Imaging of hepatic infections

Benign focal liver lesions: The role of magnetic resonance imaging

Liver lesions are common findings in radiologists' daily routine. They are a complex category of pathology that range from solitary benign lesions to primary liver cancer and liver metastases. Benign focal liver lesions can arise from different liver cell types: Epithelial (hepatocytes and biliary cells) and nonepithelial (mesenchymal cells). Liver magnetic resonance imaging (MRI) is a fundamental radiological method in these patients as it allows with its multiparametric approach optimal non-invasive tissue characterization. Furthermore, advanced liver MRI techniques such as diffusion-weighted imaging and hepatobiliary contrast agents have improved the detection of focal liver lesions and can be highly effective in differentiating pseudotumor from tumors, as well as benign from malignant lesions, and can also be used for differential diagnosis. Although histological examination can be useful in making a definitive diagnosis, MRI is an important modality in the diagnosis of liver lesions with a significant impact on patient care. This aim of this review is to provide a comprehensive overview of benign liver lesions on MRI.

A rare complication of pyogenic hepatic abscess after laparoscopic sleeve gastrectomy-case report and literature review emphasizing the role of imaging

A pyogenic hepatic abscess is an uncommon complication after laparoscopic sleeve gastrectomy (LSG) that can develop secondary to an infected hematoma or a staple line leak due to bacterial seeding. Appropriate screening for and management of a pyogenic hepatic abscess are essential in patients with clinical suspicion for complications after LSG. Early diagnosis is essential as pyogenic hepatic abscess can be fatal if not treated early. Only five cases have been reported in the literature so far. We present a case of pyogenic hepatic abscess that occurred two weeks after LSG in a 46-year-old female without immunosuppressive conditions or early postoperative leak. The abscess was diagnosed by computed tomography (CT) and was successfully treated with antibiotics and CT-guided drainage.

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.

Benign Neoplasms, Mass-Like Infections, and Pseudotumors That Mimic Hepatic Malignancy at MRI

A variety of conditions may mimic hepatic malignancy at MRI. These include benign hepatic tumors and tumor-like entities such as focal nodular hyperplasia-like lesions, hepatocellular adenoma, hepatic infections, inflammatory pseudotumor, vascular entities, and in the cirrhotic liver, confluent fibrosis, and hypertrophic pseudomass. These conditions demonstrate MRI features that overlap with hepatic malignancy, and can be challenging for radiologists to diagnose accurately. In this review we discuss the MRI manifestations of various conditions that mimic hepatic malignancy, and highlight features that may allow distinction from malignancy. Level of Evidence 5 Technical Efficacy Stage 3.

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.

Parasitic Liver Infections: Imaging Findings and Strategies for Timely Diagnosis

There are a number of parasitic infections that can affect the liver and biliary tree. These infections can be primarily related to the liver or can include secondary hepatic involvement. Imaging can narrow down the differential diagnosis in the appropriate clinical setting, and can even clinch the diagnosis with some pathognomonic findings. The various imaging modalities can also identify disease extent, help guide management, and demonstrate response to treatment. This pictorial essay will give an overview of parasitic liver infections, and will discuss the best imaging strategies and the key imaging features to help make a timely accurate diagnosis.

Imaging appearances of hepatic tuberculosis: experience with 12 patients

AIM

To review computed tomography (CT), ultrasound (US), magnetic resonance cholangiopancreatography (MRCP), endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiogram (PTC) appearances and their diagnostic value in hepatic tuberculosis.

MATERIALS AND METHODS

The imaging studies for 12 patients with biopsy-proven hepatic tuberculosis from January 2012 till March 2014 were reviewed retrospectively. These cases were confirmed via ultrasound-guided biopsy.

RESULTS

The patients were aged 24-72 years. Four patients had parenchymal tuberculosis only and eight patients had mixed parenchymal and biliary duct involvement. The parenchymal tuberculosis patients showed poorly enhancing, hypodense nodules on CT with central calcification and adjacent dilated intrahepatic ducts. Most patients had multiple lesions except for two patients with a single lesion. The size of the lesions ranged from 0.5 to 6 cm. Seven patients with biliary duct involvement showed a hilar strictures involving the intrahepatic ducts and common bile duct. Nine of the patients showed hilar stricture with atrophy of the ipsilateral lobe of the liver and compensatory hypertrophy of the contralateral lobe. Hepatolithiasis was seen in five patients. Tuberculous lung involvement was seen in seven patients.

CONCLUSION

The presence of calcified and hypodense nodules with biliary duct dilatation associated with lobar atrophy were the most consistent features of hepatic tuberculosis, especially in the presence of active lung disease.

Multimodality Imaging of Liver Infections: Differential Diagnosis and Potential Pitfalls

Imaging plays an important role in the diagnosis, characterization, and management of infectious liver disease. In clinical practice, the main contributions of imaging are in detecting early disease, excluding other entities with a similar presentation, establishing a definitive diagnosis when classic findings are present, and guiding appropriate antimicrobial, interventional, or surgical treatment. The most common imaging features of bacterial, viral, parasitic, and fungal hepatic infections are described, and key imaging and clinical manifestations are reviewed that may be useful to narrow the differential diagnosis and avoid pitfalls in image interpretation. Ultrasonography (US), computed tomography (CT), and magnetic resonance imaging allow accurate detection of most hepatic infections and, in some circumstances, may provide specific signs to identify the underlying pathogen and exclude other entities with similar imaging features. In bacterial and parasitic infections, specific imaging features may be enough to exclude a neoplasm and, occasionally, to identify the underlying infectious agent. US and CT are important means to guide percutaneous aspiration or drainage when needed. In viral infections, imaging is critical to exclude entities that may manifest with similar clinical and laboratory findings. Disseminated fungal infections require early detection at imaging because they can be fatal if not promptly treated. Familiarity with the epidemiology, pathogenesis, clinical manifestations, imaging features, and treatment of hepatic infections can aid in radiologic diagnosis and guide appropriate patient care. (©)RSNA, 2016.

Evaluation of liver lesions

The differential diagnosis of a liver mass is large and requires understanding of the clinical and imaging features of liver lesions. A detailed history, physical examination, hepatic biochemical tests, and imaging studies are all essential in making the diagnosis. Decisions regarding specific imaging modalities for diagnoses, the use of liver biopsy, therapeutic options, and appropriate follow-up are all determined by the presentation of the lesion and associated patient characteristics.

Optimised radiological diagnosis of hepatic fungal infection during the treatment of leukemia

Hepatic fungal infection is a frequent complication in patients receiving intensive chemotherapy for acute leukaemia. Hepatic lesions may be detected using computerised tomographic (CT) scans, but there is no standardised CT protocol for the diagnosis and follow-up of hepatic fungal infection. We therefore retrospectively analysed the number and the volume of hepatic fungal lesions in 24 CT of 20 consecutive patients treated for acute leukaemia during late-arterial and porto-venous phase. The mean number of lesions per patient was 31 (range: 3-105) in the late-arterial and 26 (3-81) in the porto-venous CT (P = 0.026). The mean total volume of all lesions was 6.45 ml in the late-arterial and 4.07 ml in the porto-venous CT representing a 1.6fold difference between the two CT scans (P = 0.008). The total volume of the lesions negatively correlated to the absolute contrast difference between liver parenchyma and liver vein (Pearson correlation, r = -0.62; P = 0.002). In conclusion, the late-arterial CT provides a superior distinction of hepatic lesions due to a delayed perfusion of the outer rim of the fungal lesions resulting in an extended visibility. The late-arterial CT is superior to the porto-venous CT for initial diagnosis and follow-up of hepatic fungal infection.

Echinococcosis of the liver

Echinococcosis, also known as hydatid disease, is an infection of larval stage animal tapeworm, Echinococcus. The larvae reside in the liver and lungs, producing multiloculated fluid-filled cysts. Imaging findings of Echinococcosis caused by E. granulosus are single, unilocular cyst or multiseptated cysts, showing "wheel-like", "rosette-like" or "honeycomb-like" appearances. There may be "snow-flakes" sign, reflecting free floating protoscoleces (hydatid-sand) within the cyst cavity. Degenerating cysts show wavy or serpentine bands or floating membranes representing detached or ruptured membranes. Degenerated cysts show heterogeneous, solid-looking pseudotumor that may show "ball of wool sign". Dead cysts show calcified cyst wall. Echinococcosis caused by E. multilocularis produces multilocular alveolar cysts with exogeneous proliferation, progressively invading the liver parenchyma and other tissues of the body. Imaging findings are ill-defined infiltrating lesions of the liver parenchyma, consisting of multiple small clustered cystic and solid components. On sonography, lesions are heterogeneous with indistinct margins, showing "hailstorm appearance" or "vesicular or alveolar appearance". CT and MR imaging displays multiple, irregular, ill-defined lesions. Multiple small round cysts with solid components are frequent. Large lesions show "geographical map" appearance. Calcifications are very frequent, appearing as peripheral calcification or punctuate scattered calcific foci. Invasion into the bile ducts, portal vein or hepatic vein may occur. Direct spread of infected tissue may result in cysts in the peritoneal cavity, kidneys, adrenal gland or bones.