Harmonic Power Doppler Imaging Research Articles

How to Find an Isoechoic Lesion With Breast US

: Isoechoic lesions surrounded by fat can be a challenge for radiologists and can result in false-negative interpretations and a delayed diagnosis of breast cancer. Furthermore, isoechogenicity, including slight hypoechogenicity, as a common finding in breast lesions, is being reported in up to 84% of benign nodules and 30% of malignant lesions. Thus, about one-third of breast cancers may be described as isoechoic in actual clinical practice. Isoechogenicity can be seen in usual ductal hyperplasia, atypical ductal hyperplasia, papillary apocrine metaplasia, adenosis, debris and floating cells of complex cysts in the fibrocystic and benign proliferative conditions, fibroadenomas, and papillomas, as well as in about one-third of breast carcinomas. It is important to set the ultrasonic parameters, such as the dynamic range, total gain, and time-gain compensation curve, appropriately for comparison. Complementary tools to B-mode ultrasound in the evaluation of isoechoic breast lesions include spatial compound imaging, tissue harmonic imaging, ultrasound elastography, color or power Doppler imaging, power Doppler vocal fremitus imaging, and contrast agent enhancement.

How to Find an Isoechoic Lesion with Breast US

Breast ultrasonography (US) is recognized as a useful diagnostic tool for palpable or nonpalpable breast masses, but isoechoic lesions surrounded by fat can be a challenge for radiologists and can result in false-negative interpretations and a delayed diagnosis of breast cancer. Identifying isoechoic lesions surrounded with fat by using breast US requires meticulous evaluation with B-mode US in correlation with mammography. For correlation between mammography and US, the location, surrounding tissue, and lesion characteristics, including size, shape, and internal contents, must be considered. Complementary tools to B-mode US in the evaluation of isoechoic breast lesions include spatial compound imaging, tissue harmonic imaging, US elastography, color or power Doppler imaging, power Doppler vocal fremitus imaging, and contrast agent enhancement. Specimen radiography after breast biopsy can be helpful in evaluating the adequacy of tissue sampling and the appropriateness of lesion targeting and localization, evaluations that increase confidence in the findings from tissue acquisition.

Novel ultrasound contrast agent based on microbubbles generated from surfactant mixtures of Span 60 and polyoxyethylene 40 stearate

In this study, novel perfluorocarbon-filled microbubbles as ultrasound contrast agent were fabricated using ultrasonication of a surfactant mixture of sorbitan monostearate (Span 60) and polyoxyethylene 40 stearate (PEG40S) in aqueous media. The microbubbles generated from a 1:9 mixture of PEG40S/Span 60 exhibited an average diameter of 2.08+/-1.27 microm. More than 99% of the microbubbles had a mean particle diameter less than 8 microm, indicating that they were appropriately sized for intravenous administration as ultrasound contrast agent. The stabilization mechanism of the microbubbles was investigated by the Langmuir-Blodgett technique including the measurements of surface pressure-area (pi-A) isotherms and compression-decompression cycles with a two-dimensional monolayer of Span 60 and PEG40S. The dependence on molar fraction of PEG40S in pi-A isotherms of mixed monolayers provided a strong evidence of interactions between the two microbubble-forming materials. It is suggested that the monolayer shell imparts good stability to the microbubbles by three means: (1) a low surface tension monolayer hinders dissolution through the reduction of surface tension, which introduces a mechanical surface pressure that counters the Laplace pressure; (2) the presence of a monolayer shell imparts a significant barrier to gas escaping from the core into the aqueous medium; and (3) encapsulation elasticity stabilizes microbubbles against diffusion-driven dissolution and explains the long shelf-life of microbubble contrast agent. The preliminary in vivo ultrasound imaging study showed that such stabilized microbubbles demonstrated excellent enhancement under grey-scale pulse inversion harmonic imaging and power Doppler imaging.

Comparison of Myocardial Contrast Echocardiography Versus Rest Sestamibi Myocardial Perfusion Imaging in the Early Diagnosis of Acute Coronary Syndrome

It remains unclear whether myocardial contrast echocardiography (MCE) is as accurate as myocardial perfusion imaging with technetium-99m sestamibi (MPI) for the diagnosis of acute coronary syndrome (ACS). We sought to directly compare the diagnostic accuracy of MCE with resting MPI in a head-to-head fashion. We prospectively enrolled 98 consecutive patients (mean age; 59+/-9 years, 68 males) who presented to the emergency department with chest pain suggestive of acute myocardial ischemia. Early MCE was performed by using continuous infusion of perfluorocarbon-exposed sonicated dextrose albumin (PESDA) during intermittent power Doppler harmonic imaging. Myocardial perfusion defects observed in at least one coronary territory were considered positive. Sestamibi was injected immediately after MCE and MPI was obtained within 6 hours of tracer injection. ACS was confirmed in 67 patients. There were 32 patients with acute myocardial infarction (AMI) and 35 patients with unstable angina requiring urgent revascularization. The sensitivities of MCE and MPI for the diagnosis of ACS were 72% and 61%, respectively, which were significantly higher than those of ST segment change (24%, p<0.001 vs. MCE and vs. MPI) and troponin I (27%, p<0.001 vs. MCE and vs. MPI), with similar specificities of 90% to 100%. On a receiveroperating characteristics curve demonstrating diagnostic accuracy for ACS, the area under the curve of MCE was significantly larger than that of MPI (0.86 vs. 0.77, respectively; p=0.019). MCE and MPI overcome the low sensitivity of routine triage tests for detecting ACS, and MCE is more accurate than MPI for the diagnosis of ACS in the emergency department.

Angiotensin II Receptor Blocker, Valsartan, Increases Myocardial Blood Volume and Regresses Hypertrophy in Hypertensive Patients

Although a reduction in myocardial blood volume (MBV), an in vivo index of the myocardial microvasculature, measured by myocardial contrast echocardiography in patients with hypertension (HT), can be demonstrated, it is still unknown whether a decreased MBV can be improved by antihypertensive treatment. Eleven HT patients (mean age 58 years, 7 men) with left ventricular hypertrophy (LVH) and 10 age- and sex-matched normal controls were studied. Harmonic power Doppler images were acquired at end-diastole of every 6(th) beat and MBV was calculated as 10(X/10)x100%, where X (dB) is myocardial contrast intensity minus the contrast intensity of the adjacent intracavity blood pool. Baseline blood pressure (BP) and left ventricular mass index (LVMI) in the HT patients were higher and MBV was lower than in the controls (2.52 +/-0.37% vs 3.31 +/-0.61%, P<0.01). MBV did not correlate with mean BP, but was inversely correlated with LVMI (r=0.61, P<0.01). After treatment with valsartan for 6 months, LVMI significantly decreased and MBV increased (2.72 +/-0.26%, P<0.05 vs baseline) in the patients with HT. There was a significant inverse correlation between the changes in MBV and those of LVMI (r=0.62, P<0.05), but not between MBV and mean BP. Valsartan, an angiotensin II receptor blocker, corrected the decreased MBV in association with regression of LVH in patients with HT.

Comparative Analysis of Logistic Regression, Support Vector Machine and Artificial Neural Network for the Differential Diagnosis of Benign and Malignant Solid Breast Tumors by the Use of Three-Dimensional Power Doppler Imaging

ObjectiveLogistic regression analysis (LRA), Support Vector Machine (SVM) and a neural network (NN) are commonly used statistical models in computer-aided diagnostic (CAD) systems for breast ultrasonography (US). The aim of this study was to clarify the diagnostic ability of the use of these statistical models for future applications of CAD systems, such as three-dimensional (3D) power Doppler imaging, vascularity evaluation and the differentiation of a solid mass.Materials and MethodsA database that contained 3D power Doppler imaging pairs of non-harmonic and tissue harmonic images for 97 benign and 86 malignant solid tumors was utilized. The virtual organ computer-aided analysis-imaging program was used to analyze the stored volumes of the 183 solid breast tumors. LRA, an SVM and NN were employed in comparative analyses for the characterization of benign and malignant solid breast masses from the database.ResultsThe values of area under receiver operating characteristic (ROC) curve, referred to as Az values for the use of non-harmonic 3D power Doppler US with LRA, SVM and NN were 0.9341, 0.9185 and 0.9086, respectively. The Az values for the use of harmonic 3D power Doppler US with LRA, SVM and NN were 0.9286, 0.8979 and 0.9009, respectively. The Az values of six ROC curves for the use of LRA, SVM and NN for non-harmonic or harmonic 3D power Doppler imaging were similar.ConclusionThe diagnostic performances of these three models (LRA, SVM and NN) are not different as demonstrated by ROC curve analysis. Depending on user emphasis for the use of ROC curve findings, the use of LRA appears to provide better sensitivity as compared to the other statistical models.

P46.04: Characterization of benign and malignant solid breast masses in harmonic 3D power Doppler imaging

P46.04: Characterization of benign and malignant solid breast masses in harmonic 3D power Doppler imaging

Characterization of benign and malignant solid breast masses in harmonic 3D power Doppler imaging

Purpose The authors assessed the characteristics of benign and malignant solid breast tumors in harmonic three-dimensional (3D) power Doppler imaging and proposed decision models to classify benign and malignant breast tumors. Materials and methods A total of 86 malignant and 97 benign harmonic 3D power Doppler US images were analyzed. All the harmonic 3D power Doppler images were obtained using a Voluson730 US system (GE, Zipf, Austria) equipped with a RSP 6–12 transducer and tissue harmonic imaging modalities. Imaging analysis was performed using the Virtual Organ Computer-aided Analysis (VOCAL)-imaging program. Histogram indices, the vascularization index (VI), flow index (FI) and vascularization-flow index (VFI), were calculated for the intra-tumor and for shells with an outside thickness of 3 mm surrounding the breast tumors. The receiver operating characteristic (ROC) curves were calculated to estimate the diagnostic performances. Results The results revealed that the choice of decision model comprised the parameters of patient age, intra-tumor VI, and tumor volume to classify benign and malignant breast tumors. The area under the ROC curve (Az) was 0.910, accuracy was 81.4%, and sensitivity and specificity were 81.4% and 81.4%, respectively. The parameter intra-tumor VI was the choice for all of the histogram indices in differentiating between malignant and benign lesions. Conclusion The decision model, which was composed of patient age, tumor volume and intra-tumor VI, and a cut-off value for intra-tumor VI at the upper end of patient age and tumor volume, was recommended in clinical application.

Abstract 2085: Increased Regional Coronary Vascular Resistance During Hyperemia in Hypertrophic Cardiomyopathy Is Associated with Reduced Myocardial Blood Volume

Introduction: In patients with hypertrophic cardiomyopathy ( HCM ), myocardial blood flow ( MBF ) is decreased during hyperemia because of high coronary vascular resistance. Recently myocardial blood volume ( MBV ) can be estimated in vivo using myocardial contrast echocardiography ( MCE ) with the compensation for acoustic field inhomogeneity. The relationship between MBV and coronary resistance, however, has not been investigated. We thus assessed the hypothesis that increased regional coronary vascular resistance during hyperemia in HCM is associated with reduced MBV. Methods: In 13 patients with HCM ( H , 53±16 years) with asymmetric septal hypertrophy and 9 normal volunteers ( N , 54±11 years), MCE was performed under infusion of Levovist at rest and during hyperemia induced by ATP. Apical 4-chamber views of intermittent harmonic power Doppler imaging were acquired at end-diastole of every sixth beat. MBV was calculated as 10 X/10 ×100%, where X was myocardial contrast intensity minus contrast intensity of the adjacent intracavity blood pool in dB. 15 O-water PET was performed to measure regional MBF. These parameters were measured in the interventricular septum ( IVS ) and LV posterolateral ( PL ) wall. Regional coronary vascular resistance was calculated as (mean blood pressure)/MBF. Results: Wall thickness was significantly greater in H than in N (IVS: 19±4 vs 10±1 mm, p&lt;0.0001; PL: 10±1 vs 9±1 mm, p&lt;0.05). MBV of IVS was lower in H than in N (rest: 2.1±0.7 vs 3.5±1.1%, p&lt;0.01; hyperemia: 2.1±1.3 vs 4.3±1.7%, p&lt;0.01), whereas MBV of PL wall did not differ between groups. Coronary resistance at rest did not differ between groups, but the resistance during hyperemia was significantly greater in H than in N (IVS: 59±16 vs 31±14 mmHg·min·g·ml −1 , p&lt;0.001; PL: 40±10 vs 30±11 mmHg·min·g·ml −1 , p&lt;0.05). Coronary resistance at rest did not correlate with MBV, whereas that during hyperemia inversely correlated with MBV during hyperemia (r=−0.77, p&lt;0.0001) as well as MBV at rest (r=−0.65, p&lt;0.0001). Conclusions: Increased coronary vascular resistance during hyperemia in HCM was significantly associated with reduced MBV. MCE is useful for assessing the dynamic function of coronary circulation in the clinical setting.

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.

Quantitative assessment of harmonic power doppler myocardial perfusion imaging with intravenous levovist™ in patients with myocardial infarction: comparison with myocardial viability evaluated by coronary flow reserve and coronary flow pattern of infarct-related artery

BackgroundMyocardial contrast echocardiography and coronary flow velocity pattern with a rapid diastolic deceleration time after percutaneous coronary intervention has been reported to be useful in assessing microvascular damage in patients with acute myocardial infarction.AimTo evaluate myocardial contrast echocardiography with harmonic power Doppler imaging, coronary flow velocity reserve and coronary artery flow pattern in predicting functional recovery by using transthoracic echocardiography.MethodsThirty patients with anterior acute myocardial infarction underwent myocardial contrast echocardiography at rest and during hyperemia and were quantitatively analyzed by the peak color pixel intensity ratio of the risk area to the control area (PIR). Coronary flow pattern was measured using transthoracic echocardiography in the distal portion of left anterior descending artery within 24 hours after recanalization and we assessed deceleration time of diastolic flow velocity. Coronary flow velocity reserve was calculated two weeks after acute myocardial infarction. Left ventricular end-diastolic volumes and ejection fraction by angiography were computed.ResultsPts were divided into 2 groups according to the deceleration time of coronary artery flow pattern (Group A; 20 pts with deceleration time ≧ 600 msec, Group B; 10 pts with deceleration time < 600 msec). In acute phase, there were no significant differences in left ventricular end-diastolic volume and ejection fraction (Left ventricular end-diastolic volume 112 ± 33 vs. 146 ± 38 ml, ejection fraction 50 ± 7 vs. 45 ± 9 %; group A vs. B). However, left ventricular end-diastolic volume in Group B was significantly larger than that in Group A (192 ± 39 vs. 114 ± 30 ml, p < 0.01), and ejection fraction in Group B was significantly lower than that in Group A (39 ± 9 vs. 52 ± 7%, p < 0.01) at 6 months. PIR and coronary flow velocity reserve of Group A were higher than Group B (PIR, at rest: 0.668 ± 0.178 vs. 0.248 ± 0.015, p < 0.0001: during hyperemia 0.725 ± 0.194 vs. 0.295 ± 0.107, p < 0.0001; coronary flow velocity reserve, 2.60 ± 0.80 vs. 1.31 ± 0.29, p = 0.0002, respectively).ConclusionThe preserved microvasculature detecting by myocardial contrast echocardiography and coronary flow velocity reserve is related to functional recovery after acute myocardial infarction.

Power Doppler Harmonic Imaging in the Monitoring of Free Flap Tissue Perfusion: A Pilot Study

Power Doppler Harmonic Imaging in the Monitoring of Free Flap Tissue Perfusion: A Pilot Study

1719: Detection of Prostate Cancer with Contrast Enhanced Sonography Using Harmonic Gray Scale, Color Doppler and Power Doppler Imaging

1719: Detection of Prostate Cancer with Contrast Enhanced Sonography Using Harmonic Gray Scale, Color Doppler and Power Doppler Imaging

Myocardial contrast echocardiography with a new calibration method can estimate myocardial viabilityin patients with myocardial infarction

ObjectivesWe have developed a novel calibration technique applicable for myocardial contrast echocardiography (MCE). We assessed the value of this technique in the recognition of myocardial infarction (MI) and its spatial extent, and we also performed a validation study in normal subjects. BackgroundThe heterogeneity of contrast intensity (CI) among myocardial segments limits the clinical use of MCE. MethodsWe performed MCE with a slow-bolus injection of Levovist and recorded end-systolic harmonic power Doppler images at intervals of four heart beats in 15 normal volunteers and 30 patients with MI. We divided the left ventricular (LV) wall into 12 segments and placed the region of interest in the subendocardial region in each segment and in the adjacent LV cavity. We measured calibrated CI (dB) by subtracting the cavity CI from myocardial CI. ResultsThe mean intersegmental difference in myocardial CI was 15.8 dB at baseline, whereas it was reduced to 6.3 dB after calibration (p < 0.01). Calibrated CI was higher in the kinetic segments than in the akinetic segments (−14.5 ± 2.3 dB [range −18.7 to −9.9 dB] vs. −22.5 ± 2.6 dB [−27.8 to −17.7 dB], p < 0.001), and −18.0 dB was the optimal cutoff point to discriminate these from each other. Color-coded mapping of calibrated CI may identify the spatial extent of persistently akinetic myocardium as areas of calibrated CI of ≤−18.0 dB. ConclusionsThis new calibration method reduces the intersegmental difference in CI in normal subjects. Calibrated CI provides an estimate of persistently akinetic myocardium in patients with MI, and its color-coded mapping is comprehensive and identifies the spatial extent of MI.

Potential pitfalls of visualization of myocardial perfusion by myocardial contrast echocardiography with harmonic gray scale B-mode and power Doppler imaging

The present study compared the regional variation of myocardial signal intensity in visualizing myocardial perfusion by myocardial contrast echocardiography (MCE) between harmonic gray scale and power Doppler imaging. MCE was performed in 12 patients by electrocardiographic (ECG)-gated intermittent triggered MCE with harmonic gray scale and power Doppler imaging following slow intravenous injection of 0.5 ml contrast agent (Optison). The interval between the ECG triggers (pulsing interval) was increased from every heart beat (1:1) to every 2 (1:2), 4 (1:4), and 8 (1:8) cardiac cycles to allow incremental microbubble (contrast agent) replenishment. The MCE images were recorded when attenuation produced by the left ventricular cavity was minimal. The background-subtracted videointensity was measured in 7 segments in an apical 4-chamber view: 3 (apical, mid, and basal) septal segments, 3 (apical, mid, and basal) lateral segments, and 1 apex segment (apical cap). The background-subtracted videointensity for each segment was greater with the power Doppler than the gray scale imaging (p < 0.01). With the gray scale imaging, the background-subtracted videointensity in the basal septal segment demonstrated a negative value at all pulsing intervals, and the value (-9 +/- 13) was significantly lower than that (22 +/- 20) in the apical lateral segment at a pulsing interval of 1:8 (p < 0.01). With power Doppler imaging, the background-subtracted videointensity was high even in the basal septal segment (112 +/- 33), and no significant difference was observed among each segment. The findings indicate that quantitative assessment of myocardial perfusion based upon background-subtracted video-intensity may be difficult in the far field with harmonic gray scale imaging although the attenuation is not apparent by visual analysis. Harmonic power Doppler is more sensitive for detecting basilar perfusion in the far field compared with harmonic gray scale imaging.

Detection of Coronary Artery Stenosis by Phasic Changes in Myocardial Blood Volume by Intravenous Myocardial Contrast Echocardiography in Humans

Background. Intravenous myocardial contrast echocardiography (MCE) has emerged as a novel method for assessment of myocardial blood volume (MBV), which changes in proportion to coronary stenosis severity at rest. The purpose of this study was to clarify the relation between phasic changes in MBV and the severity of coronary artery stenosis in humans.Methods. We studied 58 patients with suspected coronary artery disease who underwent MCE with harmonic power Doppler imaging and continuous infusion of Levovist. Both end-systolic and end-diastolic images were obtained separately at every cardiac cycle. Regions of interest were placed at the mid-septum, and phasic changes in myocardial signal intensity (SI) were calculated as (SI at end-diastole)-(SI at end-systole).Results. Twenty-four patients had significant coronary stenosis in the left anterior descending coronary artery (LAD), and 34 did not. The phasic changes in patients with LAD stenosis were significantly lower than that in patients without LAD stenosis (−0.5±1.2dB vs. 1.3±1.4dB, p 70% stenosis in LAD, the phasic changes <0.4 was the optimal cut-off value which provided sensitivity of 75%, specificity of 71% and accuracy of 73%.Conclusions. Phasic changes in MBV assessed by MCE have the potential for detection of coronary artery stenosis in the clinical setting at rest.

178 Quantitative evaluation of regional myocardial perfusion during dipyridamole stress by real-time myocardial contrast echocardiography in patients with and without coronary artery disease

178 Quantitative evaluation of regional myocardial perfusion during dipyridamole stress by real-time myocardial contrast echocardiography in patients with and without coronary artery disease

117 Tissue velocity imaging and myocardial contrast echocardiography with power Doppler harmonic imaging during adenosine stress

117 Tissue velocity imaging and myocardial contrast echocardiography with power Doppler harmonic imaging during adenosine stress

Intravenous myocardial contrast echocardiography during angioplasty.

Myocardial contrast echocardiography (MCE) using power Doppler harmonic imaging (PDHI) has been reported to document regional myocardial perfusion. Two case reports demonstrate the potential of intravenous myocardial contrast echocardiography during angioplasty.

Myocardial blood flow parameters derived from contrast replenishment using harmonic power doppler imaging are underestimated by ultrasound signal attenuation

The effect of ultrasound signal attenuation on myocardial blood flow parameters derived from contrast replenishment was evaluated using harmonic gray-scale (HGS) and harmonic power Doppler (HPD) imaging. In vitro experiments were performed in a flow model, whereas in vivo experiments were performed in 5 open-chest dogs. In each study, intermittent HGS and HPD images were acquired at various pulsing intervals during contrast infusion. A silicone pad was interposed between the transducer and target region to simulate attenuation conditions. Baseline-subtracted HGS and HPD signal intensities were measured with and without silicone pad, and myocardial blood flow parameters A and β were calculated using contrast replenishment. Attenuation with HGS images could be offset by baseline subtraction, as baseline images provided the reference for attenuation. However, attenuation with HPD images could not be compensated for, as baseline signal intensity was theoretically 0. In HGS mode, silicone attenuation produced no significant decreases in A and β. In HPD mode, however, A and β were significantly decreased by silicone attenuation (A, P < .001; β, P < .05). Compared with nonattenuated regions, myocardial blood flow parameters in attenuated regions are underestimated when HPD imaging is used. Baseline-subtracted HGS imaging may be useful to compensate for thoracic wall attenuation.