retrospectively. Imaging findings were analyzed for the following variables: gallbladder wall thickness (GWT), arterial heterogeneity, periportal tracking, number and maximum size of lymph nodes, presence of ascites, and size of spleen. The serum levels of alanine aminotransferase, alkaline phosphatase, bilirubin, albumin, and prothrombin time were measured on the day of admission and CT scan, and laboratory data were evaluated every 2-4 d for all subjects during hospitalization.

RESULTS: The mean age of patients was 34.4 years, and the most common cause of hepatitis was hepatitis A virus (77.4%). The mean GWT was 5.2 mm. The number of patients who had findings of arterial heterogeneity, periportal tracking, lymph node enlargement > 7 mm, and ascites was 294 (80.1%), 348 (84.7%), 346 (84.5%), and 56 (13.6%), respectively. On multivariate logistic regression, male gender [odds ratio (OR) = 2.569, 95%CI: 1.477-4.469, P = 0.001], toxic hepatitis (OR = 3.531, 95%CI: 1.444-8.635, P = 0.006), level of albumin (OR = 2.154, 95%CI: 1.279-3.629, P = 0.004), and GWT (OR = 1.061, 95%CI: 1.015-1.110, P = 0.009) were independent predictive factors for severe hepatitis. The level of bilirubin (OR = 1.628, 95%CI: 1.331-1.991, P < 0.001) and GWT (OR = 1.172, 95%CI: 1.024-1.342, P = 0.021) were independent factors for prolonged cholestasis in multivariate analysis.

CONCLUSION: In patients with acute hepatitis, GWT on CT scan was an independent predictor of severe hepatitis and prolonged cholestasis.

Prevalence of NAFLD in Healthy and Young Male Individuals

Introduction. Nonalcoholic fatty liver disease (NAFLD) is an important cause of liver disease in adults and the most common cause of liver disease in children (Lavine and Schwimmer 2004). The abnormalities include increased liver fat without inflammation (steatosis) and nonalcoholic steatohepatitis (NASH). NASH may lead to fibrosis, cirrhosis, and ultimately liver failure if it is not treated (Matteoni et al. 1999). The objective of the study is to estimate the magnitude of the problem which will help us to formulate strategies in managing the potentially difficult problem. Materials and Methods. We included 1000 individuals between the ages of 30 and 50 years who came for annual checkup. The patients with other comorbidities like diabetes, ischemic heart disease, chronic liver disease, or renal diseases were excluded from the study. History of alcohol ingestion was also taken; any individual with history of alcohol intake was also excluded. All of them underwent investigations including CBC, LFTs, height and weight. The individuals who were found to have increased ALT (50 to 150 u/L) further underwent investigations including ultrasound of abdomen hepatitis b and c serology RA and ANA antibodies. All the individuals who were found to have viral or autoimmune illness were excluded from the study. The individuals having raised ALT levels and ultrasound evidence of fatty liver were taken. Results. 13.5% of the individuals were found to have NAFLD among those selected for the study. Conclusion. Mass campaign regarding physical and dietary measures needs to be undertaken in general masses regarding the gravity and potential prevention of the disease.

Magnetic resonance imaging quantification of liver iron

Iron overload is the histologic hallmark of hereditary hemochromatosis and transfusional hemosiderosis but also may occur in chronic hepatopathies. This article provides an overview of iron deposition and diseases where liver iron overload is clinically relevant. Next, this article reviews why quantitative noninvasive biomarkers of liver iron would be beneficial. Finally, we describe current state-of-the-art methods for quantifying iron with MR imaging and review remaining challenges and unsolved problems.

Diffuse pattern of transient hepatic attenuation differences in viral hepatitis: a sign of acute hepatic injury in patients without cirrhosis

OBJECTIVES

Our objective was to describe the transient hepatic attenuation differences (THADs) on dynamic computed tomography in patients with viral hepatitis who had no evidence of cirrhosis.

METHODS

After excluding patients who had known causative factors for the development of THAD, a retrospective review of dynamic CT scans in 67 patients with viral hepatitis was performed to determine whether THAD was present. The patients were assigned to 3 groups according to the magnitude of alanine aminotransferase (ALT) level alteration (normal to mild, moderate, and marked) or hepatitis type (acute hepatitis, acute exacerbation of chronic hepatitis, and chronic infection), and differences in the presence of various CT features including THAD among these groups were evaluated.

RESULTS

Five THADs observed had a focal pattern, and 18 THADs had a diffuse pattern. All of the diffuse THADs were observed in patients with marked ALT level alteration (ALT level > 400 IU/L) and in patients with a clinical diagnosis of acute hepatitis or acute exacerbation of chronic hepatitis. In addition, there were significant differences of the presence of other CT findings including hepatomegaly, periportal tracking, gallbladder wall thickening, perihepatic lymphadenopathy, and splenomegaly among these groups (each P < 0.05).

CONCLUSIONS

A diffuse THAD of the liver and other CT features indicates acute hepatic injury in patients with viral hepatitis who have no clinical evidence of cirrhosis.

Nonalcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), the most common liver disorder in the Western world, is a clinico-histopathological entity in which excessive triglyceride accumulation in the liver occurs. Non-alcoholic steatohepatitis (NASH) represents the necroinflammatory form, which can lead to advanced liver fibrosis, cirrhosis, and hepatocellular carcinoma. The pathogenesis of NAFLD/NASH is complex but increased visceral adiposity plus insulin resistance with increased free fatty acids release play an initial key role for the onset and perpetuation of liver steatosis. Further events in the liver include oxidative stress and lipid peroxidation, decreased antioxidant defences, early mitochondrial dysfunction, iron accumulation, unbalance of adipose-derived adipokines with a chronic proinflammatory status, and gut-derived microbial adducts. New gene polymorphisms increasing the risk of fatty liver, namely APOC3 and PNPLA3, have been lately identified allowing further insights into the pathogenesis of this condition. In our review pathophysiological, genetic, and essential diagnostic and therapeutic aspects of NAFLD are examined with future trends in this field highlighted.

Imaging-based quantification of hepatic fat: methods and clinical applications

Fatty liver disease comprises a spectrum of conditions (simple hepatic steatosis, steatohepatitis with inflammatory changes, and end-stage liver disease with fibrosis and cirrhosis). Hepatic steatosis is often associated with diabetes and obesity and may be secondary to alcohol and drug use, toxins, viral infections, and metabolic diseases. Detection and quantification of liver fat have many clinical applications, and early recognition is crucial to institute appropriate management and prevent progression. Histopathologic analysis is the reference standard to detect and quantify fat in the liver, but results are vulnerable to sampling error. Moreover, it can cause morbidity and complications and cannot be repeated often enough to monitor treatment response. Imaging can be repeated regularly and allows assessment of the entire liver, thus avoiding sampling error. Selection of appropriate imaging methods demands understanding of their advantages and limitations and the suitable clinical setting. Ultrasonography is effective for detecting moderate or severe fatty infiltration but is limited by lack of interobserver reliability and intraobserver reproducibility. Computed tomography allows quantitative and qualitative evaluation and is generally highly accurate and reliable; however, the results may be confounded by hepatic parenchymal changes due to cirrhosis or depositional diseases. Magnetic resonance (MR) imaging with appropriate sequences (eg, chemical shift techniques) has similarly high sensitivity, and MR spectroscopy provides unique advantages for some applications. However, both are expensive and too complex to be used to monitor steatosis.

Noninvasive assessment of hepatic steatosis

Hepatic steatosis, the accumulation of lipids within hepatocytes, is a common condition. The prevalence of its most frequent manifestation, nonalcoholic fatty liver disease (NAFLD), has been estimated to be as high as 35% in some populations. Currently, liver biopsy is the gold standard for the diagnosis and assessment of severity of hepatic steatosis, staging of fibrosis, and is the only modality able to differentiate bland steatosis from steatohepatitis. However, its invasiveness, significant side effect profile, and susceptibility to sampling error ultimately make it a suboptimal tool. Accordingly, focus has been placed on noninvasive radiologic techniques for hepatic fat detection and quantification. The rationale, performance characteristics, and limitations of traditional noninvasive measures, including ultrasound, computed tomography, and magnetic resonance (MR) spectroscopy and imaging, are reviewed. A novel MR method, the spectrally modeled relaxation-invariant technique, overcomes the inherent weaknesses of conventional MR to diagnose and quantify hepatic steatosis over its entire range of severity. Noninvasive radiologic techniques, particularly MR, can be applied broadly, including in the diagnosis of NAFLD in asymptomatic patients with elevated serum aminotransferase levels, longitudinal monitoring of disease progression or response to treatment, population-based epidemiologic or observational studies, and drug discovery.

Nonalcoholic steatohepatitis and the cardiometabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is now considered to be the most common liver disease in the United States and involves a spectrum of progressive histopathologic changes. Common risk factors associated with NAFLD include obesity, diabetes, and hyperlipidemia. Although most patients with NAFLD have simple hepatic steatosis, a significant number develop nonalcoholic steatohepatitis, which may progress to fibrosis, cirrhosis, or end-stage liver disease. There is increasing evidence that NAFLD is a common feature in patients with the cardiometabolic syndrome, a onstellation of metabolic, cardiovascular, renal, and inflammatory abnormalities in which insulin resistance is thought to play a key role in end-organ pathogenesis. NAFLD is usually diagnosed after abnormal liver chemistry results are found during routine laboratory testing. No therapy has been proven effective for treating NAFLD/nonalcoholic steatohepatitis. Expert opinion emphasizes the importance of exercise, weight loss in obese and overweight individuals, treatment of hyperlipidemia, and glucose control.

Imaging of hepatic infections

Imaging plays a significant role in the detection, characterization and treatment of hepatic infections. Infectious diseases of the liver include pyogenic and amoebic abscesses and parasitic, fungal, viral and granulomatous infections. With increases in worldwide travel, immunosuppression and changing population demographics, identification of cases of hepatic infection is becoming more common in daily practice. Knowledge of the imaging features seen with hepatic infections can assist in early diagnosis and timely initiation of appropriate therapy. This review presents the imaging appearances of hepatic infections, emphasizing specific features that may contribute to the diagnosis. Examples of the imaging findings seen with pyogenic and amoebic abscesses, infection with Echinococcus granulosus (Hydatid), schistosomiasis, candidiasis and tuberculosis (TB) are presented.

Reversible heterogeneous arterial phase liver perfusion associated with transient acute hepatitis: findings on gadolinium-enhanced MRI

PURPOSE

To assess a possible correlation between active acute hepatitis and the development of abnormal liver perfusion demonstrated as heterogeneous enhancement on arterial phase gadolinium-enhanced MRI. Dynamically-enhanced MRI of the liver can detect reversible perfusion abnormalities that correlate with acute hepatitis.

MATERIALS AND METHODS

Six patients presenting with symptoms and clinical findings in keeping with transient acute hepatitis underwent serial MRI of the liver throughout the course of the disease. Serial liver enzyme analysis was performed for all six patients, and histopathology was assessed for three patients. Imaging included gadolinium-enhanced arterial and venous-phase gradient-echo sequences.

RESULTS

Arterial phase gadolinium-enhanced MRI showed abnormal irregular liver perfusion in the setting of acute hepatitis, and the degree of irregularity, as well as the persistence of irregular enhancement into the venous phase, correlated with the clinical severity of the disease.

CONCLUSION

Acute hepatitis can cause irregular enhancement of the liver on arterial-phase, gadolinium-enhanced, gradient-echo MRI, a reversible finding that improves with clinical improvement of the disease.

The infected liver: radiologic-pathologic correlation

Recent technologic advances have significantly enhanced the role of imaging in the detection, characterization, and management of infectious diseases involving the liver. In addition, imaging-guided percutaneous drainage has greatly improved the clinical treatment of patients with focal liver abscess. Infectious liver diseases can be accurately evaluated with ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging. Characteristic changes in US echogenicity, CT attenuation, or MR imaging signal intensity and typical enhancement patterns can contribute to the diagnosis of specific infectious diseases, including abscesses, parasitic diseases, fungal diseases, granulomatous diseases, viral hepatitis, and other less common infections. CT is particularly helpful in revealing the presence of calcifications and gas and in detailing the enhancement pattern. The multiplanar capability of MR imaging and its sensitivity to small differences in tissue composition increase its specificity for certain hepatic infections, including hydatid cyst and candidiasis. Radiologic findings may be sufficient to obviate aspiration or histologic examination, although in most instances they are less specific. Nevertheless, imaging findings taken together with appropriate clinical information may provide the most likely diagnosis, even if biopsy is sometimes required for confirmation.

Dual-echo, chemical shift gradient-echo magnetic resonance imaging to quantify hepatic steatosis: Implications for living liver donation

In living liver donation, a fatty liver poses risks for both recipient and donor. Currently, liver biopsy is the standard for assessing the presence and extent of steatosis. The goals of this study were to correlate a steatosis index derived from magnetic resonance imaging (MRI) to the histologic grade on biopsy as well as to determine the topographic distribution of steatosis within the liver. We examined the ability of dual-echo, chemical shift gradient-echo MRI to predict the degree of steatosis on liver biopsy. A total of 22 subjects received both a liver biopsy and detailed MRI evaluation. These individuals included 15 potential living donors and 7 patients with nonalcoholic fatty liver disease. MRI steatosis index was then compared with histologic grade on liver biopsy. The topographic distribution of hepatic steatosis was determined from those subjects in whom MRI detected hepatic steatosis. The steatosis index had a positive correlation with grade of steatosis on liver biopsy (correlation coefficient, 0.84). There was no significant variation in the degree of steatosis among segments. A steatosis index of >0.2 had good positive and negative predictive value for the presence of significant steatosis (>15%) on biopsy. Our quantitative MRI protocol can predict the degree of hepatic steatosis when it is minimal to moderate, and may obviate the need for liver biopsy for the purpose of quantification of steatosis in living donors. Fat saturation added to the MRI protocol may further improve diagnostic accuracy. This technique may be applicable to the larger population with hepatic steatosis.

The utility of radiological imaging in nonalcoholic fatty liver disease

BACKGROUND & AIMS

This prospective study evaluates the role of radiological modalities in establishing the diagnosis of nonalcoholic steatohepatitis (NASH).

METHODS

Consecutive patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD) were enrolled (2000-2001). Patients with other liver diseases and significant alcohol consumption (>20 g/day) were excluded. Clinicodemographic data were gathered at the time of liver biopsy. Each biopsy specimen was assessed by a hepatopathologist. Each patient underwent a limited abdominal ultrasonography (US), computerized tomography (CT), and magnetic resonance imaging (MRI). Films were interpreted by a radiologist who used a predetermined radiological protocol. Each radiological study was reread by the same radiologist and a second radiologist.

RESULTS

Patients with NASH had greater aspartate aminotransferase levels (P = 0.03), greater ferritin levels (P = 0.05), more hepatocyte ballooning (P < 0.0001), and more fibrosis (P = 0.002). None of the radiological features distinguished between NASH and other types of NAFLD. No radiological modality detected the presence of hepatocyte ballooning, Mallory's hyaline, or fibrosis, which are important features in the diagnosis of NASH. The presence of >33% fat on liver biopsy was optimal for detecting steatosis on radiological imaging.

CONCLUSIONS

Differences between NASH and nonprogressive NAFLD were not apparent with any radiological modality. Of the pathologic features important for establishing the diagnosis of NASH, only the severity of steatosis was reflected in these radiological modalities. Good intraobserver agreement was evident for each modality (US, CT, and MRI) that was superior to interobserver agreement.