CT and MR imaging of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the fifth most common tumor in the world and the incidence is expected to increase in the future due to hepatitis viral infections and increasing cirrhosis incidence. The diagnosis of HCC is no longer based on biopsy especially in cases when curative treatment is possible. The imaging criteria are usually based on the vascular findings of HCC (e.g. early arterial uptake followed by washout in the portovenous and equilibrium phase). However, there are several limitations of the assessment of HCC by using only the vascular criteria. The use of tissue-specific contrast agents, including superparamagnetic iron oxides and hepatobiliary contrast agents, improves lesion detection and characterization. Therefore, an accurate diagnosis of HCC implies, at this moment, a combination of vascular and cellular information. This review focuses on the most important findings provided by the unenhanced and dynamic-enhanced CT and MR images regarding HCC evaluation. We also discuss the various imaging characteristics of HCC at MR imaging after the administration of tissue specific contrast agents

CT/MRI LI-RADS v2017 : review of the guidelines

The Liver Imaging-Reporting and Data System (LI-RADS or LR) is a classification system for reading and reporting imaging studies in patients with high risk for hepatocellular carcinoma (HCC). One of its main goals is to improve communication between specialties, especially radiologists, hepatologists, surgeons, and pathologists. LI-RADS defines imaging features of the lesions and stratifies the risk of HCC into categories. It is the most comprehensive and highly specific system; however, its seeming complexity prevents many radiologists from using it in everyday practice. This article is a detailed review of the latest version of LI-RADS (v. 2017), which should be helpful for radiologists who are not very familiar with the system and its latest update

Characterization of the neuroendocrine pancreatic tumors nature by MDCT enhancement pattern: a radio-pathological correlation

Introduction Pre-operative suspicion of neuroendocrine pancreatic lesions nature arises both from clinical (presence and the type of secreted hormone) and imaging findings. However, imaging suggestion of lesion nature is based quite only on nodular dimension and on the presence of local and distant spreading. Aim of the study was to determine the nature of neuroendocrine pancreatic lesions by analysing lesions enhancement pattern at MDCT and by comparing it with histological findings, including the MVD. Materials and Methods We included 45 patients submitted to surgical resection for pancreatic neuroendocrine tumor. All preoperative CT examinations were performed by a multidetector CT. Post-contrastographic study included 4 phases: early arterial (delay 15-20”), pancreatic (delay 35”), venous (delay 70”) and late phases (delay 180”). Two different patterns of enhancement were defined: pattern A, including lesions showing early enhancement (during early arterial or pancreatic phase) and a rapid wash-out; pattern B, including lesions with wash-in in the early arterial or pancreatic phase with no wash-out nor in the late phase (pattern B1), and lesions showing enhancement only in the venous and/or late phases (pattern B2). Results 66 lesions were detected (30 pattern A, 26 B1 and 10 B2). At pathology 28 lesions were adenomas, 14 borderline and 24 carcinomas: 24/30 lesions showing pattern A were benign, 5 borderline and 1 carcinoma; 23/36 lesions showing pattern B were carcinomas, 9 borderline and 4 adenomas. Among the 26 B1 lesions, 13 were carcinomas, 9 borderline and 4 adenomas, while all 10 B2 lesions were malignant. Pattern A showed PPV of benignancy of 80%, and pattern B NPV of benignancy of 89%. MVD was evaluated in 22 lesions obtaining significant differences among the 3 histological and the 3 enhancement pattern. Significant differences between B1 and B2 malignant lesions existed by considering metastases (only B2 lesions) and fibrosis (all B2 lesions). Conclusion The enhancement pattern at CT is related to MVD and the histological type, thus representing a further criterium for suggesting nature of neuroendocrine lesions. The low MVD of B2 lesions, associated with the presence of fibrosis, may justify the delayed enhancement of these lesions

Detection of liver metastases in cancer patients with geographic fatty infiltration of the liver: the added value of contrast-enhanced sonography

The aim of this study is to assess the role of contrast-enhanced ultrasonography (CEUS) in the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale ultrasonography (US)

Detection and characterization of liver lesions using gadoxetic acid as a tissue-specific contrast agent

The value of cross-sectional liver imaging is evaluated by the accuracy, sensitivity, and specificity of the specific imaging technique. Magnetic resonance imaging (MRI) has become a key technique for the characterization and detection of focal and diffuse liver disease. More recently, gadoxetic acid, the hepatocyte-specific MR contrast agent, was clinically approved and introduced in many countries. Gadoxetic acid may be considered a “molecular imaging” probe because the compound is actively taken into hepatocytes via the ATP-dependent organic anion transport system in the plasma membrane for the hepatic uptake. The transport of gadoxetic acid from the cytoplasm to the bile is mainly determined by the capacity of the transport protein glutathione-S-transferase. Gadoxetic acid enhances hepatocyte-containing lesions and improves detection of lesions devoid of normal hepatocytes, such as metastases. Innovative rapid MR acquisition techniques with near isotropic 3D pulse sequences with fat saturation parallel the technical progress made by multidetector computed tomography combined with an impressive improvement in tumor–liver contrast when used for gadoxetic acid-enhanced MRI. The purpose of this review is to provide an overview of the development, clinical testing, and applications of this novel MR contrast agent

Liver involvement in patients with COVID-19 infection: A comprehensive overview of diagnostic imaging features

During the first wave of the pandemic, coronavirus disease 2019 (COVID-19) infection has been considered mainly as a pulmonary infection. However, different clinical and radiological manifestations were observed over time, including involvement of abdominal organs. Nowadays, the liver is considered one of the main affected abdominal organs. Hepatic involvement may be caused by either a direct damage by the virus or an indirect damage related to COVID-19 induced thrombosis or to the use of different drugs. After clinical assessment, radiology plays a key role in the evaluation of liver involvement. Ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI) may be used to evaluate liver involvement. US is widely available and it is considered the first-line technique to assess liver involvement in COVID-19 infection, in particular liver steatosis and portal-vein thrombosis. CT and MRI are used as second- and third-line techniques, respectively, considering their higher sensitivity and specificity compared to US for assessment of both parenchyma and vascularization. This review aims to the spectrum of COVID-19 liver involvement and the most common imaging features of COVID-19 liver damage

Top 50 highly cited articles on dual energy computed tomography (DECT) in abdominal radiology : a bibliometric analysis

This study aims to identify the 50 most highly cited articles on dual energy computed tomography (DECT) in abdominal radiology. Thomson Reuters Web of Science All Databases was queried without year or language restriction. Only original research articles with a primary focus on abdominal radiology using DECT were selected. Review articles, meta-analyses, and studies without human subjects were excluded. Fifty articles with the highest average yearly citation were identified. These articles were published between 2007 and 2017 in 12 journals, with the most in Radiology (12 articles). Articles had a median of 7 authors, with all first authors but one primarily affiliated to radiology departments. The United States of America produced the most articles (16), followed by Germany (13 articles), and China (7 articles). Most studies used Dual Source DECT technology (35 articles), followed by Rapid Kilovoltage Switching (14 articles), and Sequential Scanning (1 article). The top three scanned organs were the liver (24%), kidney (16%), and urinary tract (15%). The most commonly studied pathology was urinary calculi (28%), renal lesion/tumor (23%), and hepatic lesion/tumor (20%). Our study identifies intellectual milestones in the applications of DECT in abdominal radiology. The diversity of the articles reflects on the characteristics and quality of the most influential publications related to DECT