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Biomedical subjects

Peter Burns

Publications and source records attributed to Peter Burns.

6 recordsLinked to original sources
PubMed2006

Contrast-enhanced triggered harmonic sonography for assessment of periarticular hemodynamic changes in experimental arthritis.

BACKGROUND: Objective quantification is critical for assessment of functional sonography in inflammatory arthritis. To create a microbubble contrast-enhanced image of vessels that lie below the resolution of a standard US system, a technique is required that detects preferentially the contrast agent echo, rejecting that from background tissue: harmonic imaging. OBJECTIVES: To investigate the ability of contrast-enhanced triggered harmonic sonography (CETHS) to evaluate periarticular hemodynamic changes over the course of experimental arthritis and to discriminate presence and absence of arthritis based on measurement values obtained at specific time-points. MATERIALS AND METHODS: Arthritis was induced in rabbits knees by intra-articular injection of serum bovine albumin, which acted as an antigen. A total of 11 rabbits (8 with unilateral arthritis and 3 control animals) were imaged at 0, 1, 7, 14, 21 and 28 days of antigen-induced arthritis and euthanized at 28 days. A continuous infusion protocol was performed (triggering times 30.0, 20.0, 10.0, 5.0, 2.0, 1.0, and 0.5 s). Hemodynamic indices of synovial microvasculature (vascular volume, mean velocity and flow rate) were obtained and compared with clinical, laboratory, and histological surrogate markers. RESULTS: Although interval CETHS changes were noted for flow rate (P=0.007) and vascular volume (P=0.003) ratios in albumin-injected knees, no significant differences in ratios were identified over time between albumin-injected and non-injected knees for flow rate (P=0.52), vascular volume (P=0.23) and mean velocity (P=0.19). Flow rate most accurately differentiated between presence and absence of arthritis according to clinical measurements in early (day 1) arthritis, and mean velocity in mid-term arthritis (day 14; both P=0.02). CONCLUSION: Although the measurement properties of CETHS indices were poor in the evaluation of hemodynamic differences over time in albumin-injected knees compared with non-injected knees, they enabled discrimination between presence and absence of arthritis at specific time-points in different stages.

Animals↗
PubMed2006

A protocol for high-throughput phenotyping, suitable for quantitative trait analysis in mice.

Whole-genome genetic association studies in outbred mouse populations represent a novel approach to identifying the molecular basis of naturally occurring genetic variants, the major source of quantitative variation between inbred strains of mice. Measuring multiple phenotypes in parallel on each mouse would make the approach cost effective, but protocols for phenotyping on a large enough scale have not been developed. In this article we describe the development and deployment of a protocol to collect measures on three models of human disease (anxiety, type II diabetes, and asthma) as well as measures of mouse blood biochemistry, immunology, and hematology. We report that the protocol delivers highly significant differences among the eight inbred strains (A/J, AKR/J, BALBc/J, CBA/J, C3H/HeJ, C57BL/6 J, DBA/2 J, and LP/J), the progenitors of a genetically heterogeneous stock (HS) of mice. We report the successful collection of multiple phenotypes from 2000 outbred HS animals. The phenotypes measured in the protocol form the basis of a large-scale investigation into the genetic basis of complex traits in mice designed to examine interactions between genes and between genes and environment, as well as the main effects of genetic variants on phenotypes.

Animals↗
PubMed2006

Radiofrequency ablation of hepatocellular carcinoma: predicting success using contrast-enhanced sonography.

OBJECTIVE: This pilot study compared the utility of immediate postprocedural contrast-enhanced sonography with that of delayed enhanced sonography and CT or MRI in assessing the success of radiofrequency ablation of hepatocellular carcinoma. SUBJECTS AND METHODS: Twenty-two lesions (1.5-3.7 cm) were studied in 19 patients. Enhanced sonography was performed before and within 1 hr after radiofrequency ablation. At routine 2-week follow-up CT or MRI, additional enhanced sonography was performed. The findings of preablation CT or MRI and enhanced sonography were compared with those of postprocedural and follow-up enhanced sonography by three radiologists experienced in these techniques. The reviewers were unaware of the follow-up CT or MRI results (reference standard). Technical adequacy, ablation zone targeting, and identification of residual disease were assessed by each reviewer, and the results were analyzed by consensus. RESULTS: One postprocedural sonographic study was considered technically inadequate. Postprocedural sonography predicted the follow-up CT or MRI results in 76% (16/21) of subjects (sensitivity, 88%; specificity, 40%; positive predictive value [PPV], 82%; negative predictive value, [NPV] 50%). Follow-up CT or MRI identified accurate targeting in 17 of 22 subjects. Follow-up sonography agreed with CT or MRI in 82% (18/22) of subjects (sensitivity, 88%; specificity, 67%; PPV, 88%; NPV, 67%). Postprocedural sonography predicted the follow-up CT or MRI results in 81% (17/21) of subjects (sensitivity, 40%; specificity, 94%; PPV, 66%; NPV, 83%). Follow-up CT or MRI detected residual disease in six subjects. Follow-up sonography agreed with CT or MRI in 91% (20/22) of subjects (sensitivity, 83%; specificity, 94%; PPV, 83%; NPV, 94%). CONCLUSION: Postprocedural enhanced sonography has the potential to guide completion of radiofrequency ablation at the time of initial therapy when residual disease is detected. The procedure is less accurate in detection of residual disease than is either delayed enhanced sonography or CT or MRI.

Adult↗
PubMed1999

Real-Time Contrast Echo Assessment of Myocardial Perfusion at Low Emission Power: First Experimental and Clinical Results Using Power Pulse Inversion Imaging.

Power pulse inversion (PPI) has been developed for echocontrast specific imaging in order to reduce destruction of microbubbles. The purpose of this study was to evaluate PPI for real-time contrast echocardiography. Therefore, in vitro studies in a physiological flow-phantom and clinical examinations in patients with coronary artery disease were performed. The in vitro rersults of this study indicate that PPI allows real-time imaging at low emission power and is almost nondestructive to contrast microbubbles of Definity. At this low emission power a strong linear relationship between the dosage of the contrast agent and the resulting PPI signal intensity was found (R = 0.998, p < 0.001). In the clinical examinations real-time imaging using low mechanical index PPI resulted in strong myocardial signals and a complete filling of the cavities indicating absence of bubble destruction. Most striking was the ability of PPI to display myocardial thickening and wall motion simultaneously with the assessment of myocardial contrast replenishment following ultrasound induced bubble destruction by high power frames. We conclude that PPI allows nondestructive contrast imaging both in experimental and clinical settings. Therefore, real-time imaging of myocardial perfusion and real-time assessment of contrast replenishment following ultrasound induced destruction of microbubbles is feasible. Moreover, PPI allows simultaneous assessment of perfusion and myocardial function.

Journal Article↗