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Quantitative Imaging of Body Composition.
Hemke, R, Buckless, C, Torriani, M
Seminars in musculoskeletal radiology. 2020;(4):375-385
Abstract
Body composition refers to the amount and distribution of lean tissue, adipose tissue, and bone in the human body. Lean tissue primarily consists of skeletal muscle; adipose tissue comprises mostly abdominal visceral adipose tissue and abdominal and nonabdominal subcutaneous adipose tissue. Hepatocellular and myocellular lipids are also fat pools with important metabolic implications. Importantly, body composition reflects generalized processes such as increased adiposity in obesity and age-related loss of muscle mass known as sarcopenia.In recent years, body composition has been extensively studied quantitatively to predict overall health. Multiple imaging methods have allowed precise estimates of tissue types and provided insights showing the relationship of body composition to varied pathologic conditions. In this review article, we discuss different imaging methods used to quantify body composition and describe important anatomical locations where target tissues can be measured.
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Cushing's syndrome - Disease monitoring: Recurrence, surveillance with biomarkers or imaging studies.
Ragnarsson, O
Best practice & research. Clinical endocrinology & metabolism. 2020;(2):101382
Abstract
Pituitary surgery is the first-line treatment for patients with Cushing's disease. For patients who are not considered candidates for pituitary surgery, pituitary radiation and bilateral adrenalectomy are further treatment alternatives. Not all patients are cured with pituitary surgery, and a substantial number of patients develop recurrence, sometimes many years after an apparently successful treatment. The same applies to patients treated with radiotherapy. Far from all patients are cured, and in many cases the disease recurs. Bilateral adrenalectomy, although always curative, causes chronic adrenal insufficiency and the remaining pituitary tumour can continue to grow and cause symptoms due to pressure on adjacent tissues, a phenomenon called Nelson's syndrome. In this paper the rate of recurrence of hypercortisolism, as well as the rate of development of Nelson's syndrome, following treatment of patients with Cushing's syndrome, will be reviewed. The aim of the paper is also to summarize clinical and biochemical factors that are associated with recurrence of hypercortisolism and how the patients should be monitored following treatment.
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Fundamentals of artificial intelligence for ophthalmologists.
Ahmad, BU, Kim, JE, Rahimy, E
Current opinion in ophthalmology. 2020;(5):303-311
Abstract
PURPOSE OF REVIEW As artificial intelligence continues to develop new applications in ophthalmic image recognition, we provide here an introduction for ophthalmologists and a primer on the mechanisms of deep learning systems. RECENT FINDINGS Deep learning has lent itself to the automated interpretation of various retinal imaging modalities, including fundus photography and optical coherence tomography. Convolutional neural networks (CNN) represent the primary class of deep neural networks applied to these image analyses. These have been configured to aid in the detection of diabetes retinopathy, AMD, retinal detachment, glaucoma, and ROP, among other ocular disorders. Predictive models for retinal disease prognosis and treatment are also being validated. SUMMARY Deep learning systems have begun to demonstrate a reliable level of diagnostic accuracy equal or better to human graders for narrow image recognition tasks. However, challenges regarding the use of deep learning systems in ophthalmology remain. These include trust of unsupervised learning systems and the limited ability to recognize broad ranges of disorders.
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Imaging of Renal Cancer.
Krishna, S, Leckie, A, Kielar, A, Hartman, R, Khandelwal, A
Seminars in ultrasound, CT, and MR. 2020;(2):152-169
Abstract
Renal masses are common incidental findings on cross-sectional imaging. Accurate characterization of renal masses is essential to guide management. Renal mass CT protocol comprises of a good quality noncontrast, corticomedullary and nephrographic phases, with each phase providing complementary information for diagnosis. Attenuation measurements in different phases are central to the 'golden-rules' in renal mass imaging in the characterization of renal masses. Newer modalities like dual energy CT scan obviate need for repeat imaging by generation of iodine-overlay image and also help in eliminating artifactual pseudoenhancement which can be problematic, especially in small endophytic cysts. Contrast- enhanced ultrasound (CEUS) is extremely sensitive in identification of enhancing components in indeterminate masses, especially in the setting of renal failure as the microbubbles are not excreted via the renal route. The Bosniak classification for renal cystic masses has been revised in 2019 to standardize terminology and further improve upon the original version. The current version includes CT and MRI, although CEUS is yet to be included. Image- guided biopsy of renal mass helps confirm the diagnosis and also gives information regarding the subtype and grading and is useful in avoiding overtreatment of benign entities, and in active surveillance. Multiparametric MRI can potentially help avoid needle biopsy in a subset of patients by accurate characterization through a previously validated algorithm.
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Imaging of Acute Renal Failure in the Hospital Setting.
Alabousi, M, Alabousi, A, Patlas, MN
Radiologic clinics of North America. 2020;(1):59-71
Abstract
Acute kidney injury (AKI) is characterized by a decline in the glomerular filtration rate. AKI affects up to 20% of hospitalized patients, and is even more common among intensive care unit admissions. Complications of AKI are related to uremia (encephalopathy, neuropathy, pericarditis), volume overload (pulmonary edema), and electrolyte disturbances (hyperkalemia). In addition to having increased associated morbidity and mortality, patients who develop AKI may never fully recover their baseline kidney function. Imaging can play a valuable role in the work-up of AKI. This article discusses the utility of imaging in characterizing AKI in adult patients in a hospital setting.
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Enhancing our understanding of small bowel function using modern imaging techniques.
Spiller, R, Hoad, C
Neurogastroenterology and motility. 2020;(1):e13616
Abstract
Small intestinal function is critical to digestive health and patients believe an abnormal reaction to food is responsible for many of their symptoms. Despite this, our ability to assess disturbed function in clinical practice has been limited, particularly after ingestion of the complex nutrients which make up normal food. Recent advances in both wireless capsules and magnetic resonance imaging have provided new insights. This review will briefly describe the limitations of past techniques and focus on how these newer techniques are changing our understanding, particularly of how patients' gastrointestinal tracts respond to food.
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Smartphone-Based Fundus Imaging-Where Are We Now?
Wintergerst, MWM, Jansen, LG, Holz, FG, Finger, RP
Asia-Pacific journal of ophthalmology (Philadelphia, Pa.). 2020;(4):308-314
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Abstract
With the advent of smartphone-based fundus imaging (SBFI), a low-cost alternative to conventional digital fundus photography has become available. SBFI allows for a mobile fundus examination, is applicable both with and without pupil dilation, comes with built-in connectivity and post-processing capabilities, and is relatively easy to master. Furthermore, it is delegable to paramedical staff/technicians and, hence, suitable for telemedicine. Against this background a variety of SBFI applications have become available including screening for diabetic retinopathy, glaucoma, and retinopathy of prematurity and its applications in emergency medicine and pediatrics. In addition, SBFI is convenient for teaching purposes and might serve as a surrogate for direct ophthalmoscopy. First wide-field montage techniques are available and the combination of SBFI with machine learning algorithms for image analyses is promising. In conclusion, SBFI has the potential to make fundus examinations and screenings for patients particularly in low- and middle-income settings more accessible and, therefore, aid tackling the burden of diabetic retinopathy, glaucoma, and retinopathy of prematurity screening. However, image quality for SBFI varies substantially and a reference standard for grading appears prudent. In addition, there is a strong need for comparison of different SBFI approaches in terms of applicability to disease screening and cost-effectiveness.
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Advances in Diagnostic Imaging in Pediatric Gastroenterology.
Zember, J, Loomis, J, Vyas, P, Badalyan, V, Shet, N
Current gastroenterology reports. 2020;(5):22
Abstract
PURPOSE OF REVIEW The purpose is to provide a review of cross-sectional imaging updates in the assessment of gastrointestinal diseases, relevant to clinical practice and research. RECENT FINDINGS New magnetic resonance imaging contrast agents (Eovist) are taken up by hepatocytes and excreted via the biliary tree. As such, a lesion will retain contrast only if hepatocytes are present, which aids in refining the differential diagnosis. Magnetic resonance enterography is a method for non-invasively diagnosing and following various GI conditions, predominantly inflammatory bowel disease. Contrast-enhanced ultrasound uses gas-filled microbubbles providing superb temporal resolution most notably in the arterial phase, which aids in differentiating lesions. Elastography is a new technique which assesses stiffness of liver for evaluating fibrosis. These new techniques provide more accurate diagnoses and information, often limiting ionizing radiation exposure from other modalities. While ultrasound will still remain the initial imaging modality, familiarity with these other options is valuable for appropriate pathology workup.
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Diagnostic imaging of dementia with Lewy bodies, frontotemporal lobar degeneration, and normal pressure hydrocephalus.
Ishii, K
Japanese journal of radiology. 2020;(1):64-76
Abstract
Neuroimaging can provide important biomarkers and is very useful for supporting dementia diagnosis. This review summarizes the neuroimaging findings of dementia with Lewy bodies (DLB), frontotemporal lobar degeneration (FTLD), and normal pressure hydrocephalus (NPH). In DLB, medial temporal atrophy is milder than that of Alzheimer's disease. 2-fluoro-2-deoxy-D-glucose-positron emission tomography and brain perfusion single-photon emission computed tomography demonstrate hypometabolism and hypoperfusion in the occipital lobe, in addition to decreased metabolism and perfusion in the parietotemporal, posterior cingulate, precuneus, and frontal association cortices. The cingulate island sign, which shows relatively spared middle-to-posterior cingulate cortex metabolism compared with precuneus hypometabolism, is proposed to detect DLB in 2-fluoro-2-deoxy-D-glucose-positron emission tomography imaging. Reduced uptake in dopamine transporter imaging and reduced myocardial uptake in iodine-123 metaiodobenzylguanidine cardiac scintigraphy are indicative biomarkers for DLB diagnosis. Characteristic findings of FTLD include dominant frontotemporal atrophy, hypometabolism, and hypoperfusion. Most idiopathic NPH cases demonstrate disproportionally enlarged subarachnoid space hydrocephalus findings, including dilated ventricular systems, enlarged Sylvian fissures, tight sulci in the midline, and a high convexity.
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10.
Gastrointestinal involvement in systemic sclerosis: an update.
McMahan, ZH
Current opinion in rheumatology. 2019;(6):561-568
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Abstract
PURPOSE OF REVIEW This review provides important updates in systemic sclerosis (SSc)-related gastrointestinal disease, specifically focusing on the most recent literature. RECENT FINDINGS In the past year, several studies were published that present interesting insights into SSc and gastrointestinal disease. Studies focusing on newly identified risk factors, novel approaches to diagnosis and assessment of disease activity, survival and quality of life demonstrate progress in our understanding of this challenging area. Additional data on specific SSc gastrointestinal-related topics, such as the link between gastrointestinal and pulmonary disease, nutrition, and the microbiome, are also now available. SUMMARY SSc gastrointestinal disease is heterogeneous in its clinical presentation, which presents a challenge in diagnosis and management. In the past year, several studies have evaluated risk factors and clinical features associated with specific gastrointestinal complications in SSc. Objective gastrointestinal testing may help to identify specific SSc gastrointestinal subgroups and provide diagnostic accuracy to guide targeted therapies. Survival in very early SSc is affected by the severity of gastrointestinal involvement. Other important gastrointestinal subsets, including patients with esophageal disease and interstitial lung disease, should carefully be considered when developing a management plan for this patient population.