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Theoretical design and evaluation of endoluminal ultrasound applicators for thermal therapy of pancreatic cancer under image guidance

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AIP Conference Proceedings 2017年第1期1821卷

作者： Matthew Adams Serena Scott Vasant Salgaonkar Graham Sommer Chris Diederich 1Thermal Therapy Research Group University of California San Francisco 2340 Sutter Street S341 San Francisco CA 94109 USA 2Joint Graduate Program in Bioengineering UC Berkeley and UC San Francisco USA 3Stanford Medical Center 300 Pasteur Drive Stanford CA 94305 USA

An image-guided endoluminal ultrasound applicator has been proposed for palliative and potential curative thermal therapy of pancreatic tumors. By considering a directional transducer array of planar, tubular, or curvilinear transducers, this design offers the potential for fast volumetric therapy and 3D spatial control over the energy deposition profile. Treatment of pancreatic tumor tissue would be performed in a minimally invasive fashion with the applicator positioned in the gastrointestinal (GI) lumen, and sparing of the luminal wall would be achieved with a water-cooled balloon surrounding the transducers. A theoretical evaluation of this design was performed by developing a 3D acoustic and bioheat transfer model, with temperature and thermal dose solutions obtained using a FEM solver (COMSOL Multiphysics). Parametric studies were performed on a generalized anatomical model of the pancreas, tumor, and adjacent luminal wall to determine preferred transducer configurations and frequencies for maximizing lesion volume and penetration while sparing the luminal wall. Patient-specific models of pancreatic tumors were generated from CT studies and used to assess the feasibility of performing thermal ablation or hyperthermia on small (∼2 cm diameter) pancreatic head tumors with an endoluminal applicator positioned within the duodenum. Simulation results indicate lower transducer operating frequencies (1-3 MHz) are necessary to mitigate damage to the luminal wall, and a tradeoff between penetration depth and lesion volume emerges as the degree of focusing increases. For patient-specific ablation modeling of tumors within 30 mm of the luminal wall, approximately 95% of the volume could be ablated within 15 min using a planar or lightly focused transducer configuration without duodenal damage. Over 90% of the volume could be elevated above 40°C at steady state for hyperthermia applications (e.g., radiation sensitization, drug delivery) using a tubular transducer. For tum

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Towards a Full-Field Strain Sensor for Guiding Hernia Repairs

Towards a Full-Field Strain Sensor for Guiding Hernia Repair...

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Annual International Conference of the IEEE Engineering in Medicine and Biology Society

作者： Amy Liao Hobart W. Harris Michel M. Maharbiz the UC Berkeley/UCSF Joint Bioengineering Program Berkeley CA 94709 USA UCSF Department of Surgery San Francisco CA 77005 USA. the Electrical Engineering Department and Bioengineering Department UC Berkeley Berkeley CA 94720 USA

ISBN: (纸本)9781424492695

Each year, approximately 400,000 ventral hernia repairs are performed in the United States [1], [2]. Large ventral hernias (hernias that occur in the abdominal wall) are typically treated by suturing in a surgical mesh to cover and overlap the hernia defect. However, in 10-20% of patients, the hernia repair fails, resulting in recurrence of the hernia, along with other complications including infection and intestinal obstruction [3], [4]. One potential cause of hernia recurrence is the unequal distribution of stress across the mesh resulting in high stress concentrations at the tissue-mesh interface, particularly at the site of mesh fixation to the abdominal wall muscles[5], [6]. Strain across the mesh can be used as an indicator for how evenly stress is distributed across the surface of the mesh. To this end, we have built a full-field, 3D strain measurement system to enable physicians to actively identify and address areas of high strain during the surgery, thus decreasing the rate of hernia recurrence. The strain sensor uses an optical technique, called the grid method, in conjunction with the defocused particle image velocimetry (DPIV) technique to measure the 3D strain distribution across the mesh. The system can achieve a limit of detection down to 0.4% strain and across a 50 cm range z-axis displacement using a Canon EOS 7D camera with a pinhole aperture mask.

关键词： Towards Full-Field Strain Sensor Guiding Hernia Repairs

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Investigation of interstitial ultrasound ablation of spinal and paraspinal tumors: A patient-specific and parametric simulation study

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AIP Conference Proceedings 2017年第1期1821卷

作者： Serena J. Scott Vasant Salgaonkar Punit Prakash E. Clif Burdette Chris J. Diederich Thermal Therapy Research Group Dept. of Radiation Oncology University of California San Francisco 1600 Divisadero St. Suite H-1031 San Francisco CA 94143 USA UC Berkeley – UC San Francisco Graduate Program in Bioengineering CA USA Department of Electrical and Computer Engineering Kansas State University Manhattan KS USA Acoustic MedSystems 208 Burwash Ave. Savoy IL 61874 USA

Preferential acoustic absorption and heating of bone can significantly impact interstitial ultrasound ablation of tumors within or bordering the spine. Furthermore, intervening cortical bone may provide acoustic and thermal insulation that can protect sensitive structures nearby, such as the spinal cord. The objectives of this study are firstly, to apply parametric and patient-specific models to theoretically assess the feasibility of interstitial ultrasound ablation of tumors within and near the spine, and secondly, to identify potential energy delivery strategies, safety criteria, advantages, and disadvantages of interstitial ultrasound in this setting. Transient biothermal models using previously validated approximations for power deposition within bone from interstitial sources were employed. Multilayered axisymmetric models were used to perform a parametric assessment of the impact of tumor dimensions, attenuation (dependent on residual bone content), perfusion, and maximum temperature thresholds on necessary treatment parameters and on treatment effectiveness. 3D patient-specific finite element models were generated based on segmented CT scans for nine representative patient cases selected to bracket a range of clinical interest, with tumors in or near the vertebrae, sacrum, and ilium. Tumors were 10-27 mm in diameter, 10-43 mm long, and 0-14 mm from the spinal canal. Paraspinal tumors, osteolytic vertebral tumors, and a mixed osteolytic/osteoblastic iliac bone tumor were considered. 7 MHz (1.5 mm OD) and 3.0 MHz (3.2 mm OD) applicators with an array of 1-4 tubular transducers (0.5 -1.5 cm long, 150-360° sector angles), were applied in various implant configurations. Variable thicknesses of bone insulating critical anatomy from the tumor and insulation of the spinal cord with injected carbon dioxide were also investigated for definition of safety margins and possible protection of critical structures. 6-44 mm diameter osteolytic tumors surrounded by bone and b

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Corrigendum: Rapid and visual Chlamydia trachomatis detection using loop-mediated isothermal amplification and hydroxynaphthol blue

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Letters in applied microbiology 2017年第4期65卷 343页

作者： I Choopara N Arunrut W Kiatpathomchai D Dean N Somboonna Program in Biotechnology Faculty of Science Chulalongkorn University Bangkok Thailand. Bioengineering and Sensing Technology Laboratory National Center for Genetic Engineering and Biotechnology Khlong Nueng Khlong Luang Pathum Thani Thailand. Center for Immunobiology and Vaccine Development UCSF Benioff Children's Hospital Oakland Research Institute Oakland CA USA. Department of Medicine University of California San Francisco CA USA. Joint Graduate Program in Bioengineering University of California Berkeley CA USA. Department of Microbiology Faculty of Science Chulalongkorn University Bangkok Thailand.

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Experimental investigations of an endoluminal ultrasound applicator for MR-guided thermal therapy of pancreatic cancer

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AIP Conference Proceedings 2017年第1期1821卷

作者： Matthew Adams Vasant Salgaonkar Peter Jones Juan Plata Henry Chen Kim Butts Pauly Graham Sommer Chris Diederich 1Thermal Therapy Research Group University of California San Francisco 2340 Sutter Street S341 San Francisco CA 94109 USA 2Joint Graduate Program in Bioengineering UC Berkeley and UC San Francisco USA 3Radiological Sciences Laboratory Stanford University 1201 Welch Road Palo Alto CA 94304 USA 4Stanford Medical Center 300 Pasteur Drive Stanford CA 94305 USA

An MR-guided endoluminal ultrasound applicator has been proposed for palliative and potential curative thermal therapy of pancreatic tumors. Minimally invasive ablation or hyperthermia treatment of pancreatic tumor tissue would be performed with the applicator positioned in the gastrointestinal (GI) lumen, and sparing of the luminal tissue would be achieved with a water-cooled balloon surrounding the ultrasound transducers. This approach offers the capability of conformal volumetric therapy for fast treatment times, with control over the 3D spatial deposition of energy. Prototype endoluminal ultrasound applicators have been fabricated using 3D printed fixtures that seat two 3.2 or 5.6 MHz planar or curvilinear transducers and contain channels for wiring and water flow. Spiral surface coils have been integrated onto the applicator body to allow for device localization and tracking for therapies performed under MR guidance. Heating experiments with a tissue-mimicking phantom in a 3T MR scanner were performed and demonstrated capability of the prototype to perform volumetric heating through duodenal luminal tissue under real-time PRF-based MR temperature imaging (MRTI). Additional experiments were performed in ex vivo pig carcasses with the applicator inserted into the esophagus and aimed towards liver or soft tissue surrounding the spine under MR guidance. These experiments verified the capacity of heating targets up to 20-25 mm from the GI tract. Active device tracking and automated prescription of imaging and temperature monitoring planes through the applicator were made possible by using Hadamard encoded tracking sequences to obtain the coordinates of the applicator tracking coils. The prototype applicators have been integrated with an MR software suite that performs real-time device tracking and temperature monitoring.

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Open-top selective plane illumination microscope compatible with standard sample holders

Open-top selective plane illumination microscope compatible ...

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Novel Techniques in Microscopy, NTM 2015

作者： McGorty, Ryan Liu, Harrison Kamiyama, Daichi Huang, Bo Deparment of Pharmaceutical Chemistry University of California San Francisco San FranciscoCA94158 United States UC Berkeley - UCSF Graduate Program in Bioengineering University of California San Francisco San FranciscoCA94158 United States Department of Biochemistry and Biophysics University of California San Francisco San FranciscoCA94158 United States

Selective plane illumination microscopy (SPIM) has emerged recently as a powerful tool in optically sectioning tissue samples. We have designed a new SPIM that allows samples to be mounted in a variety of common metho... 详细信息

ISBN: (纸本)9781557529541

关键词： Aberration correction Cylindrical lenses Laser beams Light sheet microscopy Selective plane illumination microscopy Spatial resolution

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Changes in reaching reaction times due to volitional modulation of beta oscillations

Changes in reaching reaction times due to volitional modulat...

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International IEEE/EMBS Conference on Neural Engineering, CNE

作者： Preeya Khanna Jose M. Carmena UC Berkeley-UCSF Graduate Group in Bioengineering University of California Berkeley CA USA Department of Electrical Engineering and Computer Sciences University of California Berkeley CA USA

Hypotheses about what drives beta oscillations in local field potentials (LFPs) of motor areas are numerous and include action inhibition, muscle stiffening, sensorimotor processing, and increased attention. Here, a subject performs variations on a reaching task where they experience either predictable or unpredictable `go cue' times and target locations in blocks. The beta (25-40 Hz) power time course is analyzed as the subject learns the statistics of the hold time and target location. While learning a predictable target location correlates with an earlier onset in the pre-reach rise in beta, learning a predictable hold time does not alter beta dynamics. Further, during unpredictable hold times, fast reaction times that are likely in anticipation of the `go cue' exhibit reduced beta desynchronization compared to slower reaction times where the subject likely has waited for the `go cue' prior to movement initiation. These findings point to a role of beta power in inhibition of prepared actions. We test this hypothesis with a combined operant - conditioning and reaching task where subjects volitionally control their motor cortical beta power and immediately afterwards perform a reaching task. We find that when subjects lower their beta power, their reaction times are significantly faster, supporting the idea that beta power inhibits prepared actions.

关键词： Modulation Oscillators Rhythm Trajectory Conferences Neural engineering Brain stimulation

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Enabling closed-loop neurostimulation research with downloadable firmware upgrades

Enabling closed-loop neurostimulation research with download...

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IEEE Biomedical Circuits and Systems (BIOCAS)

作者： Preeya Khanna Scott Stanslaski Yizi Xiao Terry Ahrens Duane Bourget Nicole Swann Philip Starr Jose M. Carmena Timothy Denison UC Berkeley/UCSF Joint Graduate Group in Bioengineering Neuromodulation Technology PLC Department of Neurological Surgery University of California San Francisco University of California Berkeley Berkeley CA US

We present a simulated case study using investigational, downloadable firmware updates to configure an existing implanted deep brain stimulator. With the upgrade, closed-loop algorithm parameters affecting stimulation state classification and stimulation timing can be embedded within the device to allow for chronic investigation of closed-loop concepts both flexibly and incrementally. The system can be outfitted with either cortical sensing electrodes or depth electrodes to explore a variety of closed-loop paradigms. The prototype case study presented here uses motor intention signals to titrate stimulation, a relevant use case for treatment of movement disorders, though the technology is extensible to other neurological disorders. To highlight the translational capabilities of this tool, the key technology considerations of battery power usage, chronic sensitivity and stability of biomarkers, and parameter tuning are discussed using representative testing and data sources.

关键词： Algorithm design and analysis Electrodes Microprogramming Satellite broadcasting Classification algorithms Sensors Computers

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Chemical shift separation with controlled aliasing for hyperpolarized 13C metabolic imaging

Chemical shift separation with controlled aliasing for hyper...

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作者： Shin, Peter J. Larson, Peder E.Z. Uecker, Martin Reed, Galen D. Kerr, Adam B. Tropp, James Ohliger, Michael A. Nelson, Sarah J. Pauly, John M. Lustig, Michael Vigneron, Daniel B. Department of Radiology and Biomedical Imaging University of California at San Francisco 1700 4th Street San FranciscoCA94158 United States UC Berkeley - UCSF Graduate Program in Bioengineering CA United States Department of Electrical Engineering and Computer Sciences University of California at Berkeley BerkeleyCA United States Magnetic Resonance Systems Research Laboratory Department of Electrical Engineering Stanford University StanfordCA United States General Electric Healthcare FremontCA United States

Purpose A chemical shift separation technique for hyperpolarized 13C metabolic imaging with high spatial and temporal resolution was developed. Specifically, a fast three-dimensional pulse sequence and a reconstruction method were implemented to acquire signals from multiple 13C species simultaneously with subsequent separation into individual images. Theory and Methods A stack of flyback echo-planar imaging readouts and a set of multiband excitation radiofrequency pulses were designed to spatially modulate aliasing patterns of the acquired metabolite images, which translated the chemical shift separation problem into parallel imaging reconstruction problem. An eight-channel coil array was used for data acquisition and a parallel imaging method based on nonlinear inversion was developed to separate the aliased images. Results Simultaneous acquisitions of pyruvate and lactate in a phantom study and in vivo rat experiments were performed. The results demonstrated successful separation of the metabolite distributions into individual images having high spatial resolution. Conclusion This method demonstrated the ability to provide accelerated metabolite imaging in hyperpolarized 13C MR using multichannel coils, tailored readout, and specialized RF pulses. © 2014 Wiley Periodicals, Inc.

关键词： Separation

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Rapid fabrication method for plastic microfluidic devices with embedded microelectrodes and its application to electroporation and cell lysis on chip 18

Rapid fabrication method for plastic microfluidic devices wi...

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18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014

作者： Paredes, Jacobo Chooljian, Marc Fink, Kathryn D. Liepmann, Dorian CEIT and Tecnun University of Navarra Spain CIC MicroGUNE Spain UC Berkeley San Francisco Graduate Program in Bioengineering United States Department of Bioengineering UC Berkeley United States Berkeley Sensors and Actuators Center United States

ISBN: (纸本)9780979806476

Methods of fabricating microfluidic devices that are scalable, simple, and inexpensive are necessary to ease the transition of microfluidics from an academic to an industrial discipline. Here we present a method for rapid prototyping of microfluidic devices with embedded electrodes in plastic based on electroplating and hot embossing techniques. We then discuss its applicability to electroporation and lysis, two of many potential applications that could benefit from this manufacturing method. © 14CBMS.

关键词： Fabrication

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