Search results for "tomography"
showing 10 items of 2332 documents
High-Resolution Computed Tomographic Evaluation of Airway Distensibility and the Effects of Lung Inflation on Airway Caliber in Healthy Subjects and …
2001
The effects of a deep inspiration (DI) in individuals with asthma differ from those observed in healthy subjects. It has been postulated that the beneficial effect of lung inflation is mediated by airway stretch. One hypothesis to explain the defects in the function of lung inflation in asthma is that a DI may be unable to stretch the airways. This may result from attenuation of the tethering forces between the airways and the surrounding parenchyma. In the current study, we used high-resolution computed tomography (HRCT) to examine the ability of a DI to distend the airways of subjects with asthma (n = 10) compared with healthy subjects (n = 9) at baseline and after increasing airway tone …
Airway remodelling assessed by sputum and high resolution computed tomography in asthma and COPD
2004
It is not known whether sputum elastase, metalloproteinase (MMP)-9 and tissue-inhibitor metalloproteinase (TIMP)-1 are related to structural changes of the airways, as assessed by high-resolution computed tomography (HRCT) scan. The relationships between these markers and the magnitude of structural changes of the airways in asthma and chronic obstructive pulmonary disease (COPD) were assessed. Induced sputum and HRCT scan were performed in 30 asthmatics (14 mild and 16 severe) and in 12 patients with COPD. A greater extent of HRCT scan abnormalities was found in COPD than in severe and mild asthmatics. HRCT scan abnormalities correlated with the degree of airway obstruction in COPD and in …
Human dopamine receptor D2/D3 availability predicts amygdala reactivity to unpleasant stimuli
2009
r r Abstract: Dopamine (DA) modulates the response of the amygdala. However, the relation between dopa- minergic neurotransmission in striatal and extrastriatal brain regions and amygdala reactivity to affective stimuli has not yet been established. To address this issue, we measured DA D2/D3 receptor (DRD2/3) availability in twenty-eight healthy men (nicotine-dependent smokers and never-smokers) using positron emission tomography with ( 18 F)fallypride. In the same group of participants, amygdala response to unpleasant visual stimuli was determined using blood oxygen level-dependent (BOLD) functional mag- netic resonance imaging. The effects of DRD2/3 availability in emotion-related brain …
The applicability of SRTM in [18F]fallypride PET investigations: Impact of scan durations
2011
The high-affinity radioligand [18F]fallypride (FP) is frequently used for quantification of striatal/extrastriatal D2/3 receptors and the receptor occupancies of antipsychotics (APs). Its 110 minutes half-life allows long scan durations. However, the optimum scan duration is a matter of debate. This investigation focuses on scan-duration-related effects on simplified reference tissue model (SRTM) results and the time point of transient equilibrium in a large sample of dynamic FP positron emission tomography (PET) scans. Fifty drug-free and 50 AP-treated subjects underwent FP-PET scans (180 minutes scan duration). The binding potential ( BPND) of the putamen, thalamus, and temporal cortex w…
Adult exposures from MDCT including multiphase studies: first Italian nationwide survey.
2014
To evaluate the radiation dose in routine multidetector computed tomography (MDCT) examinations in Italian population.This was a retrospective multicentre study included 5,668 patients from 65 radiology departments who had undergone common CT protocols: head, chest, abdomen, chest–abdomen–pelvis (CAP), spine and cardiac. Data included patient characteristics, CT parameters, volumetric CT dose index (CTDIvol) and dose length product (DLP) for each CT acquisition phase. Descriptive statistics were calculated, and a multi-regression analysis was used to outline the main factors affecting exposure.The 75th percentiles of CTDIvol (mGy) and DLP (mGy cm) for whole head were 69 mGy and 1,312 mGy cm…
Tumori gastrointestinali stromali: Aspetti con tomografia computerizzata multidetettore (40-strati)
2006
Purpose. The purpose of this study was to describe the findings and evaluate the role of multidetector (40-slice) computed tomography (MDCT) in the preoperative assessment of gastrointestinal stromal tumours (GISTs). Materials and methods. Thirteen patients with histologically proven GIST (size: 4-30 cm; mean: 9 cm) underwent 40-slice MDCT after the ingestion of 1,000 ml of water. Images were obtained before and 70 s after intravenous injection of 120 ml of iodinated contrast agent. Two experienced radiologists reviewed the CT findings to evaluate lesion site, size, margins, attenuation, growth pattern, enhancement pattern, ascites, lymphadenopathy, direct invasion to adjacent organs and di…
TC perfusionale nell'ischemia cerebrale acuta: Valore predittivo dei parametri di perfusione cerebrale nel discriminare il tessuto vitale da quello i…
2007
Purpose. The aim of this study was to assess the value of computed tomography (CT) perfusion parameters in differentiating tissue viability in acute stoke patients. Materials and methods. Thirteen patients (mean age 63.3 years) with nonhaemorrhagic stroke underwent multidetector perfusion CT within 3 h of symptom onset. Images were continuously acquired at the basal ganglia over 40 s during injection of 90 ml of iodinated contrast medium injected at a rate of 9 ml/s with a 9-s delay. Z-axis coverage was 20 mm. All patients underwent diffusion-weighted magnetic resonance imaging (DWI) within 12 h of perfusion CT to define the extent of the infarct. Perfusion CT data were analysed in regions …
The pterygoid reflex in man and its clinical application
1992
A technique for eliciting and recording the stretch reflex (R) of the medial pterygoid muscle (Pter) is described. The latency was 6.9 ± 0.43 ms in 23 healthy volunteers (mean age 23.7 years) showing a side-to-side difference of 0.29 ± 0.21 ms. The PterR latencies were little shorter and side-to-side difference little greater than of the masseter reflex. Observations in 5 selected patients with small brainstem lesions suggest that the neurons of the PterR afferents form a cluster within the caudal portion of the trigeminal mesencephalic nucleus. Testing the masseter and pterygoid reflexes provides a more precise localization of small ponto-mesencephalic lesions. © 1992 John Wiley & Sons, In…
Peripapillary Choroidal Thickness and Choroidal Area in Glaucoma, Ocular Hypertension and Healthy Subjects by SD-OCT.
2015
Background: The exact pathogenesis of open angle glaucoma and ocular hypertension remains unclear. Hemodynamic influences are discussed as potential risk factors and the choroid may play an important role in the pathogenesis of open angle glaucoma or ocular hypertension. The current study investigates peripapillary choroidal thickness and choroidal area in patients with open angle glaucoma, subjects with ocular hypertension and healthy subjects using spectral-domain OCT. It furthermore assesses the association between peripapillary choroidal thickness and age, central corneal thickness, refractive error and intraocular pressure. Patients and Methods: Prospectively recorded data of 213 eyes …
Virtual Unenhanced Images at Dual-Energy CT: Influence on Renal Lesion Characterization
2019
Background Dual-energy (DE) CT allows reconstruction of virtual noncontrast (VNC) images from a single-phase contrast agent-enhanced examination, potentially reducing the need for multiphasic CT to characterize renal lesions. However, data regarding diagnostic performance of VNC images for the characterization of renal lesions are limited. Purpose To determine whether renal mass CT performed by using VNC images allows for reliable identification of renal lesions and differentiation of contrast-enhanced from unenhanced lesions, compared with unenhanced images. Materials and Methods This is a retrospective study of 293 patients (105 women [mean age, 65 years; age range, 18-91 years] and 188 m…