Studio del microcircolo della parete gastrica affetta da patologia infiammatoria e neoplastica mediante Color-Power Doppler ed ecografia con mezzo di contrasto endovenoso

Introduzione: Negli ultimi anni, il color-power Doppler si è dimostrato un utile strumento per valutare le alterazioni della vascolarizzazione della parete intestinale nelle patologie del tratto gastro-enterico. Più di recente, i mezzi di contrasto ecografici di II generazione associati all’ecografia real-time con basso indice meccanico (CEUS) hanno permesso di valutare ecograficamente il microcircolo, consentendo la valutazione della vascolarizzazione di parete nelle patologie associate a flogosi e neoangiogenesi. Studi recenti hanno documentato i pattern Doppler e CEUS nella malattia infiammatoria intestinale. Le alterazioni della vascolarizzazione di parete nella patologia neoplastica, invece, sono state finora valutate con sola tecnica Doppler. Recenti studi basati sull’impiego di tale metodica hanno in effetti dimostrato che l’intensità del segnale vascolare di parete correla con la variante istologica della neoplasia e con il suo grado di invasione vascolare costituendo così un parametro di neoangiogenesi tumorale. Pertanto, ottenere mediante CEUS una più accurata definizione del microcircolo di parete potrebbe aiutare nella diagnosi differenziale tra patologia infiammatoria e neoplastica dello stomaco e fornire utili informazioni per valutare l’ aggressività del cancro gastrico.

Circoli collaterali porto-sistemici all'eco-color-Doppler addominale in pazienti con ipertensione portale cirrotica: correlazione con il gradiente porto-epatico e valore prognostico

Background. Abdominal porto-systemic collaterals (APSC) on Color-Doppler ultrasound are a frequent finding in portal hypertensive cirrhotic patients. In patients with cirrhosis, an HVPG ≥ 16mmHg has been shown to be associated with increased mortality in two studies. Non-invasive indicators of HVPG ≥ 16 mmHg might define a subgroup of high-risk patients, but data on this aspect are lacking. Aims. We aimed to investigate whether HVPG predicts mortality in patients with clinically significant portal hypertension, and if APSC may predict a severe portal hypertensive state (i.e. HVPG≥16mmHg) in patients with cirrhosis and untreated portal hypertension. Methods. We analysed paired HVPG and ultrasonographic data of 86 untreated portal hypertensive cirrhotic patients. On abdominal echo-color-Doppler data on presence, type and number of APSC were prospectively collected. HVPG was measured following published guidelines. Clinical, laboratory and endoscopic data were available in all cases. First decompensation of cirrhosis and liver-disease related mortality on follow-up (mean 28±20 months) were recorded. Results. 73% of patients had compensated cirrhosis, while 27% were decompensated. All patients had an HVPG≥10 mmHg (mean 17.8±5.1 mmHg). 58% of compensated patients and 82% of decompensated patients had an HVPG over 16 mmHg. 25% had no varices, 28% had small varices, and 47% had medium/large varices. HVPG was higher in patients with esophageal varices vs. patients without varices (19.0±4.8 vs. 14.1±4.2mmHg, p<0.0001), and correlated with Child-Pugh score (R=0.494,p=0.019). 36 (42%) patients had APSC were more frequent in decompensated patients (60% vs. 35%, p=0.03) and in patients with esophageal varices (52% vs. 9%,p=0.001). HVPG was higher in patients with APSC compared with those without PSC (19.9± 4.6 vs. 16.2± 4.9mmHg, p=0.001). The prevalence of APSC was higher in patients with HVPG≥16mmHg vs. those with HVPG<16mmHg (57% vs. 13%,p<0.0001). Decompensation was significantly more frequent in patients with HVPG≥16mmHg vs. HVPG<16mmHg (35.1% vs. 11.5%, p=0.02). On multivariate analysis only HVPG and bilirubin were independent predictors of first decompensation. 10 patients died during follow-up. All had an HVPG≥16 mmHg (26% vs. 0% in patients with HVPG <16mmHg,p=0.04). On multivariate analysis only MELD score and HVPG ≥16mmHg were independent predictors of mortality. In compensated patients the detection of APSC predicted an HVPG≥16mmHg with 92% specificity, 54% sensitivity, positive and negative likelihood ratio 7.03 and 0.50, which implies that the demonstration of APSC on ultrasound increased the probability of HVPG≥16mmHg from 58% to 91%. Conclusions. HVPG maintains an independent prognostic value in the subset of patients with cirrhosis and clinically significant portal hypertension. The presence of APSC is a specific indicator of severe portal hypertension in patients with cirrhosis. Detection of APSC on ultrasound allows the non-invasive identification of a subgroup of compensated patients with bad prognosis, avoiding the invasive measurement of HVPG.

Studio della funzione cardiaca e della massa ventricolare sinistra mediante ecocardiografia convenzionale e tissue doppler imaging in una popolazione pediatrica con malattia renale cronica in terapia conservativa e sostitutiva

Background: Cardiovascular disease (CVD) is a common cause of morbidity and mortality in childhood chronic kidney disease (CKD). Left ventricular hypertrophy (LVH) is known to be one of the earliest events in CVD development. Left ventricular diastolic function (DF) is thought to be also impaired in children with CKD. Tissue Doppler imaging (TDI) provide an accurate measure of DF and is less load dependent than conventional ECHO. Aim: To evaluate the LV mass and the DF in a population of children with CKD. Methods: 37 patients, median age: 10.4 (3.3-19.8); underlying renal disease: hypo/dysplasia (N=28), nephronophthisis (N=4), Alport (N=2), ARPKD (N=3), were analyzed. Thirty-eight percent of the patients were on stage 1-2 of CKD, 38% on stage 3, 16% on stage 4. Three patients were on dialysis. The most frequent factors related to CVD in CKD have been studied. LVH has been defined as a left ventricular mass index (LVMI) more than 35.7 g/h2,7. Results: Twenty-five patients (81%) had a LVH. LVMI and diastolic function index (E’/A’) were significantly related to the glomerular filtration rate (p<0.003 and p<0.004). Moreover the LVMI was correlated with the phosphorus and the hemoglobin level (p<0.0001 and p<0.004). LVH was present since the first stages of CKD (58% of patients were on stages 1-2). Early-diastolic myocardial velocity was reduced in 73% of our patients. We didn’t find any correlation between LVH and systemic hypertension. Conclusion: ECHO evaluation with TDI is suggested also in children prior to dialysis and with a normal blood pressure. If LVH is diagnosed, a periodic follow-up is necessary with the treatment of the modifiable risk factors (hypertension, disturbances of calcium, phosphorus and PTH, anemia ).

Utilzzo dei parametri ecocardiografici tradizionali ed a Doppler tissutale nella valutazione della disfunzione atrio-ventricolare in cani affetti da malattia mitralica cronica

In questo lavoro ci siamo posti come obiettivo lo studio della disfunzione atrio-ventricolare mediante tecniche ecocardiografiche avanzate (come il Tissue Doppler Imaging - TDI) in cani affetti da malattia mitralica cronica (MVD). Una prima parte è volta alla valutazione della funzionalità diastolica del ventricolo destro. Ci siamo proposti di analizzare la funzione del ventricolo destro in cani affetti da malattia del cuore sinistro per comprendere se quest’ultima possa condizionare direttamente la performance del settore cardiaco controlaterale. I risultati più importanti che abbiamo riscontrato sono: l’assenza di differenze significative nella disfunzione sisto-diastolica del ventricolo destro in cani con MVD a diverso stadio; la diretta correlazione tra le variabili TDI di funzionalità del ventricolo destro con il grado di disfunzione del ventricolo sinistro, come indicatori di interdipendenza ventricolare; ed infine il riscontro di una maggior tendenza ad alterazioni diastoliche del ventricolo sinistro in cani con ipertensione polmonare. A quest’ultimo proposito, per quanto riguarda le variabili TDI, il rapporto E/e’ dell’anulus mitralico laterale e settale è risultato avere una differenza significativa tra i cani con ipertensione polmonare e quelli privi di ipertensione polmonare (P<0,01). Nel secondo studio abbiamo applicato il TDI per l’analisi della funzione sisto-diastolica dell’atrio sinistro. Il lavoro è stato articolato in una parte di validazione della metodica su cani normali ed una su animali affetti da MDV. I risultati ottenuti mostrano che la valutazione ecocardiografica delle proprietà di deformazione dell’atrio sinistro basata sul TDI è attuabile e riproducibile nel cane. Abbiamo fornito dei valori di normalità per questa specie e confrontato questi dati con quelli ricavati in cani portatori di MVD. Le differenza tra le varie classi di malattia, nei diversi gradi di dilatazione atriale, sono risultate limitate, ma abbiamo individuato delle correlazioni tra i parametri TDI ed alcune variabili di funzionalità atriale.

Fast and accurate numerical solutions in some problems of particle and radiation transport: synthetic acceleration for the method of short characteristics, Doppler-broadened scattering kernel, remote sensing of the cryosphere

The aim of this work is to present various aspects of numerical simulation of particle and radiation transport for industrial and environmental protection applications, to enable the analysis of complex physical processes in a fast, reliable, and efficient way. In the first part we deal with speed-up of numerical simulation of neutron transport for nuclear reactor core analysis. The convergence properties of the source iteration scheme of the Method of Characteristics applied to be heterogeneous structured geometries has been enhanced by means of Boundary Projection Acceleration, enabling the study of 2D and 3D geometries with transport theory without spatial homogenization. The computational performances have been verified with the C5G7 2D and 3D benchmarks, showing a sensible reduction of iterations and CPU time. The second part is devoted to the study of temperature-dependent elastic scattering of neutrons for heavy isotopes near to the thermal zone. A numerical computation of the Doppler convolution of the elastic scattering kernel based on the gas model is presented, for a general energy dependent cross section and scattering law in the center of mass system. The range of integration has been optimized employing a numerical cutoff, allowing a faster numerical evaluation of the convolution integral. Legendre moments of the transfer kernel are subsequently obtained by direct quadrature and a numerical analysis of the convergence is presented. In the third part we focus our attention to remote sensing applications of radiative transfer employed to investigate the Earth's cryosphere. The photon transport equation is applied to simulate reflectivity of glaciers varying the age of the layer of snow or ice, its thickness, the presence or not other underlying layers, the degree of dust included in the snow, creating a framework able to decipher spectral signals collected by orbiting detectors.