L. Landini

Automated cardiac MR image segmentation: theory and measurement evaluation.

We present a new approach to magnetic resonance image segmentation with a Gradient-Vector-Flow-based snake applied to selective smoothing filtered images. The system also allows automated image segmentation in the presence of grey scale inhomogeneity, as in cardiac Magnetic Resonance imaging. Removal of such inhomogeneities is a difficult task, but we proved that using non-linear anisotropic diffusion filtering, myocardium edges are selectively preserved. The approach allowed medical data to be automatically segmented in order to track not only endocardium, which is usually a less difficult task, but also epicardium in anatomic and perfusion studies with Magnetic Resonance. The method developed proceeds in three distinct phases: (a) an anisotropic diffusion filtering tool is used to reduce grey scale inhomogeneity and to selectively preserve edges; (b) a Gradient-Vector-Flow-based snake is applied on filtered images to allow capturing a snake from a long range and to move into concave boundary regions; and (c) an automatic procedure based on a snake is used to fit both endocardium and epicardium borders in a multiphase, multislice examination. A good agreement (P<0.001) between manual and automatic data analysis, based on the mean difference+/-SD, was assessed in a pool of 907 cardiac function and perfusion images.

Molecular and Biochemical Changes of the Cardiovascular System due to Smoking Exposure

Cigarette smoking (CS) is a major health hazard particularly for the cardiovascular system and cancer. The mechanisms involved in CS-related cardiovascular dysfunction have been largely debated. CS increases inflammation, thrombosis, and oxidation of low-density lipoproteins. Recent experimental and clinical data support the hypothesis that cigarette smoke exposure increases oxidative stress as a potential mechanism for initiating cardiovascular dysfunction. Cardiac myocytes, as well as and other long-lived postmitotic cells show dramatic smoke-related alterations that mainly affect the mitochondria and lysosomal compartment. Mitochondria are primary sites of reactive oxygen species formation that cause progressive damage to mitochondrial DNA and proteins in parallel to intralysosomal lipofuscin accumulation. There is amassing evidence that various mechanisms may contribute to accumulation of damaged mitochondria following initial oxidative injury. Such mechanisms may include clonal expansion of defective mitochondria, decreased propensity of altered mitochondria to become autophagocytosed, suppressed autophagy because of heavy lipofuscin loading of lysosomes and decreased efficiency of specific proteases involved into mitochondrial degradation. A possible interplay between microtubule plasticity and oxidative stress also exists in cardiomyocytes, so this could represent another potential mechanism by which smoking induces/accelerates atherosclerosis.

Vascular Pathology from Smoking: Look at the Microcirculation!

Both conduit and resistance arterial vessels may show vascular morphological and functional alterations due to cigarette smoking. Pathological lesions involve the arterial wall or intravascular lumen with, primarily, narrowing and thrombo-embolic events as an effect of endothelial and blood cell changes related to smoking. Functional disorders are the result of a wide spectrum of biochemical, physiological and metabolic factors. While conduit vessel alterations have been widely investigated, little is known about the changes induced by smoking on the microcirculation. It would seem that the endothelium, platelet aggregation and adhesiveness, nervous system and metabolic changes play a role in damaging resistance arteries and, then, the microcirculation. The result of these effects changes the blood flow and perfusion particularly to the heart, brain and kidney. Alterations of the microcirculation can cause severe and widespread damage because, in addition to the complications of the atherosclerotic lesion which characterizes large arteries, there is a failure of body organs linked to the degree of microvascular damage. Moreover, it seems that 2 major compounds of cigarette smoke are capable of determining vascular damage; initially, nicotine acts preferably on large arteries and carbon monoxide on small arteries, although both compounds damage the vascular system.

Smoking and Hypertension: Effects on Clinical, Biochemical and Pathological Variables Due to Isolated or Combined Action on Cardiovascular System

Changes in clinical, biochemical and pathological variables characterize cardiovascular damage from smoking and hypertension when it acts independently. However, combined action of these major risk factors increases the rate of cardiovascular events. Ischaemic heart disease with stable effort angina, myocardial infarction and post-infarction arrhythmias may affect cardiovascular system because of smoking exposure. Among cerebrovascular disease, there is evidence that stroke would be related primarily to active smoking. Isolated hypertension plays significantly major action to cause cerebrovascular disease including stroke, recurrent stoke and transient ischaemic attack. Among cardiac events, heart failure is, often, the end-point of hypertensive disease, even if manifestations of ischaemic heart disease similar to those caused by smoking may be increased in rate. Combined action of smoking and hypertension usually increases the rate of cardiovascular complications and leads to a progression of atherosclerosis with narrowing and plaque primarily at the the level of coronary, carotid and cerebrovascular arteries. A pattern specific of both active and passive smoking exposure, but not hypertension, is the thromboangiitis obliterans that dramatically worsens in continuing smokers while it can be improved by stopping smoking.

What is Tobacco Smoke? Sociocultural Dimensions of the Association with Cardiovascular Risk

The definition of smoking as the inhalation of the smoke of burned tobacco that may occur occasionally or habitually as a consequence of a physical addiction to some chemicals, primarily nicotine, cannot be fully accepted today since several clinical, biological, metabolic, epidemiologic, statistic and socio-economic factors which play a basic role in determining individual damage due to smoking are missing in this assessment. The analysis of findings shows undoubtedly that several constituents of cigarette smoking play a strong role in the development and progression of cardiovascular damage, primarily atherosclerotic lesions. Nicotine and its metabolites, carbon monoxide and thiocyanate seem to be the most specific markers of damage that, in the time, becomes irreversible. Cigarette smoking is addictive because of nicotine and nicotine withdrawal causes many side effects of quitting smoking as well as nicotine itself usually increases cardiovascular risk. Therefore, what is smoking? Smoking must be defined as a chemical toxicosis which is able to cause detrimental effects either of acute or chronic type on different structures of the body being some of these like cardiovascular system, respiratory system and epithelial glands target organs. Smoking also causes physical addiction, primarily due to nicotine, that adversely influences smoking cessation. From these observations there is evidence that a large number of socio-economic and epidemiologic implications arise in smokers and that requires the necessity of specific structures which may help to face up the problem.

Effect of Bariatric Surgery on Adipose Tissue Glucose Metabolism in Different Depots in Patients With or Without Type 2 Diabetes

OBJECTIVE We investigated fat distribution and tissue-specific insulin-stimulated glucose uptake (GU) in seven fat compartments (visceral and subcutaneous) and skeletal muscle in morbidly obese patients with (T2D) and without (ND) type 2 diabetes before and 6 months after bariatric surgery. RESEARCH DESIGN AND METHODS A total of 23 obese patients (BMI 43.0 ± 3.6 kg/m2; 9 T2D and 14 ND) were recruited from a larger, randomized multicenter SLEEVEPASS study. MRI (for fat distribution) and [18F]-fluorodeoxyglucose PET (for GU) studies were performed for the obese patients before and 6 months postsurgery; 10 lean subjects served as control subjects and were studied once. RESULTS At baseline, visceral fat GU was 30 ± 7% of muscle GU in control subjects and 57 ± 5% in obese patients. Visceral and deep subcutaneous fat were more abundant (despite same total fat mass) and less insulin sensitive in T2D than ND; in both, GU was impaired compared with control subjects. Postsurgery, visceral fat mass decreased (∼40%) more than subcutaneous fat (7%). Tissue-specific GU was improved, but not normalized, at all sites in T2D and ND alike. The contribution of visceral fat to whole-body GU was greater in T2D than ND but decreased similarly with surgery. Subcutaneous fat made a fourfold greater contribution to whole-body GU in obese versus lean subjects (15% vs. 4%) both before and after surgery. CONCLUSIONS Bariatric surgery leads to sustained weight loss and improves tissue-specific glucose metabolism in morbidly obese patients. We conclude that 1) enhanced visceral fat accumulation is a feature of T2D, 2) severe obesity compromises muscle insulin sensitivity more than fat insulin sensitivity, and 3) fat mass expansion is a sink for plasma glucose.

Ultrasound Techniques for Drug Delivery in Cardiovascular Medicine

In this review, we will give a critical update of published studies using ultrasound for targeted therapeutic use. We will briefly discuss the interaction mechanisms and their effects in non-invasive delivery of therapeutic agents. Moreover, the mechanisms by which ultrasonic contrast agents facilitate the delivery of drugs and genes into tissue will be discussed, together with recent applications and perspectives of targeted-microbubbles in cardiovascular medicine.

Automatic time sequence alignment in contrast enhanced MRI by maximization of mutual information

The use of a contrast medium allows the high-resolution anatomical information provided by standard magnetic resonance to be combined with functional information obtained by means of diffusion of contrast agent in tissues or in the vascular net. To effectively use this kind of image for medical diagnosis, quantitative analysis should be performed. We propose an automatic registration procedure based on maximization of the mutual information that address the requirement of fast and automatic tools for quantitative analysis of contrast medium enhanced MR images. Two optimization algorithms for maximization of the mutual information are discussed, taking into account both time performance and registration quality. We present also preliminary results on cardiac and wrist MR images showing that misalignments and artifacts introduced by patient movement during the examination are greatly reduced by our application.

Fatty acid uptake and blood flow in adipose tissue compartments of morbidly obese subjects with or without type 2 diabetes: effects of bariatric surgery

Body fat accumulation, distribution, and metabolic activity are factors in the pathophysiology of obesity and type 2 diabetes (T2D). We investigated adipose blood flow, fatty acid uptake (FAU), and subcutaneous and visceral fat cellularity in obese patients with or without T2D. A total of 23 morbidly obese (mean body mass index = 42 kg/m2) patients were studied before and 6 mo after bariatric surgery; 15 nonobese subjects served as controls. Positron emission tomography was used to measure tissue FAU (with 18F-FTHA) and blood flow (with H215O); MRI was used for fat distribution and fat biopsy for adipocyte size. Obese subjects had subcutaneous hyperplasia and hypertrophy and lower blood flow; when expressed per cell, flow was similar to controls. FAU into subcutaneous and visceral depots was increased in the obese; per unit tissue mass, however, FAU was similar to controls but reduced in skeletal muscle. Fatty acid fractional extraction in subcutaneous fat and muscle was only increased in obese patients with T2D. We conclude that surgery reduces subcutaneous fat hyperplasia and hypertrophy; subcutaneous blood flow and FAU decrease in absolute terms and per cell while fractional FAU remains unchanged in T2D. In the obese, subcutaneous blood flow is a determinant of FAU and is coupled with cellularity; efficiency of FAU is enhanced in subcutaneous fat and muscle in T2D.

Non-linear prediction for oesophageal voice analysis

Herein, non-linear prediction methods are applied to oesophageal voice analysis. The research aims to investigate normal and pathological subjects, in order to improve knowledge of the oesophageal voice behaviour. Analysis is performed in the reconstructed phase space, using both non-linear prediction with local linear approximation and the S-Map method. Preliminary results seem to confirm that in normal subjects a non-linear stable deterministic behaviour takes place, while in pathological subjects the non-linear contribution reduces while the time series becomes unstable.