Ultrasound in Medicine and Biology

Masthead

2010-09-01

Editorial Advisory Board

2010-09-01

Biomedical Applications of Radiation Force of Ultrasound: Historical Roots and Physical Basis

Armen P. Sarvazyan, Oleg V. Rudenko, Wesley L. Nyborg — 2010-09-01

Abstract: Radiation force is a universal phenomenon in any wave motion, electromagnetic or acoustic. Although acoustic and electromagnetic waves are both characterized by time variation of basic quantities, they are also both capable of exerting a steady force called radiation force. In 1902, Lord Rayleigh published his classic work on the radiation force of sound, introducing the concept of acoustic radiation pressure, and some years later, further fundamental contributions to the radiation force phenomenon were made by L. and P. . Many of the studies discussing radiation force published before 1990 were related to techniques for measuring acoustic power of therapeutic devices; also, radiation force was one of the factors considered in the search for noncavitational, nonthermal mechanisms of ultrasonic bioeffects. A major surge in various biomedical applications of acoustic radiation force started in the 1990s and continues today. Numerous new applications emerged including manipulation of cells in suspension, increasing the sensitivity of biosensors and immunochemical tests, assessing viscoelastic properties of fluids and biological tissues, elasticity imaging, monitoring ablation of lesions during ablation therapy, targeted drug and gene delivery, molecular imaging and acoustical tweezers. We briefly present in this review the major milestones in the history of radiation force and its biomedical applications. In discussing the physical basis of radiation force and its applications, we present basic equations describing the relationship of radiation stress with parameters of acoustical fields and with the induced motion in the biological media. Momentum and force associated with a plane-traveling wave, equations for nonlinear and nonsteady-state acoustic streams, radiation stress tensor for solids and biological tissues and radiation force acting on particles and microbubbles are considered. (E-mail: armen@artannlabs.com)

Investigation of Acoustic Changes Resulting from Contrast Enhancement in Through-Transmission Ultrasonic Imaging

Tamara Rothstein, Diana Gaitini, Zahava Gallimidi, Haim Azhari — 2010-09-01

Abstract: Through-transmitted ultrasonic waves can be used for computed projection imaging of the breast. The goal of this research was to analyze the acoustic properties changes associated with the propagation of ultrasonic waves through media before and after ultrasound contrast agent (UCA) injection and to study the feasibility of a new imaging method combining projection imaging and UCA. Two transmission techniques were examined: Gaussian pulses and pulse inversion. In the latter, three different double inverted pulses were studied: double Gaussian, double square and double sine. A computerized automatic ultrasonic scanning system was used for imaging. To simulate blood vessels, a phantom, consisting of a latex tube through which saline was circulated, was assembled. The phantom was placed within the scanner and sets of acoustic projection images were acquired. Then, a suspension of the UCA Definity™ was added to the saline and a new set of images was obtained. The pre and postcontrast images were quantitatively compared in terms of amplitude and time-of-flight (TOF). In addition, nonlinearity was evaluated by comparing the relative alteration of the positive and negative parts of the signal. Statistically significant (p < 0.001) changes in the projection images resulting from the UCA injection were observed in wave amplitude (22% ± 13%), TOF (7.9 ns ± 6.3 ns) and nonlinear properties (35% ± 32% and 56% ± 17% for Gausian pulses and pulse inversion, respectively). One in vivo study of a female breast is also presented and its preliminary outcomes discussed. Together, these results indicate the technical feasibility of the suggested method and its potential to detect breast tumors. (E-mail:haim@bm.technion.ac.il)

Evaluation of the Intraobserver and Interobserver Reliability of Data Acquisition for Three-Dimensional Power Doppler Angiography of the Whole Placenta at 12 Weeks Gestation

Nia Wyn Jones, Nick Raine-Fenning, Hatem Mousa, Eileen Bradley, George Bugg — 2010-09-01

Abstract: The aim of this study was to investigate the intra- and interobserver reproducibility of three-dimensional (3-D) power Doppler (3-DPD) data acquisition from women at 12 weeks gestation, which were then subsequently measured by a single observer. Women with an uncomplicated, viable singleton pregnancy were scanned between 12 + 0 and 13 + 6 weeks gestations with a Voluson 730 Expert. 3-DPD data were acquired of the whole placenta by two observers: the first observer captured two datasets and the second a single dataset. Each dataset was analysed using VOCAL™ in the A plane with 9 degree rotation steps. Eighteen low risk women were recruited with a total of 54 datasets analysed. The intraclass correlation coefficient (ICC) was highest for the vascular indices vascularisation index (VI) and vascularisation-flow index (VFI), greater than 0.75. ICC for flow index (FI) showed moderate correlation at 0.47 to 0.65. Bland Altman plots showed the most precise vascular index to be the FI (–15% to 10% for interobserver agreement). There was no bias between datasets. Prospective studies are now required to identify if this analysis tool and method is sensitive enough to recognise patients with early-onset placental dysfunction. (E-mail: nia.jones@nuh.nhs.uk)

Ultrasound Measurements of the Masseter Muscle as Predictors of Cephalometric Indices in Orthodontics: A Pilot Study

S. Naser-Ud-Din, W.J. Sampson, C.W. Dreyer, K. Thoirs — 2010-09-01

Abstract: This study investigated the potential of ultrasound measurements of the masseter muscle to accurately predict indices normally derived from cephalograms. Masseter muscle measurements on 11 adults (22 to 30 y) were made using lateral cephalometrics and extended field-of-view ultrasound. The ultrasound technique was validated in a simulation pilot study using 12 dry skulls and raw chicken breasts. Twenty cephalometric variables were analyzed against four ultrasound measurements of the masseter muscle. Highly significant correlations (r = 0.81–0.85, p = 0.001–0.002) between ultrasound measurements of the masseter muscle and cephalometric measurements representing the length of the superficial masseter muscle, the length and shape of the mandible and vertical facial proportions were demonstrated. Predictive equations from regression analyses were constructed to deduce ramus length and shape from the ultrasound measurements. The results provide pilot data suggesting that ultrasound is a potential clinical tool for sequential evaluation of masseter muscle length in orthodontics and facial muscle growth studies. (E-mail: Kerry.thoirs@unisa.edu.au)

Normative Cross-Sectional Area of the C5-C8 Nerve Roots Using Ultrasonography

Daniel W. Haun, John C.S. Cho, Norman W. Kettner — 2010-09-01

Abstract: This study will define a normal range of values for the cross-sectional area (CSA) of the C5-C8 ventral rami in normal subjects and will assess the interexaminer reliability of the CSA measurements. We also describe the normal sonoanatomy of the C5-C8 ventral rami. Thirty-three normal subjects (20 female) were scanned bilaterally. The mean CSA and reference ranges for the C5, C6, C7 and C8 ventral rami were 7.1 ± 4.1 mm2, 10.6 ± 4.3 mm2, 12.1 ± 4.1 mm2 and 10.7 ± 4.8 mm2, respectively. The intraclass correlation coefficient (ICC) demonstrated good reliability with a coefficient of 0.76 overall, with individual level coefficients at C5, C6, C7 and C8 of 0.69, 0.71, 0.76 and 0.72, respectively. This is the first study to obtain normative CSA measurements of the C5-C8 ventral rami. (E-mail: daniel.haun@logan.edu)

Ultrasound-Guided Core Needle Biopsy of Cervical Lymphadenopathy in Patients with Lymphoma: The Clinical Efficacy and Factors Associated with Unsuccessful Diagnosis

Pei Ching Huang, Chia Yee Liu, Wen Yu Chuang, Lee Yung Shih, Yung Liang Wan — 2010-09-01

Abstract: This study attempts to identify factors that influence the success or failure of subclassifying 154 cases of neck lymphoma by ultrasound-guided core needle biopsy (UGCNB). Variables including age, gender, nodal size, cutting needle bore, number of core tissues obtained, presence of nodal necrosis or infarct, fragmentation of the specimens and subclassification of lymphoma were reviewed and statistically analyzed to check if they were related to the success of UGCNB. UGCNB was successful in subclassifying lymphoma in 138 (89.7%) cases, in diagnosing lymphoma in 11 (7.1%) and unsuccessful in diagnosing lymphoma in five (3.2%) cases. No complications were encountered. The factors leading to failure in subclassification included the presence of composite lymphoma (p = 0.001), nodal necrosis or infarct (p = 0.001) and insufficiency or fragmentation of the specimens (p < 0.001). UGCNB is a safe and efficient procedure in subclassifying lymphoma. It may obviate surgical biopsy in 89.7% of cases. (E-mail: ylw0518@adm.cgmh.org.tw)

Pathological Changes on Human Breast Cancer Specimens Ablated in vitro with High-Intensity Focused Ultrasound

2010-09-01

Abstract: The purpose of this study was to evaluate the pathologic changes of human breast cancer specimens ablated with high-intensity focused ultrasound (HIFU) in vitro. Twenty specimens of pathologically confirmed breast cancer tissue were ablated with ultrasound-guided HIFU. The evaluation methods include histopathologic observation using hematoxylin-eosin staining, electron microscopic imaging, enzyme histochemical and immunohistochemical examination on tumor antigens. Vacuole-like structures in cytoplasm were observed by histopathologic observation but there were no significant changes in cell morphology and nucleus karyotype. Typical phenomena related to coagulation necrosis were observed in electron microscopic studies; the contour of cell structure was still preserved but the structures of cell (all kinds of organelles and nucleus) were damaged or disappeared. Acid phosphatase and succinate dehydrogenase staining showed that tumor cells were inactivated. In immunohistochemical evaluations, estrogen receptor, progesterone receptor, cerbB-2 and P53 expression changed from 85%, 82%, 75% and 80% in nonablation tissue to no expression in ablated tumor tissue, respectively. We, therefore, conclude that breast cancer cells appear normal contour immediately after ablation with HIFU under light microscopic but they were evaluated to be dead by electron microscopic imaging, enzyme histochemical and immunohistochemical examinations. (E-mail:wangzbpaper@haifu.com.cn)

Multi-Modality Safety Assessment of Blood-Brain Barrier Opening Using Focused Ultrasound and Definity Microbubbles: A Short-Term Study

Babak Baseri, James J. Choi, Yao-Sheng Tung, Elisa E. Konofagou — 2010-09-01

Abstract: As a potentially viable method of brain drug delivery, the safety profile of blood-brain barrier (BBB) opening using focused ultrasound (FUS) and ultrasound contrast agents (UCA) needs to be established. In this study, we provide a short-term (30-min or 5-h survival) histological assessment of murine brains undergoing FUS-induced BBB opening. Forty-nine mice were intravenously injected with Definity microbubbles (0.05 μL/kg) and sonicated under the following parameters: frequency of 1.525 MHz, pulse length of 20 ms, pulse repetition frequency of 10 Hz, peak rarefactional acoustic pressures of 0.15–0.98 MPa and two 30-s sonication intervals with an intermittent 30-s delay. The BBB opening threshold was found to be 0.15–0.3 MPa based on fluorescence and magnetic resonance imaging of systemically injected tracers. Analysis of three histological measures in hematoxylin and eosin–stained sections revealed the safest acoustic pressure to be within the range of 0.3–0.46 MPa in all examined time periods post sonication. Across different pressure amplitudes, only the samples 30 min post opening showed significant difference (p < 0.05) in the average number of distinct damaged sites, microvacuolated sites, dark neurons and sites with extravasated erythrocytes. Enhanced fluorescence around severed microvessels was also noted and found to be associated with the largest tissue effects, whereas mildly diffuse BBB opening with uniform fluorescence in the parenchyma was associated with no or mild tissue injury. Region-specific areas of the sonicated brain (thalamus, hippocampal fissure, dentate gyrus and CA3 area of hippocampus) exhibited variation in fluorescence intensity based on the position, orientation and size of affected vessels. The results of this short-term histological analysis demonstrated the feasibility of a safe FUS-UCA–induced BBB opening under a specific set of sonication parameters and provided new insights on the mechanism of BBB opening. (E-mail: ek2191@columbia.edu)

Effects of Focused Ultrasound and Microbubbles on the Vascular Permeability of Nanoparticles Delivered into Mouse Tumors

Chung-Yin Lin, Yen-Lin Huang, Jia-Rong Li, Fu-Hsiung Chang, Win-Li Lin — 2010-09-01

Abstract: Ultrasound sonication with microbubbles (MBs) was evaluated for enhancement of the release of nanoparticles from vasculature to tumor tissues. In this study, tumor-bearing Balb/c mice were insonicated with focused ultrasound (FUS) in the tumors after the injection of MBs (SonoVue®) and then lipid-coated quantum dot (LQD) nanoparticles (130 ± 25 nm) were injected through the tail vein. We studied the effects of the injected MB dose (0–300 μL/kg), sonication duration (0–300 s) and treatment-procedure sequence on the accumulation of nanoparticles in the tumors 24 h after the treatment and the time response of the accumulation (0.5–24 h). After the treatment, the mice were sacrificed and perfused and then the tumor tissues were harvested for quantifying the amount of nanoparticles using graphite furnace atomic absorption spectrometry (GF-AAS). The results showed that pulsed-FUS sonication with MBs can effectively enhance the vascular permeability for LQD nanoparticle delivery into the sonicated tumors. It indicates that this technique is promising for a better nanodrug delivery for tumor chemotherapy. (E-mail: winli@ntu.edu.tw)

Targeted Gene Transfection from Microbubbles into Vascular Smooth Muscle Cells Using Focused, Ultrasound-Mediated Delivery

Linsey C. Phillips, Alexander L. Klibanov, Brian R. Wamhoff, John A. Hossack — 2010-09-01

Abstract: We investigated a method for gene delivery to vascular smooth muscle cells using ultrasound triggered delivery of plasmid DNA from electrostatically coupled cationic microbubbles. Microbubbles carrying reporter plasmid DNA were acoustically ruptured in the vicinity of smooth muscle cells in vitro under a range of acoustic pressures (0 to 950 kPa) and pulse durations (0 to 100 cycles). No effect on gene transfection or viability was observed from application of microbubbles, DNA or ultrasound alone. Microbubbles in combination with ultrasound (500-kPa, 1-MHz, 50-cycle bursts at a pulse repetition frequency [PRF] of 100 Hz) significantly reduced viability both with DNA (53 ± 27%) and without (19 ± 8%). Maximal gene transfection (∼1% of cells) occurred using 50-cycle, 1-MHz pulses at 300 kPa, which resulted in 40% viability of cells. We demonstrated that we can locally deliver DNA to vascular smooth muscle cells in vitro using microbubble carriers and focused ultrasound. (E-mail: jh7fj@virginia.edu)

Determining if the Relative Shear Modulus or the Inverse of the Relative Shear Modulus Should be Imaged Using Axial Strain Ratios on Agar Phantoms

Chikayoshi Sumi, Yuuki Takanashi, Kunio Shimizu, Yousuke Ishii — 2010-09-01

Abstract: An axial strain image is considered to be an image of a relative shear modulus. However, through simulations of focal lesions, it was previously confirmed that reconstruction imaging of the 1-D relative shear modulus or its inverse obtained from the ratio of the axial strain in the axial direction (i.e., the axial strain ratio), with respect to a reference strain, produces larger contrast-to-noise ratios (CNRs) than that of the axial strain, although both of the reconstructions have smaller relative contrasts than that of the original shear modulus. The reference strain is appropriately chosen in the area of a homogeneous neighborhood in front of or behind the target by viewing in the B-mode and strain images. It has also been confirmed that the evaluations of CNRs of reconstructions immediately after strain measurement permit a prediction of which reconstructions should be imaged, i.e., a decision can be made without obtaining the reconstruction images, but by using the statistical evaluations of the measured strains in the focal lesion and in the surrounding region. In this study, the feasibility of using this prediction is verified through agar phantom experiments using actual measured axial strains obtained with the 2-D cross-spectrum phase-gradient method. The resulting successful prediction revealed that the assumptions of independent stationary and random axial-strain measurement errors in the focal lesion and in the surrounding region are appropriate. (E-mail: c-sumi@sophia.ac.jp)

Ultrasound Dynamic Micro-Elastography Applied to the Viscoelastic Characterization of Soft Tissues and Arterial Walls

Cédric Schmitt, Anis Hadj Henni, Guy Cloutier — 2010-09-01

Abstract: Quantitative noninvasive methods that provide in vivo assessment of mechanical characterization of living tissues, organs and artery walls are of interest because information on their viscoelastic properties in the presence of disease can affect diagnosis and treatment options. This article proposes the dynamic micro-elastography (DME) method to characterize viscoelasticity of small homogeneous soft tissues, as well as the adaptation of the method for vascular applications [vascular dynamic micro-elastography (VDME)]. The technique is based on the generation of relatively high-frequency (240–1100 Hz) monochromatic or transient plane shear waves within the medium and the tracking of these waves from radio-frequency (RF) echoes acquired at 25 MHz with an ultrasound biomicroscope (Vevo 770, Visualsonics). By employing a dedicated shear wave gated strategy during signal acquisition, postprocessed RF sequences could achieve a very high frame rate (16,000 images per s). The proposed technique successfully reconstructed shear wave displacement maps at very high axial (60 μm) and lateral (250 μm) spatial resolutions for motions as low as a few μm. An inverse problem formulated as a least-square minimization, involving analytical simulations (for homogenous and vascular geometries) and experimental measurements were performed to retrieve storage (G′) and loss (G″) moduli as a function of the shearing frequency. Viscoelasticity measurements of agar-gelatin materials and of a small rat liver were proven feasible. Results on a very thin wall (3 mm thickness) mimicking artery enabled to validate the feasibility and the reliability of the vascular inverse problem formulation. Subsequently, the G′ and G″ of a porcine aorta showed that both parameters are strongly dependent on frequency, suggesting that the vascular wall is mechanically governed by complex viscoelastic laws. (E-mail: guy.cloutier@umontreal.ca)

A Method for Arterial Diameter Change Measurements Using Ultrasonic B-Mode Data

2010-09-01

Abstract: Arterial diameter change is related to distending blood pressure and is used in estimation of arterial stiffness parameters. A common technique to track the arterial walls is by integration of wall velocities estimated by different methods using cross correlation or tissue Doppler. However, because of the high pulse repetition frequency and the need for separate pulsing sequences, the B-mode image quality is affected. We have previously developed a fast algorithm for direct measurement of lumen diameter using B-mode images. In this study we have improved the technique to be more robust and also implemented measurements of diameter change, maximum differential wall velocity and relative diameter change of the common carotid artery noninvasively in vivo. The influence of the lateral width of the region of interest (ROI; 1 pixel, 0.1 mm, 0.5 mm, 1 mm, 2.5 mm and 5 mm) was evaluated. Using the optimal lateral width (2.5 mm), the systematic and random differences between two consecutive measurements were 21 μm and 105 μm, respectively, for lumen diameter measurement; –7 μm and 39 μm, respectively, for lumen diameter change measurements; –0.2 mm/s and 0.9 mm/s, respectively, for maximum relative wall velocity; and –0.2 % and 0.8 %, respectively, for measurements of the relative diameter change. The coefficient of variation (CV) was 1.9%, 5.2%, 7.9% and 6.0%, respectively. The study indicates that the reproducibility is sufficient for in vivo studies when the width of the ROI is 1.0 mm or wider. (E-mail: magnus.cinthio@elmat.lth.se)

Optimization of Doppler Echocardiographic Velocity Measurements Using an Automatic Contour Detection Method

2010-09-01

Abstract: Intra- and interobserver variability in Doppler echocardiographic velocity measurements (DEVM) is a significant issue. Indeed, imprecisions of DEVM can lead to diagnostic errors, particularly in the quantification of the severity of heart valve dysfunctions. To reduce the variability and rapidity of DEVM, we have developed an automatic method of Doppler velocity wave contour detection, based on active contour models. To validate our new method, results obtained with this method were compared with those obtained manually by two experienced echocardiographers on Doppler echocardiographic images of left ventricular outflow tract and transvalvular flow velocity signals recorded in 30 patients with aortic or mitral stenosis, 20 with normal sinus rhythm and 10 with atrial fibrillation. We focused on the three essential variables that are measured routinely using Doppler echocardiography in the clinical setting: the maximum velocity (Vmax), the mean velocity (Vmean) and the velocity-time integral (VTI). Comparison between the two methods has shown a very good agreement. A small bias value was found between the two methods (between –3.9% and 0.5% for Vmax, between –4.6% and –1.4% for Vmean and between –3.6% and 4.4% for VTI). Moreover, the computation time was short, ∼5 s. This new method applied to DEVM could, therefore, provide a useful tool to eliminate the intra- and interobserver variabilities associated with DEVM and thereby to improve the accuracy of the diagnosis of cardiovascular disease. This automatic method could also allow the echocardiographer to realize these measurements within a much shorter period of time compared with the standard manual tracing method. From a practical point of view, the model developed can be easily implemented in a standard echocardiographic system. (E-mail: emmanuel.gaillard@ircm.qc.ca)

Computer Aided Diagnosis of Parotid Gland Lesions Using Ultrasonic Multi-Feature Tissue Characterization

2010-09-01

Abstract: In this article, an ultrasound based system for computer aided characterization of biologic tissue and its application to differential diagnosis of parotid gland lesions is proposed. Aiming at an automated differentiation between malignant and benign cases, the system is based on a supervised classification using tissue-describing features derived from ultrasound radio-frequency (RF) echo signals and image data. Standard diagnostic ultrasound equipment was employed to acquire ultrasound RF echo data from parotid glands of 138 patients. Lesions were manually demarcated as regions-of-interest (ROIs) in the B-mode images. Spectral ultrasound backscatter and attenuation parameters are estimated from diffraction corrected RF data, yielding spatially resolved parameter images. Histogram based statistical measures derived from the parameters distributions inside the ROI are used as tissue describing features. In addition, texture features and shape descriptors are extracted from demodulated ultrasound image data. The features are processed by a maximum likelihood classifier. An optimal set of 10 features was chosen by a sequential forward selection algorithm. The classifier’s performance is evaluated using total cross validation and receiver operating characteristic (ROC) analysis. As a reference method, postoperative pathohistologic analysis was conducted and proved malignancy or prospective malignancy in 51 patients. The classification using the proposed system yielded an area under the ROC curve of 0.91, proving significant potential for differentiating between malignant and benign parotid gland lesions. (E-mail: stefan.siebers@rub.de)

Amplitude-Modulation Chirp Imaging for Contrast Detection

Meng-Lin Li, Yu-Chen Kuo, Chih-Kuang Yeh — 2010-09-01

Abstract: We propose an amplitude-modulation chirp imaging method for contrast detection with high-frequency ultrasound. Our proposed method detects microbubbles by extracting and then selectively compressing the component of the backscattered chirp signal modulated by changes in the radii of microbubbles at their resonance frequency. Microbubbles are sonicated simultaneously with a narrowband, low-frequency pumping signal at their resonance frequency and a wideband, high-frequency imaging chirp signal. Changes in the radii of the resonant microbubbles result in periodic changes in their acoustic cross section that modulate the amplitude of the backscattered imaging chirp signal, forming pumping and imaging frequency sum-and-difference chirp terms. The frequency-sum or -difference chirp component is then extracted by a bandpass filter (BPF). Because a long imaging pulse duration is required to obtain a sufficient modulation depth on the chirp for contrast detection and to facilitate frequency-sum-and-difference signal extraction with the BPF, a chirp with a longer-than-usual waveform is used so pulse compression of the extracted chirp signal can then be performed to maintain the axial resolution, and even further improve the signal-to-noise ratio and contrast-to-tissue ratio. Experiments performed on flow phantoms with and without a speckle-generating background were performed to demonstrate the efficacy of the proposed technique. These results indicate that our proposed method can potentially provide high-resolution contrast detection in the microvasculature. (E-mail: ckyeh@mx.nthu.edu.tw)

An Increase in Cellular Size Variance Contributes to the Increase in Ultrasound Backscatter During Cell Death

2010-09-01

Abstract: This study aims to explain the contribution of changes in cellular size variance (CSV) to increases in ultrasound-integrated backscatter (UIB) measured from cell samples undergoing cell death. A Monte Carlo algorithm was used to compare simulations of 2D distributions of cells, uniform (CSV = 0) versus heterogeneous (CSV > 0) and the same mean cellular size (). UIB increased in arrangements with heterogeneous cellular sizes from 3.6dB ( = 20 μm, CSV = 0 μm/CSV = 18 μm) to 5.6 dB (=10 μm, CSV = 0 μm/CSV = 8 μm). Experimentally, UIB (10 to 30 MHz) was measured from cell samples of four tumor cell lines viable and undergoing cell death after radiotherapy and chemotherapy treatment. An increase of 3.8–7.5 dB (p < 0.001) in UIB was measured from three cell lines. No increase in UIB was measured from one cell line. An increase in CSV was found for all cell samples after cell death. The results suggest that an increase in CSV could have a significant contribution to the increases measured in UIB after cell death in cell samples exposed to anticancer therapies. (E-mail: rvlad@lakeridgehealth.on.ca)

Ultrasound in Medicine and Biology

Masthead

Editorial Advisory Board

Contents

Biomedical Applications of Radiation Force of Ultrasound: Historical Roots and Physical Basis

Investigation of Acoustic Changes Resulting from Contrast Enhancement in Through-Transmission Ultrasonic Imaging

Evaluation of the Intraobserver and Interobserver Reliability of Data Acquisition for Three-Dimensional Power Doppler Angiography of the Whole Placenta at 12 Weeks Gestation

Ultrasound Measurements of the Masseter Muscle as Predictors of Cephalometric Indices in Orthodontics: A Pilot Study

Normative Cross-Sectional Area of the C5-C8 Nerve Roots Using Ultrasonography

Ultrasound-Guided Core Needle Biopsy of Cervical Lymphadenopathy in Patients with Lymphoma: The Clinical Efficacy and Factors Associated with Unsuccessful Diagnosis

Pathological Changes on Human Breast Cancer Specimens Ablated in vitro with High-Intensity Focused Ultrasound

Multi-Modality Safety Assessment of Blood-Brain Barrier Opening Using Focused Ultrasound and Definity Microbubbles: A Short-Term Study

Effects of Focused Ultrasound and Microbubbles on the Vascular Permeability of Nanoparticles Delivered into Mouse Tumors

Targeted Gene Transfection from Microbubbles into Vascular Smooth Muscle Cells Using Focused, Ultrasound-Mediated Delivery

Determining if the Relative Shear Modulus or the Inverse of the Relative Shear Modulus Should be Imaged Using Axial Strain Ratios on Agar Phantoms

Ultrasound Dynamic Micro-Elastography Applied to the Viscoelastic Characterization of Soft Tissues and Arterial Walls

A Method for Arterial Diameter Change Measurements Using Ultrasonic B-Mode Data

Optimization of Doppler Echocardiographic Velocity Measurements Using an Automatic Contour Detection Method

Computer Aided Diagnosis of Parotid Gland Lesions Using Ultrasonic Multi-Feature Tissue Characterization

Amplitude-Modulation Chirp Imaging for Contrast Detection

An Increase in Cellular Size Variance Contributes to the Increase in Ultrasound Backscatter During Cell Death