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PubMed2006

Measurement of bubble and pellet size distributions: past and current image analysis technology.

Measurements of bubble and pellet size distributions are useful for biochemical process optimizations. The accuracy, representation, and simplicity of these measurements improve when the measurement is performed on-line and in situ rather than off-line using a sample. Historical and currently available measurement systems for photographic methods are summarized for bubble and pellet (morphology) measurement applications. Applications to cells, mycelia, and pellets measurements have driven key technological developments that have been applied for bubble measurements. Measurement trade-offs exist to maximize accuracy, extend range, and attain reasonable cycle times. Mathematical characterization of distributions using standard statistical techniques is straightforward, facilitating data presentation and analysis. For the specific application of bubble size distributions, selected bioreactor operating parameters and physicochemical conditions alter distributions. Empirical relationships have been established in some cases where sufficient data have been collected. In addition, parameters and conditions with substantial effects on bubble size distributions were identified and their relative effects quantified. This information was used to guide required accuracy and precision targets for bubble size distribution measurements from newly developed novel on-line and in situ bubble measurement devices.

Forecasting↗
PubMed2005

Estimation of the malignant potential of gastrointestinal stromal tumors: the value of contrast-enhanced coded phase-inversion harmonics US.

BACKGROUND: Recently, contrast agents for ultrasonography (US) such as Levovist have been introduced for routine clinical use. The contrast-enhanced US with Levovist permits evaluation of the intratumoral vascularity of hepatic and pancreatic tumors and is useful for their differential diagnosis. The purpose of the present study was to assess tumor vessels and the parenchymal flow of gastrointestinal stromal tumors (GISTs) by contrast-enhanced coded phase-inversion harmonic US and to evaluate whether vascularity is related to the malignant grade of the GISTs. METHODS: Thirteen patients with GISTs were included in the present study. Tumors were observed in a real-time fashion of contrast-enhanced coded phase-inversion harmonic US after the injection of Levovist (400 mg/ml). The vascular patterns were compared with tumor size, histological diagnosis, KIT mutations, and clinical findings such as metastasis. RESULTS: The contrast-enhanced US images of the GISTs were classified into two types according to the blood flow area of the tumors as seen by real-time continuous imaging of the tumor vessels. The image pattern "Poor" represented vessels flowing only in the peripheral part of the tumor, and "Rich" represented abundant vessels flowing from the periphery to the central part of the tumor. According to the contrast-enhanced US images, five GISTs were classified as "Poor" and the others as "Rich." Based on the final diagnosis, all tumors with "Poor" images were determined to be benign GISTs, and the rest tumors except one with "Rich" images were determined to be malignant GISTs. CONCLUSIONS: Contrast-enhanced US image is more closely correlated with the final diagnosis than the histological findings.

Blood Flow Velocity↗
PubMed2004

Incidental liver lesions: diagnostic value of cadence contrast pulse sequencing (CPS) and SonoVue.

The widespread use of modern imaging modalities has led to an increase in the frequency of detecting coincidental focal liver lesions (cysts, haemangiomas, focal nodular hyperplasia, adenoma, focal fatty sparing and infiltration) in patients with no symptoms of liver disease. A positive diagnosis is needed to avoid overinvestigation or protracted follow-up. The limitations of conventional sonography have led to the use of other imaging modalities and invasive or costly procedures such as CT, MRI or biopsy. The availability of real-time contrast-enhanced ultrasound imaging (CEUS) has changed the strategy in the characterization of such lesions without inconvenience for the patient. Cadence contrast pulse sequencing (CPS) gives strong contrast signals as well as simultaneous acquisition of conventional scans for a perfect match of these two images. In our personal experience, in comparison with reference imaging, CPS with SonoVue has differentiated benign from malignant lesions in all cases and has accurately characterized 96% of lesions. These results are slightly better than those reported in the literature, probably because of the higher sensitivity of CPS in detecting bubbles, whether flowing or stationary, and also because of the possibility of matching simultaneously recorded contrast and conventional images which reinforces confidence in lesion assessment. The high diagnostic value of CEUS makes this method a candidate to be considered a reference imaging modality for incidental lesions.

Contrast Media↗
PubMed2004

Future prospects for SonoVue and CPS.

Though long considered unlikely because of the resonance pattern of agents such as SonoVue, high frequency applications for small parts and intracavitary applications now seem very promising. Excellent non-linear signals can be obtained at 7 MHz and higher using recently developed CPS software, and preliminary results suggest that this may prove useful for assessing superficial lymph nodes, the thyroid and parathyroid, breast masses and many superficial masses including those in the skin. Some other potentially useful "fringe" applications of the now-familiar transabdominal transducers with CPS are the pancreas, gall bladder and spleen, though these have not been investigated formally as yet.

Blood Vessels↗
PubMed2004

The use of contrast-enhanced ultrasound in large vessels.

The introduction of perfluoro-based contrast agents such as SonoVue together with sensitive realtime scanning modes such as cadence contrast pulse sequences (CPS) have made possible significant advances in the management of patients with pathology affecting large vessels. This has been particularly valuable in aortic graft procedures where the lack of nephrotoxicity allows multiple repeat studies for follow-up of leaks. It has also proved valuable in situations where the flow is very slow and undetectable on conventional Doppler

Aneurysm↗
PubMed2005

Comparison of transthoracic versus transesophageal echocardiography for detection of right-to-left atrial shunting using agitated saline contrast.

Agitated saline contrast studies (bubble studies) can be performed with either transthoracic or transesophageal echocardiography for the detection of right-to-left atrial shunts. The echocardiograms of 94 consecutive patients who underwent saline contrast studies with transthoracic and transesophageal approaches were reviewed to compare the ability of these modalities to detect right-to-left atrial shunts.

Adolescent↗
PubMed2006

Aortopulmonary fistula occurring 4 years after replacement of the ascending aorta.

A 62-year-old man presenting with congestive heart failure due to a fistula between an aortic pseudoaneurysm and the right pulmonary artery is described. The shunt occurred 4 years after aortic valve and supracoronary graft replacement and was diagnosed by transesophageal contrast echocardiography. After redo surgery the patient made an uneventful recovery.

Aortic Dissection↗
PubMed2005

Two-dimensional micro-bubble actuator array to enhance the efficiency of molecular beacon based DNA micro-biosensors.

Two-dimensional micro-bubble actuator arrays were developed and studied in detail to enhance the hybridization kinetics of a DNA micro-biosensor. The hybridization between a molecular beacon, a kind of oligonucleotide probe, and its complement was investigated in a millimeter-sized PDMS based reaction chamber, where various 2D micro-heater arrays were distributed on the bottom for micro-bubble generation. The hybridization assay without the micro-bubble actuation revealed that the fluorescence increased fast at the beginning and slowed down after that. However, a uniform fluorescence increase was observed when periodic micro-bubble agitation was introduced in the static hybridization solution. A comparison of hybridization assays with and without micro-bubble agitation revealed that the hybridization time could be effectively shortened by 33% with 10 cycles of micro-bubble agitation from a 2 x 1 bubble actuator array, and by 43% with 10 cycles of micro-bubble agitation from a 2 x 2 bubble actuator array.

Biosensing Techniques↗
PubMed2004

Imaging technologies and techniques.

Equipment manufacturers provide contrast-specific detection techniques that have excellent sensitivity and excellent agent-to-tissue specificity along with helpful tools that improve workflow efficiency dramatically. Excellent contrast agents have been approved for LV opacification and are available worldwide. Techniques designed for low-MI imaging offer real-time acquisition capabilities and lead to faster examinations. Techniques designed for medium-MI imaging offer better sensitivity than low-MI techniques while maintaining the benefit of rapid image acquisition. Techniques designed for high-MI imaging offer the best sensitivity with longer acquisition times. These techniques are viable means for imaging contrast agents tailored to clinical needs. Progress by contrast agent manufacturers, equipment manufacturers, and physicians will continue to drive improvements in the areas of detection and clinical workflow for improved patient care.

Coronary Circulation↗
PubMed2004

Implementing contrast echocardiography in the laboratory.

Contrast echocardiography is an important and a significant addition to a modern echocardiography laboratory. Its successful implementation is dependent on a team approach between sonographers, nurses, and physicians. A practical plan is one that includes a proper understanding of indications, logistical matters, technical and performance standards, and reimbursement issues.

Artifacts↗
PubMed2004

The coronary microcirculation in health and disease.

Apart from being the site of nutrient and gas exchange for the myocardium, the capillary bed is a dynamic participant in the regulation of coronary and myocardial blood flow. MBV also responds to changes in myocardial oxygen demand. Because MCE can be used to assess MBF and MBV in vivo, it can be used to provide unique insights into tissue perfusion.

Blood Flow Velocity↗
PubMed2004

Myocardial contrast echocardiography in the detection of coronary stenosis.

The need for the capillary bed to maintain normal hydrostatic pressure results in capillary derecruitment distal to a stenosis during hyperemia. This pathophysiologic behavior is seen irrespective of the method by which coronary driving pressure is reduced. The functional consequences of the decrease in MBV are an increase in myocardial vascular resistance and a concomitant reduction in hyperemic MBF. These phenomena form the basis for the detection of CAD with MCE, which isa unique noninvasive tool that allows the separate assessment of both MBV and MBF velocity. Because of its excellent spatial and temporal resolution, portability, widespread availability,and relatively low cost, MCE should provide an attractive method for the noninvasive detection of CAD and for the quantification of stenosis severity.

Blood Flow Velocity↗
PubMed2004

Myocardial contrast echocardiography in acute coronary syndromes.

MCE is a reliable, bedside technique for assessment of a patient with acute coronary syndrome. It can be used to estimate the myocardial risk-area and infarct size and to establish peri-infarct viability. This information is critical in both management decision-making and in assigning prognosis in the setting of acute coronary syndromes.

Echocardiography↗
PubMed2004

Ultrasound.

Explore the source record for details and available documents.

Contrast Media↗
PubMed2006

Deformation of phosphate-bonded investment materials at elevated temperatures.

OBJECTIVES: To determine deformation in phosphate-bonded investment (PBI) materials for "in-service conditions" and to investigate the influence of air bubble pores on deformation at 900 degrees C. METHODS: Surviving high and low strain-rate disc-rupture strength test samples were assessed for deformation. A dental centrifugal casting machine and a dental superplastic-forming machine were used to apply the loads. An indirect technique was used to measure the deformation of investment diaphragms with both a wide pore size distribution and with very low porosity for four investment materials. A total of 128 high strain-rate and 29 low strain-rate samples were investigated. A one-way analysis of variance was carried out. RESULTS: All but one of the high strain-rate test samples showed measurable deformation. All of the low strain-rate test samples containing pores showed measurable deformation. Six out of 14 samples, in which pores had been eliminated, showed no deformation. There was no statistically significant difference in deformation between samples with no pores and those with a large pore size distribution for either the high or low strain-rate tests (P>0.05). SIGNIFICANCE: PBI must survive all forming procedures without deformation if the resultant prosthesis is to fit. One hundred micrometres is generally recognized as the acceptable tolerance of fit for removable metal-based prostheses. The vast majority of deformations measured during this investigation were considerably greater than 100 microm.

Acrylates↗
PubMed2005

Clinical application of harmonic power Doppler imaging in the assessment of myocardial perfusion by contrast echocardiography.

Myocardial contrast echocardiography has moved from the research laboratory to clinical echocardiography. As with any emerging technology, background information and understanding the process of image acquisition will help to integrate the technology into everyday practice. Harmonic power Doppler imaging (HPDI) is a high-power, triggered imaging modality used to assess myocardial perfusion. Contrast agents used in echocardiography provide microvascular tracers that enable HPDI to accurately visualize myocardial blood flow. This article aims to provide direction in the clinical performance of myocardial contrast echocardiography by providing background in the theory and physics of HPDI and a guide to the technical acquisition of images and recognition of artifacts that arise during HPDI.

Art↗
PubMed2006

A critical review of patent foramen ovale detection using saline contrast echocardiography: when bubbles lie.

Saline and indocyanine green dye were the first agents noted to produce a contrast effect when injected peripherally during M-mode echocardiographic imaging, although it was subsequently found that almost any type of injected solution would have this effect. These first-generation contrast agents were limited to opacification of right heart structures, and they prompted subsequent development of agents that traverse pulmonary circulation. Although opacification limited to right heart structures is considered a limitation of these first-generation agents, this is an advantage when attempting to identify the presence of right-to-left shunt. First-generation air contrast is considered the gold standard for identification of patent foramen ovale (PFO). However, PFO investigators have used varying criteria to define abnormal contrast studies. There are also multiple mechanisms by which saline contrast studies may produce both false-positive and false-negative results for presence of PFO. There is mounting experimental evidence that PFO is associated with cerebral ischemia and migraine headache, with a resulting evolution of devices for percutaneous closure of these shunts. Echocardiographic physicians must be aware of potential pitfalls of the air contrast technique to avoid exposing patients to unnecessary risk of closure devices, and missing the potential benefit of shunt closure in appropriately selected patients.

Contrast Media↗