Search results for "tomography"

Blind Radio Tomography

2018

From the attenuation measurements collected by a network of spatially distributed sensors, radio tomography constructs spatial loss fields (SLFs) that quantify absorption of radiofrequency waves at each location. These SLFs can be used for interference prediction in (possibly cognitive) wireless communication networks, for environmental monitoring or intrusion detection in surveillance applications, for through-the-wall imaging, for survivor localization after earthquakes or fires, etc. The cornerstone of radio tomography is to model attenuation as the bidimensional integral of the SLF of interest scaled by a weight function. Unfortunately, existing approaches (i) rely on heuristic assumpti…

Applications and development of acoustic and microwave atomic force microscopy for high resolution tomography analysis

2016

The atomic force microscope (AFM) is a powerful tool for the characterization of organic and inorganic materials of interest in physics, biology and metallurgy. However, conventional scanning probe microscopy techniques are limited to the probing surface properties, while the subsurface analysis remains difficult beyond nanoindentation methods. Thus, the present thesis is focused on two novel complementary scanning probe techniques for high-resolution volumetric investigation that were develop to tackle this persisting challenge in nanometrology.The first technique considered, called Mode Synthesizing Atomic Force Microscopy (MSAFM), has been exploited in collaboration with Dr. Laurene Teta…

Human settlement dynamics and alluvial dynamics of the Rhine River during the Holocene: Geoarchaeology of the site of Oedenburg (Haut-Rhin, France).

2007

The relationship between alluvial dynamics and control parameters such as climate are well known and understood at plurimillennial and pluriannual time-scales. But it is not really the case at multicentennial and multidecennal time-scales compatible with human society settlement time-scales. In a present and near future context, when human settlement may be affected by strong climatic variation, alluvial dynamics understanding is however a major centre of attention to the development of efficient models. To approach this scale-related question, a segment of the Upper Rhine River presenting both anastomosed and braided was investigated. This area also gives us the opportunity to study settle…

Metabolic mapping with bioluminescence: basic and clinical relevance

2002

This review is focused on metabolic mapping in biological tissue with quantitative bioluminescence and single photon imaging. Metabolites, such as ATP, glucose and lactate, can be imaged quantitatively and within microscopic dimensions in cryosections from shock frozen biological specimens using enzyme reactions and light emission by luciferases. The technique has been applied in numerous targets and models of experimental biomedical research, such as multicellular spheroids, various organs of laboratory animals in a physiological or pathophysiological state, and even in plant seeds. Among numerous other aspects, data obtained with this method have contributed to the elucidation of mechanis…

Three-Dimensional Surface Display in Blood Pool Gated SPECT

1994

In 14 patients (4 in good health and 10 with coronary heart disease) a blood pool gated single photon emission computed tomography (SPECT) was executed. The transaxial slices of the cardiac blood pool were reconstructed. A three-dimensional surface display was employed for the analysis of the tomographic data. A fixed distance, a fixed threshold (50%), and some different planes of view were employed. The test permitted visualiza tion of the ventricular and the atrial movements in all patients. The right ventricle was clearly seen in the right anterior oblique plane of view. The aortic beating was seen. In normal patients the left ventricle, clearly seen in left anterior oblique plane, shra…

X-ray microtomography and laser ablation in the analysis of ink distribution in coated paper

2015

A novel method was developed for studying the ink-paper interface and the structural variations of a deposited layer of ink. Combining high-resolution x-ray tomography with laser ablation, the depth profile of ink (toner), i.e., its varying thickness, could be determined in a paper substrate. X-ray tomography was used to produce the 3D structure of paper with about 1 μm spatial resolution. Laser ablation combined with optical imaging was used to produce the 3D structure of the printed layer of ink on top of that paper with about 70 nm depth resolution. Ablation depth was calibrated with an optical profilometer. It can be concluded that a toner layer on a light-weight-coated paper substrate …

Quantitative structural analysis of trabecular alveolar bone in the mandible by multidetector computed tomography: Differences according to tooth pre…

2019

Background and objective: There is a lack of quantitative measures of the quality of alveolar trabecular bone, an important factor in implantology. This study aimed to develop a method of objectively assessing the quality of trabecular bone by means of image processing and structural analysis of multidetector computed tomography images and to establish differences between tooth types and tooth presence/absence. Materials and methods: We analyzed 20 patients who underwent multidetector computed tomography to evaluate mandibular bone and tooth positioning. Image analysis included automatic segmentation of the mandible, obtainment of sections perpendicular to the dental arch, and structural an…

Aortic valve and vascular calcium score in pre-TAVI CT: correlation with early post-procedural complications

2023

Abstract Purpose The aim of our study was to evaluate the prevalence of early complications after Transcatheter Aortic Valve Implantation (TAVI) and their correlation with the Calcium Score (CS) of the aortic valve, aorta and ilio-femoral arteries derived from pre-procedural computed tomography (CT). Materials and methods We retrospectively reviewed 226 patients (100 males, mean age 79.4 ± 6.7 years) undergoing 64-slice CT for pre-TAVI evaluation from January 2018 to April 2021. The population was divided into CS quartiles. Results Overall, 173 patients underwent TAVI procedure, of whom 61% presented paravalvular leak after the procedure, 28% presented bleeding or vascular complications, 25…

Management of synchronous vascular and ductal anomalies in living donor liver transplantation for hepatic epithelioid hemangioendothelioma

2013

Pulmonary contusion: CT vs plain radiograms.

1989

In experimentally induced pulmonary contusions, CT (n = 27) and chest X-ray (n = 24) findings were compared with the findings at autopsy. Twenty-seven of 27 (100%) pulmonary contusions were visible by CT immediately after trauma compared with 9 of 24 (37.5%) in the chest X-ray. After 30 min follow-up, 18 of 24 (75%) lesions were seen on the plain film. Five of 24 (21%) contusions escaped detection on conventional radiographs. Computed tomography underestimated lesion size in 5 of 60 (8%) measurements, conventional radiographs in 21 of 36 (58%) measurements. Pathological examination never revealed a pulmonary contusion that was not demonstrated by CT. Therefore, pulmonary contusion seems unl…