Analysis of ultrasound fields in cell culture wells for in vitro ultrasound therapy experiments

Ultrasound is an established therapy method for bone fracture healing, hyperthermia and the ablation of solid tumors. In this new emerging field, ultrasound is further used for microbubble-enhanced drug delivery, gene therapy, sonoporation and thrombolysis. To study selected therapeutic effects in defined experimental conditions, in vitro setups are designed for cell and tissue therapy. However, in vitro studies often lack reproducibility and the successful transfer to other experimental conditions. This is partly because of the uncertainty of the experimental conditions in vitro. In this paper, the ultrasound wave propagation in the most common in vitro ultrasound therapy setups for cell culture wells is analyzed in simulations and verified by hydrophone measurements. The acoustic parameters of the materials used for culture plates and growth media are determined. The appearance and origin of standing waves and ring interference patterns caused by reflections at interfaces is revealed in simulations and measurements. This causes a local maximal pressure amplitude increase by up to the factor of 5. Minor variations of quantities (e.g., growth medium volume variation of 2.56%) increase or decrease the peak rarefaction pressure at a cell layer by the factor of 2. These pressure variations can affect cell therapy results to a large extent. A sealed cell culture well submersed in a water bath provides the best reproducibility and therefore promises transferable therapy results.     

High-resolution ultrasound imaging of human skin in vivo by using three-dimensional ultrasound microscopy

Observing the morphology of human skin is important in the diagnosis of skin cancer and inflammation and in the assessment of skin aging. High-frequency ultrasound imaging provides high spatial resolution of the deep layers of the skin, which cannot be visualized by optical methods. The objectives of the present study were to develop a three-dimensional (3-D) ultrasound microscope and to observe the morphology of normal human skin in vivo. A concave polyvinylidene fluoride transducer with a central frequency of 120 MHz was excited using an electric pulse generated by semiconductor switching. The transducer was scanned two-dimensionally by using two linear motors on the region-of-interest and the ultrasonic reflection was digitized with 2-GHz sampling. Consecutive B-mode images perpendicular to the skin surface were reconstructed to generate multiplanar reconstructed images and 3-D volume-rendering images clearly showing microstructures such as sebaceous glands and hair follicles. The 3-D ultrasound microscope could be used to successfully image the morphology of human skin noninvasively and may provide important information on skin structure.     

High-frequency ultrasound for in vivo measurement of colon wall thickness in mice

Mouse models are becoming increasingly important in the study of molecular mechanisms of colorectal disease and in the development of novel therapeutics. To enhance this phase of preclinical research, cost-effective, easy to use noninvasive imaging is required to detect and monitor changes in the colon wall associated with disease pathology. This study investigated the feasibility of using 40-MHz (high frequency) B-mode ultrasound (HF-US) to image the normal mouse colon and measure its thickness in vivo by establishing a robust imaging protocol and conducting a blinded comparison of colon wall thickness (CWT) measurement between and within operators. The in vivo and ex vivo appearance of mouse colon under HF-US revealed distinct patterns. Colon wall thickness was reproducibly and accurately measured using HF-US compared with histology measurement. The technique was more sensitive in detecting changes in CWT in distal than proximal colon as it showed the highest level of inter- and intraoperator reproducibility. Using the protocol described, it is possible to detect changes in thickness of 0.09 mm and 0.25 mm in distal and proximal colon, respectively. In conclusion, HF-US provides an easy to use and noninvasive method to perform anatomical investigations of mouse colon and to monitor changes in CWT.     

Localizing target structures in ultrasound video – A phantom study

The problem of localizing specific anatomic structures using ultrasound (US) video is considered. This involves automatically determining when an US probe is acquiring images of a previously defined object of interest, during the course of an US examination.Localization using US is motivated by the increased availability of portable, low-cost US probes, which inspire applications where inexperienced personnel and even first-time users acquire US data that is then sent to experts for further assessment. This process is of particular interest for routine examinations in underserved populations as well as for patient triage after natural disasters and large-scale accidents, where experts may be in short supply.The proposed localization approach is motivated by research in the area of dynamic texture analysis and leverages several recent advances in the field of activity recognition. For evaluation, we introduce an annotated and publicly available database of US video, acquired on three phantoms. Several experiments reveal the challenges of applying video analysis approaches to US images and demonstrate that good localization performance is possible with the proposed solution.     

Endoscopic ultrasound, where are we now in 2012?

Topics related with endoscopic ultrasound (EUS) made up considerable portion among many invited lectures presented in International Digestive Endoscopy Network 2012 meeting. While the scientific programs were divided into the fields of upper gastrointestinal (UGI), lower gastrointestinal, and pancreato-biliary (PB) categories, UGI and PB parts mainly dealt with EUS related issues. EUS diagnosis in subepithelial lesions, estimation of the invasion depth of early gastrointestinal cancers with EUS, and usefulness of EUS in esophageal varices were discussed in UGI sessions. In the PB part, pancreatic cystic lesions, EUS-guided biliopancreatic drainage, EUS-guided tissue acquisition, and improvement of diagnostic yield in indeterminate biliary lesions by using intraductal ultrasound were discussed. Advanced techniques such as contrast-enhanced EUS, EUS elastography and forward-viewing echoendoscopy were also discussed. In this paper, I focused mainly on topics of UGI and briefly mentioned about advanced EUS techniques since more EUS related papers by other invited speakers were presented afterwards.     

Work-related musculoskeletal disorders in ultrasound: Can you reduce risk?

Work-related musculoskeletal disorders are a common cause of pain and sickness absence for ultrasound practitioners. This article aims to provide background information about factors increasing the chance of developing work-related musculoskeletal disorders and potential ways to reduce risk. Factors influencing ultrasound professionals’ likelihood of developing work-related musculoskeletal disorders include poor posture, repetitive movements, transducer pressure and poor grip, stress, workload, limited support or sense of control and other psychosocial factors. The impact of these risk factors on the health and well being of ultrasound practitioners can be reduced by following recommendations published by professional bodies and the Health and Safety Executive. Ultrasound practitioners should remember that optimising the examination should not be at the detriment of their health. Some hints and tips to reduce the chance of developing work-related musculoskeletal disorders are provided.     

Role of ultrasound in the active management of osteogenesis during compression–distraction osteosynthesis in children

Purpose

To determine whether distraction-induced regeneration (DR) can be optimized based on consecutive ultrasound findings during the course of compression–distraction osteosynthesis (CDO).

Materials and methods

Sixty-nine children ranging in age from 2 weeks to 15 years with congenital (37 patients) or acquired (32 patients) microgenia were treated with CDO. Radiological diagnostic studies included orthopantomography (OPG) and ultrasonography (US). The patients were divided into two groups: in group I a standard distraction rate (SDR) (1 mm/day) was used (33 patients, 47.8%); in group II (36 patients, 52.2%) individual distraction rates (IDR) were used based on US findings.

Results

DR was classified as normotrophic, hypertrophic, or hypotrophic based on US findings. In group I, 11 (33.3%) of the patients presented normotrophic DR, 8 (24.2%) had hypertrophic DR, and in 14 (42.4%), the DR was hypotrophic. In group II, all patients presented normotrophic DR at the end of the treatment.

Conclusion

US offers a unique opportunity to study DR development, and the results can be used to actively manage and optimize the osteogenesis process during mandibular CDO in children.     

Assessment of emergency physician–performed ultrasound in evaluating nonspecific abdominal pain

Study objective

The objective of this pilot study was to lay the groundwork for future studies assessing the impact of emergency physician–performed ultrasound (EPUS) on diagnostic testing and decision making in emergency department (ED) patients with nonspecific abdominal pain (NSAP).

Methods

This was a prospective, noninterventional study using a consecutive sample of patients presenting to the ED with NSAP as determined by nursing triage when a participating physician was available. Nonspecific abdominal pain was defined as abdominal pain for which the patient was seeking evaluation without a presumed diagnosis or referral for specific evaluation. Patients were evaluated by a physician who documented their differential diagnosis and planned diagnostic workup. Then, the physician performed EPUS, recorded their findings, and documented their post-EPUS differential diagnosis and planned diagnostic workup. This was compared with the patient's final diagnosis as determined by 2 emergency physicians blinded to the EPUS results.

Results

A total of 128 patients were enrolled. Fifty-eight (45%; 95% confidence interval [CI], 36%-54%) had an improvement in diagnostic accuracy and planned diagnostic workup using EPUS. Sixty-four (50%; 95% CI, 41%-59%) would have been treated without further radiographic imaging. Fifty (39%; 95% CI, 31%-48%) would have been treated without any further laboratory testing or imaging.

Discussion

Based on our findings, a future trial of 164 consecutive patients would have 90% power to confirm a 25% reduction in testing and a 25% improvement in decision making.

Conclusion

Emergency physician–performed ultrasound appears to positively impact decision making and diagnostic workup for patients presenting to the ED with NSAP and should be studied further.     

Features of in vitro ultrasound biomicroscopic imaging and colonoscopy for detection of colon tumor in mice

The present work tested the capability of ultrasound biomicroscopy (UBM), at 45 MHz, to provide cross-sectional images with appropriate resolution and contrast to detect tumors and determine their penetration depths on the colon of mice, Mus musculus (Linnaeus 1758), treated with carcinogen for colon tumor induction. B-mode images were obtained, in vitro, from each animal (13 treated and 4 untreated) colon opened longitudinally and immersed in saline solution at room temperature. Prior to UBM inspection, all animals were also examined by colonoscopy. The layers of normal colon identified by UBM are: mucosa (hyperechoic), muscularis mucosae (hypoechoic), submucosa (hyperechoic) and muscularis externa (hypoechoic). UBM images of colon lesions presented structures corresponding to tumors (hyperechoic), lymphoid hyperplasia (hypoechoic) and polypoid tumors (hyperechoic). Additionally, tumoral lesion invasion through the colon was also identified. When compared with histopathologic analysis, all colon lesions detected by UBM were confirmed, while colonoscopic findings had two false negatives.     

Is there still an increase in knowledge in basic abdominal ultrasound?--congress report DLT Graz 2006

The number of articles on abdominal ultrasound has been declining in the last few years. The proportion of presentations containing significant new developments amongst the 23 submitted papers which were accepted is low, some presentations are partially new or utilise ultrasound as a clinical tool, and about half the articles have already been presented in a different form or context at former meetings. Without contrast enhanced ultrasound, innovative contributions would be a rarity. The following article summarises the scientific meetings of the DLT in Graz. In addition to a short evaluation, the scientific objectives of abdominal ultrasound in the next few years are discussed.     

Tuberous sclerosis in a term newborn with opisthotonus – The value of ultrasound

Purpose

We describe the clinical findings and the results of cerebral imaging studies [ultrasound (US), magnetic resonance imaging (MRI)] in a full-term newborn with tuberous sclerosis (TS) complex. This condition is inherited as an autosomal dominant trait and characterized by hamartomas involving multiple organs. Diagnosis is based on physical examination together with imaging support.

Methods

Since the TS complex can result in numerous CNS abnormalities, cerebral US should be used to further characterize this malformation.

Conclusion

Sonography is a useful modality for evaluation of the full-term neonatal brain.     

Three-dimensional ultrasound in small parts: is it just a nice picture?

For longer than 40 years, ultrasound (US) has been a widely used imaging tool in medical practice, which has proved helpful for the diagnosis and staging of diseases. Although three-dimensional ultrasound (3D) US has been available for more than 10 years, it was only through the development of the most recent computer technologies and its adaptation to ultrasound systems, that 3D US has become able to achieve the high level of sensitivity and performance necessary to be considered seriously in clinical practice. 3D US is rapidly turning into a technology with an ever-increasing range of applications in numerous fields because, among other reasons, it helps overcome some of the key limitations related to two-dimensional imaging. 3D US can be used in ultrasonography for small parts, among other medical areas. The assessment of the testicle, parotid, thyroid and parathyroid glands is properly achieved. The multiplanar presentation and niche mode are quite useful to determine the extension--inside or outside the organs-, of nodules, cysts or tumors. The volume measurement is better assessed with 3D US and given this, we can perform studies that follow growth in order to decide medical or surgical treatment. The VOCAL makes it possible to obtain a proper after-treatment follow-up of focal disorders in these small organs. Neovascularization is clearly viewed with 3D US and probably can suggest malignant origin of a neoplasm. 3D US offers a more comprehensive image of anatomical structures and pathological conditions and also permits to observe the exact spatial relationships. We are aware more studies are needed to demonstrate specificity and sensibility of 3D US in particular clinical conditions, not only in small parts but also is some other non-Ob/Gyn applications.     

Where's the tube? Evaluation of hand-held ultrasound in confirming endotracheal tube placement

INTRODUCTION: The diagnosis of endotracheal tube (ETT) mal-position may be delayed in extreme environments. Several methods are utilized to confirm proper ETT placement, but these methods can be unreliable or unavailable in certain settings. Thoracic sonography, previously utilized to detect pneumothoraces, has not been tested to assess ETT placement. HYPOTHESIS: Thoracic sonography could correlate with pulmonary ventilation, and thereby, help to confirm proper ETT placement. METHODS: Thirteen patients requiring elective intubation under general anesthesia, and data from two trauma patients were evaluated. Using a portable, hand-held, ultrasound (PHHU) machine, sonographic recordings of the chest wall visceral-parietal pleural interface (VPPI) were recorded bilaterally in each patient during all phases of airway management: (1) pre-oxygenation; (2) induction; (3) paralysis; (4) intubation; and (5) ventilation. RESULTS: The VPPI could be well-imaged for all of the patients. In the two trauma patients, right mainstem intubations were noted in which specific pleural signals were not seen in the left chest wall VPPI after tube placement. These signs returned after correct repositioning of the ETT tube. In all of the elective surgery patients, signs correlating with bilateral ventilation in each patient were imaged and correlated with confirmation of ETT placement by anesthesiology. CONCLUSIONS: This report raises the possibility that thoracic sonography may be another tool that could be used to confirm proper ETT placement. This technique may have merit in extreme environments, such as in remote, pre-hospital settings or during aerospace medical transports, in which auscultation is impossible due to noise, or capnography is not available, and thus, requires further scientific evaluation.     

Contrast enhanced ultrasound in the liver using low mechanical index--what is the difference?

Echo-enhancing agents (EEA), also known as ultrasound contrast media, have improved the diagnostic potential of gastroenterologic ultrasound within the last years. Initially used to increase color-Doppler signals the potential to use harmonic waves being generated by the use of EEAs was established later. The effect was based upon the distraction of the EEA bubbles and the resulting pseudo-Doppler signal, the exam was carried out with high ultrasound energy and intermittent switching on and off of the ultrasound beam. Using this effect in real-time during continuous scanning is possible since the introduction of new EEAs with a flexible shell. This flexible shell oscillates during the scan process emitting harmonic signals. This new technology opens new possibilities for the detection of liver tumors including the possible characterisation. The detection rate for liver metastases can be increased by app. 40 % with this new technology. Correct sonographic characterisation of liver tumors can be achieved in nearly 100 % more cases.