Computational investigation of wall shear stress-driven in-stent restenosis

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Diagnostic imaging for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) occurs mostly in individuals with cirrhosis, which is why the guidelines of the most important scientific societies indicate that these patients are included in surveillance programs through the repetition of an ultrasound examination every 6 months. The aim is to achieve early identification of the neoplasia in order to increase the possibility of curative therapies (liver transplantation, surgery or local ablative therapies) and to increase patient survival. HCC nodules arising in cirrhotic livers show characteristic angiographic behavior that can be evaluated with dynamic multidetector computed tomography and dynamic magnetic resonance imaging (MRI). However, the use of these techniques in real life is often hindered by the lack of uniform terminology in reporting and in the interpretation of the exams reflected in the impossibility of comparing examinations performed in different centers and/or at different times. Liver Imaging Reporting and Data System® was created to standardize reporting and data collection of computed tomography and MRI for HCC. In some cases HCC arises in patients with healthy livers and, although there is evidence that angiographic behavior is not different from cirrhotic patients in this clinical situation, the guidelines still indicate the execution of a biopsy. Frequent use of palliative therapeutic techniques such as transarterial chemoembolization, transarterial radioembolization or administration of antiangiogenic drugs (sorafenib) poses problems of interpretation of the therapeutic response with repercussions on the subsequent choices that have been attempted to resolve with the use of stringent criteria such as Modified Response Evaluation Criteria In Solid Tumors

TIPS and HCC: friends or foes ?

Portal hypertension and hepatocellular carcinoma [HCC] are major complications of liver cirrhosis and may coexist in the same patient. Transjugular intrahepatic portosystemic shunt [TIPS] is an effective treatment for recurrent variceal bleeding and refractory ascites although accumulating evidence has shown that its indication is gradually expanding. TIPS placement reduces portal flow by connecting splanchnic vessels to systemic circulation. As a consequence parenchymal portal venous flow is decreased so inducing an ischemic injury. In this condition, a possible activation of hepatic stellate cells, an induction of neoangiogenesis and an increase in secretion of HGF and VEGF may represent possible triggers for hepatocarcinogenesis. On these bases, several studies have explored a possible influence of TIPS on the onset of hepatocellular carcinoma [HCC] in cirrhotic patients. To date the results are controversial and the role of TIPS as risk factor for HCC is still unclear. Moreover, the diversion of portal flow and the onset of arterioportal shunts following TIPS insertion, may reduce the efficacy and the safety profile of transarterial treatments. Until now, very little evidence has been collected regarding this topic and the results are conflicting. Therefore, whether TIPS and hepatocellular carcinoma are either "Friends or Foes" is still an ongoing dilemma

An Active Set Algorithm for Robust Combinatorial Optimization Based on Separation Oracles

We address combinatorial optimization problems with uncertain coefficients varying over ellipsoidal uncertainty sets. The robust counterpart of such a problem can be rewritten as a second-oder cone program (SOCP) with integrality constraints. We propose a branch-and-bound algorithm where dual bounds are computed by means of an active set algorithm. The latter is applied to the Lagrangian dual of the continuous relaxation, where the feasible set of the combinatorial problem is supposed to be given by a separation oracle. The method benefits from the closed form solution of the active set subproblems and from a smart update of pseudo-inverse matrices. We present numerical experiments on randomly generated instances and on instances from different combinatorial problems, including the shortest path and the traveling salesman problem, showing that our new algorithm consistently outperforms the state-of-the art mixed-integer SOCP solver of Gurobi