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R Ventrone

Publications and source records attributed to R Ventrone.

11 recordsLinked to original sources
PubMed1998

Assessment of myocardial perfusion by intermittent harmonic power Doppler using SonoVue, a new ultrasound contrast agent.

RATIONALE AND OBJECTIVES: The authors evaluated the potential of SonoVue, a new echo contrast agent, for the detection of myocardial perfusion abnormalities using intermittent harmonic power Doppler (IHPD) imaging and different pulse repetition frequencies (PRFs). METHODS: Experiments were performed in vitro (in a tissue-mimicking phantom) and in vivo (in minipigs) in harmonic power Doppler using an ATL HDI 3000 with second harmonic software. SonoVue was injected intravenously in an auricular vein in bolus (dose range 0.01-0.05 mL/kg) in closed-chest animals or as an infusion (rate = 0.1 mL/kg/minute) in open-chest minipigs with reversible left anterior descending coronary artery (LAD) occlusion. The animals were imaged using IHPD gated on the electrocardiogram at end-systole (pulsing interval at each cardiac cycle). The efficacy of SonoVue was evaluated at six PRFs from 500 to 6000 Hz either qualitatively using a subjective scoring system or quantitatively using a digital image analyzer. RESULTS: SonoVue at a dose of 0.01 mL/kg produced a strong and homogeneous myocardial opacification in IHPD. Higher doses prolonged the duration of the contrast effect. Varying the PRF allowed the discrimination of flow velocities in vitro and the detection of perfusion differences within the myocardium during transient LAD occlusion and during immediate reperfusion in vivo. Low PRFs were particularly useful to differentiate the ischemic bed from the healthy one during LAD occlusion. The high flows caused by coronary hyperemia during immediate reperfusion were detected clearly in the reperfused area at high PRFs. CONCLUSIONS: SonoVue is a promising agent for myocardial opacification studies using IHPD. The latter imaging modality is particularly well suited for blood flow detection in tissues. Varying the PRF provides additional information on flow velocity and improves the detection of perfusion differences in the myocardium.

Animals↗
PubMed1997

Gray-scale liver enhancement in VX2 tumor-bearing rabbits using BR14, a new ultrasonographic contrast agent.

RATIONALE AND OBJECTIVES: We evaluated the potential of BR14, a novel gas-based echo contrast agent, for gray-scale liver imaging and VX2 tumor detection/delineation in the conventional and harmonic imaging modes. METHODS: A single dose (0.2 mL/kg) of BR14 was administered to eight VX2 tumor-bearing rabbits. Imaging was performed with an ATL-HDI 3000. The B-mode gray levels were analyzed by videodensitometry in areas selected in the liver tissue, tumors, aorta, and the portal vein from frames recorded up to 1 hour after injection. The tumors were further assessed using subjective scores just before and after contrast injection, as well as 15 minutes later in both conventional gray-scale and harmonic imaging modes. RESULTS: Gray-scale enhancement of the liver tissue was detectable soon after BR14 injection and remained at a high level even after clearance of the agent from the blood stream. On precontrast, of 42 observed tumors, 4 were perfectly detected (4/42). After injection of BR14, the number rose to 10/20 in the vascular phase and 12/20 in the delayed phase. In harmonic imaging, the corresponding numbers were even higher, 17/22 in the vascular phase and 18/22 in the delayed phase. The number of tumors perfectly delineated increased after BR14 from 1/42 to 3/20 in the vascular phase and 5/20 in the delayed phase. In the harmonic mode, 9 of 22 tumors were perfectly delineated in the vascular phase and 10 of 22 in the delayed phase. CONCLUSIONS: BR14 is a promising new agent for the study of tissue perfusion and in particular for liver imaging. It shows not only strong, but also persistent gray scale enhancement of the parenchyma but not of the tumors. The increased conspicuousness allows considerable improvements in tumor detection and tumor delineation in conventional imaging and even more so in harmonic imaging.

Animals↗
PubMed1995

BR1: a new ultrasonographic contrast agent based on sulfur hexafluoride-filled microbubbles.

RATIONALE AND OBJECTIVES: The basic characteristics of BR1, a novel echo contrast agent based on stabilized sulfur hexafluoride (SF6) microbubbles have been evaluated. METHODS: The authors determined the physicochemical properties (bubble concentration, bubble size distribution, resistance to pressure, and stability) and the acoustic properties (backscatter and attenuation coefficients) of BR1. The diagnostic value of BR1 was evaluated further in minipigs. Left heart images were recorded before and after injection of different doses of BR1. RESULTS: BR1 is formulated as a lyophilized product, which after addition of saline, provides a suspension containing 2 x 10(8) SF6 microbubbles/mL with a number mean diameter of 2.5 microns. More than 90% of the bubbles are below 8 microns. The use of SF6 rather than air provides an improved resistance to pressure increases such as the ones occuring in the left heart during systole. After reconstitution, the echogenicity and the bubble characteristics are unchanged for more than 8 hours. The high echogenicity remains almost constant over the entire medical frequency range (1-10 MHz). BR1 injections in animals resulted in a homogenous, dose-dependent opacification of the left heart. CONCLUSIONS: Considering its high echogenicity, outstanding stability, and resistance to pressure changes, BR1 is a very promising ultrasound contrast agent.

Animals↗
PubMed1985

On-line data acquisition and control in a physiology laboratory.

A series of programs are described for use in estimating the pulmonary function of laboratory animals. Data acquisition and control are through a Hewlett-Packard (HP) 1000-F minicomputer. The system allows the estimation of respiratory parameters similar to those obtained in laboratories estimating pulmonary function in humans.

Animals↗
PubMed1982

Changes in the minute ventilation of rats exposed to different concentrations of cigarette smoke.

Measurements of tidal volume and breathing frequency were made in rats during a 30-min period of exposure to cigarette smoke, and were compared with those obtained during a 10-min pre-exposure period. All measurements were made in animals previously habituated to smoke exposure. Both tidal volume and breathing frequency were decreased by low-dose exposure to smoke, resulting in a 34% decrease in minute volume. At high-dose exposures (double the low-dose smoke concentration) tidal volumes showed a 23% increase over pre-exposure values with little change in breathing frequency, giving a net 20% increase in minute ventilation. This apparent inverse dose-relationship is discussed.

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