Search results for "Perfusion"

Measurements of Tumor Blood Flow Using Intraperitoneal Deuterium and 2H-NMR Spectroscopy

1992

Tumors usually have a sparse, disorganized, and inefficient vascular network that leaves a large fraction of the tumor cells in an oxygen deprived and hostile metabolic microenvironment. Hence tumor blood flow, or more correctly nutritive perfusion, has important interactions with treatment efficacy. For example, hypoxic tumor cells, which occur in tumors with low blood flow, are less susceptible to radiation and are probably responsible for most radiation treatment failures (Adams, 1981). Similarly, cytotoxic drug delivery could be predicted by blood flow measurements, with clear implications regarding the expected success of chemotherapy. Thus, the ability to conveniently measure tumor bl…

Battered child syndrome: cerebral ultrasound and CT findings after vigorous shaking.

1992

Child abuse by whiplash-shaking can lead to severe cerebral damage, neurological defects and mental retardation. Cerebral damage has been found with and without external evidence of head injury. We report the sonographic findings in two children after traumatization due to repetitive vigorous whiplash shaking. Cerebral sonography revealed cerebral edema at admission or within 48 hours thereafter. Follow-up studies demonstrated development of marked brain atrophy in both cases. The sonographic findings were confirmed by cranial computerized tomography. Doppler sonography was used to monitor cerebral perfusion by measuring intracranial blood flow. The clinical history of the patients demonstr…

Atropine-resistant effects of the muscarinic agonists McN-A-343 and AHR 602 on cardiac performance and the release of noradrenaline from sympathetic …

1974

Abstract 1 The effects of 4-(m-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium chloride (McN-A-343) and N-benzyl-3-pyrrolidyl acetate methobromide (AHR 602) on cardiac performance and noradrenaline release from terminal sympathetic fibres were measured in isolated perfused hearts of rabbits. 2 In the presence of sufficient atropine to block muscarinic receptors, high concentrations of McN-A-343 and AHR 602 caused no cardiac stimulation and there was no increase in the resting output of noradrenaline into the perfusates. 3 McN-A-343 and AHR 602 increased both the mechanical responses and the transmitter overflow evoked by electrical stimulation of the sympathetic nerves (SNS) but inhibi…

Cerebral blood flow and cerebral death

1969

At present the diagnosis of cerebral death is based on the absence of manifestations of cerebral function (deep coma, wide pupils, absence of reflexes and spontaneous respiration, isoelectric EEG, etc.) during a variable period of time. However, the absence of vital signs of an organ, even for prolonged periods, is no proof of its death. The death of an organ can only be considered as proved by the demonstration that this organ has remained completely deprived of its blood flow during a period of time that surpasses its ability to survive circulatory arrest. In the case of the brain, the permanent absence of clearance of a radioactive tracer deposed within the brain is considered to demonst…

Iteratively Learning a Liver Segmentation Using Probabilistic Atlases: Preliminary Results

2016

This works deals with the concept of liver segmentation by using a priori information based on probabilistic atlases and segmentation learning based of previous steps. A probabilistic atlas is here understood as a probability or membership map that tells how likely is that a point belongs to a shape drawn from the shape distribution at hand. We devise a procedure to segment Perfusion Magnetic Resonance liver images that combines both: a probabilistic atlas of the liver and a segmentation algorithm based on global information of previous simpler segmentation steps, local information from close segmented slices and finally a mathematical morphology procedure, namely viscous reconstruction, to…

Mean sets for building 3D probabilistic liver atlas from perfusion MR images

2012

This paper is concerned with liver atlas construction. One of the most important issues in the framework of computational abdominal anatomy is to define an atlas that provides a priori information for common medical task such as registration and segmentation. Unlike other approaches already proposed so far (to our knowledge), in this paper we propose to use the concept of random compact mean set to build probabilistic liver atlases. To accomplish this task a two-tier process was carried out. First a set of 3D images was manually segmented by a physician. We see the different 3D segmented shapes as a realization of a random compact set. Secondly, elements of two known definitions of mean set…

Mobile phone based laser speckle contrast imager for assessment of skin blood flow

2014

Assessment of skin blood flow is of interest for evaluation of skin viability as well as for reflection of the overall condition of the circulatory system. Laser Doppler perfusion imaging (LDPI) and laser speckle contrast imaging (LASCI) are optical techniques used for assessment of skin perfusion. However, these systems are still too expensive and bulky to be widely available. Implementation of such techniques as connection kits for mobile phones have a potential for primary diagnostics. In this work we demonstrate simple and low cost LASCI connection kit for mobile phone and its comparison to laser Doppler perfusion imager. Post-occlusive hyperemia and local thermal hyperemia tests are us…

Evaluation of the registration of temporal series of contrast-enhanced perfusion magnetic resonance 3D images of the liver.

2011

The registration of 2D and 3D images is one of the key tasks in medical image processing and analysis. Accurate registration is a crucial preprocessing step for many tasks; consequently, the evaluation of its accuracy becomes necessary. Unfortunately, this is a difficult task, especially when no golden pattern (true result) is available and when the signal values may have changed between successive images to be registered. This is the case this paper deals with: we have a series of 3D images, magnetic resonance images (MRI) of the liver and adjacent areas that have to be registered. They have been taken while a contrast is diffused through the liver tissue, so intensity of each observed poi…

Stable microvascular angina: instrumental evaluation of coronary microvascular dysfunction with coronary angiography and myocardial scintigraphy

2014

Quantitative Coronary Angiography and Digital Densitometric Perfusion Measurements?How to Assess the Success of Intracoronary Balloon Dilatation

1988

Densitometric evaluation of digital subtraction angiocardiograms allows the assessment of local myocardial perfusion before and after pharmacological stimulation of coronary flow reserve during the catheterization procedure. This report deals with a case of a severe stenosis of the left coronary artery in which PTCA was regarded successful based on an appropriate increase in luminal diameter while an intima and media dissection at the dilatation site was documented. The perfusion measurements, however, pointed out a clear impairment of poststenotic myocardial perfusion after PTCA.