No description available.

Brachial plexus block (BPB) techniques provide significant benefits including better pain control, faster discharge and reduced adverse effects compared to general anaesthesia. Prior to 2005 BPBs were performed using landmark, paraesthesia or electrical nerve stimulation (PNS) methods and were associated with reasonable success (70-80%) but were still associated with risk of failure and complications. Use of ultrasound (US) to guide local anaesthetic injection was first reported in 1989 but until 2004 remained unexplored. From 2004 we aimed to explore the feasibility, success and safety of ultrasound-guided brachial plexus block (USBPB) compared to techniques guided by anatomical landmarks or peripheral nerve stimulation. We hypothesized that USBPB would be feasible, have greater success and safety compared to standard methods. In 2004 we identified the possibility of using US to place infraclavicular block (ICB) and identified a pattern of local anaesthetic spread that predicated successful block. A subsequent randomized trial found improved success of US compared to existing methods. We examined success of US-guided axillary brachial plexus block (ABPB) and found that performance time and success were improved. In a large retrospective review of ABPB techniques we identified that US techniques were faster to perform, had a higher success and were safer compared to standard methods. We also assessed existing nerve localization methods in an observational study and found that both have poor sensitivity and specificity possibly explaining some of the limitations of these techniques. A bench study examining local anaesthetic injection using ultrasound found that both novices and experts could accurately determine local anaesthetic spread. In practice this is a useful marker for safe injection and could explain findings of increased safety with ultrasound methods. we systematically reviewed the literature for studies examining USBPB and this demonstrated that US improved block success and performance time. Subsequent pilot work indicated that US, in addition to improves block success and performance time. Subsequent pilot work indicated that US, in addition to improving quality, could also reduce volume of local anaesthetic required for successful block and we hypothesized that for certain techniques such as interscalene block this may improve safely. we compared US-guided interscalene block (ISB) using traditional volumes (20ml) and compared with a low volume (5ml) of ropivacaine 0.5%. Results demonstrated no difference in efficacy or duration but significant reduction in respiratory (and other) complications with lower volumes. We then compared US-guide ISB to PNS using and Up and Down Sequential Allocation design to estimate the minimum effective anaesthetic volume (MEAV50) for ropivavaine 0.5% for major shoulder surgery. Our findings indicated that volumes of local anaesthetic could be dramatically reduced with US (0.9 vs 5.4ml) whilst still providing effective pain relief. In the last ten years the cases and studies described have demonstrated that US improves BPB success and safety. For ISB US reduces volumes of local anaesthetic required for success whilst also reducing respiratory and other complications.

No description available.

Ultrasound wavefronts travelling through inhomogeneous materials such as biological tissues and tissue mimics are distorted by scattering processes. It has been proposed that measurements of these transmitted wavefronts may be used to define the contribution of coherent and incoherent scattering to the attenuation coefficient of such materials, by means of a comparison between the outputs of phase sensitive and phase insensitive receivers. Measurements of the complex pressure fields transmitted by scattering specimens consisting of glass beads in silicone rubber and by specimens of ox liver, kidney and myocardium have been carried out by point- by-point mapping of the amplitude and phase of the fields using a new design of pvdf needle hydrophone in a high precision scanning tank. It is demonstrated that transmission measurements of the scattered fields are not independent of the size and location of the measurement plane, and the proposed method is unlikely to be helpful in quantifying material properties. Alternative techniques based on the measurement of the angular scattering pattern of such materials are shown to be able to characterise scattering specimens consisting of glass beads in agar and gelatin, and to be able to distinguish normal ox myocardium from ox liver and kidney.

A pose estimation method is proposed for measuring the position and orientation of a biopsy needle. The technique is to be used as a touchless needle guide system for guidance of percutaneous procedures with 4D ultrasound. A pair of uncalibrated, light-weight USB cameras are used as inputs. A database is prepared offline, using both the needle line estimated from camera-captured images and the true needle line recorded from an independent tracking device. A nonparametric learning algorithm determines the best fit model from the database. This model can then be used in real-time to estimate the true position of the needle with inputs from only the camera images. Simulation results confirm the feasibility of the method and show how a small, accurately made database can provide satisfactory results. In a series of tests with cameras, we achieved an average error of 2.4mm in position and 2.61° in orientation. The system is also extended to real ultrasound imaging, as the two miniature cameras capture images of the needle in air and the ultrasound system captures a volume as the needle moves through the workspace. A new database is created with the estimated 3D position of the needle from the ultrasound volume and the 2D position and orientation of the needle calculated from the camera images. This study achieved an average error of 0.94 mm in position and 3.93° in orientation. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

The thesis deals with the ultrasonic velocity measurement. The ultrasonic velocity was determined on basis of ultrasonic flight time from a transmitter to a receiver. Three methods how to determine the ultrasonic velocity in medium were proposed. Special algorithms have been created and later on build in the developed program. All the software was developed in Agilent VEE Pro 8.5. The thesis contains a proposal of two experiments tutorials for the department of Biomedical engineering that will be used during experimental lessons. The experiments deal with ultrasonic velocity measurement.

archives@tulane.edu / Hepatocellular carcinoma is an intractable cancer with a high mortality rate. Transarterial chemoembolization, a non-curative method, is the first line therapy for intermediate stage patients. This effectively extends patient survival but requires a complicated intraarterial catheterization procedure and is poorly suited to repeated administration. Gas embolization has been proposed as a fast, easily administered, more spatially selective, and less invasive alternative. This process involves generating emboli in situ using acoustic droplet vaporization, the noninvasive focused ultrasound-mediated conversion of intravenously administered perfluorocarbon microdroplets into microbubbles. The work presented in this dissertation provides the first evidence of the feasibility and efficacy of gas embolization in vivo. Following confirmation of the cessation of tumor growth after treatment in a preliminary study, two additional preclinical studies were conducted. Varying treatment parameters and the use of systemic chemotherapy alongside gas embolization resulted in consistent, substantial tumor regression and a suppression of tumor recurrence following the cessation of treatment. Subsequent steps toward optimizing the treatment method, primarily intended to mitigate off-target tissue damage and to maximize the uniformity of treatment coverage across a lesion, involved the implementation of two specialized imaging modes for tumor detection and treatment planning and the development of an ultrasound-guided treatment method. Finally, retention of the lipid droplet shell upon vaporization was investigated in the context of selective targeting for localized drug delivery. The dissertation closes with a discussion of the implications of the presented work and proposed future studies. / 1 / Jonah Harmon

archives@tulane.edu / 1 / Genevieve Mattei

OBJECTIVE: To evaluate the incidence of chromosomal abnormalities in ectopic pregnancy chorionic villi. METHODS: A prospective study of patients with the diagnosis of ectopic pregnancy was conducted, with chorionic villi obtained at the time of surgical therapy cultured and analyzed for karyotype. Review of the patient's medical record and ultrasound evaluation was then completed and findings correlated with karyotype results. RESULTS: Twenty- two patients undergoing surgery for the diagnosis of ectopic pregnancy yielded chorionic villi for culture. Successful culture was performed in 21 patients, with 3 (14%) revealing abnormal karyotypes. Review of the medical record showed ultrasound results consistent with fetal development or a gestational sac in 15 of 18 patients with normal chromosomal analysis. Three of 6 patients without fetal development yielded abnormal chromosomal findings. CONCLUSION: Our results confirm that a high degree of success can be achieved in the karyotype analysis of ectopic pregnancy chorionic villi and that these conceptuses have a rate of abnormality similar to that reported for intrauterine gestations. Our data further suggest that when a gestational sac or fetal pole is identified by ultrasound, there is usually a normal karyotype.

No description available.