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Yuko Kono

Publications and source records attributed to Yuko Kono.

10 recordsLinked to original sources
PubMed2006

Angiogenesis: noninvasive quantitative assessment with contrast-enhanced functional US in murine model.

PURPOSE: To evaluate quantitative functional ultrasonography (US) in a murine gel model by using microbubble destruction kinetics to determine whether parametric indices provided with US could help assess angiogenesis. MATERIALS AND METHODS: Institutional Animal Subjects Committee approved experiments and procedures. In 36 normal mice, two 0.4-mL gel implants were placed subcutaneously on either side of spine. One implant contained 0.5, 1.0, or 1.5 microg human basic fibroblast growth factor (bFGF) per milliliter of gel. Functional US quantitative analysis of angiogenesis with microbubble contrast agent was performed on days 3, 6, 9, and 12; histologic data were collected. Time-intensity curve of implant was fitted to mathematic decay model to calculate fractional blood volume and fraction of blood replaced per unit of time. Microvascular density (MVD) and percentage of microvascular area (MVA) were measured after anti-CD31 staining. Spearman rank order correlation was used in analyses. RESULTS: bFGF-containing implants induced MVD of eight, 35, 42, and 42 vessels per square millimeter on days 3, 6, 9, and 12, respectively; in controls, MVD was four vessels/mm2 (P<.05 on days 6, 9, and 12). bFGF-containing implants induced percentage MVA of 2%, 5%, 20%, and 27%, respectively; in controls, it was 0.5% (P<.05). Maximum enhancement was significantly increased in bFGF implants (23.3 gray level+/-14.1 [standard deviation]) compared with controls (11.0+/-5.5, P<.001). Implants containing bFGF showed poor correlations between fractional blood volume and MVD (r2=0.42) or percentage MVA (r2=0.51) at US. There was no correlation between microbubble velocity and MVD (r2<0.05) or percentage MVA (r2<0.13). CONCLUSION: Functional US perfusion parameters do not correlate with current histologic indices for quantifying angiogenesis. MVD, as a histologic quantitative measurement of angiogenesis, may not be an appropriate standard for contrast-enhanced imaging that relies on perfused neovessels.

Animals↗
PubMed2005

Ultrasound of the liver.

This article summarizes the recent advances in ultrasound imaging of the liver, especially contrast-enhanced imaging. Contrast-enhanced ultrasound has dramatically changed the role of ultrasound in liver tumor characterization, detection, and other applications. Available ultrasound contrast agents, agents under development, contrast-specific imaging techniques, and its applications in liver imaging are discussed.

Contrast Media↗
PubMed2005

[A case of malignant lymphoma diagnosed by thoracoscopy with local anesthesia].

A 67-year-old woman was hospitalized with right pleural effusion on chest radiography. Chest CT showed a thickened parietal pleura and pleural effusion in the right thorax. Cytological examination of pleural effusion showed atypical plasma cells. We performed thoracoscopy with local anesthesia for diagnosis and observed an about 5 x 5 cm seized red soft tumor on the parietal pleura. Pathological and immunohistochemical examination of the pleural tumor revealed that it was marginal zone B-cell malignant lymphoma. In this case, we could not reach a diagnosis only by cytological examination of the pleural effusion. Thoracoscopy with local anesthesia was safe and useful for diagnosis of malignant lymphoma with pleural effusion. Most cases of primary pleural malignant lymphoma have a history of chronic pyothorax. This case is thought to be a very rare case of primary pleural malignant lymphoma with no history of pyothorax.

Aged↗
PubMed2004

Angiogenesis model for ultrasound contrast research: exploratory study.

RATIONALE AND OBJECTIVES: To optimize an angiogenesis model for imaging research that is stable and can be imaged several times over the angiogenic time course. MATERIALS AND METHODS: Mice and rats received two injections of 0.4 mL of extract of basement membrane matrix (Matrigel; Becton Dickinson Labware, Bedford, MA) in the subcutaneous spaces on either side of the spine. One of the two Matrigel plugs in each animal had either 0.1 microg/mL of basic fibroblast growth factor (bFGF) (11 mice), 1.0 microg/mL of bFGF (12 mice, 5 rats), or 1.0 microg/mL of bFGF and 60 U/mL of heparin (11 mice). Three to 12 days after implantation, animals were imaged before and after the administration of up to four injections of 0.1 mL AF0150. Phase inversion imaging was used on a Siemens Elegra (Siemens ultrasound, Issaquah, WA) equipped with a 13 MHz VFX transducer. Three observers subjectively assessed the pattern of enhancement using a four-point scale. The Matrigel plugs were then removed and two observers graded the angiogenic response on a four-point scale. Ten Matrigel plugs, five with 1.0 microg/mL bFGF and five without, were evaluated histologically following immunohistochemical staining with anti-CD31. RESULTS: The angiogenic response was greater in Matrigel plugs with 1.0 than with 0.1 microg/mL of bFGF. Heparin did not increase the angiogenic response. Vessels were predominantly at the periphery of the plugs with variable central penetration. Plugs appeared anechoic and homogeneous on ultrasound. Contrast enhancement within the plug occurred in 44% of mice with an angiogenic response at or after day 6 and the enhancement increased with the angiogenic response. In the others, peripheral enhancement could not be distinguished from the enhancement of surrounding tissues that were also hyperemic. The thicker rat skin interfered with plug assessment. CONCLUSION: A stable angiogenesis model without the complexity of tumors is described. This model offers the opportunity to image the development and/or inhibition of angiogenesis. Neovasculature in Matrigel was detectable using ultrasound contrast. Quantitative studies correlating the degree of enhancement to microvascular density will be determined in subsequent studies.

Animals↗
PubMed2004

Model to quantify lymph node enhancement on indirect sonographic lymphography.

OBJECTIVE: Our goal was to develop a reliable technique that has minimal operator dependence for quantifying lymph node enhancement to test and optimize new sonography contrast formulations. MATERIALS AND METHODS: Twenty healthy rabbits were studied using five agents, labeled A-G. Agents D and E were the same agent and agents F and G were Imagent, studied blindly to test reproducibility. One milliliter of contrast agent was injected into each hind footpad. A 13-MHz transducer was fixed over the popliteal node, which was imaged at a 4.8-MHz central transmit frequency using phase-inversion technology at 100% power and one frame per second. Immediately after each injection, the footpad was massaged 12 times for 30 sec each time and then imaged after each massage to assess the number of times the node could be refilled from each injection. Lymph node video intensity was measured, and the degree of enhancement was evaluated using analysis of variance with the massage number and the agent used as independent variables. RESULTS: Lymph node enhancement was observed after the first massage with all agents. Degree of enhancement was least with agents A and B, intermediate with agents D and F, and greatest with agent C. Agent A was effective after the first two massages, agent B after the first four, agent C after all 12, agent D after the first eight, and agent F after the first nine. Performance of agents D and F was similar to that of their duplicates, E and G. CONCLUSION: We established a reproducible technique to quantify lymph node enhancement that can distinguish between different agents. The differences in performance suggest that it is possible to optimize agent formulation for indirect sonographic lymphography.

Analysis of Variance↗
PubMed2004

Noninvasive estimation of the pressure gradient across stenoses using sonographic contrast: in vitro validation.

OBJECTIVE: Because velocity measurements to estimate the degree of arterial stenosis are susceptible to local and systemic factors, we aimed to investigate the feasibility of estimating the pressure gradient across a stenosis noninvasively by using sonographic contrast. METHODS: Using a gravity-fed flow system, a 1:4000 dilution of a contrast agent in water was circulated through silicone tubes that had either focal or long-segment stenoses of varying severity in a water bath. We measured the cross-sectional areas of the normal and stenotic regions with B-mode sonography and the flow velocity with spectral Doppler sonography and calculated the pressure gradients across the stenoses using the empirically derived Young mathematical model and the simplified Bernoulli equation. Estimated gradients were compared with those measured manometerically. RESULTS: Both methods yielded estimates of pressure gradients that correlated with measured gradients (r > 0.988). In focal and long-segment stenoses, the Young model yielded gradients that agreed more closely with manometerically measured values than the Bernoulli equation (+/- 8% versus -24%-57%). Both methods were highly dependent on the ability to measure the luminal cross-sectional area. The presence of sonographic contrast in the vascular lumen highlighted the inner wall, allowing the accurate measurement of the luminal area to +/- 3.0%. CONCLUSIONS: The pressure gradient can be estimated across stenoses noninvasively. The Young model was more accurate than the simplified Bernoulli equation in this model using steady flow. Estimated gradients are highly dependent on the definition of the vascular lumen, a process aided by the use of sonographic contrast.

Carotid Stenosis↗
PubMed2003

Carotid arteries: contrast-enhanced US angiography--preliminary clinical experience.

B-mode ultrasonographic (US) angiography enhanced with a microbubble-based US contrast agent (FS069) was evaluated in human subjects with carotid artery disease. Results at contrast material-enhanced US angiography and duplex US were compared with those at conventional angiography. Both US angiography and duplex US accurately depicted stenoses of 70% or more compared with those depicted at conventional angiography. The percentage diameter stenosis of the internal carotid artery measured at US angiography strongly correlated with that measured at conventional angiography (r = 0.988). The percentage area stenosis measured at US angiography strongly correlated with ex vivo measurements of the resected carotid plaque at magnetic resonance imaging (r = 0.979). US angiography depicted unsuspected wall irregularities, ulceration, and dissection.

Aged↗
PubMed2003

Validation of ultrasound contrast destruction imaging for flow quantification.

Our purpose was to validate in vitro a kinetic flow model based on microbubble signal decay curve. Using a 3.5 MHz transducer and phase-inversion (1.8 MHz central transmit frequency), a renal dialysis cartridge oriented vertically was imaged in the transverse plane as 1:1000 dilution of AF0150 was infused at 50, 100, 200, 300 and 400 mL/min. Ten gray-scale images were acquired at each infusion rate using 2.5, 5 and 10 frames/s at 100%, 40%, 15% or 1% of maximum transmit power. Video-intensity measured on each 10 images was fit to a kinetic model using Sigma Plot that yielded microbubble concentration, velocity and destruction per frame. These were correlated with the experimental conditions. At 100% power, video-intensity on the first frame (microbubble concentration at equilibrium) was similar for all flow and frame rates. The model fit the experimental data for all flows at 10 frames/s and for flows lower than 400 and 100 mL/min at 5 frames/s and 2.5 frames/s, respectively. The calculated flow was similar to the experimental flow rates, regardless of technique (r(2) = 0.98). Microbubble fraction destroyed per frame was similar for all flow and frame rates and increased linearly with transmit power (r(2) > 0.98). These results suggest that using appropriate power and frame rate for a given flow rate, estimates of fractional blood volume, flow and destruction fraction can be calculated from the decay curve using 10 frames that can be acquired in 1 to 4 s.

Contrast Media↗
PubMed2002

Mechanism of parenchymal enhancement of the liver with a microbubble-based US contrast medium: an intravital microscopy study in rats.

PURPOSE: To investigate the mechanism of prolonged contrast material enhancement of the liver observed with the lipid-shell ultrasonographic (US) contrast agent AF0150, with use of intravital microscopy. MATERIALS AND METHODS: Eight Sprague-Dawley rats were used. Six received fluorescent microspheres to label the Kupffer cells; two were used as controls. The edge of the middle lobe of the liver was transilluminated with white light. Fluorescent microspheres were observed under fluorescence light. After injection of AF0150, behavior of microbubbles was observed for 6 minutes while viewing a single high-power field. Multiple other fields were then assessed for stationary bubbles and their relation to Kupffer cells. The number of bubbles in motion, aggregated, stationary, and associated with labeled cells were counted. RESULTS: Of 590 bubbles, 34 (5.8%) became stationary and 556 (94.2%) kept moving. Of the 34 stationary microbubbles, 21 dislodged within 30 seconds. Microbubbles were homogeneously distributed throughout the lobule, in contrast to the dominant periportal distribution of the labeled Kupffer cells. Among 83 stationary bubbles observed from all fields of view, only 14 (17%) were associated with fluorescent-labeled cells. CONCLUSION: The late parenchymal liver enhancement effect of AF0150 is likely not related to Kupffer-cell uptake, but rather to a mechanical slowdown within the sinusoids.

Animals↗