Characterization Of Focal Lesions Research Articles

Clinical impact of artificial intelligence-based solutions on imaging of the pancreas and liver.

Artificial intelligence (AI) has experienced substantial progress over the last ten years in many fields of application, including healthcare. In hepatology and pancreatology, major attention to date has been paid to its application to the assisted or even automated interpretation of radiological images, where AI can generate accurate and reproducible imaging diagnosis, reducing the physicians' workload. AI can provide automatic or semi-automatic segmentation and registration of the liver and pancreatic glands and lesions. Furthermore, using radiomics, AI can introduce new quantitative information which is not visible to the human eye to radiological reports. AI has been applied in the detection and characterization of focal lesions and diffuse diseases of the liver and pancreas, such as neoplasms, chronic hepatic disease, or acute or chronic pancreatitis, among others. These solutions have been applied to different imaging techniques commonly used to diagnose liver and pancreatic diseases, such as ultrasound, endoscopic ultrasonography, computerized tomography (CT), magnetic resonance imaging, and positron emission tomography/CT. However, AI is also applied in this context to many other relevant steps involved in a comprehensive clinical scenario to manage a gastroenterological patient. AI can also be applied to choose the most convenient test prescription, to improve image quality or accelerate its acquisition, and to predict patient prognosis and treatment response. In this review, we summarize the current evidence on the application of AI to hepatic and pancreatic radiology, not only in regard to the interpretation of images, but also to all the steps involved in the radiological workflow in a broader sense. Lastly, we discuss the challenges and future directions of the clinical application of AI methods.

Non-focal liver signal abnormalities on hepatobiliary phase of gadoxetate disodium-enhanced MR imaging: a review and differential diagnosis.

Gadoxetate disodium (Gd-EOB-DTPA) is a linear, non-ionic paramagnetic MR contrast agent with combined extracellular and hepatobiliary properties commonly used for several liver indications. Although gadoxetate disodium is commonly used for detection and characterization of focal lesions, a spectrum of diffuse disease processes can affect the hepatobiliary phase of imaging (i.e., when contrast accumulates within the hepatocytes). Non-focal signal abnormalities during the hepatobiliary phase can be seen with multiple disease processes such as deposition disorders, infiltrating tumors, vascular diseases, and post-treatment changes. The purpose of this paper is to review the different processes which result in non-focal signal alteration during the hepatobiliary phase and to describe imaging patterns that may order a differential diagnosis and facilitate patient management.

State-of-the-art cross-sectional liver imaging: beyond lesion detection and characterization.

Cross-sectional imaging with computed tomography or magnetic resonance imaging is routinely used to detect and diagnose liver lesions; however, these examinations can provide additional important information. The improvement of equipment and techniques has allowed outstanding evaluation of the vascular and biliary anatomy, which is practicable in most routine examinations. Anatomical variants may exclude patients from certain therapeutic options and may be the cause of morbidity or mortality after surgery or interventional procedures. Diffuse liver disease, such as steatosis, hemochromatosis, or fibrosis, must be diagnosed and quantified. Usually these conditions are silent until the late stages, and imaging plays an important role in detecting them early. Additionally, a background of diffuse disease may interfere in a focal lesion systematic reasoning. The diagnostic probability of a particular nodule varies according to the background liver disease. Nowadays, most diffuse liver diseases can be easily and accurately quantified by imaging, which has allowed better understanding of these diseases and improved patient management. Finally, cross-sectional imaging can calculate total and partial liver volumes and estimate the future liver remnant after hepatectomy. This information helps to select patients for portal vein embolization and reduces postoperative complications. Use of a specific hepatic contrast agent on magnetic resonance imaging, in addition to improving detection and characterization of focal lesions, provides functional global and segmental information about the liver parenchyma.

Focal lesions in cirrhotic liver: what else beyond hepatocellular carcinoma?

Detection and characterization of focal lesions in the cirrhotic liver may pose a diagnostic dilemma. Several benign and malignant lesions may be found in a cirrhotic liver along with hepatocellular carcinoma (HCC), and may exhibit typical or atypical imaging features. In this pictorial essay, we illustrate computed tomography and magnetic resonance imaging findings of lesions such as simple bile duct cysts, hemangioma, focal nodular hyperplasia-like nodules, peribiliary cysts, intrahepatic cholangiocarcinoma, lymphoma, and metastases, all of which occur in cirrhotic livers with varying prevalences. Pseudolesions, such as perfusion anomalies, focal confluent fibrosis, and segmental hyperplasia, will also be discussed. Imaging characterization of non-HCC lesions in cirrhosis is important in formulating an accurate diagnosis and triaging the patient towards the most appropriate management.

New Liver Imaging Techniques

Over the past decade, major technological advances have occurred in all the imaging modalities that have provided a completely new perspective to hepatic imaging. Dual-energy computed tomography (CT) acquires images at two different photon energies concurrently, and permits material decomposition based on the energy-dependent attenuation profile of specific material. It provides both morphologic and functional information in the same study, and potentially benefits hepatic tumor imaging. Hardware and software improvements in magnetic resonance imaging (MRI) technology have enabled faster MRI scanning and improved image quality. In addition to several newer MRI pulse sequences, the introduction of a new hepatocyte-specific contrast agent, gadoxetate disodium, offers additional benefits for improved detection and characterization of focal lesions, and allows functional hepatic and biliary imaging. In this article, we discuss the recent advances in CT and MRI technology and their applications for improving hepatic imaging.

Role of Shear-Wave Elastography (SWE) in detection and characterization of focal lesions of the prostate

Role of Shear-Wave Elastography (SWE) in detection and characterization of focal lesions of the prostate

Standards of the Polish Ultrasound Society - update. Sonomammography examination.

Epidemiologic data suggest that the incidence of breast cancer is on the rise, as is the incidence of early-onset breast cancer in premenopausal women. Breast cancer is the most common malignancy worldwide. According to data of the International Agency for Research on Cancer (IARC), over one million women are newly diagnosed with breast cancer each year, and the annual mortality rate is 410,000. In view of this situation, ultrasound is gaining an increasing role as a breast imaging modality. It is the most widely used complementary imaging modality supplementing mammography in the workup of unclear breast lesions in young women, in women with a family history of breast cancer, and in women with dense breasts. Therefore, ultrasonography should have high sensitivity and specificity in characterizing focal breast lesions. An important prerequisite is a standardized examination procedure and documentation of findings. The Polish Ultrasound Society adopted the BIRADS classification in 2010. As described in the article of W. Jakubowski, K. Dobruch-Sobczak and B. Migda in the “Journal of Ultrasonography”(1), the sonographic characterization of focal breast lesions relies on morphologic evaluation. Besides a focus on how to differentiate between malignant and benign lesions, the authors provide a comprehensive overview of the use of elastography in conjunction with inspection, palpation, B-mode ultrasound, and histology. Evaluation of tissue compressibility is part of standard breast ultrasound in the characterization of focal lesions. A tumor that cannot be compressed in the B-mode examination is more likely to be malignant. Many international studies have shown the new technique of elastography to improve the specificity of ultrasound in characterizing breast lesions. The 2003 version of the BIRADS classification of the American College of Radiology (ACR) does not yet include elastography among breast imaging modalities. The Polish authors highlight the classification of breast lesions according to BIRADS categories 1 to 6 including histology and clinical consequences. In contrast to other European countries, the Polish policy is to perform annual ultrasound examinations already in women after age 30. The authors not only present the technical prerequisites and required skills but also provide an excellent overview of interpretation algorithms according to the BIRADS classification. This can ultimately improve the comparability of publications and the quality of documentation of sonographic findings on an international scale. In summary, the authors provide a detailed and comprehensive overview on the interpretation of breast ultrasound findings in Poland. The classification allows estimating the probability of malignancy of a focal breast lesion. The sonographic findings should be interpreted in conjunction with the patient's history, palpation and clinical findings, and other imaging findings such as mammography and MRI. Elastography is a novel technique; however, many studies have proven its benefit, and it should be included in the ACR BIRADS lexicon. Taken together, the results of major international publications(2, 3) indicate that the use of elastography can be recommended in women with suspicious B-mode findings (subjective classification) and in high-risk women (SR calculation). The elastography findings should be classified according to the BIRADS lexicon.

Role of Shear Wave Elastography (SWE) in Detection and Characterization of Focal Lesions of the Prostate

Role of Shear Wave Elastography (SWE) in Detection and Characterization of Focal Lesions of the Prostate

Targeted Contrast-Enhanced Ultrasound: An Emerging Technology in Abdominal and Pelvic Imaging

In vivo molecular imaging provides the ability to measure expression levels of molecules by quantifying imaging signals generated with the help of contrast agents accumulating at sites of molecular target expression. These contrast agents can be directed to bind various molecular targets in vivo (eg, proteins, DNA, etc), thereby quantifying disease processes at the molecular level in various disease processes. Thus, molecular imaging has the potential to obtain tissue expression profiles in a volumetric manner without invasive tissue sampling procedures and without the limitation of potential sampling errors from biopsies. Emerging research in ultrasound technology and contrast agent design for ultrasound imaging has paved the way for targeted contrast-enhanced ultrasound imaging to be translated to clinical applications in the near future.1–6 Ultrasound imaging is a widely available, inexpensive, and real-time imaging modality that does not expose patients to irradiation. It is already the first-line imaging modality for assessment of many diseases in the abdomen and pelvis. Through the introduction of ultrasound contrast agents (eg, lipid-shelled, gas-filled, 1- to 4-micron-sized microbubbles), the sensitivity and specificity of ultrasound for detection and characterization of for example focal liver lesions7,8 has been substantially improved. Recently, targeted contrast-enhanced ultrasound (molecular ultrasound) imaging has gained great momentum in preclinical research by the introduction of ultrasound contrast microbubbles that are targeted at molecular markers overexpressed on the vasculature of certain diseases (Figure 1A and Supplementary Figure 1). By combining the advantages of ultrasound with the ability to image molecular signatures of diseases, molecular ultrasound has great potential as a highly sensitive and quantitative method that could be used for various clinical applications, including screening for early stage diseases (such as cancer); further characterization of focal lesions and quantitative monitoring of disease processes at the molecular level; assisting in image-guided procedures (eg, biopsy, surgery, or ablation); enhancing drug delivery; and confirming target expression for treatment planning and monitoring (including novel drug candidates in preclinical studies).1,4,6,9,10 Figure 1 Principles of nontargeted and molecularly targeted contrast-enhanced ultrasound imaging with contrast microbubbles. (A) The gas core of lipid- or protein-shelled microbubbles (left) makes them highly echogenic compared to surrounding tissue and blood. ... We describe herein concepts and applications in contrast-enhanced and molecular ultrasound imaging with particular focus on imaging cancer and inflammatory diseases in the abdomen and pelvis.

Characterization of cirrhotic nodules with gadoxetic acid‐enhanced magnetic resonance imaging: The efficacy of hepatocyte‐phase imaging

To evaluate the efficacy of hepatocyte-phase imaging (HP) in characterization of focal hepatic lesions in cirrhotic liver using gadoxetic acid-enhanced magnetic resonance imaging (MRI). A total of 66 nodules of 38 patients with liver cirrhosis undergoing gadoxetic acid-enhanced MRI were prospectively enrolled in this study. The histological examination revealed 15 dysplastic nodules (DNs), 7 well-differentiated hepatocellular carcinomas (wHCCs), and 44 moderately differentiated HCCs (mHCCs). Two imaging sets (Set A without HP, Set B with HP) were prepared to evaluate the efficacy of HP in lesion characterization. The mean enhancement ratios (ERs) of mHCC were significantly increased in arterial phase followed by a subsequent decreased in hepatocyte phases. The mean ERs of wHCC were increased in dynamic study and followed by a plateau in the hepatocyte phase. The mean ERs of DNs were increased in dynamic study and hepatocyte phase. The mean liver-to-lesion contrasts of mHCCs were increased in arterial phase and HP (P < 0.05). wHCCs were only increased in HP (P < 0.05). DNs showed no significant difference in any phase (P > 0.05). There were seven additional HCCs that were detected in HP using imaging Set B compared to Set A. The diagnostic performance of Set B was significantly higher than that of Set A (P = 0.016). The combination of gadoxetic acid-enhanced dynamic study and hepatocyte-phase T1WI may provide better diagnostic performance than only dynamic study in characterization of focal lesions in cirrhotic liver.

Imagerie de diffusion hépatique

Diffusion-weighted imaging studies the motion of water molecules within a given tissue. Initially used for neuroradiological applications, it is now routinely used for abdominal imaging, especially liver imaging. The diffusion pulse sequence is a T2 echo-planar sequence where diffusion gradients are applied. In this article, we will review the sequence itself and the parameters used to optimize the sequence, quantitative and qualitative image evaluation, and the main applications for liver imaging: characterization of focal lesions, detection of focal lesions, evaluation of response to therapy and quantification of liver fibrosis.

Double-contrast MRI (DC-MRI) in the study of the cirrhotic liver: utility of administering Gd-DTPA as a complement to examinations in which SPIO liver uptake and distribution alterations (SPIO-LUDA) are present and in the identification and characterisation of focal lesions

The aim of this study was to compare the performance of double-contrast magnetic resonance imaging (DC-MRI) with the sequential use of superparamagnetic iron oxide (SPIO) and gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) contrast agents compared with unenhanced MRI and SPIO-enhanced MRI (SPIO-MRI) in the study of the cirrhotic liver. Special attention was paid to cases in which alterations of liver uptake and distribution of the SPIO contrast medium [SPIO-liver uptake and distribution alterations (SPIO-LUDA)] could lead to diagnostic errors at SPIO-MRI. We used DC-MRI to study 67 patients suffering from hepatic cirrhosis and on a waiting list for liver transplant. The study was performed with a 1.5-Tesla device and characterised by three phases: the first phase without contrast material (unenhanced MRI), the second after the administration of ferumoxides (SPIO-MRI), and the third, a double-contrast study following the injection of a bolus of paramagnetic contrast material (DC-MRI). The sensitivity of unenhanced MRI, SPIO-MRI and DC-MRI in identifying and characterising hepatic focal lesions was assessed, together with the diagnostic increment of one technique with respect to the others. The gold standard was histological confirmation in 38 cases and clinical-radiological follow-up in all cases. Liver function, kidney function, blood tests and urinalysis were performed in all patients 24-48 h before and after the MRI examination. In 14/67 cases (20.8%), SPIO-LUDA were present, which posed a limitation to the SPIO-MRI examination. Focal lesions were absent in 44 patients, and the action of the ferumoxides was reduced by the presence of SPIO-LUDA in nine cases. There were five cases of confluent fibrosis, two of decompensated cirrhosis, one of vascular thrombosis, and one of scarring in a patient who had undergone hepatic resection for hepatocellular carcinoma (HCC). In all these cases, completion of the MR examination with the DC technique clarified the MR picture, confirming the absence of focal lesions. Twenty-three patients had a total of 68 lesions, which consisted of 37 dysplastic nodules (DN), 19 HCC nodules, two relapses of HCC following chemoembolisation, two HCC associated with portal thrombosis, one cancer-cirrhosis, two angiomas and five small cysts. SPIO-LUDA were present in five patients, thus limiting the identification, characterisation or assessment of the real size of the lesions. SPIO-LUDA were the result of vascular thrombosis in one case and fibrosis in four cases. In all of these cases, DC-MRI proved useful for diagnosis. The sensitivity of unenhanced MRI, SPIO-MRI and DC-MRI for lesion detection was 57.3%, 67.6% and 75%, respectively. The results obtained in the characterisation of the lesions were 20.5%, 63.2% and 73.5% for unenhanced MRI, SPIO-MRI and DC-MRI, respectively. The diagnostic increment of SPIO-MRI over unenhanced MRI for lesion identification and characterisation was 9% and 42.7%, respectively, whereas the diagnostic increment of DC-MRI over SPIO-MRI was 7.4% and 10.3%, respectively. In our study, the combined use of two contrast agents, negative and positive, provided greater diagnostic confidence and caused no side effects in the patients.

Hepatocellular Carcinoma in the Cirrhotic Liver with Helical CT and MRI: Imaging Spectrum and Pitfalls of Cirrhosis-Related Nodules

This article reviews the imaging spectrum of cirrhosis-related nodules on CT and MRI and differentiates between hepatocellular carcinoma (HCC) and common focal lesions that can simulate HCC in the cirrhotic liver. Knowledge of cirrhotic nodules and focal lesions and how they mimic HCC will improve the diagnosis and characterization of focal lesions in cirrhotic liver on CT and MRI.

Does T2-weighted MR Imaging Really Add No Value in Detection and Characterization of Focal Lesions in Cirrhotic Liver?

Does T2-weighted MR Imaging Really Add No Value in Detection and Characterization of Focal Lesions in Cirrhotic Liver?

T2-weighted MR imaging in the assessment of cirrhotic liver.

To assess if T2-weighted magnetic resonance (MR) imaging provides added diagnostic value in combination with dynamic gadolinium-enhanced MR imaging in the detection and characterization of nodular lesions in cirrhotic liver. Two readers retrospectively and independently analyzed 54 MR imaging studies in 52 patients with cirrhosis. In session 1, readers reviewed T1-weighted and dynamic gadolinium-enhanced images. In session 2, readers reviewed T1-weighted, dynamic gadolinium-enhanced, and respiratory-triggered T2-weighted fast spin-echo images. Readers identified and characterized all focal lesions by using a scale of 1-4 (1, definitely benign; 4, definitely malignant). Multireader correlated receiver operating characteristic (ROC) analysis was employed to assess radiologist performance in session 2 compared with session 1. The difference in the areas under the ROC curves for the two sessions was tested. In a third session, readers assessed conspicuity of biopsy-proved lesions on T2-weighted MR images by using a scale of 1-3 (1, not seen; 3, well seen) and identified causes of reduced conspicuity. Two additional benign lesions were detected by each reader in session 2. Fifty-five lesions had pathologic verification, including 32 malignant, three high-grade dysplastic, and 20 benign nodules. There was no significant difference in the area under the ROC curves between the two sessions (P =.48). Thirty-two lesions were inconspicuous on T2-weighted MR images because of parenchymal heterogeneity, breathing artifacts (particularly in patients with ascites), and lesion isointensity with liver parenchyma. T2-weighted MR imaging was useful in the evaluation of cysts and lymph nodes. T2-weighted MR imaging does not provide added diagnostic value in the detection and characterization of focal lesions in cirrhotic liver.

Liver imaging with multidetector helical computed tomography.

The speed and flexibility of multidetector computed tomography (MDCT) have led to improvements in liver imaging, particularly related to the detection and characterization of focal lesions. This report discusses the different phase of liver enhancement following the bolus administration of iodinated contrast material, and the enhancement pattern of various liver lesions during these phases. We also propose guidelines for designing protocols for MDCT of the liver and discuss the principles of contrast media delivery.

Focal Lesions in the Cirrhotic Liver: High Resolution Ex Vivo MRI with Pathologic Correlation

Cirrhosis is a progressive, diffuse process of liver fibrosis that is characterized by architectural distortion and the development of a spectrum of nodules ranging from benign regenerative nodules to premalignant dysplastic nodules to overtly malignant hepatocellular carcinoma. The purpose of this essay is to demonstrate the ex vivo MR and pathology findings of these nodules as well as other masses that can be seen in the cirrhotic liver. The optimal conditions under which ex vivo imaging can be performed allow greater spatial resolution than that achieved with in vivo imaging, without artifacts that may degrade image quality. Clearly, contrast-enhanced MRI is essential for both the diagnosis and the characterization of focal lesions in the cirrhotic liver. However, the use of ex vivo imaging precludes the evaluation of these important in vivo pulse sequences.

Benign liver lesions: differentiation by magnetic resonance

Optimal hepatic imaging involves both detection and characterization of focal lesions. Detection involves both determination of the presence of lesions and of their segmental extent of liver involvement. In the evaluation of hypervascular lesions, magnetic resonance imaging (MRI) has a greater impact on patient management than ultrasound (US) and computed tomography (CT). Most benign tumors are incidental findings and do not produce clinical symptoms. They must be accurately diagnosed without using aggressive procedures. Knowledge of their imaging features is essential to avoid unnecessary work-up and to minimize patient anxiety. In this article, the MR appearance, vascular and functional behavior of the most common benign liver tumors will be discussed.