PubMed · 14903409
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1952. ROUND table discussion on vascular problems.. https://doi.org/10.1016/0002-9610(52)90288-2
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Poly(ethylene terephthalate) (PET) film and PET vascular graft were modified by layer-by-layer (LBL) assembly of collagen and chondroitin sulfate (CS) to mimic the natural composition and structure of extracellular matrix. PET materials were first hydrolyzed to endow the surfaces with negative charge. Alternative assembly of positively charged collagen and negatively charged CS was then conducted in an LBL manner to produce biological multilayers. X-ray photoelectron spectroscopy confirmed the occurrence of hydrolysis and existence of collagen and CS. The stepwise layer growth on the PET film was monitored by UV-vis spectroscopy. The multilayers had sufficient stability to pass through the cell culture period (8 days). In vitro endothelial cell culture revealed that the incorporated biomacromolecules could significantly improve the cell attachment, proliferation, and viability. Cells showed more spreading morphology with preserved phenotype, as illustrated by scanning electron microscopy and factor VIII-related antigen immunocytochemistry, respectively.
Intravascular ultrasound (IVUS) imaging is used along with X-ray coronary angiography to detect vessel pathologies. Manual analysis of IVUS images is slow and time-consuming and it is not feasible for clinical purposes. A semi-automated method is proposed to generate 3D reconstructions from IVUS video sequences, so that a fast diagnose can be easily done, quantifying plaque length and severity as well as plaque volume of the vessels under study. The methodology described in this work has four steps: a pre-processing of IVUS images, a segmentation of media-adventitia contour, a detection of intima and plaque and a 3D reconstruction of the vessel. Preprocessing is intended to remove noise from the images without blurring the edges. Segmentation of media-adventitia contour is achieved using active contours (snakes). In particular, we use the gradient vector flow (GVF) as external force for the snakes. The detection of lumen border is obtained taking into account gray-level information of the inner part of the previously detected contours. A knowledge-based approach is used to determine which level of gray corresponds statistically to the different regions of interest: intima, plaque and lumen. The catheter region is automatically discarded. An estimate of plaque type is also given. Finally, 3D reconstruction of all detected regions is made. The suitability of this methodology has been verified for the analysis and visualization of plaque length, stenosis severity, automatic detection of the most problematic regions, calculus of plaque volumes and a preliminary estimation of plaque type obtaining for automatic measures of lumen and vessel area an average error smaller than 1mm(2) (equivalent aproximately to 10% of the average measure), for calculus of plaque and lumen volume errors smaller than 0.5mm(3) (equivalent approximately to 20% of the average measure) and for plaque type estimates a mismatch of less than 8% in the analysed frames.
BACKGROUND AND OBJECTIVES: Intense pulsed light (IPL) sources have been successfully used for coagulation of blood vessels in clinical practice. However, the broadband emission of IPL hampers the clinical evaluation of optimal light parameters. We describe a mathematical model in order to visualize the thermal effects of IPL on skin vessels, which was not available, so far. STUDY DESIGN/MATERIALS AND METHODS: One IPL spectrum was shifted towards the near infrared range (near IR shifted spectrum: NIRSS) and the other was heavily shifted toward the visible range (visible shifted spectrum: VSS). The broadband emission was separated in distinct wavelengths with the respective relative light intensity. For each wavelength, the light and heat diffusion equations were simultaneously solved with the finite element method. The thermal effects of all wavelengths at the given radiant exposure (15 or 30 J/cm2) were added and the temperature in the vessels of varying diameters (60, 150, 300, 500 microm) was calculated for the entire pulse duration of 30 milliseconds. RESULTS: VSS and NIRSS both provided homogeneous heating in the entire vessel. With the exception of the small vessels (60 microm), which showed only a moderate temperature increase, all vessels exhibited a temperature raise within the vessel sufficient for coagulation with each IPL parameter. The time interval for effective temperature raise in larger vessels (diameter >60 microm) was clearly shorter than the pulse duration. In most instances, the vessel temperature was higher for VSS when compared to NIRSS. CONCLUSIONS: We presented a mathematical model capable of calculating the photon distribution and the thermal effects of the broadband IPL emission within cutaneous blood vessels.