Social media and disasters: a functional framework for social media use in disaster planning, response, and research.

A comprehensive review of online, official, and scientific literature was carried out in 2012-13 to develop a framework of disaster social media. This framework can be used to facilitate the creation of disaster social media tools, the formulation of disaster social media implementation processes, and the scientific study of disaster social media effects. Disaster social media users in the framework include communities, government, individuals, organisations, and media outlets. Fifteen distinct disaster social media uses were identified, ranging from preparing and receiving disaster preparedness information and warnings and signalling and detecting disasters prior to an event to (re)connecting community members following a disaster. The framework illustrates that a variety of entities may utilise and produce disaster social media content. Consequently, disaster social media use can be conceptualised as occurring at a number of levels, even within the same disaster. Suggestions are provided on how the proposed framework can inform future disaster social media development and research.

Coherent ultrasonic Doppler tomography.

Ultrasonic imaging based on the pulse-echo principle is widely used throughout the world, particularly in medical applications. However, its spatial resolution is poor (around 2 times the wavelength, or 200 µm at 15 MHz), limiting its ability to detect small but clinically important lesions (such as microcalcifications in breast cancer). The work presented here is different from the traditional approach. Continuous-wave ultrasound is transmitted to insonate a rotating object, then the amplitude and phase of the returned signals are coherently processed to reconstruct a Doppler tomographic image of the object's backscatter field. It is demonstrated numerically that the spatial resolution is up to 0.19 wavelengths and the sampling requirement and image formation method are given. To show the performance of the method, we present the results obtained by applying the new technique in simulation and experiment. A string phantom consisting of very thin copper wires and two cylindrical phantoms constructed by tissue-mimicking-material were scanned. It is demonstrated that the copper wires were located very accurately with very high spatial resolution, and good shape approximation for the cylindrical phantoms was achieved.

Continuous wave ultrasonic Doppler tomography.

In continuous wave ultrasonic Doppler tomography (DT), the ultrasonic beam moves relative to the scanned object to acquire Doppler-shifted frequency spectra which correspond to cross-range projections of the scattering and reflecting structures within the object. The relative motion can be circular or linear. These data are then backprojected to reconstruct the two-dimensional image of the object cross section. By using coherent processing, the spatial resolution of ultrasonic DT is close to an order of magnitude better than that of traditional pulse-echo imaging at the same ultrasound frequency.

Three-dimensional ultrasound imaging of mammary ducts in lactating women: a feasibility study.

OBJECTIVE: The main function of the breast is to produce milk for offspring. As such, the ductal system, which carries milk from the milk-secreting glands (alveoli) to the nipple, is central to the natural function of the breast. The ductal system is also the region in which many malignancies originate and spread. In this study, we aimed to assess the feasibility of manual mapping of ductal systems from 3-dimensional (3D) ultrasound data and to evaluate the structures found with respect to conventional understanding of breast anatomy and physiology. METHODS: Three-dimensional ultrasound data of the breast were acquired using a mechanical system, which captures data in a conical shape covering most of the breast without excessive compression. Manual mapping of the ductal system was performed using custom software for data from 4 lactating volunteers. RESULTS: Observational results are presented for ultrasound data from the 4 lactating volunteers. For all volunteers, only a small number of ductal structures were engorged with milk, suggesting that the lactiferous activity of the breast may be localized. These enlarged ducts were predominantly found in the inferior lateral quadrant of each breast. The observation was also made that the enlarged, milk-storing parts of the duct were spread throughout the ductal system and not directly below the nipple as conventional anatomy suggests. CONCLUSIONS: Ultrasound visualization of the 3D structure of milk-laden ducts in an uncompressed breast has been shown. Using manual tracing, it was possible to track milk-laden ducts of diameters less than 1 mm.

True local recurrence rate in the conserved breast after magnetic resonance imaging-targeted radiotherapy.

PURPOSE: Better accuracy of local radiotherapy may substantially improve local control and thus long-term breast cancer survival. Magnetic resonance imaging (MRI) has high resolution and sensitivity in breast tissue and may depict the tumor bed more accurately than conventional planning techniques. A postoperative complex (POCx) comprises all visible changes thought to be related to surgery within the breast and acts as a surrogate for the tumor bed. This study reports on local recurrence rates after MRI-assisted radiotherapy planning to ensure adequate coverage of the POCx. METHODS AND MATERIALS: Simple opposed tangential fields were defined by surface anatomy in the conventional manner in 221 consecutive patients. After MRI, fields were modified by a single radiation oncologist to ensure encompassment of the POCx with a 10-mm margin. Genetic analysis was performed on all local relapses (LRs) to distinguish true recurrences (TRs) from new primaries (NPs). RESULTS: This was a high risk cohort at 5 years: only 9.5% were classified as low risk (St Gallen): 43.4% were Grade 3 and 19.9% had surgical margins <1 mm; 62.4% of patients received boosts. Adjustments of standard field margins were required in 69%. After a median follow-up of 5 years, there were 3 LRs (1.3%) as the site of first relapse in 221 patients, comprising two TRs (0.9%) and one NP (0.4%). CONCLUSIONS: Accurate targeting of the true tumor bed is critical. MRI may better define the tumor bed.

Temperature measurement by thermal strain imaging with diagnostic power ultrasound, with potential for thermal index determination.

Over the years, there has been a substantial increase in acoustic exposure in diagnostic ultrasound as new imaging modalities with higher intensities and frame rates have been introduced; and more electronic components have been packed into the probe head, so that there is a tendency for it to become hotter. With respect to potential thermal effects, including those which may be hazardous occurring during ultrasound scanning, there is a correspondingly growing need for in vivo techniques to guide the operator as to the actual temperature rise occurring in the examined tissues. Therefore, an in vivo temperature estimator would be of considerable practical value. The commonly-used method of tissue thermal index (TI) measurement with a hydrophone in water could underestimate the actual value of TI (in one report by as much as 2.9 times). To obtain meaningful results, it is necessary to map the temperature elevation in 2-D (or 3-D) space. We present methodology, results and validation of a 2-D spatial and temporal thermal strain ultrasound temperature estimation technique in phantoms, and its apparently novel application in tracking the evolution of heat deposition at diagnostic exposure levels. The same ultrasound probe is used for both transmission and reception. The displacement and thermal strain estimation methods are similar to those used in high-intensity focused ultrasound thermal monitoring. The use of radiofrequency signals permits the application of cross correlation as a similarity measurement for tracking feature displacement. The displacement is used to calculate the thermal strain directly related to the temperature rise. Good agreement was observed between the temperature rise and the ultrasound power and scan duration. Thermal strain up to 1.4% was observed during 4000-s scan. Based on the results obtained for the temperature range studied in this work, the technique demonstrates potential for applicability in phantom (and possibly in vivo tissue) temperature measurement for the determination of TI.

Magnetic resonance imaging appearances in the postoperative breast: the clinical target volume-tumor and its relationship to the chest wall.

PURPOSE: To describe and measure the postoperative complexes and their relationship to the chest wall in 100 randomly chosen MRI breast scans, to attempt a better understanding of the changes taking place in the postoperative breast. METHODS AND MATERIALS: Appearances and measurements of MRI postoperative cavities were analyzed in a cohort of 100 randomly selected patients who underwent a single open MRI scan in the conventional breast radiotherapy treatment position before routine two-dimensional simulation. RESULTS: Magnetic resonance imaging appearances of postoperative cavities seem to differ qualitatively from descriptions of CT and ultrasound cavities in the literature. Rather than being principally homogeneous, heterogeneous cavities were seen in 85%, irregular in 51%. The size of cavity was inversely related to the time elapsed since surgery. Cavities directly touched the chest wall in 53% of cases; 89% lay within 10 mm of the chest wall. Regular, annular concentric rings of differing signal were seen in 32% of cases; such appearances have not been previously described. These patterns suggest that seromas may not shrink entirely as a result of simple serous fluid absorption; instead, new tissue may be being laid down. Because large, regular spheroidal/ellipsoidal cavities with crisp margins may be seromas under pressure, greater target shifts during radiation may need to be anticipated in such cases. CONCLUSIONS: Postsurgical cavities in the conserved breast on MRI are commonly heterogeneous, irregular, and lie close to the chest wall. Magnetic resonance imaging studies may help in better understanding the natural history of postoperative cavities.

Preparation, characterization and in vivo observation of phospholipid-based gas-filled microbubbles containing hirudin.

The objective of this work was to prepare echogenic phospholipid-based gas-filled microbubbles (PGM) and investigate their physical characteristics, echogenicity and loading ability of hirudin under various NaCl concentrations. PGM were prepared by a sonication-lyophilization method. Hirudin was used as a model drug to evaluate the drug encapsulation efficiency of the PGM. PGM loaded with hirudin were prepared by dissolving lyophilized powder with hirudin solution. The morphology, particle size and microbubble concentration of PGM were measured. The hirudin encapsulation efficiency as a function of NaCl concentration was determined. The mean particle size and microbubble concentration of PGM were unchanged by the presence of hirudin for at least 60 min after preparation. Hirudin encapsulation quantity was proportional to the hirudin concentration until saturation occurred at high concentration, and the encapsulation efficiency had an inverse relationship. Hirudin encapsulation efficiency was affected by NaCl concentration. When NaCl concentration was increased from 10 mg mL(-1) to 20 mg mL(-1) in PGM solution, hirudin encapsulation efficiency decreased from 35.8 to 26.7%, and microbubble concentration decreased from 2.7 x 10(8) to 1.7 x 10(8) microbubbles per mL. The PGM were shown easily to be visible in in vivo rabbit liver. There was no difference in echogenicity between the loaded and unloaded bubbles. PGM prepared by the sonication-lyophilization method exhibited satisfactory physical characteristics and loading ability and are suitable for use in imaging and ultrasound-triggered delivery.

Optimisation of ultrasound-mediated gene transfer (sonoporation) in skeletal muscle cells.

Ultrasound (US) is a promising tool for facilitating direct gene transfer to skeletal muscle, but no systematic optimisation study has been performed. We exposed H2K myoblast cells to US with varying intensity of exposure and duration to evaluate its effect on cell viability and transfection efficiency using as endpoints transfection rate, average fluorescence intensity (fluorescence normalised by the number of transfected cells) and overall expression (the product of transfection rate and average fluorescence intensity) as indices. Cell viability decreased with exposure time and intensity, consistent with previous findings. Optimal setting of US was observed at the range of 0.5 to 1 W cm(-2) with duration of 20 s, producing maximum efficiency (transfection = 4.5%) in gene transfection with minimum cell toxicity (cell viability = 83%). Higher intensity alone or in combination with low intensity and long duration did not improve cell viability and transfection. The increase of eGFP (enhanced green fluorescence protein) plasmid concentration up to 200 microg per mL was related to an increase in average fluorescence intensity and overall expression. However, transfection rate saturated when DNA concentration reached 50 microg per mL despite initial increase with DNA concentration. The average fluorescence intensity was linearly proportional to the logarithm of DNA concentration, suggesting a diffusion-based model for DNA uptake under sonoporation. We conclude that low-intensity US irradiation provides a safe and effective alternative for gene delivery.

Incoherent imaging using continuous wave ultrasound. A preliminary study using bovine intervertebral discs.

As an object rotates with respect to a stationary planar ultrasonic beam, the scattering centres within the object return echoes that are Doppler-shifted in frequency by amounts depending on the velocities of the individual scatterers. The backscattered echo amplitude at any particular frequency is the line integral of the scattered radiation at the cross-range corresponding to that frequency. The amplitude as a function of frequency can be interpreted as a tomographic projection. A tomographic reconstruction algorithm can produce an image of the distribution of scattering centres in the insonified object from these projections. This paper describes the development and characterisation of a microscanner to investigate the approach of using continuous wave ultrasound for three-dimensional cross-sectional imaging. The results of preliminary tissue investigation, conducted using bovine coccygeal intervertebral discs, are described. The radial imaging resolution improves as the Doppler frequency resolution improves but the circumferential resolution degrades proportionally. As the number of projections increases, there is a finite increase in image quality. Two- and three-dimensional images of the intervertebral disc reveal an alternate light and dark banding pattern that is characteristic of the laminar structure of the annulus fibrosus.