Showing papers in "Abdominal Radiology in 2018"
TL;DR: This work discusses general trends pertaining to geographic region, age, gender, ethnicity, impact of surveillance on survival, mortality, and future trends.
Abstract: Hepatocellular carcinoma (HCC) is the sixth most common cancer and the second leading cause of cancer mortality worldwide. Incidence rates of liver cancer vary widely between geographic regions and are highest in Eastern Asia and sub-Saharan Africa. In the United States, the incidence of HCC has increased since the 1980s. HCC detection at an early stage through surveillance and curative therapy has considerably improved the 5-year survival. Therefore, medical societies advocate systematic screening and surveillance of target populations at particularly high risk for developing HCC to facilitate early-stage detection. Risk factors for HCC include cirrhosis, chronic infection with hepatitis B virus (HBV), hepatitis C virus (HCV), excess alcohol consumption, non-alcoholic fatty liver disease, family history of HCC, obesity, type 2 diabetes mellitus, and smoking. Medical societies utilize risk estimates to define target patient populations in which imaging surveillance is recommended (risk above threshold) or in which the benefits of surveillance are uncertain (risk unknown or below threshold). All medical societies currently recommend screening and surveillance in patients with cirrhosis and subsets of patients with chronic HBV; some societies also include patients with stage 3 fibrosis due to HCV as well as additional groups. Thus, target population definitions vary between regions, reflecting cultural, demographic, economic, healthcare priority, and biological differences. The Liver Imaging Reporting and Data System (LI-RADS) defines different patient populations for surveillance and for diagnosis and staging. We also discuss general trends pertaining to geographic region, age, gender, ethnicity, impact of surveillance on survival, mortality, and future trends.
321 citations
TL;DR: Leading machine learning approaches and research directions in US are reviewed, with an emphasis on recent ML advances, and an outlook on future opportunities for ML techniques to further improve clinical workflow and US-based disease diagnosis and characterization is presented.
Abstract: Ultrasound (US) imaging is the most commonly performed cross-sectional diagnostic imaging modality in the practice of medicine. It is low-cost, non-ionizing, portable, and capable of real-time image acquisition and display. US is a rapidly evolving technology with significant challenges and opportunities. Challenges include high inter- and intra-operator variability and limited image quality control. Tremendous opportunities have arisen in the last decade as a result of exponential growth in available computational power coupled with progressive miniaturization of US devices. As US devices become smaller, enhanced computational capability can contribute significantly to decreasing variability through advanced image processing. In this paper, we review leading machine learning (ML) approaches and research directions in US, with an emphasis on recent ML advances. We also present our outlook on future opportunities for ML techniques to further improve clinical workflow and US-based disease diagnosis and characterization.
147 citations
TL;DR: The physical principles of ultrasoundElastography are discussed, differences between different ultrasound elastographic techniques are discusses, and the advantages and disadvantages of these techniques in clinical practice are reviewed.
Abstract: Tissue stiffness has long been known to be a biomarker of tissue pathology. Ultrasound elastography measures tissue mechanical properties by monitoring the response of tissue to acoustic energy. Different elastographic techniques have been applied to many different tissues and diseases. Depending on the pathology, patient-based factors, and ultrasound operator-based factors, these techniques vary in accuracy and reliability. In this review, we discuss the physical principles of ultrasound elastography, discuss differences between different ultrasound elastographic techniques, and review the advantages and disadvantages of these techniques in clinical practice.
147 citations
TL;DR: Key differences between CT/MRI and CEUS are described, and a diagnostic algorithm of CEUS LI-RADS is provided with detailed, step-by-step instructions and imaging examples of CE US LI- RADS categories.
Abstract: Contrast-enhanced ultrasound (CEUS) is a specialized form of ultrasound (US) performed with an intravenous injection of microbubble contrast agents. It has been successfully used for a variety of applications including characterization of liver tumors. In April 2014, the American College of Radiology (ACR) convened a working group of international experts to develop ACR CEUS Liver Imaging Reporting and Data System (CEUS LI-RADS). An initial version of CEUS LI-RADS was published in August 2016. Although the CEUS LI-RADS concept and principles for liver lesion characterization, using dynamic contrast enhancement features, are similar to those for CT or MRI, there are significant differences between CT/MRI and CEUS LI-RADS. Therefore, CEUS LI-RADS has different diagnostic features and a unique characterization algorithm. The size of a lesion, the type and degree of arterial phase enhancement, the presence of washout, and the timing and degree of washout are the major features used for categorization. This paper describes key differences between CT/MRI and CEUS, and provides a diagnostic algorithm of CEUS LI-RADS with detailed, step-by-step instructions and imaging examples of CEUS LI-RADS categories.
138 citations
TL;DR: Microbubble ultrasound contrast agents (UCAs) were recently approved by the Food and Drug Administration for non-cardiac imaging as discussed by the authors, and they are used in echocardiography in the U.S. and in the rest of the world.
Abstract: Microbubble ultrasound contrast agents (UCAs) were recently approved by the Food and Drug administration for non-cardiac imaging. The physical principles of UCAs, methods of administration, dosage, adverse effects, and imaging techniques both current and future are described. UCAs consist of microbubbles in suspension which strongly interact with the ultrasound beam and are readily detectable by ultrasound imaging systems. They are confined to the blood pool when administered intravenously, unlike iodinated and gadolinium contrast agents. UCAs have a proven safety record based on over two decades of use, during which they have been used in echocardiography in the U.S. and for non-cardiac imaging in the rest of the world. Adverse effects are less common with UCAs than CT/MR contrast agents. Compared to CT and MR, contrast-enhanced ultrasound has the advantages of real-time imaging, portability, and reduced susceptibility to metal and motion artifact. UCAs are not nephrotoxic and can be used in renal failure. High acoustic amplitudes can cause microbubbles to fragment in a manner that can result in short-term increases in capillary permeability or capillary rupture. These bioeffects can be beneficial and have been used to enhance drug delivery under appropriate conditions. Imaging with a mechanical index of < 0.4 preserves the microbubbles and is not typically associated with substantial bioeffects. Molecularly targeted ultrasound contrast agents are created by conjugating the microbubble shell with a peptide, antibody, or other ligand designed to target an endothelial biomarker associated with tumor angiogenesis or inflammation. These microbubbles then accumulate in the microvasculature at target sites where they can be imaged. Ultrasound contrast agents are a valuable addition to the diagnostic imaging toolkit. They will facilitate cross-sectional abdominal imaging in situations where contrast-enhanced CT and MR are contraindicated or impractical.
137 citations
Memorial Sloan Kettering Cancer Center1, Tata Memorial Hospital2, Netherlands Cancer Institute3, Baylor University Medical Center4, University of Toronto5, University of Western Ontario6, University of Texas MD Anderson Cancer Center7, University of Wisconsin-Madison8, Oregon Health & Science University9, University of California, Irvine10, Wake Forest University11, University of Ottawa12, Emory University13, Mayo Clinic14, Harvard University15
TL;DR: Recommendations regarding patient preparation, technical performance, pulse sequence acquisition, and criteria for MRI assessment at initial staging and restaging exams and for MRI reporting were constructed and can be used as guidelines for primary and post-treatment staging of rectal cancer using MRI.
Abstract: To propose guidelines based on an expert-panel-derived unified approach to the technical performance, interpretation, and reporting of MRI for baseline and post-treatment staging of rectal carcinoma. A consensus-based questionnaire adopted with permission and modified from the European Society of Gastrointestinal and Abdominal Radiologists was sent to a 17-member expert panel from the Rectal Cancer Disease-Focused Panel of the Society of Abdominal Radiology containing 268 question parts. Consensus on an answer was defined as ≥ 70% agreement. Answers not reaching consensus (< 70%) were noted. Consensus was reached for 87% of items from which recommendations regarding patient preparation, technical performance, pulse sequence acquisition, and criteria for MRI assessment at initial staging and restaging exams and for MRI reporting were constructed. These expert consensus recommendations can be used as guidelines for primary and post-treatment staging of rectal cancer using MRI.
93 citations
TL;DR: The background of chronic liver disease, the types of ultrasound elastography, how to perform an examination, and how to interpret the results are discussed, suggesting that p-SWE is as accurate as but more reliable than TE, while 2D-S THE AUTHORS is more accurate than TE.
Abstract: Chronic liver disease is a substantial world-wide problem. Its major consequence is increasing deposition of fibrous tissue within the liver leading to the development of cirrhosis with its consequences of portal hypertension, hepatic insufficiency, and hepatocellular carcinoma. The stage of liver fibrosis is important to determine prognosis, surveillance, prioritize for treatment, and potential for reversibility. The process of fibrosis is dynamic and regression of fibrosis is possible with treatment of the underlying conditions. Previously, the only method of staging the degree of fibrosis was liver biopsy. The recent development of ultrasound elastography techniques allows a non-invasive method of estimating the degree of liver fibrosis. Transient elastography (TE) is a non-imaging elastographic technique, while point shear wave (p-SWE) and 2D-SWE combine imaging with elastography. The evidence at this time suggests that p-SWE is as accurate as but more reliable than TE, while 2D-SWE is more accurate than TE. This review discusses the background of chronic liver disease, the types of ultrasound elastography, how to perform an examination, and how to interpret the results.
88 citations
TL;DR: Primary indications for intervention in patients with AAA include development of symptoms, rupture, rapid aneurysm growth, or presence of a fusiform aneurYSm with maximum diameter of 5.5 cm or greater.
Abstract: Abdominal aortic aneurysm (AAA) is most commonly defined as a maximal diameter of the abdominal aorta in excess of 3 cm in either anterior-posterior or transverse planes or, alternatively, as a focal dilation ≥ 1.5 times the diameter of the normal adjacent arterial segment. Risk factors for the development of AAA include age > 60, tobacco use, male gender, Caucasian race, and family history of AAA. Aneurysm growth and rupture risk appear to be associated with persistent tobacco use, female gender, and chronic pulmonary disease. The majority of AAAs are asymptomatic and detected incidentally on various imaging studies, including abdominal ultrasound, and computed tomographic angiography. Symptoms associated with AAA may include abdominal or back pain, thromboembolization, atheroembolization, aortic rupture, or development of an arteriovenous or aortoenteric fistula. The Screening Abdominal Aortic Aneurysms Efficiently (SAAAVE) Act provides coverage for a one-time screening abdominal ultrasound at age 65 for men who have smoked at least 100 cigarettes and women who have family history of AAA disease. Medical management is recommended for asymptomatic patients with AAAs 5 mm/6 months), or presence of a fusiform aneurysm with maximum diameter of 5.5 cm or greater. Intervention for AAA includes conventional open surgical repair and endovascular aortic stent graft repair.
83 citations
TL;DR: Technical recommendations for successful liver CEUS lesion characterization are described, and imaging protocol and Lexicon of imaging findings are provided.
Abstract: Contrast-enhanced ultrasound (CEUS) is a specific form of ultrasound imaging performed with intravenous administration of microbubble contrast agents. It has been extensively used for liver tumor characterization and was recently added to the American College of Radiology Liver Imaging Reporting and Data System (CEUS LI-RADS). This paper describes technical recommendations for successful liver CEUS lesion characterization, and provides imaging protocol and Lexicon of imaging findings.
81 citations
TL;DR: A new treatment response algorithm is included in the 2017 update of LI-RADS to assist radiologists in image interpretation of HCC after locoregional therapy.
Abstract: Radiologists play a central role in the assessment of patient response to locoregional therapies for hepatocellular carcinoma (HCC). The identification of viable tumor following treatment guides further management and potentially affects transplantation eligibility. Liver Imaging Reporting and Data Systems (LI-RADS) first introduced the concept of LR-treated in 2014, and a new treatment response algorithm is included in the 2017 update to assist radiologists in image interpretation of HCC after locoregional therapy. In addition to offering imaging criteria for viable and nonviable HCC, new concepts of nonevaluable tumors as well as tumors with equivocal viability are introduced. Existing guidelines provided by response evaluation criteria in solid tumors (RECIST) and modified RECIST address patient-level assessments and are routinely used in clinical trials but do not address the variable appearances following different locoregional therapies. The new LI-RADS treatment response algorithm addresses this gap and offers a comprehensive approach to assess treatment response for individual lesions after a variety of locoregional therapies, using either contrast-enhanced CT or MRI.
77 citations
TL;DR: The purpose of this paper is to provide a brief background on LR-M, discuss the diagnostic criteria new to v2017, special considerations for its application, and management implications.
Abstract: LI-RADS v2017 introduces major changes to the diagnostic criteria for LR-M observations to better guide radiologists in the use of this malignant category designation LR-M is intended to preserve the specificity of the LI-RADS algorithm for diagnosis of HCC while not losing sensitivity for diagnosis of malignancy The purpose of this paper is to provide a brief background on LR-M, discuss the diagnostic criteria new to v2017, special considerations for its application, and management implications
TL;DR: The American College of Radiology (ACR) has developed the Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) algorithm, which has two components: detection scores and visualization scores.
Abstract: Ultrasound is the most widely used imaging tool for hepatocellular carcinoma (HCC) screening and surveillance. Until now, this method has lacked standardized guidelines for interpretation, reporting, and management recommendations [1–5]. To address this need, the American College of Radiology (ACR) has developed the Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) algorithm. The proposed algorithm has two components: detection scores and visualization scores. The detection score guides management and has three categories: US-1 Negative, US-2 Subthreshold, and US-3 Positive. The visualization score informs the expected sensitivity of the ultrasound examination and also has three categories: Visualization A: No or minimal limitations; Visualization B: Moderate limitations; and Visualization C: Severe limitations. Standardization in ultrasound utilization, reporting, and management in high-risk individuals has the capacity to improve communication with patients and referring physicians, unify screening and surveillance algorithms, impact outcomes, and supply quantitative data for future research.
TL;DR: Ancillary features included in LI-RADS v2017 are discussed, the rationale for their use, potential pitfalls encountered in their interpretation, and tips on their application.
Abstract: The Liver Imaging Reporting and Data System (LI-RADS) uses an algorithm to assign categories that reflect the probability of hepatocellular carcinoma (HCC), non-HCC malignancy, or benignity. Unlike other imaging algorithms, LI-RADS utilizes ancillary features (AFs) to refine the final category. AFs in LI-RADS v2017 are divided into those favoring malignancy in general, those favoring HCC specifically, and those favoring benignity. Additionally, LI-RADS v2017 provides new rules regarding application of AFs. The purpose of this review is to discuss ancillary features included in LI-RADS v2017, the rationale for their use, potential pitfalls encountered in their interpretation, and tips on their application.
TL;DR: In patients with lesions indeterminate on CT and MRI, CEUS is a helpful problem-solving complementary tool that improves patient management and variations of CEUS such as DCE-US and ultrasound molecular imaging are emerging for quantitative monitoring of treatment effects and possible earlier detection of cancer.
Abstract: Contrast-enhanced ultrasound (CEUS) is a safe, relatively inexpensive, and widely available imaging technique using dedicated imaging ultrasound sequences and FDA-approved contrast microbubbles that allow detection and characterization of malignant focal liver lesions with high diagnostic accuracy. CEUS provides dynamic real-time imaging with high spatial and temporal capability, allowing for unique contributions to the already established protocols for diagnosing focal liver lesions using CT and MR imaging. In patients with lesions indeterminate on CT and MRI, CEUS is a helpful problem-solving complementary tool that improves patient management. Furthermore, CEUS assists guidance of liver biopsies and local treatment. Variations of CEUS such as DCE-US and ultrasound molecular imaging are emerging for quantitative monitoring of treatment effects and possible earlier detection of cancer. In this review, basic principles of CEUS techniques and ultrasound contrast agents along with a description of the enhancement patterns of malignant liver lesions are summarized. Also, a discussion of the role of CEUS for treatment guidance and monitoring, intraoperative CEUS, and an outlook on emerging applications is provided.
University of Texas MD Anderson Cancer Center1, University of Toronto2, Yeshiva University3, University of Michigan4, University of Pittsburgh5, Naval Medical Center San Diego6, University of California, San Diego7, Université de Montréal8, Duke University9, Columbia University10, Stanford University11, University of Arkansas for Medical Sciences12, Mount Sinai Hospital13, Vanderbilt University14, University of California, Davis15, University of Kansas16, University of Western Ontario17, Rutgers University18, Georgetown University19, University of Ottawa20, Oregon Health & Science University21, New York University22, University of Kentucky23, Thomas Jefferson University24, University of São Paulo25, Memorial Sloan Kettering Cancer Center26, University of Texas Health Science Center at Houston27
TL;DR: An overview of the key changes including the removal of the requirement for visibility on antecedent surveillance ultrasound for LI-RADS 5 (LR-5) categorization, and adoption of the Organ Procurement and Transplantation Network definition of threshold growth are provided.
Abstract: The Liver Imaging and Reporting Data System (LI-RADS) is a comprehensive system for standardizing the terminology, technique, interpretation, reporting, and data collection of liver imaging with the overarching goal of improving communication, clinical care, education, and research relating to patients at risk for or diagnosed with hepatocellular carcinoma (HCC) In 2018, the American Association for the Study of Liver Diseases (AASLD) integrated LI-RADS into its clinical practice guidance for the imaging-based diagnosis of HCC The harmonization between the AASLD and LI-RADS diagnostic imaging criteria required minor modifications to the recently released LI-RADS v2017 guidelines, necessitating a LI-RADS v2018 update This article provides an overview of the key changes included in LI-RADS v2018 as well as a look at the LI-RADS v2018 diagnostic algorithm and criteria, technical recommendations, and management suggestions Substantive changes in LI-RADS v2018 are the removal of the requirement for visibility on antecedent surveillance ultrasound for LI-RADS 5 (LR-5) categorization of 10-19 mm observations with nonrim arterial phase hyper-enhancement and nonperipheral "washout", and adoption of the Organ Procurement and Transplantation Network definition of threshold growth (≥ 50% size increase of a mass in ≤ 6 months) Nomenclatural changes in LI-RADS v2018 are the removal of -us and -g as LR-5 qualifiers
TL;DR: VMIs improve assessment of arterially hyper-enhancing liver lesions since they increase lesion contrast while maintaining low image noise throughout the entire keV spectrum, and these data suggest that to consider VMI screening after arteriallyhyper-enhanced liver lesions.
Abstract: To investigate a benefit from virtual monoenergetic reconstructions (VMIs) for assessment of arterially hyper-enhancing liver lesions in phantom and patients and to compare hybrid-iterative and spectral image reconstructions of conventional images (CI-IR and CI-SR). All imaging was performed on a SDCT (Philips Healthcare, Best, The Netherlands). Images of a non-anthropomorphic phantom with a lesion-mimicking insert (containing iodine in water solution) and arterial-phase images from contrast-enhanced patient examinations were evaluated. VMIs (40–200 keV, 10 keV increment), CI-IR, and CI-SR were reconstructed using different strengths of image denoising. ROIs were placed in lesions, liver/matrix, muscle; signal-to-noise, contrast-to-noise, and lesion-to-liver ratios (SNR, CNR, and LLR) were calculated. Qualitatively, 40, 70, and 110 keV and CI images were assessed by two radiologists on five-point Likert scales regarding overall image quality, lesion assessment, and noise. In phantoms, SNR was increased threefold by VMI40keV compared with CI-IR/SR (5.8 ± 1.1 vs. 18.8 ± 2.2, p ≤ 0.001), while no difference was found between CI-IR and CI-SR (p = 1). Denoising was capable of noise reduction by 40%. In total, 20 patients exhibiting 51 liver lesions were assessed. Attenuation was the highest in VMI40keV, while image noise was comparable to CI-IR resulting in a threefold increase of CNR/LLR (CI-IR 1.3 ± 0.8/4.4 ± 2.0, VMI40keV: 3.8 ± 2.7/14.2 ± 7.5, p ≤ 0.001). Subjective lesion delineation was the best in VMI40keV image (p ≤ 0.01), which also provided the lowest perceptible noise and the best overall image quality. VMIs improve assessment of arterially hyper-enhancing liver lesions since they increase lesion contrast while maintaining low image noise throughout the entire keV spectrum. These data suggest that to consider VMI screening after arterially hyper-enhancing liver lesions.
TL;DR: Studies are underway to evaluate the utility of PET/MRI in PDAC, including in initial staging and treatment response assessment and to determine the subgroup of patients that will benefit from PET/ MRI.
Abstract: Pancreatic ductal adenocarcinoma (PDAC) remains a difficult disease to treat and continues to portend a poor prognosis, as most patients are unresectable at diagnosis. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with CT (PET/CT) has been a cornerstone in oncological imaging of different cancers; however, the role of PET/CT in PDAC is continually evolving and currently not well established. Studies have shown the potential of PET/CT in guiding the management of patients with PDAC, with possible added benefit over anatomic imaging with CT or MRI in certain scenarios. PET/CT may be useful in diagnosis, initial staging, treatment response assessment, differentiation of recurrent tumor from post-treatment fibrosis, and radiotherapy planning. Additionally, PET/CT may be a cost-effective modality due to upstaging of patients originally deemed as surgical candidates. Recently, the advent of simultaneous PET/MRI represents an exciting advancement in hybrid functional imaging with potential applications in the imaging of PDAC. The advantages of PET/MRI include simultaneous acquisition to improve registration of fusion images, lower radiation dose, superior soft tissue contrast, and availability of multiparametric imaging. Studies are underway to evaluate the utility of PET/MRI in PDAC, including in initial staging and treatment response assessment and to determine the subgroup of patients that will benefit from PET/MRI. Further studies are warranted in both PET/CR and PET/MRI to better understand the role of these modalities in PDAC.
TL;DR: There was strong agreement between the abbreviated T1-only MRI protocol and a full liver MRI, with only 5% of cases changing LI-RADS categorization due to the inclusion of T2 and DWI.
Abstract: In this study, we compare an abbreviated screening MRI protocol (aMRI), utilizing only dynamic contrast-enhanced images, to a conventional liver MRI (cMRI) for the characterization of observations in at-risk patients. 164 consecutive HCC screening MRIs were retrospectively analyzed. Two sets of de-identified image sets were created: one with all acquired sequences including T2- and diffusion-weighted sequences (cMRI), and one with only T1-weighted precontrast and dynamic post-contrast images utilizing an extracellular gadolinium contrast agent (aMRI). Three readers assigned a LI-RADS score based on the lesion with the highest LI-RADS category using the aMRI and cMRI datasets during separate reads. There was no change between the aMRI and cMRI LI-RADS categorization in 93%, 96%, and 96% of cases for readers 1, 2, and 3, respectively. In the majority of the discrepant cases, the score increased from LI-RADS 3 to LI-RADS 4 due to the presence of ancillary features on T2 and DWI. Kappa values for interobserver variability demonstrated fair-to-moderate LI-RADS agreement among the 3 readers. There was strong agreement between the abbreviated T1-only MRI protocol and a full liver MRI, with only 5% of cases changing LI-RADS categorization due to the inclusion of T2 and DWI. The estimated time to run this abbreviated MRI is approximately 7–10 min, possibly allowing for a more cost-effective screening MRI than our cMRIs.
TL;DR: Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention.
Abstract: The introduction of ultrasound contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable complementary technique to address clinically significant problems. This pictorial review describes the use of CEUS guidance in abdominal intervention and illustrates such application for a range of clinical indications. Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention. The purpose of this article is to further familiarize readers with the application of CEUS, particularly its specific strength over alternative imaging modalities, in abdominal intervention.
TL;DR: LI-RADS major features are discussed, including definitions, rationale for selection as major features, and imaging examples, including arterial phase hyperenhancement, washout appearance, enhancing capsule appearance, size, and threshold growth.
Abstract: The Liver Imaging Reporting and Data System (LI-RADS) was designed to standardize the interpretation and reporting of observations seen on studies performed in patients at risk for development of hepatocellular carcinoma (HCC). The LI-RADS algorithm guides radiologists through the process of categorizing observations on a spectrum from definitely benign to definitely HCC. Major features are the imaging features used to categorize observations as LI-RADS 3 (intermediate probability of malignancy), LIRADS 4 (probably HCC), and LI-RADS 5 (definite HCC). Major features include arterial phase hyperenhancement, washout appearance, enhancing capsule appearance, size, and threshold growth. Observations that have few major criteria are assigned lower categories than those that have several, with the goal of preserving high specificity for the LR-5 category of Definite HCC. The goal of this paper is to discuss LI-RADS major features, including definitions, rationale for selection as major features, and imaging examples.
TL;DR: In contrast-enhanced ultrasound (CEUS) as mentioned in this paper, the enhancement pattern of a kidney lesion is evaluated in real-time by contrast enhancement of the ultrasound image and then compared with traditional imaging modalities such as computed tomography and magnetic resonance imaging.
Abstract: Incidental discovery of renal lesions on cross-sectional imaging studies performed for other indications is not uncommon. With the increased reliance on medical imaging, the number of incidentally detected renal lesions has also grown over time. While simple cysts account for the majority of these lesions, the presence of complex features within a cystic lesion, such as septations and solid components, can present a confusing picture. Solid lesions, too, can be indeterminate, and distinguishing between benign solid masses (like lipid-poor angiomyolipomas and oncocytomas) and renal cell carcinoma affects patient management and can prevent unnecessary interventions. Indeterminate renal lesions are traditionally further characterized by multiphase imaging, such as contrast-enhanced computed tomography and magnetic resonance imaging. Contrast-enhanced ultrasound (CEUS) is a new, relatively inexpensive technique that has become increasingly employed in the diagnostic workup of indeterminate renal lesions. With its lack of nephrotoxicity, the absence of ionizing radiation, and the ability to evaluate the enhancement pattern of renal lesions quickly and in real-time, CEUS has unique advantages over traditional imaging modalities. This article provides an overview of the current clinical applications of CEUS in characterizing renal lesions, both cystic and solid. Additional applications of CEUS in the kidney, including its roles in renal transplant evaluation and guidance for percutaneous biopsy, will also be briefly discussed.
TL;DR: The technical requirements for liver imaging are reviewed, including the description of minimum acceptable technical standards, such as the scanner hardware requirements, recommended dynamic imaging phases, and common technical challenges of liver imaging.
Abstract: Accurate detection and characterization of liver observations to enable HCC diagnosis and staging using LI-RADS requires a technically adequate imaging exam. To help achieve this objective, LI-RADS has proposed technical requirements for CT, MR, and contrast-enhanced ultrasound of liver. This article reviews the technical requirements for liver imaging, including the description of minimum acceptable technical standards, such as the scanner hardware requirements, recommended dynamic imaging phases, and common technical challenges of liver imaging.
TL;DR: Congenital portosystemic shunts (CPSS) are rare vascular malformations that create an abnormal connection between portal and systemic veins resulting in complete or partial diversion of the portal flow away from the liver to the systemic venous system.
Abstract: Congenital portosystemic shunts (CPSS) are rare vascular malformations that create an abnormal connection between portal and systemic veins resulting in complete or partial diversion of the portal flow away from the liver to the systemic venous system. Different anatomic types exist and several classifications have been proposed. They can be associated with other malformations especially cardiac and heterotaxia. The main complications include hepatic encephalopathy, liver tumors, portopulmonary hypertension, and pulmonary arteriovenous shunts. Diagnosis relies on imaging, and prenatal diagnosis is possible. Spontaneous closure of the CPSS is possible in some anatomic forms during the first year of life. When the CPSS remains patent, radiologic or surgical closure of the CPSS may prevent, resolve, or stabilize complications. Interventional radiology plays a key role for both the preoperative evaluation with occlusion test to assess the exact anatomy and to measure portal pressure after occlusion of the CPSS. Endovascular closure is the first option for treatment when possible.
TL;DR: Ultrasound with the benefit of contrast enhancement meets these requirements and is shown in meta-analysis to be equivalent to CT and MRI scans for these indications.
Abstract: Contrast-enhanced ultrasound (CEUS) of the gastrointestinal tract provides vascular information helpful for characterizing masses and other pathologies in and around the bowel, similar to contrast applications in other solid organs. However, the use of microbubble contrast agents for the bowel provides additional unique contributions as it gives both subjective and objective information about mural and mesenteric blood flow, invaluable for the determination of disease activity in those many patients affected by inflammatory bowel disease (IBD). IBD is a lifelong chronic disease and has its peak age of onset in adolescence or young adult life. Today, we have moved away from treating patient's symptoms and strive instead to alter the course of disease by obtaining mucosal healing. Expensive and aggressive biologic therapies and lack of agreement of patient's symptoms with their disease activity and complications necessitate frequent imaging surveillance, which must be safe, readily available, inexpensive, and effective. Ultrasound with the benefit of contrast enhancement meets these requirements and is shown in meta-analysis to be equivalent to CT and MRI scans for these indications.
TL;DR: HCC and non-HCC show significant differences in the prevalence of imaging features defined by LI-RADS, and are identified by radiologists with moderate interreader agreement.
Abstract: To evaluate the prevalence of major and ancillary imaging features from liver imaging reporting and data systems (LI-RADS) version 2014 and their interreader agreement when comparing hepatocellular carcinoma (HCC) to intrahepatic cholangiocarcinoma (ICC) and combined tumor (cHCC-CC). The Institutional Review Board approved this HIPAA-compliant retrospective study and waived the requirement for patients’ informed consent. Patients with resected HCC (n = 51), ICC (n = 40), and cHCC-CC (n = 11) and available pre-operative contrast-enhanced MRI were included from 2000 to 2015. Imaging features and final LI-RADS category were evaluated by four radiologists. Imaging features were compared by Fisher’s exact test and interreader agreements were assessed by κ statistics. None of the features were unique to either HCC or non-HCC. Imaging features that were significantly more common among HCC compared to ICC and cHCC-CC included washout (76%–78% vs. 10%–35%, p < 0.001), capsule (55%–71% vs. 16%–49%, p < 0.05), and intralesional fat (27%–52% vs. 2%–12%, p < 0.002). Features that were more common among ICC and cHCC-CC included peripheral arterial phase hyperenhancement (40%–64% vs. 10%–14%, p < 0.001) and progressive central enhancement (65%–82% vs. 14%–25%, p < 0.001). The interreader agreement was moderate for each of these imaging features (κ = 0.41–0.55). Moderate agreement was also achieved in the assignment of LR-M (κ = 0.53), with an overall sensitivity and specificity for non-HCC malignancy of 86.3% and 78.4%, respectively. HCC and non-HCC show significant differences in the prevalence of imaging features defined by LI-RADS, and are identified by radiologists with moderate interreader agreement. Using LI-RADS, radiologists also achieved moderate interreader agreement in the assignment of the LR-M category.
TL;DR: The historical evolution of HCC imaging systems is discussed and the potential benefits of unifying the systems are highlighted, which are anticipated to enable sharing, pooling, and meta-analysis of data; facilitate multi-center trials; and accelerate dissemination of knowledge.
Abstract: Over the past 16 years, several scientific organizations have proposed systems that incorporate imaging for surveillance, diagnosis, staging, treatment, and monitoring of treatment response of hepatocellular carcinoma (HCC). These systems are needed to standardize the acquisition, interpretation, and reporting of liver imaging examinations; help differentiate benign from malignant observations; improve consistency between radiologists; and provide guidance for management of HCC. This review article discusses the historical evolution of HCC imaging systems. We indicate the features differentiating these systems, including target population, screening and surveillance algorithm, diagnostic imaging modalities, diagnostic scope, expertise and technical requirements, terminology, major and ancillary imaging features, staging and transplant eligibility, and assessment of treatment response. We highlight the potential benefits of unifying the systems, which we anticipate will enable sharing, pooling, and meta-analysis of data; facilitate multi-center trials; and accelerate dissemination of knowledge.
TL;DR: The objective of this pictorial review is to recapture the essentials of MRE technique and illustrate with examples, the utility of stiffness maps in other chronic liver disorders and focal liver lesions.
Abstract: Magnetic resonance elastography (MRE) has been introduced for clinical evaluation of liver fibrosis for nearly a decade. MRE has proven to be a robust and accurate technique for diagnosis and staging of liver fibrosis. As clinical experience with MRE grows, the possible role in evaluation of other diffuse and focal disorders of liver is emerging. Stiffness maps provide an opportunity to evaluate mechanical properties within a large volume of liver tissue. This enables appreciation of spatial heterogeneity of stiffness. Stiffness maps may reveal characteristic and differentiating features of chronic liver diseases and focal liver lesions and therefore provide useful information for clinical management. The objective of this pictorial review is to recapture the essentials of MRE technique and illustrate with examples, the utility of stiffness maps in other chronic liver disorders and focal liver lesions.
TL;DR: The exact benefit of pancreatic cancer screening remains unclear at this time, but emerging evidence suggests that there is a window of opportunity to detect precursor lesions and early pancreatic adenocarcinomas in high-risk patient populations.
Abstract: This article reviews the current evidence surrounding pancreatic cancer screening. The current targets of screening include identification of early pancreatic cancer, as well as the two most important precursor lesions; intraductal papillary mucinous neoplasm and high grade pancreatic intraepithelial neoplasia. Given the relatively low incidence of pancreatic adenocarcinoma in the general population, patients with elevated risk based on family history or an underlying genetic syndrome are felt to be the most appropriate patients to undergo screening. An extensive review of the literature was performed and the major findings of the available literature regarding pancreatic screening are reviewed in detail. Several prospective trials have evaluated pancreatic cancer screening in high-risk groups. The results of those trials are summarized in this article. Current consensus guidelines and recommendations from the International Cancer of the Pancreas Screening Consortium Summit are also discussed. The exact benefit of pancreatic cancer screening remains unclear at this time, but emerging evidence suggests that there is a window of opportunity to detect precursor lesions and early pancreatic adenocarcinomas in high-risk patient populations. Better understanding of the pathway of carcinogenesis will hopefully improve our ability to detect early, resectable pancreatic carcinomas, and provide a mortality benefit to patients at significantly elevated risk of pancreatic adenocarcinoma.
TL;DR: This article reviews artifacts that may be encountered in CEUS, and where possible discuss how to minimize them or mitigate their effect on image quality and interpretation.
Abstract: Although contrast-enhanced ultrasound (CEUS) has become a widely utilized and accepted modality in much of the world, the associated contrast agents have only recently received approval in the United States. As with all radiological techniques, image artifacts are encountered in CEUS, some of which relate to commonly encountered ultrasound artifacts, while others are unique to this technique. Image artifacts must be recognized when performing and interpreting examinations to improve technique and diagnostic accuracy. In this article, we review artifacts that may be encountered in CEUS, and where possible discuss how to minimize them or mitigate their effect on image quality and interpretation.
TL;DR: A greater number of liver malignancy radiomic features were reproducible compared to liver parenchyma features, but the proportion of reproducible features decreased with increasing variations in contrast injection rates and pixel resolution.
Abstract: To evaluate the short-term reproducibility of radiomic features in liver parenchyma and liver cancers in patients who underwent consecutive contrast-enhanced CT (CECT) with intravenous iodinated contrast within 2 weeks by chance. The Institutional Review Board approved this HIPAA-compliant retrospective study and waived the requirement for patients’ informed consent. Patients were included if they had a liver malignancy (liver metastasis, n = 22, intrahepatic cholangiocarcinoma, n = 10, and hepatocellular carcinoma, n = 6), had two consecutive CECT within 14 days, and had no prior or intervening therapy. Liver tumors and liver parenchyma were segmented and radiomic features (n = 254) were extracted. The number of reproducible features (with concordance correlation coefficients > 0.9) was calculated for patient subgroups with different variations in contrast injection rate and pixel resolution. The number of reproducible radiomic features decreased with increasing variations in contrast injection rate and pixel resolution. When including all CECTs with injection rates differences of less than 15% vs. up to 50%, 63/254 vs. 0/254 features were reproducible for liver parenchyma and 68/254 vs. 50/254 features were reproducible for malignancies. When including all CT with pixel resolution differences of 0–5% or 0–15%, 20/254 vs. 0/254 features were reproducible for liver parenchyma; 34/254 liver malignancy features were reproducible with pixel differences up to 15%. A greater number of liver malignancy radiomic features were reproducible compared to liver parenchyma features, but the proportion of reproducible features decreased with increasing variations in contrast injection rates and pixel resolution.