Chest Radiographs in Congestive Heart Failure: Visualizing Neural Network Learning.

Purpose To examine Generative Visual Rationales (GVRs) as a tool for visualizing neural network learning of chest radiograph features in congestive heart failure (CHF). Materials and Methods A total of 103 489 frontal chest radiographs in 46 712 patients acquired from January 1, 2007, to December 31, 2016, were divided into a labeled data set (with B-type natriuretic peptide [BNP] result as a marker of CHF) and unlabeled data set (without BNP result). A generative model was trained on the unlabeled data set, and a neural network was trained on the encoded representations of the labeled data set to estimate BNP. The model was used to visualize how a radiograph with high estimated BNP would look without disease (a "healthy" radiograph). An overfitted model was developed for comparison, and 100 GVRs were blindly assessed by two experts for features of CHF. Area under the receiver operating characteristic curve (AUC), κ coefficient, and mixed-effects logistic regression were used for statistical analyses. Results At a cutoff BNP of 100 ng/L as a marker of CHF, the correctly trained model achieved an AUC of 0.82. Assessment of GVRs revealed that the correctly trained model highlighted conventional radiographic features of CHF as reasons for an elevated BNP prediction more frequently than the overfitted model, including cardiomegaly (153 [76.5%] of 200 vs 64 [32%] of 200, respectively; P < .001) and pleural effusions (47 [23.5%] of 200 vs 16 [8%] of 200, respectively; P = .003). Conclusion Features of congestive heart failure on chest radiographs learned by neural networks can be identified using Generative Visual Rationales, enabling detection of bias and overfitted models. © RSNA, 2018 See also the editorial by Ngo in this issue.

Foramen tympanicum with symptomatic temporomandibular joint herniation.

Foramen tympanicum (FT), or foramen of Huschke, describes an uncommon anatomicvariant of a persistent bony defect connecting the external acoustic meatus to the temporomandibular joint (TMJ). Although rare, it can be associated with significant complications, such as TMJ herniation, salivary gland fistula, infectious or tumoral spread between the external acoustic meatus and the TMJ, or result in inadvertent ear injury during TMJ arthroscopy. To the best of our knowledge, this is the first case report of a symptomatic FT with a full description of computed tomography and magnetic resonance imaging findings. Surgical exploration confirmed the presence of FT with TMJ herniation with subsequent successful closure of the defect obtained.

Using Social Media to Share Your Radiology Research: How Effective Is a Blog Post?

PURPOSE: The aim of this study was to compare the volume of individuals who viewed online versions of research articles in 2 peer-reviewed radiology journals and a radiology blog promoted by social media. METHODS: The authors performed a retrospective study comparing online analytic logs of research articles in the American Journal of Neuroradiology (AJNR) and the American Journal of Roentgenology (AJR) and a blog posting on Radiopaedia.org from April 2013 to September 2014. All 3 articles addressed the topic of reporting incidental thyroid nodules detected on CT and MRI. The total page views for the research articles and the blog article were compared, and trends in page views were observed. Factors potentially affecting trends were an AJNR podcast and promotion of the blog article on the social media platforms Facebook, Tumblr, and Twitter to followers of Radiopaedia.org in February 2014 and August 2014. RESULTS: The total numbers of page views during the study period were 2,421 for the AJNR article and 3,064 for the AJR article. The Radiopaedia.org blog received 32,675 page views, which was 13.6 and 10.7 times greater than AJNR and AJR page views, respectively, and 6.0 times greater than both journal articles combined. Months with activity above average for the blog and the AJNR article coincided with promotion by Radiopaedia.org on social media. CONCLUSIONS: Dissemination of scientific material on a radiology blog promoted on social media can substantially augment the reach of more traditional publication venues. Although peer-reviewed publication remains the most widely accepted measure of academic productivity, researchers in radiology should not ignore opportunities for increasing the impact of research findings via social media.

Pancreatic polypeptide meal response may predict gastric band-induced weight loss.

BACKGROUND: Unknown hormonal and neural satiety signals are thought to drive sustainable weight loss following laparoscopic adjustable gastric banding (LAGB). The objective of this study was to investigate whether the structurally related satiety hormones pancreatic polypeptide (PP) and peptide YY (PYY) influence total percentage weight loss after LAGB. METHODS: A cross-sectional study examined 17 postoperative individuals who had already achieved a mean of 28% LAGB-induced weight loss (range, 10-38%). A prospective study assessed plasma PP and PYY meal responses in 16 obese individuals prior to LAGB. RESULTS: In the cross-sectional study, individuals with higher weight loss had lower PP meal responses (2-h AUC, R = -0.60, p = 0.01) and lower fasting PYY levels (R = -0.55, p = 0.02). In the prospective study, subsequent mean weight loss was 20% (range, 5-50%) after a mean of 53 months. Low preoperative PP meal response (2-h AUC) predicted significantly higher subsequent weight loss after LAGB (R = -0.56, p = 0.024). The eight individuals with the lowest PP meal response lost more weight than the eight with the highest PP meal response (median 25% vs. 14%, p = 0.004). When compared across all three groups, mean PP meal responses did not differ. Fasting PYY levels, however, were significantly lower in the postoperative group compared to the group tested pre-operatively, or the BMI-matched controls (-30%, p = 0.03). CONCLUSIONS: PYY appears reduced in proportion to weight loss following LAGB, possibly representing attempted orexigenic homeostatic compensation. Although PP responses appear unchanged by weight loss status, low PP meal response may predict higher weight loss. PP meal response may be a biological marker that could predict an individual's susceptibility to the mechanism underlying LAGB-induced weight loss.

Obesity management: update on orlistat.

Over the past 20 years obesity has become a worldwide concern of frightening proportion. The World Health Organization estimates that there are over 400 million obese and over 1.6 billion overweight adults, a figure which is projected to almost double by 2015. This is not a disease restricted to adults - at least 20 million children under the age of 5 years were overweight in 2005 (WHO 2006). Overweight and obesity lead to serious health consequences including coronary artery disease, stroke, type-2 diabetes, heart failure, dyslipidemia, hypertension, reproductive and gastrointestinal cancers, gallstones, fatty liver disease, osteoarthritis and sleep apnea (Padwal et al 2003). Modest weight loss in the obese of between 5% and 10% of bodyweight is associated with improvements in cardiovascular risk profiles and reduced incidence of type 2 diabetes (Goldstein 1992; Avenell et al 2004; Padwal and Majumdar 2007). Orlistat, a gastric and pancreatic lipase inhibitor that reduces dietary fat absorption by approximately 30%, has been approved for use for around ten years (Zhi et al 1994; Hauptman 2000). There is now a growing body of evidence to suggest that Orlistat assists weight loss and that it may also have additional benefits. The aim of this review is to provide a brief update on the current literature studying the efficacy, safety and significance of the use of Orlistat in clinical practice.

Laparoscopic adjustable gastric banding induces prolonged satiety: a randomized blind crossover study.

The sustainability of surgically induced weight loss implies that energy homeostasis is favorably altered. We investigated the hypothesis that laparoscopic adjustable gastric banding (LAGB) induces prolonged satiety and that plasma ghrelin is involved. Seventeen weight-stable subjects who had achieved LAGB-induced weight loss attended blind crossover breakfast tests, one with optimal band restriction and one with reduced restriction. Standardized meals were consumed (0900 h) after 14-h fasting. Satiety visual analog scales were completed hourly (0700-1100 h) before and after feeding. Blood glucose, plasma insulin, ghrelin, and leptin levels were measured. Seventeen body mass index-matched controls were tested. Optimal restriction was associated with significantly greater fasting and postprandial satiety levels than reduced restriction (P < 0.01). Glucose, insulin, ghrelin, and leptin levels did not alter between optimal and reduced restriction. LAGB subjects displayed higher ghrelin (+12%, P = 0.13) and lower glucose (-17%, P = 0.018), insulin (-33%, P = 0.016), and leptin (-32%, P = 0.05) 4-h area under the curve levels than controls. Optimal LAGB restriction increased fasting and postprandial satiety levels. This supports the hypothesis that LAGB provides prolonged satiety, present even during fasting, favorably influencing energy homeostasis. Plasma insulin, leptin, and ghrelin appeared unrelated to the satiety effect and displayed orexigenic compensatory changes. Identifying the mechanisms underlying LAGB-induced satiety may assist the understanding of human energy homeostasis and obesity.

Pro-fibrotic polymorphisms predictive of advanced liver fibrosis in the severely obese.

BACKGROUND/AIMS: Insulin resistance and systemic hypertension are predictors of advanced fibrosis in obese patients with non-alcoholic fatty liver disease (NAFLD). Genetic factors may also be important. We hypothesize that high angiotensinogen (AT) and transforming growth factor-beta1 (TGF-beta1) producing genotypes increase the risk of liver fibrosis in obese subjects with NAFLD. METHODS: One hundred and five of 130 consecutive severely obese patients having a liver biopsy at the time of laparoscopic obesity surgery agreed to have genotype analysis. Influence of specific genotype or combination of genotypes on the stage of hepatic fibrosis was assessed after controlling for known risk factors. RESULTS: There was no fibrosis in 70 (67%), stages 1-2 in 21 (20%) and stages 3-4 fibrosis in 14 (13%) of subjects. There was no relationship between either high AT or TGF-beta1 producing genotypes alone and hepatic fibrosis after controlling for confounding factors. However, advanced hepatic fibrosis occurred in five of 13 subjects (odds ratio 5.7, 95% confidence interval 1.5-21.2, P=0.005) who inherited both high AT and TGF-beta1 producing polymorphisms. CONCLUSIONS: The combination of high AT and TGF-beta1 producing polymorphisms is associated with advanced hepatic fibrosis in obese patients with NAFLD. These findings support the hypothesis that angiotensin II stimulated TGF-beta1 production may promote hepatic fibrosis.

Cardiovascular benefit of light to moderate alcohol consumption.

BACKGROUND: In recent years strong epidemiological evidence has arisen associating significant cardiovascular benefit with light to moderate alcohol consumption. Increased benefit in high cardiovascular risk individuals has been particularly evident. With Australian levels of obesity and type 2 diabetes now reaching epidemic proportions, lifestyle factors that can reduce cardiovascular risk are of critical importance. OBJECTIVE: This article aims to inform general practitioners of the potential cardiovascular benefit of light to moderate alcohol consumption. DISCUSSION: In offering tailored alcohol advice to patients, the GP should have two goals: to minimise harm and maximise benefit. Blanket discouragement of all levels of alcohol consumption can no longer be justified.