Galactose-based intravenous sonographic contrast agent: experimental studies

A galactose-based sonographic contrast agent, which produces stable microbubbles capable of traversing the cardiopulmonary circulation, was used to enhance Doppler signals in blood vessels of varying size after intravenous injection. A series of experiments using dogs, rabbits, and woodchucks was conducted to establish the ability of the agent to enhance the reflectivity of normal tissue, tumor tissue, and blood. Although no enhancement was perceptible in tissue on the sonogram, significant enhancement of color and spectral Doppler signals was demonstrated in a variety of vessels. These included the aorta, vena cava, and portal vein as well as such small vessels as those of the retina of the eye, renal cortex, liver parenchyma, and gallbladder wall. Both spectral and color Doppler enhancement was shown in naturally occurring woodchuck hepatomas. Peak Doppler signal enhancement after bolus injection was approximately 10 dB with a dose of 0.01 ml/kg. Recirculation of the agent provided enhancement after intravenous bolus injection for more than 3 min. With a steady intravenous infusion of 0.2 ml/min/kg, Doppler signal enhancement of about 14 dB was maintained continuously for more than 5 min. The results of these animal experiments, in particular in small vessels and with recirculation after intravenous injection, suggest excellent potential for future clinical applications.     

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.     

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.     

多层螺旋CT血管成像评价肝移植受者移植前后血管结构

背景:多层螺旋CT具有先进的扫描技术和强大的图像后处理功能,其亚秒级的扫描速度及各向同性的成像功能,在血管成像上有很多优势.目的:探讨多层螺旋CT血管成像技术对肝移植受者移植前后血管结构评价的应用价值.设计、时间及地点:回顾性分析,以肝移植受者肝脏血管为观察对象,自身对照观察,于2003-10/2006-12在中山大学附属第五医院放射科完成.对象:选择拟行原位肝移植患者27例,年龄31～67岁,男17例,女10例.方法:轴位螺旋扫描范围为膈顶上方2 cm至双肾下极以下.电压120 kV,动脉期准直0.75 mm,平扫、门脉期、肝静脉期准直1.5 cm;使用非离子型对比剂优维显,注射速度为3 mL/s,三期增强扫描延迟时间分别为20～25 s,50～55 s,75～80 s.重建增强的薄层图像序列,动脉期层厚1 mm,间隔0.7 mm;门脉期、肝静脉期层厚2 mm,间隔1 mm.将图像序列传入后处理工作站,以MIP、VR等方式显示腹腔干系、门脉系、肝静脉及下腔静脉血管的三维结构.主要观察指标:肝移植前后患者血管三维结构.结果:移植前所有患者腹腔干系均得到良好显示,21例肝动脉走形正常,6例患者肝动脉变异,其中门静脉海绵样变2例,门脉多发血栓1例,因不适宜手术此3例未进行肝移植.24例患者第二肝门及下腔静脉肝内段血管结构显示清楚,肝右静脉单独汇入下腔静脉、肝左静脉和肝中静脉先汇合后再注入下腔静脉18例,肝有静脉、肝中静脉及肝左静脉分别单独汇入下腔静脉6例,下腔静脉肝后段狭窄2例.17例肝移植后CT血管成像发现肝动脉吻合口部狭窄2例,门脉高压侧支迂曲缓解10例,另7例患者因检查费用问题选择B超检查.结论:多层螺旋CT血管成像能够清晰显示肝移植患者移植前后血管结构,对适宜手术的病例筛选、指导手术方案及移植后血管结构的评价具有重要意义.     

Comparison of different injection forms in CT examination of the upper abdomen

Background: The optimal technique for administration of intravenous contrast medium in computed tomography (CT) remains controversial. Therefore, we analyzed the influence of variable-rate injection protocols. Methods: A double-blind, parallel-group study was conducted in 60 patients studied with the same helical CT contrast-enhanced protocol. Patients were randomly distributed into three groups: monophasic (123 mL at 2.5 mL/s), biphasic (123 mL, 60 mL at 1.5 mL/s and then 63 mL at 2.5 mL/s), and sigmoid (0.6 mL/s ending at 2.5 mL/s). Contrast-enhancement efficacy was evaluated by attenuation coefficient measurements. Results: The monophasic injection protocol produced a statistically higher liver, inferior vena cava, and portal enhancement than did the low–high biphasic and sigmoid protocols. The biphasic protocol produced a statistically higher enhancement in the superior aorta. The enhancement obtained with the monophasic protocol was always higher than or equal to those obtained with the biphasic protocol in all measurement protocols except in the superior aorta and the aortic bifurcation. Conclusions: A monophasic injection produces better parenchymal and venous enhancement. When arterial enhancement is important, a low–high biphasic protocol can be used. A sigmoid protocol, with the parameters used in our series, is significantly less effective.     

移植肝肝静脉血流变化的彩色多普勒超声检测

目的 探讨彩色多普勒超声检测肝移植术后肝静脉血流动力学变化,早期诊断术后肝静脉及下腔静脉并发症和评价肝功能的临床价值。方法 67例原位肝移植术后患者行彩色多普勒超声检查,观察肝移植患者肝实质、血管、胆管声像图改变和肝静脉血流动力学变化时。对54例无肝静脉及下腔静脉并发症患者,记录血浆凝血酶原时间（PT）、血清总胆红素（Tbil）、白蛋等相关指标,观察有无腹水、肝性脑病,按Child—Pugh评分分级,并且与肝静脉血流改变对照。结果 67例原位肝移植术后,下腔静脉栓塞5例,肿瘤复发伴下腔静脉、肝静脉狭窄8例。54例无肝静脉及下腔静脉并发症患者肝静脉血流改变随着肝功能Child—Pugh分级变化改变明显,具有统计学意义（P〈0．005）。结论 彩色多普勒超声检测对肝移植术后肝静脉、下腔静脉并发症诊断和肝功能评价有重要临床意义。     

Comparison of the efficacy of two air-based contrast agents in dogs.

OBJECTIVE: The aim of this study was to evaluate the differences of the in vivo efficacies of Levovist(SH U 508 A) and Albunex, air-based contrast agents (CAs) with different shell materials, by direct comparison. METHODS: SH U 508 A, 300 mg/ml, and Albunex were injected intravenously at doses of 0.1 and 0.15 ml/kg, respectively, into the same dogs (n=6). Contrast enhancement in the left ventricle was evaluated visually and by off-line measurement of brightness. RESULTS: Both CAs yielded good peak contrast, while the duration of contrast enhancement with SH U 508 A was seven times that with Albunex. With Albunex, reduction of contrast enhancement at end-systole and in the late phase of diastole during one heartbeat was observed, and a positive correlation was observed between contrast enhancement and heart rate. Contrast enhancement was nearly constant during one heartbeat with SH U 508 A. CONCLUSION: SH U 508 A yielded consistent and longer contrast enhancement in the left ventricle than Albunex under the same conditions.     

The effects of Levovist and DD-723 in activating platelets and damaging hepatic cells of rats.

OBJECTIVE: The purpose of this study was to compare platelet activation and hepatic cell damage produced by 2 ultrasonographic contrast agents with flow cytometric and ultrastructural analysis. METHODS: Suspension samples were made by mixing Levovist (SH U508A; Schering AG, Berlin, Germany) or DD-723 (Nycomed; Amersham Health, Princeton, NJ) with whole blood. The final concentrations of Levovist in citrated whole blood were 0, 15, and 75 mg/mL, and those of DD-723 were 0, 5, and 50 microL/mL. After exposure to ultrasound in vitro, flow cytometric analysis was performed to determine the concentration of the CD62P activation-specific antigen. To compare the hepatic cell damage associated with these 2 agents, we divided 15 rats into 5 groups as follows: group 1, sham operation; group 2, Levovist injection only; group 3, DD-723 injection only; group 4, Levovist injection (contrast agent) and ultrasound exposure; and group 5, DD-723 injection and ultrasound exposure. The ultrasonographic contrast agents Levovist and DD-723 were administered through the femoral vein and sonicated continuously for the first minute; this was followed by sweeping for 5 minutes 10 seconds after the contrast agent was injected. The rats were perfused via the heart with a fixative solution immediately after the sweeping, and then the liver was excised; the specimens were studied with electron and light microscopy. RESULTS: The percentage of CD62P-expressing platelets increased in both contrast agent-ultrasound exposure groups, and the percentage of CD62P-expressing platelets was greater in the Levovist group. We observed vacuolation and round deposits in the hepatocytes in both contrast agent-ultrasound exposure groups. Microbubbles were observed in the rat Kupffer cells, and a few hepatocytes were seen unexpectedly in the DD-723 group but were found in neither the Kupffer cells nor the hepatocytes in the Levovist group. CONCLUSIONS: Both contrast agents, Levovist and DD-723, produced platelet activation and structural change in the rat hepatic cells, but only the microbubbles of DD-723 were taken up by the Kupffer cells and a few hepatocytes.     

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。     

3.0T MR门静脉和下腔静脉血管成像对腹部肿瘤血管侵犯的评价

[目的]探讨阴道镜检查在宫颈病变诊断中的临床价值.[方法]2007年6月至2009年6月诊治275例宫颈病变患者,对其宫颈阴道镜及镜下活检结果进行分析.[结果]经病理确诊为慢性宫颈炎221例,宫颈上皮内瘤变（CIN） 39例 （CIN Ⅰ10例、CINⅡ16例、CIN Ⅲ13例）,宫颈癌15例.阴道镜检查对CIN的灵敏度为69%,特异度为94%,阳性预测值为64.3%,阴性预测值为94.8%,阳性似然比为10.89,阴性似然比为0.33,诊断符合率为90.18%.阴道镜检查对宫颈癌的灵敏度为67%,特异度为98%,阳性预测值为71.4%,阴性预测值为98.1%,阳性似然比为43.33,阴性似然比为0.34,诊断符合率为96.73%.[结论]阴道镜检查对宫颈癌尤其是癌前病变的早期诊断有重要的临床价值.     

Experimental evaluation of portal venous pulsatile flow synchronized with heartbeat intervals: effects of vascular clamping on portal hemodynamics

Purpose

We previously showed that blood flow in the portal vein was pulsatile and influenced by both the inferior vena cava and the arterial system in a complex manner (Nihei et al., 38:141–149, 2011). The objective of the present study is to identify determinants of blood flow and to clarify the source of pulsatile flow in the portal vein.

Methods

Three-breed terminal crossbreed mini-pigs underwent general anesthesia. Pressure and flow in the portal vein, inferior vena cava, hepatic artery, and mesenteric artery were measured simultaneously. Vascular occluders were placed in the inferior vena cava, hepatic artery, and mesenteric artery to examine the effects of clamping on portal venous flow.

Results

Clamping of the mesenteric artery altered pressure and flow waves in the portal vein to waveforms similar to those in the inferior vena cava. Waves resembling those of the inferior vena cava superimposed on portal venous flow appeared later than waves of the inferior vena cava. Clamping of the inferior vena cava promptly altered portal venous pressure and flow. Because clamping of the inferior vena cava led to a sharp rise in portal venous pressure, detailed evaluations were not feasible. Clamping of the hepatic artery had no effect on flow-wave pulsation in the portal vein.

Conclusions

In the hepatic circulation, flow-wave pulsation in the portal vein is influenced by flow in the inferior vena cava via the sinusoids and by flow in the mesenteric artery via the capillary vessels of the intestine.     

多层螺旋CT静脉血管成像价值探讨

目的探讨多层螺旋CT静脉血管造影的应用价值.方法收集不同部位CT静脉血管造影21例,颈静脉及门静脉系统血管造影由上肢静脉注入对比剂,下腔静脉及下肢造影由小隐静脉注入对比剂,行三维重建及多平面重建,结合临床资料分析血管成像技术及诊断价值.结果静脉血管CT造影表现不同于动脉CT造影,不同部位的静脉血管表现不同.21例中发现颈鼻咽癌侵犯血管1例,血管走行纡曲1例;下腔静脉瘤1例,肿瘤压迫下腔静脉1例;门静脉高压1例,疑肠系膜上静脉内血栓1例;11例下肢静脉血栓.结论不同部位的静脉影像表现存在差异,不同的重建技术对血管的显示有影响.下腔静脉造影应注意假象的存在.     

超声造影及多普勒增强效应在布—加氏综合征介入治疗中的应用

在超声引导下下胜静脉支架置入和肝静脉支架置入术中，通过置入相应血管内的导管注入3～5ml生理盐水或5％碳酸氢销与5％维生素C的混合液，观察局部血管内血流回声灰度的变化及其流动特征，以及造影时彩色多普勒血流显像和脉冲多普勒频谱形态的改变。结果表明血管的不同病变具有不同的超声造影表现和多普勒增强效应。超声造影在布-加氏综合征介入治疗术中具有重要价值，可以进一步明确病变类型和血流动力学变化，有利于引导操作，应成为超声引导介入治疗的常现技术。     

Enhancement of ultrasound-accelerated thrombolysis by echo contrast agents: dependence on microbubble structure

The combination of ultrasound (US) exposure and ultrasound contrast agent (UCA) further increases the amount of drug-mediated thrombolysis. The aim of this study was to examine the efficacy of the combination of US and UCA on tissue plasminogen activator (tPA) thrombolysis, and the dependence on the microbubble structure. A catheter-type transducer capable of US emission (10 MHz, spatial peak temporal average intensity = 1.02 W/cm² and peak negative pressure = 0.33 MPa) in the continuous-wave mode was employed. In 28 artificial white thrombi, serial changes in acoustic properties monitored by echography and histopathology during the tPA-mediated thrombolysis were analyzed. The thrombi were assorted to 4 groups; UCA nontreated (Control), sonicated albumin (A)-, SH-U508A (SH)- and dodecafluoropentane emulsion (DDFP)-treated groups. Persistence of microbubble opacification and thrombus weight were also measured. After the sample was suspended in a beaker with tPA (8000U) and 100 mL of saline, the UCA was administered and the mixture exposed to US for 10 min. Weight reduction of the thrombus was greatest in the DDFP Group (−49 ± 8%), and that in the A Group (−8 ± 5%) was not significantly different from that in the Control Group (−5 ± 1%). The persistence of the microbubbles expressed as the decay of the time-intensity curve, was longest in the DDFP Group. The echo intensity of the superficial layer of the thrombus exposed to US was high and weight loss was marked. Multiple cavity formation was observed histopathologically. The stability of the microbubbles was an important factor of the US and UCA enhancement effect on tPA-mediated thrombolysis. This combination therapy has potential for clinical application in patients with thrombotic arterial and venous occlusion and left arterial thrombus.     

下腔静脉、髂外静脉节段性切除且不重建血管在复杂腹盆腔肿瘤手术中的应用（附视频二维码）

目的 总结联合节段性切除下腔静脉、髂外静脉且不重建血管的复杂腹盆腔肿瘤手术的相关经验。方法 回顾性分析接受手术治疗且于术中节段性切除了下腔静脉、髂外静脉的11例腹盆腔复杂肿瘤患者的临床资料。结果 11例患者中结直肠癌术后转移3例,肾盂癌并癌栓、淋巴结转移2例,肾盂癌并淋巴结转移1例,输尿管癌并淋巴结转移1例,肾盂癌术后腹盆腔种植1例,宫颈癌术后转移1例,腹膜后平滑肌肉瘤1例,膀胱癌1例。涉及血管的手术包括：下腔静脉节段性切除5例,右侧髂外静脉节段性切除+右侧髂内动静脉节段性切除1例, 右侧髂内动静脉节段性切除+左侧髂外静脉节段性切除1例,下腔静脉节段性切除+双侧髂总静脉节段性切除+右侧髂总动脉与髂外动脉人工血管搭桥术1例,下腔静脉节段性切除+右侧髂外动脉静脉节段性切除+右侧髂外动脉人工血管置换1例,髂外静脉节段性切除2例。所有手术均顺利完成,手术时间570（390 ~ 900）min,术中输红细胞4（2 ~ 15）单位,输血浆600（150 ~ 1800）ml,术后住ICU 0（0 ~ 517） h。术后5例出现下肢静脉血栓,4例予以保守治疗后下肢水肿逐渐消退,1例予以介入溶栓治疗。结论 对于复杂的腹盆腔肿瘤,如肿瘤包绕、侵犯或粘连下腔静脉、髂外静脉,可考虑节段性切除累及的主干静脉,单纯结扎且不予重建,虽然术后有发生下肢静脉血栓的风险,但因此而导致的严重不良后果并非常见。     

预先腹内控制下腔静脉防治肝切除术中肝静脉及下腔静脉损伤大出血

作者对7例半肝以上肝切除术及2例ⅦⅧ肝段切除应用止血带在腹腔内围绕肝下肾上及膈下肝上之下腔静脉,同时用橡皮管控制肝门血管,而暂不阻断,以预防术中可能发生的肝静脉或/和下腔静脉损伤大出血,其中2例还同时控制膈下腹腔动脉以上的腹主动脉。9例中7例无意外,2例术中发生肝中静脉损伤大出血,经止血带迅速控制,修补裂口,抢救成功。本文对肝叶切除术中误伤肝静脉或/和下腔静脉的原因和预防处理方法进行了讨论,认为在病变接近或累及第二肝门或下腔静脉的肝叶肝段切除,以及在半肝或三叶切除术中常规控制下腔静脉和肝门是一个简而有效的防治肝静脉或/和下腔静脉损伤大出血的好方法。     

Extent of ischaemia caused by hepatic vascular exclusion as evaluated in a canine model.

1. The difference in the extent of liver ischaemia between a hepatic vascular exclusion model and an inflow occlusion model were investigated by determining Indocyanine Green retention and hepatic mitochondrial redox state during 2 h of ischaemia in 10 mongrel dogs. The splanchnic venous bed and/or the infra-hepatic inferior vena cava were decompressed by pump-driven veno-venous bypass. 2. The Indocyanine Green retention test revealed that there was no hepatic blood flow in the hepatic vascular exclusion model during ischaemia (96.8 +/- 0.73% retention of the dye after 20 min), whereas hepatic blood perfusion was still present significantly in the inflow occlusion model (78.1 +/- 1.19% retention of the dye after 20 min) (P less than 0.01). 3. The mitochondrial redox potential of the liver in the dogs with hepatic vascular exclusion decreased immediately after the induction of ischaemia and remained fixed at extremely low levels. By contrast, in the dogs with inflow occlusion the redox potential decreased gradually after induction and was maintained significantly higher than that in dogs with hepatic vascular exclusion during 2 h of ischaemia (P less than 0.01). 4. It is concluded that the extent of liver ischaemia in the hepatic vascular exclusion model with pump-driven shunt is significantly different from that in the inflow occlusion model with shunt.     

永存左上腔静脉畸形的超声诊断及其临床意义

目的 探讨永存左上腔静脉的超声表现及临床意义。方法 21例患者行常规心脏超声检查及经双上肢双氧水心脏声学造影。结果 二维超声心动图检测，全部患者均见冠状静脉窦扩张，经左上肢静脉注射双氧水后，可见冠状静脉窦内充满微气泡；而经右上肢静脉注射双氧水后，仅于右房及右室内充满微气泡，冠状静脉窦内则无微气泡显示，结论 常规心脏超声检查结合经双上肢行双氧水心脏声学造影可准确诊断永存左上腔静脉，提高此类患者心内直视手术的安全性及心内导管插入的成功率。     

Subharmonic contrast intravascular ultrasound for vasa vasorum imaging

The feasibility of subharmonic contrast intravascular ultrasound (IVUS) imaging was investigated using a prototype nonlinear IVUS system and the commercial contrast agent Definity™. The system employed a mechanically scanned commercial catheter with a custom transducer element fabricated to have sensitivity at both 15 and 30 MHz. Experiments were conducted at a fundamental frequency of 30 MHz (F30; 25% bandwidth), with on-axis pressures ranging from 0.12 to 0.79 MPa, as measured with a needle hydrophone. In vitro characterization experiments demonstrated the detection of 15 MHz subharmonic signals (SH15) when pressure levels reached 360 kPa. The formation of SH15 images was shown, with tissue signals suppressed to near the noise floor and contrast to tissue ratios were improved by up to 30 dB relative to F30. In vivo experiments were performed using the atherosclerotic rabbit aorta model. Following the bolus injection of contrast agent upstream of the imaging catheter, agent was detected within the aorta, vena cava and within the perivascular space. These results provide a first in vivo demonstration of subharmonic contrast IVUS and suggest its potential as a new technique for imaging vasa vasorum. (E-mail: goertz@sri.utoronto.ca)     

Relationship of skeletal muscle perfusion measured by contrast-enhanced ultrasonography to histologic microvascular density.

OBJECTIVE: The purpose of this study was to compare skeletal muscle perfusion measured by contrast-enhanced ultrasonography (CEUS) with microvascular density in muscle biopsies. METHODS: Power Doppler sonography after intravenous bolus injection of Levovist (SH U 508A; Schering AG, Berlin, Germany) was used to examine perfusion of vastus lateralis muscle in 23 healthy volunteers. Local blood volume (B), blood flow velocity (v), and blood flow (f) were calculated by analyzing replenishment kinetics. CEUS perfusion was compared with vascularization of biopsy samples from vastus lateralis muscle. Subjects were selected such that their aerobic capacity (maximal oxygen uptake [VO(2)max]) per body weight ranged between 23 and 66 mL . min(-1) . kg(-1) to render a large variability of skeletal muscle capillarization. Moreover, subjects' venous blood hematocrit (Hkt) was determined to estimate the plasmatic intravascular volume fraction (1-Hkt=PVF) in which the microbubbles can distribute. RESULTS: Median capillary density was 331/mm(2) (range, 207-469/mm(2)), and median capillary fiber contacts (CFC) were 3.6 (range, 2.3-6.5). CFC was correlated with VO(2)max (r=0.59; P<.01). Among CEUS parameters, B showed the closest correlation to CFC (r=0.53; P<.01). When CFC was normalized for PVF, correlation of B to CFC was r=0.64 (P<.01). CEUS could depict the physiologic large variability of vastus lateralis muscle perfusion at rest (median [range]: B, 2.5 [0.1-12.3] approximately mL; v, 0.3 [0.1-3.7] mm/s; f, 0.7 [0.1-5.3] approximately mL . min(-1) . 100 g tissue(-1)). CONCLUSIONS: B is significantly related to fiber-adjacent capillarization and may represent physiologic capillary recruitment (eg, through metabolic fiber-related signals). CEUS is feasible for skeletal muscle perfusion quantification.