Search PubMed⌕ Search

Biomedical subjects

R C Brasch

Publications and source records attributed to R C Brasch.

At least 199 records · Page 11Linked to original sources
PubMed1978

The right paratracheal stripe in children.

The width of the right paratracheal stripe (RPS) has been established in normal adults but not in normal children. The thymus and great vessels are relatively larger in children than in adults and could obscure or widen the RPS. We found that obscuration does occur and, therefore, the RPS is less often measurable in children than in adults. Widening by the thymus and great vessels, however, does not occur. The width of the RPS in normal children, 0.5 to 3.0 mm, is slightly less than in adults. From this study of normal children and our subsequent experience with pediatric patients, we conclude that in a child an RPS 4 mm or wider is reliable evidence of disease affecting the trachea, mediastinum, or pleura.

Adolescent↗
PubMed1978

The effect of gastrografin and glucagon on CT scanning of the pancreas: a blind clinical trial.

The effect of Gastrografin and glucagon on pancreatic CT scanning was studied in a blind clinical trial. Twenty-five patients had a pancreatic CT scan performed on an 18-second scanner and a repeat pancreatic CT scan following administration of Gastrografin and glucagon. The results were statistically significant: decreased streak artifacts; improved pancreatic head, body and tail delineation; and improved overall pancreatic visualization. Gastrografin-glucagon administration is recommended prior to pancreatic CT scanning if the scanning cycle is 18 seconds or longer.

Diatrizoate↗
PubMed1978

Computed body tomography in children: evaluation of 45 patients.

Computed tomographic (CT) body scans from a series of 45 infants and children were reviewed for the indications leading to the examinations, for technical quality of the images, and for diagnostic value of CT scanning. Useful diagnostic information was obtained in 30 of the 39 cases with technically satisfactory images. Individual case reports of CT examinations including findings from other imaging studies demonstrate how CT can interface with other methods to yield additional diagnostic information. Methods of patient preparation and suggested indications for CT body scan examinations of children are presented.

Adolescent↗
PubMed1978

Computed tomographic scanning in children: comparison of radiation dose and resolving power of commercial CT scanners.

Surface and internal radiation doses for abdominal computed tomography (CT) of children were determined using child-sized phantoms and seven models of CT body scanners. Resolving power of each scanner was determined simultaneously with the radiation dose determination. The average surface skin dose for a complete CT body examination ranged from 0.39 to 5.60 rad, varying with patient size and model of CT scanner employed. A high contrast (12%) resolving power phantom of water-filled holes in acrylic showed a range of 1.75--2.25 mm.

Child↗
PubMed1976

Delay in the prehospital phase of acute myocardial infarction. Lack of influence on incidence of sudden death.

Prehospital delay is considered to be an important cause of out-of-hospital coronary mortality. Behavior of patients and physicians in response to the symptoms of myocardial infarction (MI) or impending out-of-hospital death (OHD) was studied for 107 consecutive acute coronary events in Framingham, Mass. Delay due to inappropriate patient behavior was the most important component of total delay. Delay related to patient-physician contact occurred in two thirds of MI cases and was more than 30 minutes in half of these. Office visits and inappropriate triage by nurses and receptionists were important factors in physician delay. However, 60% to 75% of OHDs occur so rapidly that their prevention by reduction of prehospital delay seems impossible. A strategy for reduction of delay that might be of benefit in preventing some of the remaining OHDs is described.

Acute Disease↗
PubMed1974

Community surveillance for coronary heart disease: the Framingham Cardiovascular Disease Survey. Methods and preliminary results.

The Framingham Cardiovascular Disease Survey was undertaken to test the hypothesis that a short-term surveillance study of a defined population could yield incidence data comparable to those obtained by an elaborate longitudinal study of the same population, at a fraction of the cost. New cases of coronary heart disease (CHD), congestive heart failure (CHF) and stroke occurring from June 15, 1970 through June 14, 1971, were detected by monitoring admissions to hospitals and nursing homes, reporting of new events by local physicians and perusal of death certificates, Necessary data on each case were collected and reviewed by a panel of physicians using strict diagnostic criteria. Incidence rates based on 332 CHD or CHF events were calculated and were found to be consistent with findings of the Framingham Heart Study. A one-year community surveillance study is an economical and reasonably accurate method of determining the incidence of CHD and CHF.

Adult↗
PubMedDate not supplied

Detection of zonal renal ischemia with contrast-enhanced MR imaging with a macromolecular blood pool contrast agent.

The potential of magnetic resonance (MR) imaging enhanced with albumin-(gadolinium diethylenetriaminepentaacetic acid [DTPA])35, a macromolecular blood pool marker, for detection of focal changes in renal perfusion was studied in a myoglobinuric acute renal failure (ARF) model in the rat. T1-weighted spin-echo postcontrast images of injured kidneys at 3 hours after glycerol injection showed three distinct zones: a strongly enhanced outer cortex, a low-intensity inner cortex, and a strongly enhanced medulla. The distinct band of low intensity in the inner cortex indicated zonal decreased blood volume, corresponding to published microsphere data showing zonal low perfusion in the inner cortex. Contrast differences between parenchymal zones were significant for at least 30 minutes. No focal ischemic changes could be delineated on nonenhanced images. Enhanced and nonenhanced images of injured kidneys obtained at 24 hours after glycerol injection revealed no zonal differentiation. Contrast-enhanced MR imaging data in this ARF model correlated well with pathologic data and microsphere perfusion results. Contrast-enhanced characterization of the ischemic phase of renal injury with MR imaging may improve specificity for the diagnosis of ARF and may serve as a marker for therapeutic intervention.

Albumins↗
PubMedDate not supplied

Comparison of Gd-EOB-DTPA and Gd-DTPA for contrast-enhanced MR imaging of liver tumors.

A new hepatobiliary contrast agent for magnetic resonance (MR) imaging, gadolinium-ethoxybenzyl (EOB)-diethylemetriaminepentaacetic acid (DTPA), was compared with Gd-DTPA to define the potential for improving tumor-liver contrast in a rodent liver adenocarcinoma model. With a T1-weighted spin-echo sequence, the contrast-to-noise ratio (C/N) for tumor before contrast agent administration was 5 (arbitrary units), the tumor appearing slightly hypo-intense with respect to liver parenchyma. After Gd-DTPA injection (0.1 mmol/kg), tumor enhanced more strongly than liver, resulting in an equalization of tumor and liver signal intensities and a decline in C/N to zero at 3 minutes after injection. After Gd-EOB-DTPA injection (0.1 mmol/kg), liver enhanced more strongly than tumor. Five minutes after injection, C/N increased from 5 to 25 and remained above 17 for 50 minutes. The data indicate that Gd-EOB-DTPA yields higher and more prolonged tumor-liver contrast than Gd-DTPA on T1-weighted spin-echo images. The high liver-tumor contrast after Gd-EOB-DTPA administration should prove clinically advantageous for MR imaging detection of focal hepatic masses.

Animals↗
PubMedDate not supplied

Safety aspects and pharmacokinetics of inhaled aerosolized gadolinium.

This study evaluated the pharmacokinetics and potential toxicity of inhaled aerosolized gadopentetate dimeglumine. The pharmacokinetics were evaluated with in vitro relaxometry of the lungs, blood, urine, and liver before and for up to 36 hours after a 5-minute inhalation of aerosolized gadopentetate dimeglumine (0.25 mol/L). For assessment of potential toxicity, hemodynamic variables were monitored during and for 10 minutes after inhalation. Extravascular lung water was measured before and after exposure. Finally, the potential for tissue damage was evaluated histologically. Pulmonary clearance of aerosolized gadopentetate dimeglumine was monoexponential with a half-time of 2.16 hours. Aerosolized gadopentetate dimeglumine was excreted through the kidneys, as shown by the decrease in urinary T1. Renal elimination was completed by 30 hours. No acute hemodynamic effect, histologic change, or induction of edema was demonstrated. This study shows that inhalation of aerosolized gadopentetate dimeglumine is well tolerated in rats and favors the further evaluation of this administration route, including clinical trials.

Aerosols↗
PubMedDate not supplied

MR imaging of blood oxygenation-dependent changes in focal renal ischemia and transplanted liver tumor in rat.

The potential of using fast magnetic resonance (MR) imaging in conjunction with apnea-induced blood deoxygenation for the noninvasive monitoring of relative perfusion in the rat abdomen has been studied with two experimental models: glycerol-induced focal renal ischemia and transplanted liver tumor. Gradient-echo echo-planar imaging (GRE-EPI) (TE of 20 msec at 2T) of liver and kidney was performed before, during, and after a 60-second apnea episode and then was followed in the same rat by contrast-enhanced (a) GRE-EPI and (b) T1-weighted spin-echo imaging (TR msec/TE msec = 200/6) with polylysine-(gadolinium-DTPA [diethylenetriaminepentaacetic acid]). The results indicate that a noninvasive vascular challenge due to apnea can be used for the detection of focal tissue perfusion abnormalities in rat kidney and liver tumor.

Animals↗
PubMedDate not supplied

Effect of varying the molecular weight of the MR contrast agent Gd-DTPA-polylysine on blood pharmacokinetics and enhancement patterns.

The effects of varying the molecular weight of gadolinium-DTPA (diethylenetriaminepentaacetic acid)-polylysine, a macromolecular magnetic resonance (MR) imaging contrast agent, on blood pharmacokinetics and dynamic tissue MR imaging signal enhancement characteristics were studied in normal rats. Blood elimination half-life, total blood clearance, volume of the central compartment (Vcc) and the steady-state distribution volume (Vssd) were calculated for four Gd-DTPA-polylysine polymers with average molecular weights of 36, 43.9, 139, and 480 kd and compared with corresponding values for Gd-DTPA (0.57 kd) and Gd-DTPA-albumin (92 kd). Blood elimination half-life increased seven-fold with an increase in molecular weight from 36 to 480 kd. The Vcc values for all polylysine polymers did not differ significantly from the Vcc value for Gd-DTPA-albumin but were significantly smaller than the Vcc value for Gd-DTPA. The Vssd value for Gd-DTPA did not differ significantly from the Vssd value for the 36- and 43.9-kd polymers but was significantly larger than the Vssd values for the 139- and 480-kd polymers and for Gd-DTPA-albumin. On T1-weighted coronal spin-echo MR images, dynamic signal enhancement profiles in liver and kidney for the 36-, 43.9-, and 480-kd Gd-DTPA-polylysine chelates corresponded to the blood pharmacokinetic data. Increasing molecular weight of Gd-DTPA-polylysine formulations substantially slows blood clearance and produces a prolonged, almost constant tissue signal enhancement for the 60-minute observation period.

Animals↗
PubMedDate not supplied

Contrast enhancement in experimental radiation-induced liver injury: comparison of hepatocellular and reticuloendothelial particulate contrast agents.

We compared the liver enhancement of two superparamagnetic agents, polycrystalline iron oxide nanoparticles (PION) and PION coated with asialofetuin (ASF), in an experimental model of focal radiation-induced hepatitis. PION, a reticuloendothelial system-directed agent, and PION-ASF, a hepatocellular-directed agent, were compared for time-dependent liver enhancement in an experimental model of radiation-induced liver injury. Using the reticuloendothelial system (RES)-directed PION, the normal, nonirradiated portion of the liver decreased in signal intensity (SI) with a mean negative enhancement of -66% +/- 4, whereas the irradiated portion (60 Gy, 3 days before imaging) of the liver decreased in SI by -24% +/- 2, significantly less (P <.05). SI changes in irradiated liver tissue using PION were dose-dependent, being more pronounced with lower radiation exposure. The difference in SI changes induced by PION-ASF between irradiated and nonirradiated liver was not statistically different, but SI decreased with a mean negative enhancement of -80% +/- 2. The RES-directed PION is more sensitive for the detection of radiation-induced hepatitis than is the hepatocyte-directed PION-ASF. The insensitivity of PION-ASF enhancement for diffuse liver injury may be clinically advantageous for detecting focal lesions in the presence of diffuse hepatic injury.

Animals↗
PubMedDate not supplied

Comparison of albumin-(Gd-DTPA)30 and Gd-DTPA-24-cascade-polymer for measurements of normal and abnormal microvascular permeability.

The purpose of this study was to compare a new MR macromolecular contrast medium (MMCM), gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-24-cascade-polymer, to a well-studied prototype MMCM, for the potential of distinguishing tissues of varying endothelial permeability. Three tissue models of varying capillary permeability were studied in a total of 46 rats: normal myocardium (normal capillaries), subcutaneously implanted adenocarcinoma (mild capillary leak), and reperfused infarcted myocardium (high capillary leak). TI-weighted MRI was performed before and dynamically after injection of either albumin-(Gd-DTPA)30 or the cascade polymer (each .02 mmol gadolinium [Gd] per kg). Data analysis based on a two-compartment kinetic model yielded estimates of fractional blood volume (BV) (percentage) and fractional leak rate (FLR) (1 per hour). Permeability to the cascade polymer as reflected in FLR was considerable in normal myocardium (8.24 per hour), of similar value in tumors (8.55 per hour), but significantly greater in infarcted myocardium (39.17 per hour, P < .01) versus normal myocardium. The larger albumin-(Gd-DTPA)30 demonstrated minimal extravasation in normal myocardium (FLR .33 per hour); FLR in tumors was 100% higher (.66 per hour, P < .002) and FLR in reperfused capillaries was significantly greater (7.94 per hour, P < .001). Based on capillary permeability measurements, the cascade polymer may have limited utility for detection of mildly increased microvascular permeabilities. For severe tissue injury, the cascade polymer can resolve abnormal microvascular integrity.

Analysis of Variance↗
PubMedDate not supplied

Histologic confirmation of microvascular hyperpermeability to macromolecular MR contrast medium in reperfused myocardial infarction.

A macromolecular MR contrast medium (MMCM) designed to permit histochemical staining and specific tissue localization, albumin-(biotin)10-(Gd-DTPA)25 (Bio-Alb-Gd), was used in a rat model of reperfused myocardial infarction to confirm the presence and distribution of microvascular hyperpermeability. T1-weighted spin-echo images were acquired before and after administration of Bio-Alb-Gd. An avidin-biotin-complex (ABC) stain, specific for the biotinylated MR contrast medium, was used to define the MMCM distribution and to detect any regional change in microvascular permeability related to infarction. Immediately after Bio-Alb-Gd administration, the infarcted region was enhanced, with greatest signal intensity noted at the rim and less at the center. There was a gradual increase in signal intensity of the initially hypointense central region. The steady increase in signal intensity of the central region suggested convection transport of MMCM through the interstitial space and its influx into cellular compartment after leakage from the vascular compartment. Histologic findings confirmed regional microvascular hyperpermeability corresponding to the site of infarction and a predominant rim distribution of the MMCM. Bio-Alb-Gd was identified at high microscopic power in the intravascular, interstitial, and intracellular spaces at the periphery of reperfused infarcted myocardium. Bio-Alb-Gd can be used as an MR contrast medium in reperfused infarcted myocardium to confirm the existence and to localize altered microvascular permeability to macromolecules. Bio-Alb-Gd contrast technique removes all the ambiguity between the distribution of the MR or other imaging contrast agent and the distribution of the substrate for histochemical staining.

Albumins↗
PubMedDate not supplied

Comparison of gadopentetate dimeglumine and albumin-(Gd-DTPA)30 for microvessel characterization in an intracranial glioma model.

To compare the performance of macromolecular albumin gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)30 and low molecular weight gadopentetate dimeglumine for microvessel characterization, we examined an intracranial 9L glioma model in which increased angiogenesis, hypervascularity, and hyperpermeability mimic characteristics of clinical malignant brain tumors. Dynamic MRI data were analyzed using a bidirectional, two-compartment kinetic model to extract quantitative estimates for fractional blood volume (fBV) and permeability surface area product (PS). Three criteria were used for comparison of contrast agent performance: (a) tumor conspicuity, defined as the contrast-to-noise ratio (CNR); (b) dynamic range of differential permeability estimates between tumor and normal brain; (c) reasonableness of blood volume estimates. Gadopentetate was superior to macromolecular albumin-(Gd-DTPA)30 for detection of 9L brain gliomas and for measurements of hyperpermeability.

Albumins↗