Improvement of endocardial border delineation in suboptimal stressechocardiograms using the new left heart contrast agent SH U 508 A

Recent studies have shown that the saccharide based echocardiographic contrast agent SH U 508 A opacifies the left ventricle after i.v. injection, thus possibly improving endocardial border definition. This study was performed to determine whether SH U 508 A can enhance the wall motion analysis in suboptimal echocardiographic images at rest and following pharmacological stress. Ten male patients (mean 58 years) exhibiting ≥30% endocardial border dropout were examined prior to a diagnostic left heart catheterization. Five patients were stressed with Dobutamine, 5 with Dipyridamole. The wall motion was assessed visually (qualitatively) as well as computer-aided (quantitatively). The concordance between left ventricular angiography as ‘gold standard’ and resting echocardiography regarding the wall motion analysis was significantly improved from 64.5% to 90.3% following the injection of SH U 508 A (p < 0.05). A delineation score (0 = not delineated, 1 = delineated) of 12 individual wall segments was used. The mean delineation score at baseline was 6.1 ±1.4 at rest and 6.6 ±1.9 during stress. SH U 508 A significantly (p < 0.01) increased the score to 9.6 ±1.9 and 10.3 ±1.7, respectively. The intraobserver variability for assessing the delineation score was significantly (p < 0.04) improved by SH U 508 A. SH U 508 A, however, did not improve the quantitative assessment of the left ventricular function. Only 40% of the patients could be analyzed following SH U 508 A injection. No severe adverse reactions were seen. SH U 508 A led to a significant, clinically important, improvement in the interpretation of stress echocardiograms in patients with inconclusive routine echocardiograms.     

The influence of intravenous Albunex injections on pulmonary arterial pressure, gas exchange, and left ventricular peak intensity.

Contrast ultrasonography may be used to assess regional tissue perfusion. The purpose of this study was to evaluate the safety and efficacy of a new, commercially prepared ultrasound contrast agent (Albunex) in dogs. The injections were administered from peripheral intravenous (IV), right atrial (RA), and pulmonary artery (PA) sites. Acute pulmonary hemodynamic and gas exchange effects of low-dose (0.5, 1.0, 2.0 ml) Phase I injections, and high-dose (2.0, 5.0, 10, 20 ml) Phase II injections of Albunex were evaluated in nine dogs. Immediately before and after each injection, pulmonary artery pressure (PAP) and oxygen tension (PO2) were determined. In addition, left ventricular cavity opacification was assessed visually and by videodensitometric off-line analysis. Visual assessment was performed by four blinded observers who graded on a scale of 0 to 3 (0 = no contrast enhancement of the left ventricular (LV) cavity; 1 = weak or suboptimal contrast enhancement; 2 = optimal or excellent contrast enhancement; and 3 = attenuation of the ultrasound signal following a contrast injection). Peak pixel intensity was also determined with videodensitometric analysis. Results showed that significant changes in PAP or PO2 were not noted after Albunex injections, regardless of injection site or dose range. The average change in PAP after Albunex injection was 1.0 mm Hg +/- 1.2 mm Hg (NS), and the average change in PO2 after Albunex injections was 6.2 mm Hg +/- 6.7 mm Hg (NS). The left ventricular cavity peak pixel intensity was dependent on both injection site (PA = RA > IV) and dose range (2.0 = 1.0 > 0.5).(ABSTRACT TRUNCATED AT 250 WORDS)     

彩色多普勒血流显像评价肾癌的血管性——一种新的超声造影剂的应用价值

目的：评价超声造影剂利声显对彩超检测肾细胞癌血流状况的增强效应,并探讨其临床应用价值。资料与方法：应用彩色多普勒血流显像检查１９例（个）肾细胞癌,均经手术病理证实,经周围静脉注射超声造影剂利声显（ＳＨＵ５０８Ａ）,浓度３００ｍｇ／ｍｌ,平均注射剂量７９ｍｌ。观察注射前后瘤内血流信号显像情况。结果：超声造影前１９个肾癌彩超显示４个无血流信号,１１个周边部分环绕血流,４个瘤周瘤内见散在点状、短条状血流;超声造影后,１９个肾癌瘤内血流信号均增强,１６／１９（８４．２１％）明显增强,３／１９（１５．７９％）轻度增强,增强效应主要表现为血流信号明显增多,分布区域增大,血管显示段延长,分枝更清晰完整。结论：超声造影剂利声显能显著增强肾细胞癌内彩色多普勒血流信号,更完整显示肾癌的血管形态、分布等,明显改善彩超对肾癌血供的评价,对肾肿瘤诊断有重要的临床应用价值。     

Albunex: a safe and effective commercially produced agent for myocardial contrast echocardiography

Microbubble solutions of sonicated human serum albumin have been shown to be effective echocardiographic contrast agents free from adverse effects on coronary blood flow, left ventricular function, and systemic hemodynamics. Albunex is a commercially prepared solution of air-filled albumin microspheres prepared from sonicated 5% human serum albumin. The effects of Albunex on coronary blood flow, left ventricular function, and systemic hemodynamics, as well as contrast enhancement were evaluated in 10 open chest, anesthetized dogs. After an intracoronary injection, Albunex did not alter left atrial, left ventricular systolic or end-diastolic, or mean aortic pressures. It did not cause a coronary hyperemic response, alter left ventricular systolic thickening, or lower the peak positive left ventricular dp/dt. It did not alter these measurements even in the presence of a critical coronary stenosis. The contrast opacification produced by Albunex microbubbles was dose dependent (optimal dose range of 0.033 to 0.5 ml/kg), with attenuation occurring at higher doses. In conclusion, although Albunex provides adequate contrast enhancement, intracoronary injection of Albunex does not significantly alter coronary blood flow, left ventricular function, or systemic hemodynamics. Because of the standardized size and concentration of the microspheres, Albunex may be an ideal agent for myocardial contrast echocardiography.     

Improved imaging of hepatic metastases with delayed pulse inversion harmonic imaging using a contrast agent SH U 508A: preliminary study

To investigate the feasibility of delayed pulse-inversion harmonic imaging (PIHI) with the SH U 508A to improve imaging of hepatic metastases, we evaluated 20 patients with known hepatic metastases. Conventional ultrasound (US) was performed before administration, and PIHI was performed 5 min after a bolus injection of 4 G of microbubble contrast agent (300 mg/mL of SH U 508A). Intense, homogeneous enhancement in the liver parenchyma was seen in all patients on delayed PIHI. In 10 patients (50%), 1 or more focal liver lesions that were not seen on unenhanced imaging were detected on delayed PIHI. When comparing 55 lesions that were seen on both techniques, delayed PIHI was superior to unenhanced imaging in terms of lesion conspicuity and lesion-to-liver contrast (p < 0.001, respectively). Delayed PIHI with SH U 508A can improve conspicuity of hepatic metastases and reveal focal liver lesions that are not detected on unenhanced imaging.     

In vivo kinetics of microbubbles of SH U 508 A (Levovist): comparison with indocyanine green in rabbits

The aim of this study was to evaluate in vivo kinetics of microbubbles of SH U 508 A, in comparison with Indocyanine Green, a dye used as an indicator of blood flow. Microbubble kinetics were evaluated in various vessels (i.e., vena cava, aorta, renal artery, renal vein and portal vein) in rabbits after injection of SH U 508 A by measuring Doppler signals (n = 5). The kinetics of Indocyanine Green were evaluated by measuring absorbance using a photodiode (n = 5). Test substances (SH U 508 A 300 mg/mL and Indocyanine Green 1.25 mg/mL) were injected IV at a dose of 0.1 mL/kg B.W. Peak signal intensity was observed immediately after injection of SH U 508 A, followed by biphasic decay. The rates of biphasic decay were similar in all vessels. A second peak of the signal, which indicated recirculation of the microbubbles, was observed in the vena cava. The circulation and recirculation times of the microbubbles after injection of SH U 508 A were similar to that of Indocyanine Green. These findings suggest that the majority of SH U 508 A microbubbles circulate through the body similarly to blood flow, without retention, in the vasculature.     

Contrast-enhanced agent detection imaging: value in the characterization of focal hepatic lesions.

OBJECTIVE: To assess the value of SH U 508A-enhanced agent detection imaging in the characterization of focal hepatic lesions. METHODS: Contrast-enhanced agent detection imaging was performed on 78 focal hepatic lesions: 34 hepatocellular carcinomas, 22 metastases, 9 hemangiomas, 9 abscesses, 3 cysts, and 1 focal nodular hyperplasia. After administration of SH U 508A, interval delay scanning with agent detection imaging was performed with intervals of approximately 7 seconds (phase I), 30 seconds (phase II), and 90 seconds (phase III) after the first arrival of the contrast agent to the liver. Two observers blinded to the final diagnosis reviewed selected images and assessed the enhancement patterns of the lesions. For quantitative analysis, we calculated the enhancement ratio of the lesions and the difference of enhancement between the lesions and the liver parenchyma. RESULTS: Agent detection imaging showed a distinctive enhancement pattern in focal liver lesions compared with that in the liver. Hepatocellular carcinomas were characterized by early enhancement (phase I) and washout (phases II and III; sensitivity, 94.1%; specificity, 93.2%; positive predictive value, 91.4%). Metastases showed peripheral rim or targetlike enhancement (phase I, phase II, or both) and a defect (phase III) and had sensitivity of 77.3%, specificity of 100%, and a positive predictive value of 100%. Hemangiomas showed peripheral nodular or inhomogeneous (phase I, phase II, or both) and gradually centripetal (phase II, phase III, or both) enhancement (sensitivity, 88.9%; specificity, 100%; positive predictive value, 100%). Abscesses were partially enhanced from phase I to phase III (sensitivity, 66.7%; specificity, 95%; positive predictive value, 85.7%). The results of the quantitative analysis of lesion enhancement were compatible with those of the qualitative analysis. CONCLUSIONS: SH U 508A-enhanced agent detection imaging may yield distinctive enhancement characteristics in focal liver lesions that would contribute positively to the characterization of these hepatic lesions.     

Characterization of portal vein thrombus with the use of contrast-enhanced sonography.

OBJECTIVES: To select an appropriate treatment regimen, it is essential to accurately characterize the nature of a thrombus. This study prospectively assessed the ability of contrast-enhanced sonography to differentiate between benign and malignant portal vein thrombosis in a population of high-risk patients. METHODS: Fifty-five patients (43 men and 12 women; mean age, 66 years; range, 55-83 years) with thrombi of the portal venous system were examined by power Doppler sonography and contrast-enhanced sonography with the intravenous contrast agent SH U 508A (Levovist; Schering AG, Berlin, Germany). Of the thrombi, 40 were characterized as malignant and 15 as benign. Pulsatile flow in the thrombus on power Doppler sonography and positive enhancement of the thrombus on contrast-enhanced sonography were judged as indications of a malignant thrombus. The sensitivity and specificity of both methods in differentiating the nature of the thrombus were evaluated. RESULTS: The detection of pulsatile flow in a portal vein thrombus as the criterion for diagnosing malignant portal vein thrombus yielded overall sensitivity of 82.5% and specificity of 100%, whereas positive enhancement of the portal vein thrombus itself as a criterion for diagnosing malignancy yielded overall sensitivity and specificity of 100% for each. CONCLUSIONS: Contrast-enhanced sonography can be helpful in discriminating between benign and malignant portal vein thrombi.     

Sonographic investigation of flow patterns in the perfused human placenta and their modulation by vasoactive agents with enhanced visualization by the ultrasound contrast agent Albunex.

PURPOSE: Our objective was to demonstrate sonographically the flow distribution in the circulation of human placentae as well as the sensitivity of the human fetal capillary bed to vasoconstriction and dilatation. METHODS: Five human full-term placental lobules were maintained in vitro with fetal and maternal flow. Commercial ultrasound scanners were used for imaging. Albunex (1 ml bolus) was administered to the fetal "artery" to monitor patterns of flow. U46619 (1 ml, 10(-6) M; a thromboxane agonist and potent vasoconstrictor) and/or nitroglycerin (a potent vasodilator) were added to the fetal artery. RESULTS: Following the addition of U46619, mean "fetal pressures" rapidly rose from 23.2 +/- 0.8 to 118 +/- 2. 9 mm Hg (mean +/- standard error of mean; p < 0.001); venous flow rates decreased. As demonstrated by color Doppler imaging, flow markedly changed from a pattern of general distribution throughout the lobule to flow only near the chorionic plate. Color persistence was 94.4 +/- 6.5 seconds with Albunex after nitroglycerin and 39.8 +/- 3.4 seconds with Albunex after injection of U46619 (p < 0.001). Nitroglycerin had no effect when injected by itself but returned "constricted" flow to a "normal" pattern when injected after U46619. CONCLUSIONS: The contrast medium Albunex improved visualization of the fetal circulation throughout the lobule. Flow in the human placental capillary bed can be regionally manipulated throughout the placental lobule by vasomodulators and monitored by Albunex-enhanced sonographic examination.     

Optimizing Albunex in the left ventricle: An analysis of the technical parameters of four ultrasound systems in canines and humans

Albunex, an intravascular ultrasound contrast agent, has been used clinically to enhance echocardiographic images. The purpose of this study is (1) to determine whether varying the settings on commercially available ultrasound machines has an effect on left ventricular opacification after intravenously administered Albunex and if there is an effect on left ventricular opacification and (2) to determine the ideal settings for each ultrasound scanner. Six canine hearts were imaged with 1 ml injections of intravenously administered Albunex while varying the transducer frequency, preprocessing curves, postprocessing curves, and dynamic range on a variety of ultrasound units. Subsequently, 50 human subjects underwent imaging with the various machines while the dynamic range and transducer frequencies were altered. All subjects received two or three intravenous injections of 10 ml Albunex. The opacification of the left ventricular cavitary images in both parts of the study were interpreted visually on a scale of 0 to 4 (0 = none, 1 = trace, 2 = moderate, 3 = dense, and 4 = ideal) by four observers. The maximum compression and transducer frequency of 3.5 MHz showed significant improvement of left ventricular opacification in both canines and humans. These studies have shown that (1) varying the ultrasound unit's parameters affects the quality of left ventricular imaging when Albunex is used to enhance the image, and (2) higher compression and a transducer frequency of 3.5 MHz tend to enhance Albunex images of canine and human hearts.     

Contrast echocardiography of the left ventricle an independent predictor of pulmonary artery pressure?

To test the hypothesis that left heart opacification is dependent on pulmonary artery pressure, we analyzed consecutively 12 patients with normal and 8 patients with abnormal pulmonary artery pressure with a new lung capillary stable echo contrast agent. Patients underwent contrast echocardiographic examination within 6 hours before right and left heart catheterization with 200 mg/ml and 400 mg/ml SHU 508A intravenously. The mean pulmonary artery pressure was 15.4 mmHg in the patients with normal pulmonary artery pressures and 46.4 mmHg in the patients with pulmonary hypertension (p< 0.000). Echocardiograms were video-intensitometrically analyzed for intensity maximum (MAX), half-time of video-intensity decay (T1/2), area under the intensity curve (AUC) in the right and left ventricle and transit time from left to right heart (TT). Patients with normal pulmonary artery pressure showed sufficient left heart opacification, in the left ventricle MAX was 37±15 IU, AUC measured 653±463 IUxs and Tl/2 was 4.4±2.6 s, while patients with elevated pulmonary artery pressure showed no significant left heart opacification. In the left ventricle MAX was 8±10 IU (p=0.006), AUC measured 66±108 (p=0.003) and T1/2 was 2.0±2.0 s (p=0.041). TT was significantly increased in patients with elevated pulmonary artery pressure (11.8±4.6 s versus 6.5±2.8 s in patients with normal pulmonary artery pressure, p=0.005). Thus, elevated pulmonary pressure has a significant impact on left heart opacification, which may be used for diagnostic purposes.     

静注声振微气泡左心声学造影的实验研究

在１０条开胸犬，经周围静脉分别注射声振７０６代血浆及Ｇｅｌｉｆｕｎｄｏｌ（０．５ｍｌ／ｋｇ）进行左心声学造影。结果：左室显影成功率１００％。二种造影右室密庥显影时间。肺转动时间及左室显影持续时间间无差异（Ｐ＞０．０５）。     

急性冠脉闭塞犬心肌内血流改变的多普勒显像研究

目的应用冠脉血流多普勒显像技术观察急性前降支冠脉闭塞后后壁心肌内血流改变,并探讨这种变化的意义。方法15条杂种犬常规麻醉开胸后,应用冠脉血流程序观察前降支结扎后后壁内的血流信号改变,测量冠脉结扎前后后壁内血流速度,计算结扎后峰值血流速度和速度时间积分的变化值与结扎前相应指标之比;自主动脉根部注射Albunex进行心肌声学造影显像,观察前壁内造影效果,并进行造影评分,测量充填缺损区面积。结果根据前壁内显影效果,将实验犬分为A、B两组A组5条,前降支冠脉结扎后声学造影时前壁内完全未见造影剂充填,造影评分为0分;B组9条,声学造影时前壁内有不同程度的造影增强,评分为1或2分。A组结扎后后壁峰值血流速度变化分数[(V2－V1)/V1]和速度时间积分变化分数[(VTI2－VTI1)/VTI1]明显低于B组,差异有显著性意义[A、B两组(V2－V1)/V1分别为0.068±0.100和0.690±0.460,P＜0.01;(VTI2－VTI1)/VTI1分别为0.123±0.197和0.990±0.770,P＜0.01]。冠脉结扎后,两组前壁增厚率和左室射血分数均较结扎前明显降低,A、B两组各相对应参数间差异无显著性(P均＞0.05)。结论冠脉血流显像技术不但能发现冠脉结扎后靶血管供血区心肌内血流变化,而且可观察对侧心肌内血流的改变,在缺血区有侧支血流供应组(B组)对侧后壁内血流增加,通过对侧心肌内血流速度的变化,能间接判断侧支循环的开放情况。     

国产八氟丙烷微泡造影剂左心室超声显像效果研究

目的评价八氟丙烷微泡超声造影剂(C3F8)的左心室超声显像效果。方法7头实验猪分别接受低剂量(0．002ml／kg)和高剂量(0．02ml／kg)C3F8静脉注射，观察造影剂注射前后左心室显影等级、左室内膜边界改善效果和Simpson法左室射血分数测定，同时评价其对实验猪的心率、呼吸的影响。结果C3F8注射后左室显影等级强度和内膜边界增强节段数均显著改善，部分心肌也可以显影；对心率和呼吸未见明显影响。结论经静脉注射C3F8可使得左心室显影明显增强，显著改善左心室内膜边界显示，安全性好。     

Observation on the integrity of the blood-brain barrier after microbubble destruction by diagnostic transcranial color-coded sonography.

OBJECTIVE: To investigate alteration of the blood-brain barrier from ultrasonic contrast agent destruction by diagnostic transcranial color-coded sonography using gadolinium-enhanced magnetic resonance imaging. METHODS: Healthy male volunteers received 10 mL (400 mg/dL) of Levovist (SH U 508A; Schering AG, Berlin, Germany; n = 6) or 3 mL of Optison (FS069; Mallinckrodt Inc, St Louis, MO; n = 4) followed by 0.3 mmol/kg magnetic resonance imaging contrast agent (Magnevist; Schering) intravenously. Then transcranial color-coded sonography was performed with a conventional color duplex sonographic system, which insonated the brain in a slightly angulated axial plane with temporal average intensity of less than 700 mW/cm2 or acoustic pressure amplitude of less than 2.69 MPa, attenuated by the temporal bone. Before, immediately after, and 2 hours after insonation, T1-weighted axial magnetic resonance imaging was performed. All magnetic resonance images were individually assessed, and T1 signal intensities were measured in 2 regions of interest in both hemispheres at the 3 time points. RESULTS: No focal contrast enhancement or damage to the brain and no significant difference between T1 signal intensities in the right and left brain regions could be detected during early or late phases when either ultrasonic contrast agent was used. CONCLUSIONS: This bioeffects study gives further evidence of the safety of ultrasonic destruction of Levovist and Optison microbubbles by diagnostic transcranial color-coded sonography. However, more subtle local effects may have been missed by gadolinium-enhanced magnetic resonance imaging. Studies on diagnostic contrast-enhanced transcranial color-coded sonography as well as microbubble-based drug delivery strategies should consider ultrasonic contrast agent microbubble characteristics and concentration as well as ultrasound transmission power levels.     

Evaluation of hepatic focal nodular hyperplasia with contrast-enhanced gray scale harmonic sonography: initial experience.

OBJECTIVE: To assess the potential of contrast-enhanced gray scale harmonic sonography in the evaluation of the typical vascular and enhancement patterns of hepatic focal nodular hyperplasia. METHODS: Thirteen patients with 13 lesions of hepatic focal nodular hyperplasia underwent contrast-enhanced gray scale harmonic sonography. After the injection of a microbubble contrast agent (SH U 508A), gray scale harmonic sonographic studies using a Coded Harmonic Angio technique were performed with a combination of a period of continuous scanning to assess the vascular pattern (vascular imaging) and interval delay scanning to determine the sequential enhancement pattern (acoustic emission imaging). Each imaging pattern was categorized and analyzed by consensus of 2 experienced radiologists. RESULTS: In 12 (92%) of 13 lesions, vascular imaging during the arterial phase showed central arteries of a spoked wheel pattern, whereas the remaining lesion had stippled vascularity. On acoustic emission imaging, 11 (85%) of 13 lesions were hyperechoic during the early phase, and the remaining 2 (15%) were isoechoic compared with surrounding parenchyma. Ten (77%) of 13 lesions remained either hyperechoic (5 of 13) or isoechoic (5 of 13) during the delay phase, whereas the remaining 3 lesions (23%) were hypoechoic. CONCLUSIONS: Contrast-enhanced gray scale harmonic sonography showed the typical vascularity of a spoked wheel pattern during the vascular phase and persistent enhancement on serial acoustic emission imaging in most cases of hepatic focal nodular hyperplasia, and thereby it can be a promising technique in noninvasive diagnosis of this entity.     

Improved sonographic imaging of hepatic hemangioma with contrast-enhanced coded harmonic angiography: comparison with MR imaging

The aim of this study was to compare peripheral nodular enhancement with centripetal progression on contrast-enhanced coded harmonic angio (CHA) with those as seen on magnetic resonance imaging (MRI) scan. A total of 20 patients with 24 hemangiomas confirmed by dynamic contrast-enhanced MRI were included in this study. All 20 patients were examined with CHA in conjunction with a galactose-based microbubble contrast agent (SH U 508A) and with interval delay scanning. The pattern and the time of contrast enhancement were recorded on CHA images. We compared CHA images with MRI in terms of the similarity of contrast-enhanced peripheral nodules. The significance of size of tumor and baseline echogenicity on the ability to see peripheral nodular enhancement was independently assessed. Peripheral nodular enhancement was shown on CHA in 22 (92%) of 24 hemangiomas. Of 22 hemangiomas, 21 (95%) with peripheral nodular enhancement had progressive centripetal fill-in on CHA images. In 4 (80%) of 5 hemangiomas less than 1.5 cm in diameter, contrast-enhanced peripheral nodules were depicted on CHA images. In terms of the similarity of peripheral nodules, CHA images showed the similarity more than "similar" grade with MRI in 21 (95%) of 22 hemangiomas. This study shows that CHA is approximately equal to MRI in its ability to show peripheral nodular enhancement with centripetal progression, even in small hemangiomas.     

Hepatocellular carcinoma: assessment of vascularity with single-level dynamic ultrasonography during the arterial phase.

OBJECTIVE: To evaluate the hemodynamic features of hepatocellular carcinoma on single-level dynamic ultrasonography during the arterial phase. METHODS: Twenty-two hepatocellular carcinomas were examined by single-level dynamic ultrasonography with high transmit intensity and SH U 508A. The scans were performed for 40 seconds with a 1-second interval between each ultrasound transmission and with individual optimization of the scan delay time. The times of initiation of enhancement for both the hepatic artery and the tumor and the time of maximal enhancement for the tumor were recorded, and the mean echo values at every second for the tumor and hepatic parenchyma were measured. RESULTS: Twelve tumors showed hyperechoic enhancement compared with hepatic parenchyma throughout the scans. The other 10 showed hyperechoic enhancement during some segments (range, 8-34 seconds) and either isoechoic (n = 5) or hypoechoic (n = 5) enhancement during the remaining parts; the hyperechoic segments were often short (< 20 seconds, 14%). Although the times for initiation of enhancement for the hepatic artery and hepatocellular carcinoma and the time of maximal enhancement for the tumor varied, the tumor usually initiated enhancement immediately after the hepatic artery (r = 0.986; P = .000001). The interval between the time of initiation of enhancement for the tumor or hepatic artery and that of maximal enhancement for the tumor was significantly correlated with the tumor size (r = 0.700; P = .008; and r = 0.780; P = .002). CONCLUSIONS: With individual optimization of the scan delay time, single-level dynamic ultrasonography is useful for depicting the hypervascularity of hepatocellular carcinoma during the arterial phase.     

Feasibility of mitral flow assessment by echo-contrast ultrasound, part I: determination of the properties of echo-contrast agents

Data on the ultrasonic properties of commercially available contrast agents are limited by being instrument-dependent, especially with regard to their backscattering properties. The present work describes methods of measurements that provide instrument-independent estimations of a contrast agent's attenuation coefficient and integrated backscatter index and provide them as functions of its concentration. The two studied commercially available contrast agents were Albunex and Levovist SHU 508-A, both representative of agents in common use for echocardiography. The attenuation coefficients and integrated backscatter indices of both agents were found to be a linear function of their concentrations. Proportionality coefficients +/- their standard deviations are provided. Actually, square root values of the averaged backscatter indices normalized with respect to the rms of the reference signal were determined. The coefficients of proportionality were found to be: C(A) = 3.11+/-0.1813 dB/mm; C(L) = 0.07+/-0.005 dB/mm for attenuation coefficients of the Albunex and Levovist contrast agents, respectively, and the corresponding values for backscattering were: D(A) = 0.07+/-0.0054; D(L) = 0.02+/-0.0012. Being apparatus-independent, the findings of the study are important prerequisites for the use of these echo-contrast agents as an indicator in research for a quantitative assessment of blood flow.     

Sonographic diagnosis of pancreatic islet cell tumor: value of intermittent harmonic imaging

We describe a case of nonfunctioning islet cell tumor of the pancreas diagnosed preoperatively by intermittent harmonic power Doppler imaging and digital subtraction gray-scale harmonic imaging and the use of the contrast agent SH U 508A (Levovist). Hypervascularity and tumor perfusion were clearly demonstrated with both harmonic imaging techniques in the early arterial phase. Sonographic findings were confirmed by other modalities and by histopathologic examination.