Search results for " Subtraction"
showing 10 items of 68 documents
Detection of central pulmonary artery thromboemboli by transesophageal echocardiography in patients with severe pulmonary embolism.
1992
Transthoracic echocardiography generally provides only indirect signs of pulmonary embolism. In contrast, with transesophageal echocardiography the thromboembolus itself can be visualized in the central parts of the pulmonary artery. The aims of our study were to evaluate, first, the incidence of central pulmonary artery thromboemboli in patients with severe pulmonary embolism, and second, the accuracy of the echocardiographic diagnosis. Our study group comprised 60 patients with proved severe pulmonary embolism. All patients were examined by transthoracic and transesophageal echocardiography. The echocardiographic findings concerning the absence or presence of central pulmonary artery thro…
MR angiography of the pedal arteries with gadobenate dimeglumine, a contrast agent with increased relaxivity, and comparison with selective intraarte…
2007
Purpose To compare gadobenate dimeglumine (Gd-BOPTA)–enhanced MR angiography (i.e., contrast-enhanced MRA [CE-MRA]) of the pedal vasculature with selective digital subtraction angiography (DSA) in patients with peripheral arterial occlusive disease (PAOD). Materials and Methods A total of 22 patients with PAOD were prospectively examined at 1.5T. For contrast enhancement, 0.1 mmol/kg body weight of Gd-BOPTA were applied. MRA consisted of dynamic imaging with acquisition of six consecutive data sets. Acquisition time for each data set was 24 seconds, voxel size was 1.0 × 1.0 × 1.3 mm3. A total of 20 out of 22 patient underwent selective DSA, two patients fine-needle DSA. DSA and MRA were per…
Durability of open popliteal artery aneurysm repair
2014
Objective The objective of this study was to analyze our long-term results after open surgery for popliteal artery aneurysm. Methods Records of patients who received surgery between 1998 and 2010 were retrieved from a computerized database and analyzed retrospectively. End points of the study were perioperative mortality and morbidity and patency and limb salvage rate. Results Two hundred and six popliteal aneurysms (median diameter, 30 mm; interquartile range, 18 mm) were treated (161 elective, 45 emergent) in 154 patients (mean age, 67 ± 11 years) using vein grafts (82%) via the medial approach (92%). Above-knee popliteal artery (45%) and below-knee popliteal artery (65%) were the predomi…
Endovascular Embolization of a Large High-Flow Splenic Arteriovenous Fistula and Aneurysm Using the Amplatzer Vascular Plug II.
2015
We describe the use of an Amplatzer Vascular Plug (AVP) II for embolizing a large high-flow splenic arteriovenous fistula and an aneurysm in a young patient. This patient presented to our center with persistent mild abdominal discomfort, 5 years after open splenectomy. Contrast-enhanced computed tomography angiography showed the presence of a fistula between the splenic arterial and splenic venous remnants and a resultant fusiform aneurysmal dilatation of the residual splenic vein. We decide to embolize the splenic artery with a 12-mm diameter AVP II with an oversizing by 70% of the vessel diameter. Celiac angiography performed 5 min postembolization revealed complete obliteration of the sp…
Quantifying stenosis in renal arteriograms: a fuzzy syntactic analysis.
1999
AbstractThe introduction of fuzzy logic improves a system for the automatic quantification of renal artery lesions seen in digital subtraction angiograms. A two-step approach has been followed. An earlier system based on non-fuzzy syntactic analysis provided a clear symbolic description of the stenotic lesions. Although this system worked correctly, it did not take into account the variability and uncertainty inherent to image processing and to knowledge on the reference diameter. This system has been improved by the introduction of fuzzy logic in the representation of the reference diameter. It provides a description of the stenosis in terms of fuzzy quantities. To illustrate the benefits …
Kontrastverstärkte MR-Angiographie abdomineller Gefäßean einem 1.0 T-System*
2000
Purpose To evaluate the efficacy of breath-hold, three-dimensional, contrast-enhanced magnetic resonance angiography with a 1.0 T system for imaging the abdominal vessels in comparison to conventional arteriography (CA). Methods The abdominal aorta and visceral arteries were studied in 54 patients (60 examinations) on a 1.0 T scanner using an ultrafast gadolinium-enhanced gradient-echo sequence with the following parameters: TR/TE = 3.8/1.4 ms, flip angel 25 degrees, matrix 198 x 256, field 380-420 mm, pixel size 1.9 x 1.48 mm2, slice thickness 1.5-2.5 mm, acquisition time 22-26 sec. Individual circulation times were determined by a test bolus before each MR angiography. Conventional arteri…
Background subtraction for aerial surveillance conditions
2014
International audience; The first step in a surveillance system is to create a representation of the environment. Background subtraction is widely used algorithm to define a part of an image that most time remains stationary in a video. In surveillance tasks, this model helps to recognize those outlier objects in an area under monitoring. Set up a background model on moving platforms (intelligent cars, UAVs, etc.) is a challenging task due camera motion when images are acquired. In this paper, we propose a method to support instabilities caused by aerial images fusing spatial and temporal information about image motion. We used frame difference as first approximation, then age of pixels is …
Quantitative Cerebral Blood Flow Mapping in Stroke and During Mental Stimulation After Intravenous Injection of 195mAu
1985
The new short life isotope 195mAu has some suitable features for quantitative cerebral blood flow mapping. Its half-life is 30.5 s; therefore an injection can be repeated after 3 min (six half-lives) without any need for background subtraction and with the same specific activity. The calculated whole body radiation dose after three successive administrations of 25 mCi 195mAu amounts to 50 mrad. In comparison to a 99mTc pertechnetate injection it is estimated that the dose to the patients is reduced by a factor of eight (Garcia et al. 1981).
TAKING A LOOK AT CHINESE PEDAGOGY IN SHUXUE [MATHEMATICS]: A DIALOGUE BETWEEN CULTURES TO APPROACH ARITHMETIC AT FIRST AND SECOND ITALIAN PRIMARY CLA…
2013
The purpose of this paper is to analyze two cases of task design about straws and word problems in different cultural traditions (the Eastern and Western one). By means of two paradigmatic examples developed in Italy, we aim at showing, on the one hand, the effects and advantages of intercultural dialogue and, on the other hand, the need to take into account and to respect culturally rooted pedagogies, avoiding uncritical transfer from one culture to another. This perspective implies a reciprocal respect of the different approach modalities and hence a continuous back and forth between the practical and the deeply related theoretical dimension
Noise assisted image processing by ensembles of R-SETs
2017
AbstractWe study how noise can assist the processing of an image in a resistance-single electron transistor (R-SET) model. The image is an 8-bit black and white picture. Every grey level is codified linearly into a sub-threshold input potential applied for a prescribed time window to an ensemble of R-SETs that transforms it into a spiking frequency. The addition of a background white noise potential of high amplitude permits the ensemble to process the image by means of the stochastic resonance phenomenon. Aside from the positive aspects, we analyse the negative impact of using noise and how we can minimize it using redundancy and a longer measuring time. The results are compared with the c…