-
[show abstract]
[hide abstract]
ABSTRACT: Previous studies have highlighted the associations between abdominal, cardiac or total fat accumulation and cardiovascular disease. The aim of this study was to investigate the impact of different ectopic fat depots on measurements of metabolic dysfunction and cardiovascular disease risk.
Using magnetic resonance imaging in 113 subjects, we measured abdominal (visceral and subcutaneous) and cardiac (epicardial and extra-pericardial) fat depots and examined their association with overall (BMI) and abdominal obesity (waist circumference), dyslipidaemia (triglycerides, total and HDL cholesterol), glucose tolerance (by an oral glucose tolerance test) and insulin sensitivity, blood pressure and 10-year coronary heart disease risk by Framingham score.
Fat accumulation was proportional to the degree of obesity, with body fat ranging from 14 to 33 kg, visceral fat from 0.8 to 1.8 kg and cardiac fat from 134 to 236 g. Most cardiac fat (70% on average) was extra-pericardial, with a wide variability for both cardiac depots (epicardial: 172-2008 mm(2); extra-pericardial: 100-5056 mm(2)). Only visceral and extra-pericardial fat, but not epicardial or subcutaneous fat, could discriminate between subjects with three or more factors of the metabolic syndrome or medium-to-high coronary heart disease risk score. Controlling for gender and BMI by multivariable analysis, the best marker of reduced insulin sensitivity was visceral fat (partial r = -0.35); extra-pericardial fat was the closest associate of increased blood pressure (partial r = 0.26) and both extra-pericardial and visceral fat clustered with hypertriglyceridaemia (partial r = 0.29 and 0.24; both P < 0.02).
Increased epicardial fat per se does not necessarily translate into presence or prediction of disease. In contrast, increased deposition of visceral abdominal and extra-pericardial mediastinal fat are both associated with an enhanced cardiovascular disease risk profile.
Diabetic Medicine 10/2011; 29(5):622-7. · 2.90 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Management of heart failure is challenging for all healthcare systems, due to the need of several expensive imaging examinations and image analysis procedures to address different clinical questions. In particular, a correct identification of transmural extent of irreversible myocardial damage is cost effective, identifying subjects who will most benefit of coronary revascularization. This study show how a dedicated software tool, to be integrated within a clinical decision support system, may help to preserve the information content of medical images in the assessment of myocardial viability in management of the left ventricular dysfunction.
eChallenges, 2010; 11/2010
-
A Meloni,
A Ramazzotti,
V Positano,
C Salvatori,
M Mangione,
P Marcheschi,
B Favilli,
D De Marchi,
S Prato,
A Pepe,
G Sallustio,
M Centra,
M F Santarelli, M Lombardi,
L Landini
[show abstract]
[hide abstract]
ABSTRACT: To build and evaluate a national network able to improve the care of thalassemia, a genetic disorder in haemoglobin synthesis often associated with iron accumulation in a variety of organs, due to the continuous blood transfusions.
The MIOT (Myocardial Iron Overload in Thalassemia) network is constituted by thalassemia and magnetic resonance imaging (MRI) centers. Thalassemia centers are responsible for patient recruitment and collection of anamnestic and clinical data. MRI centers have been equipped with a standardized acquisition technique and an affordable workstation for image analysis. They are able to perform feasible and reproducible heart and liver iron overload assessments for a consistent number of thalassemia patients in a robust manner. All centers are linked by a web-based network, configured to collect and share patient data.
On 30th March 2008, 695 thalassemia patients were involved in the network. The completion percentage of the patient records in the database was 85+/-6.5%. Six hundred and thirteen patients (88%) successfully underwent MRI examination. Each MRI center had a specific absorption capacity that remained constant over time, but the network was capable of sustaining an increasing number of patients due to continuous enrollment of new centers. The patient's comfort, assessed as the mean distance from the patient home locations to the MRI centers, significantly increased during the network's evolution.
The MIOT network seems to be a robust and scalable system in which T2* MRI-based cardiac and liver iron overload assessment is available, accessible and reachable for a significant and increasing number of thalassemia patients in Italy (about 420 per year), reducing the mean distance from the patient locations to the MRI sites from 951km to 387km. A solid, wide and homogeneous database will constitute an important scientific resource, shortening the time scale for diagnostic, prognostic and therapeutical evidence-based research on the management of thalassemia disease.
International Journal of Medical Informatics 05/2009; 78(8):503-12. · 2.41 Impact Factor
-
A. Meloni,
A. Ramazzotti,
V. Positano,
C. Salvatori,
P. Marcheschi,
B. Favilli,
D. De Marchi,
S. Prato,
M. Mangione,
A. Pepe,
G. Rossi, M. Lombardi,
M.F. Santarelli,
L. Landini
[show abstract]
[hide abstract]
ABSTRACT: Today there are about 6000 thalassemia patients in Italy, with a marked prevalence in the south, Sardinia and Sicily. Cardiac magnetic resonance (CMR) measurement of myocardial iron overload allows early diagnosis and treatment of these patients. To optimize patient care, CMR centers should be easily accessible for the patients and should be able to perform iron overload measurement in a standardized way. To accomplish this objective, an analysis system was developed and distributed to six CMR centers. Fifty haematological and paediatric centers specialized in thalassemia care were also involved. All centers are linked by a web-based network, configured to collect and share patient data, assuring personal data protection. The inter-center variability of the proposed methodology was evaluated, demonstrating the effectiveness of the network.
Advances in Medical, Signal and Information Processing, 2008. MEDSIP 2008. 4th IET International Conference on; 08/2008
-
[show abstract]
[hide abstract]
ABSTRACT: Cardiovascular magnetic resonance is able to detect myocardial fibrosis by delayed enhancement of a contrast media. However, detection and quantification of fibrosis is difficult due to the complex pattern of the fibrotic tissue signal. In this study a software model of the signal distribution in normal and fibrotic myocardium was inferred from MR images of healthy subjects and patients with hypertrophic cardiomyopathy. The developed model allowed to define a methodology for the discrimination of fibrotic areas. The method was based on the fitting of the signal histogram with a modified gamma function. The scale parameter characterizing the gamma function was used as discriminating factor in MR image analysis, reaching a sensitivity of 85% and a specificity of 86%. The proposed approach outperformed the standard approach used in the clinical practice.
Biomedical Imaging: From Nano to Macro, 2008. ISBI 2008. 5th IEEE International Symposium on; 06/2008
-
[show abstract]
[hide abstract]
ABSTRACT: Assessment of iron overload in liver by T2* magnetic resonance imaging (MRI) is a widely used clinical procedure. In the common clinical practice, measurement is performed locally by manually drawing a small region of interest in liver. This procedure may be affected by a noticeable intra- and inter-observer variability. In this study, a new approach is proposed that performs a global semi-automatic measurement of T2* involving the whole liver extension. Parenchyma is automatically segmented by an adaptive fuzzy-clustering algorithm. The liver T2* global value is evaluated using a pixel-wise approach by introducing an appropriate signal decay model. The proposed method was tested on a synthetic software model and on MR images acquired from 30 thalassemia major patients. The methods was demonstrated to increase the measure precision in T2* assessment and to significantly reduce the intra- and inter- observer variability.
Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE; 09/2007
-
Heart (British Cardiac Society) 06/2006; 92(5):689-90. · 4.22 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Preferential visceral adipose tissue (VAT) accumulation has been clearly associated with insulin resistance. In contrast, the impact of visceral obesity on beta cell function is controversial.
In 62 non-diabetic women and men (age 24-69 years, BMI 21-39 kg/m2), we measured VAT and subcutaneous adipose tissue (SAT) fat mass by magnetic resonance imaging. We also measured insulin secretion and beta cell function by C-peptide deconvolution and physiological modelling of data from a frequently sampled, 75-g, 3-h OGTT, respectively.
VAT (range 0.1-3.1 kg) was strongly related to sex, age and BMI; SAT was related to sex and BMI. Controlling for sex, age, BMI and SAT by multivariate analysis, excess VAT was associated with a clinical phenotype comprising higher plasma glucose levels, BP, heart rate and serum transaminases. The corresponding metabolic phenotype consisted of insulin resistance (partial r=-0.38) and hyperinsulinaemia (partial r=0.29). The latter, however, was appropriate for the degree of insulin resistance regardless of obesity and abdominal fat distribution. Moreover, none of the model-derived parameters describing beta cell function (glucose sensitivity, rate sensitivity and potentiation) was independently associated with excess VAT.
In non-diabetic Caucasian adults of either sex, preferential visceral fat deposition in itself is part of an insulin-resistant phenotype. The insulin secretory response to a physiological challenge is increased to fully compensate for the insulin resistance, but the dynamics of beta cell function (glucose sensitivity, rate sensitivity and potentiation) are largely preserved.
Diabetologia 11/2005; 48(10):2090-6. · 6.81 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Myocardial viability is a fundamental question in the clinical and therapeutic decision making process. Contrast-enhanced MRI can distinguish between viable and necrotic myocardium in non-invasive manner and with excellent definition of endocardial and epicardial borders. Aim of this study is to propose a software methodology that allows to assess the global, transmural and intramural extent of myocardial necrosis providing both bull-eyes and 3D representation of contrast delayed enhanced area in MRI cardiac images.
Computers in Cardiology, 2003; 10/2003
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
Medical Engineering & Physics 03/2003; 25(2):149-59. · 1.62 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Aim of the study was to assess a new method to followup patients with angiographically documented coronary artery disease (CAD), by noninvasive MRI angiography. The method is based on 3D reconstruction of planar cineangiographic images. It is addressed to expand informative content and to extract data from conventional 2D-images, aiming to guide and optimize the use of magnetic resonance for coronary artery visualization. The preliminary tests have shown that it is possible to obtain a fast MRI localization of peripheral coronary segments due to a more precise target volume of scan. This could overcome some limits of MRI examination of coronary tree and expands the use of noninvasive MRI technique in CAD follow-up.
Computers in Cardiology, 2002; 10/2002
-
[show abstract]
[hide abstract]
ABSTRACT: Contrast agents together with second harmonic imaging improve endocardial border detection in echo images. Aim of the study was to assess whether non linear anisotropic filtering after segmentation of gradient vector flow (GVF) based active contour algorithm can be applied on contrast echo images for automatic detection of left ventricular (LV) contours. LV volumes were measured in 20 subjects by cine Magnetic Resonance (MR) and transthoracic second harmonic echo after intravenous administration of the contrast agent Levovist. Contrast echo images were analyzed both manually and automatically; MR images were automatically analyzed. LV volumes were calculated according to Simpson's rule. A good correlation with MR volumes was found for manual LV volumes (r.93 and .92 for end diastolic and end systolic volumes, respectively, p <.05). A still good correlation was found for the automatically assessed volumes in both phases (r=.90 and .91, p<05). Thus automatic endocardial border delineation by anisotropic filtering and GVF based active contour algorithm is feasible on contrast echo images. This method may represent an approach for automatic endocardial border analysis in ultrasonic imaging.
Computers in Cardiology, 2002; 10/2002
-
M Lombardi,
J Kvaerness,
G Torheim,
J Soma,
F Cellerini,
M Consalvo,
M C Landini,
C A Cecchi,
C Michelassi,
T Skjaerpe,
R A Jones,
P A Rinck,
A L'Abbate
[show abstract]
[hide abstract]
ABSTRACT: To assess the relationship between baseline left ventricle function, functional reserve and resting myocardial perfusion in patients with acute myocardial infarction (AMI). After AMI the presence of dysfunctioning but viable myocardium plays a determinant role in clinical outcome. Regional ventricular function was evaluated by echocardiography both in resting conditions and during dobutamine infusion (10 microg/kg/min). Perfusion was assessed by magnetic resonance imaging in a single slice approach where the first pass of an intravenously injected bolus of gadolinium-based contrast agent was followed through six regions of interest within the myocardium. In each patient a region with normal function was used as reference and the cross-correlation coefficient (CCC), which described the myocardial perfusion relatively to the reference region (CCC = 1 means equivalent perfusion), was obtained for the other five myocardial regions. Twenty-two patients were enrolled into the study. Sixty-one segments had normal function and normal perfusion (CCC = 0.92+/-0.23). The perfusion deficit was more marked in the 29 regions with resting akinesia-dyskinesia than in the 20 hypokinetic regions (CCC = 0.71+/-0.45 vs. 0.84+/-0.23; p < 0.05). Out of the 29 regions with resting akinesia-dyskinesia the 13 segments which showed functional improvement following dobutamine had a higher resting perfusion than the 16 segments which were unresponsive to dobutamine (CCC = 0.83+/-0.32 vs. 0.61+/-0.52, p < 0.05). Similarly, out of the 20 regions with resting hypokinesia the 11 segments having functional reserve showed an higher resting perfusion than the segments which did not (0.96+/-0.21 vs. 0.69+/-0.19; p < 0.05). Early after AMI, the perfusion deficit reflects the severity of the mechanical dysfunction. In regions with baseline dyssynergy resting perfusion is, in general, higher when contractile reserve can be elicited by stress-echo.
The International Journal of Cardiovascular Imaging 10/2001; 17(5):383-93. · 2.29 Impact Factor
-
MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 12/2000; 11(1-2):87-8. · 1.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Results of the present study show that accurate estimates of myocardial blood flow may be obtained using a spatially distributed
model of residual curves of an intravascular indicator. In order to improve myocardial blood flow reliability in blood flow
estimates, also in presence of background noise inT/I curves, a wavelet-based denoising technique was successfully applied to residue curves.
MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 01/2000; 11(1):87-88. · 1.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A simple two-compartment model was used to study the effects of water exchange on the signal produced by an inversion recovery prepared rapid gradient-echo sequence during the first passage of a low dose of an intravascular contrast agent. Water exchange at intermediate rates of exchange (1-10 Hz) between the vascular and extravascular spaces caused the form of the signal changes during the first pass to be dependent on both the fractional sizes of the vascular and extravascular compartments and on the exchange rate. Unless the effects of exchange are minimized by using a very short inversion time, parameters such as the peak height and area under the curve will be affected by regional and/or pathological variations in the exchange rate and the size of the vascular fraction. The mean transit time (MTT) is, however, less affected by water exchange. Experimental first-pass data produced by intravascular low-dose injections of iron oxide particles were studied in five pigs at 0.5 T. The MTT as derived from the first-pass curves, without deconvolution with the arterial input function, was well correlated with the myocardial blood flow (MBF) as measured using radioactive microspheres (r = 0.70, n = 52, P < 0.01). Other first-pass parameters such as the peak height or area under the curve exhibited either a poorer, or no, correlation with the MBF. The data suggest that the MTT of the first pass of an intravascular contrast agent may be a robust, quantitative method for assessing myocardial blood flow in patients.
Journal of Magnetic Resonance Imaging 03/1999; 9(3):402-8. · 2.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The evaluation of myocardial perfusion is of clinical relevance in ischemic heart disease. New noninvasive and nonionizing imaging techniques for the evaluation of myocardial perfusion are progressing. The present status and the future development of echo-contrast and dynamic-contrast MR imaging are discussed for myocardial perfusion studies.
Acta radiologica. Supplementum 02/1997; 412:79-84.
-
[show abstract]
[hide abstract]
ABSTRACT: Some fundamentals of image processing, its applications to MR imaging, and inherent problems are discussed. Processing of contrast-enhanced dynamic imaging studies is introduced and some clinical examples explain the applications in research and clinical routine.
Acta radiologica. Supplementum 02/1997; 412:7-19.
-
[show abstract]
[hide abstract]
ABSTRACT: A computer system for the manual, semi-automatic, and automatic analysis of dynamic MR images was to be developed on UNIX and personal computer platforms. The system was to offer an integrated and standardized way of performing both image processing and analysis that was independent of the MR unit used.
The system consists of modules that are easily adaptable to special needs. Data from MR units or other diagnostic imaging equipment in techniques such as CT, ultrasonography, or nuclear medicine can be processed through the ACR-NEMA/DICOM standard file formats. A full set of functions is available, among them cine-loop visual analysis, and generation of time-intensity curves. Parameters such as cross-correlation coefficients, area under the curve, peak/maximum intensity, wash-in and wash-out slopes, time to peak, and relative signal intensity/contrast enhancement can be calculated. Other parameters can be extracted by fitting functions like the gamma-variate function. Region-of-interest data and parametric values can easily be exported.
The system has been successfully tested in animal and patient examinations.
Acta Radiologica 02/1997; 38(1):165-72. · 1.37 Impact Factor
-
D Rovai,
M Zanchi, M Lombardi,
E Magagnini,
P Chella,
A Pieroni,
E Picano,
M Ferdeghini,
H Morris,
A Distante,
A L'Abbate
[show abstract]
[hide abstract]
ABSTRACT: In patients with previous myocardial infarction and left ventricular asynergy, dipyridamole infusion may have the capacity to unmask myocardial viability through transient recovery of contractile function in asynergic segments. The purpose of this study was to assess simultaneous changes in myocardial perfusion and LV function--elicited by dipyridamole infusion--in infarcted, asynergic segments. The echo contrast agent Albunex was injected into the left coronary artery of 19 patients (17 males, age 49-70 years) with previous myocardial infarction and baseline left ventricular asynergy, both before and after dipyridamole infusion (up to 0.56 mg.kg-1, i.v.). Analysis was not possible in three patients due to inadequate image quality and in two due to weak contrast. There were no major adverse events, or changes in vital signs or demonstrated on the electrocardiogram. After dipyridamole, 7/14 patients, showed an improvement in regional function of asynergic segments ('responders'), whereas seven patients did not ('non-responders'). Among non-responders, five had a myocardial perfusion deficit corresponding to 41% of the total left ventricular area before dipyridamole and to 38% after dipyridamole. No baseline perfusion deficits were observed in the remaining two non-responders; one of these, however, developed transient asynergy and perfusion deficit after dipyridamole. Among responders, five showed a normal perfusion pattern, both before and after dipyridamole, while the remaining two showed a perfusion deficit which markedly decreased after dipyridamole (from 32% to 13% of total left ventricular area). Thus, residual contractile reserve of asynergic, infarcted ventricular segments appears to be associated with myocardial perfusion either preserved at baseline or recruitable by a coronary dilator stimulus.
European Heart Journal 03/1996; 17(2):296-301. · 10.48 Impact Factor
