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To quantify the cooling effect of hepatic vessels on liver radiofrequency (RF) ablation ex situ. Bipolar RF applicators (diameter = 1.8 mm, electrode length = 30 mm) were inserted parallel to perfused glass tubes (diameter = 5 and 10 mm; flow = 250–1,800 ml/min) at distances of 5 and 10 mm in porcine livers ex vivo. RF ablation was performed at 30 W/15 kJ. RF lesions were analyzed by measuring the maximum (r max) and minimum radius (r min) and the lesion area. Glass tubes without flow showed no influence on RF lesions, whereas perfused glass tubes had a significant cooling effect on lesions. r min was reduced to 50% at 5 mm applicator-to-vessel distance and the lesion area was reduced from 407 to 321 mm2 (p

Accurate knowledge of partial anatomy is essential in hepatic surgery but is difficult to acquire. We describe the potential impact of a new technique for constructing three-dimensional virtual images of the portal vein, hepatic artery, and bile ducts and present a representative case. An 80-year-old man was suspected of having papillary cholangiocarcinoma arising in S8 of the liver and extending to the hepatic hilum intraluminaly. Right hemihepatectomy with bile duct resection was planned. However, it was uncertain whether duct-to-duct biliary reconstruction would be possible based on the appearance of the confluence of the right and left hepatic ducts on cholangiogram and conventional computed tomograph. Virtual three-dimensional images of the liver were constructed and revealed vascular and biliary anatomy. They showed that the upper margin of bile duct excision would be 19 mm from the umbilical point of the left portal vein, and that the site of the left branch of the caudate lobe bile duct could be preserved. Based on this information, we performed a sphincter-preserving biliary operation safely without complications. Planning complex biliary surgery may be improved by the use of virtual three-dimensional images of the liver. This approach is especially useful in candidates for postoperative regional chemotherapy.

The carriers of the German Statutory Health Care System have recognized that only mammographic screening according to the European Guidelines for the Quality Assurance of Mammography Screening will permit early detection of breast cancer with an acceptable risk/benefit ratio. In the German pilot projects, regional mammography screening programmes according to the European guidelines are being tested in the framework of the German health care system. The European guidelines require comprehensive quality assurance of all relevant steps in the chain of events involved in screening, from invitation on to therapy and follow-up. Such comprehensive quality assurance involves several medical specialities and other professional groups dealing with out-patient and in-patient health care and requires long-term cooperation with public institutions (population registries, cancer registries). The objective of the pilot projects is to test the organizational and legal conditions essential to introduction of a mammographic screening programme according to the European quality assurance guidelines in Germany.

Die Bedeutung von VR-Anwendungen ergibt sich v.a. dadurch, dass neben dem geometrischen Modell auch ein funktionelles Modell erstellt wird, das Manipulationen erlaubt und quantitative Analysen einschliest.

Background Late Gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) imaging can be used to visualise regions of fibrosis and scarring in the left atrium (LA) myocardium. This can be important for treatment stratification of patients with atrial fibrillation (AF) and for assessment of treatment after radio frequency catheter ablation (RFCA). In this paper we present a standardised evaluation benchmarking framework for algorithms segmenting fibrosis and scar from LGE CMR images. The algorithms reported are the response to an open challenge that was put to the medical imaging community through an ISBI (IEEE International Symposium on Biomedical Imaging) workshop. Methods The image database consisted of 60 multicenter, multivendor LGE CMR image datasets from patients with AF, with 30 images taken before and 30 after RFCA for the treatment of AF. A reference standard for scar and fibrosis was established by merging manual segmentations from three observers. Furthermore, scar was also quantified using 2, 3 and 4 standard deviations (SD) and full-width-at-half-maximum (FWHM) methods. Seven institutions responded to the challenge: Imperial College (IC), Mevis Fraunhofer (MV), Sunnybrook Health Sciences (SY), Harvard/Boston University (HB), Yale School of Medicine (YL), King’s College London (KCL) and Utah CARMA (UTA, UTB). There were 8 different algorithms evaluated in this study. Results Some algorithms were able to perform significantly better than SD and FWHM methods in both pre- and post-ablation imaging. Segmentation in pre-ablation images was challenging and good correlation with the reference standard was found in post-ablation images. Overlap scores (out of 100) with the reference standard were as follows: Pre: IC = 37, MV = 22, SY = 17, YL = 48, KCL = 30, UTA = 42, UTB = 45; Post: IC = 76, MV = 85, SY = 73, HB = 76, YL = 84, KCL = 78, UTA = 78, UTB = 72. Conclusions The study concludes that currently no algorithm is deemed clearly better than others. There is scope for further algorithmic developments in LA fibrosis and scar quantification from LGE CMR images. Benchmarking of future scar segmentation algorithms is thus important. The proposed benchmarking framework is made available as open-source and new participants can evaluate their algorithms via a web-based interface.

On considere la famille a 2 parametres d'equations elliptiques sur un domaine Ω⊂R n a frontiere δΩC ∞ donnee par Δu+αf(u)=μg dans Ω et u=uO sur δΩ, (λ,M)∈R 2 , f 1 g:R→R lisses, f(0)=0 et O≡0 lisse. On montre que, sous certaines restrictions sur f, une bifurcation autour de la solution u≡0 proche (λ 0 ,M 0 ) ou λ 0 est une valeur propre simple de l'equation linearisee Δw+λ 0 f(0)w=0 dans Ω, w=0 sur δΩ et μ 0 =0, peut se decrire par la catastrophe en cusp de Thom