Angle Of Insonation Research Articles

Acceleration time in the fetal middle cerebral artery during the second half of pregnancy

We made a longitudinal ultrasonographic study of 33 healthy fetuses from 22 to 38 weeks of gestation to determine the acceleration time in the middle cerebral artery (ATMCA) and its relationship with fetal cardiac output. Doppler ultrasound (US) was performed by a single observer always using the same apparatus. The Doppler tracing was obtained with a sample volume of 1 mm; placement was on the anterior middle cerebral artery, as close as possible to the skullcap. The insonation angle was kept between 5° and 19° and the wall filter was adjusted to a frequency of 50 to 100 Hz. The ATMCA was 40 ms at 22 and 26 weeks, 50 ms at 30 and 34 weeks and 60 ms at the 38th week. There was a significant positive correlation between gestational age and ATMCA values (r = 0.45, p < 0.001). The ATMCA values became significantly higher than the initial values at the 30th week of gestation ( p < 0.05). The ATMCA values for normal fetuses could be compared with those obtained during high-risk pregnancies; this would be useful for the detection of fetal cardiac anomalies. (E-mail: iggadelha@ig.com.br)

Curvature affects Doppler investigation of vessels: Implications for clinical practice

In clinical practice, blood velocity estimations from Doppler examination of curved vascular segments are normally different from those of nearby straight segments. The observed “accelerations,” sometimes considered as a sort of stochastic disturbances, can actually be related to very specific physical effects due to vessel curvature (i.e., the development of nonaxial velocity [NAV] components) and the spreading of the axial velocity direction in the Doppler sample volume with respect to the insonation axis. The relevant phenomena and their dependence on the radius of curvature of the vessels and on the insonation angle are investigated with a beam-vessel geometry as close as possible to clinical setting, with the simplifying assumptions of steady flow, mild vessel curvature, uniform ultrasonic beam and complete vessel insonation. The insonation angles that minimize the errors are provided on the basis of the study results. (Email: caterina.guiot@unito.it)

Three‐ and four‐dimensional reconstruction of the aortic and ductal arches using inversion mode: a new rendering algorithm for visualization of fluid‐filled anatomical structures

Three-dimensional (3D) and four-dimensional (4D) sonography have been proposed as adjunctive diagnostic imaging modalities for prenatal diagnosis of congenital heart disease1–24. Here we report 3D and 4D rendering of the aortic and ductal arches using a novel approach to 3D reconstruction of hollow structures (Inversion 3D mode using a Voluson 730 Expert (General Electric Medical Systems Kretztechnik, Zipf, Austria) ultrasound machine and 4DView 2000 version 2.1, General Electric Medical Systems Kretztechnik). This rendering algorithm transforms echolucent structures into solid voxels. Thus, anechoic structures such as the heart chambers, lumen of the great vessels, stomach and bladder appear echogenic on the rendered image, whereas structures that are normally echogenic prior to gray-scale inversion (e.g. bones) become anechoic. Figure 1 shows volume-rendered images of the aortic and ductal arches of a fetus with normal cardiac anatomy examined at 22 + 2 weeks. The volume dataset was acquired with sagittal sweeps through the fetal chest and abdomen using the spatio-temporal image correlation (STIC) technique. 3D reconstruction was performed with a combination of ‘gradient light’ and inversion rendering algorithms. Low threshold and transparency levels were adjusted until the structures of interest were visualized. In this particular case, the transparency level was set to 57, and the low threshold level to 91 (both scales range from 0 to 250). Although we chose to use the gradient light algorithm for better visualization, similar images could be visualized using a combination of ‘X-ray’ and ‘surface smooth’ algorithms, or the surface smooth algorithm alone. This volume dataset was rendered with the direction of view set from the right to the left side of the body. As the inversion mode cannot distinguish between blood vessels and other hollow structures (e.g. stomach and gallbladder), the rendered image depicts all anechoic structures contained within the region of interest. This characteristic of the method allowed for simultaneous visualization of the esophagus, ascending aorta, aortic arch, descending aorta, pulmonary artery, ductus arteriosus and superior vena cava in the 3D rendered image. Since the diaphragm is normally visualized as a hypoechoic structure by two-dimensional ultrasound, it appeared as a thin echogenic rim separating the thorax from the abdomen after applying the inversion mode. Abdominal structures depicted in Figure 1 include the portal vein, stomach and a portion of the gallbladder. Four-dimensional rendering of this image can be downloaded from the Journal’s website (Videoclip S1). A case of transposition of the great arteries at 28 weeks is presented in Figure 2. In this image, the anterior vessel represents the aorta. The pulmonary artery courses parallel to the ascending aorta. Left and right branches of the pulmonary artery and the ductus arteriosus are clearly visualized. As this fetus was not swallowing at the time of acquisition, the esophagus was not visualized. The rendering technique used to obtain this image was identical to the one used for Figure 1, except that the transparency and low threshold levels were set to 49 and 106, respectively. Four-dimensional rendering of this image can be downloaded from the Journal’s website (Videoclip S2). In conclusion, we have described the application of 3D and 4D rendering of the outflow tracts and other hollow structures of the thorax and abdomen using the novel inversion mode. Since this technique does not use color or power Doppler sonography as a ‘digital contrast’ to highlight the blood vessels, it does not have the inherent limitations to image reconstruction related to the angle of insonation, temporal resolution, or intensity of the Doppler signal. In addition, the technique does not differentiate blood vessels from other hollow structures. Therefore, the relationships between the fetal heart and great vessels and other fluid-filled non-vascular structures such as the esophagus and stomach can be visualized in

Intracranial collateral pathways assessed by contrast-enhanced three-dimensional transcranial color-coded sonography

Individual parameter settings of the duplex machine and limited insonation angles may influence the visualization of small intracranial vessels in 2-D transcranial color-coded sonography. The aim of our study was the morphologic assessment of intracranial collateral pathways (first auditory area celiac artery, A 1CA; anterior communicating artery, AComA; first parental generation celiac artery P 1CA; posterior communicating artery, PComA) using 3-D transcranial color-coded duplex sonography (3-D TCCS) and digital subtraction angiography (DSA). A total of 41 patients with large vessel disease and 30 patients who had suffered subarachnoidal hemorrhage (mean age 52 ± 15 years) were involved. In all patients, angiography was performed within 10 days following 3-D sonography. The patients were investigated with a color-coded duplex system using the power mode. Contrast enhancement was achieved by continuous infusion of a galactose-based echo-enhancer using a perfusor pump. The 3-D system consists of an electromagnet that induces a low-intensity magnetic field near the head of the patient. A magnetic position sensor is attached to the ultrasound (US) probe and transmits the spatial orientation to a personal computer, which also receives the corresponding 2-D images from the video port of the duplex machine. Angiography revealed a “complete” circle of Willis in one third of the patients and, in the remaining patients at least one vessel was hypoplastic or absent. Sufficient temporal bone windows allowed the sonographic investigation of 466 (94%) of 497 expected arterial segments. The comparison of both techniques resulted in a weighted kappa value of 0.56 for the A 1CA and 0.63 for the AComA. In the posterior circulation kappa values of 0.56 for the P 1CA and 0.43 for the PComA were calculated. In 50 vessels (10%), 3-D sonography misdiagnosed the diameter of a collateral vessel as normal and angiography revealed hypoplasia or aplasia of this vessel. The main advantage of 3-D TCCS is that it enables the investigator to reconstruct virtually any arbitrary view angle. Compared with angiography or magnetic resonance (MR) angiography, 3-D sonography can be performed easily in critically ill patients on stroke units or intensive care units. The noninvasive assessment of the circle of Willis may be useful in patients who undergo carotid surgery without angiography. Combined with hemodynamic information, contrast-enhanced 3-D TCCS might increase the diagnostic impact of transcranial US. (E-mail: tiemo.wessels@neuro.med.uni-giessen.de)

Changes in Ultrasonographic Echogenicity and Visibility of Needles with Changes in Angles of Insonation

To objectively compare the echogenicity of several types of needles at clinically important angles of insonation. Four commercial needles (Echotip, Mini-Stick, Echo-Coat, Surflo) and a prototype dimpled needle were tested in a liver phantom at angles of insonation ranging from 90 degrees to 15 degrees. Photodensity measurement determined echogenicity levels in arbitrary echogenicity units (EU). At 90 degrees angles of insonation all needles were easily seen (60-76 EU) and echogenic levels were similar (P =.264). All values decreased with angulation. From the 35 degrees to 15 degrees angles, the prototype and Echotip needles were superior (P <.05). At 15 degrees the values were 43 EU for the prototype needle, 40 EU for the Echotip needle, 9.0 EU for the Echo-Coat needle, and 5.0 EU for the Surflo needle. With angulation, all needles drop in echogenicity, with prototype dimpled and Echotip best maintaining visibility at clinically important angles.

On the ultrasonic properties of tendon

The strong dependence of tendon echogenicity on insonation angle is explored by analyzing echo spectra. Combining echo spectra with high-resolution images from several modalities reveals that fluid spaces surrounding fascicles and bundles are likely sources of ultrasonic scatter. Mathematical models of tendon structure are proposed to explain how the anisotropic microstructure of tendon gives rise to angle-dependent echogenicity. Echo spectra from spontaneously damaged equine tendon samples were compared with normal equine tendon and found to exhibit a dramatic decrease in anisotropic properties that appears to be related to the spatial organization and type of collagen generated during repair. Variation in echo spectra with insonation angle is a robust indicator of mechanical damage. (E-mail: wjhornof@ucdavis.edu)

The diagnostic relevance of colour Doppler artefacts in carotid artery examinations

Purpose: Physical and technical artefacts of the colour Doppler method are examined with regard to their diagnostic relevance for the carotid artery. Materials and methods: After recording all diagnostic problems arising from physical and technical artefacts in 30,000 consecutively carotid arteries, the quantitative significance of relevant artefacts was determined in minor subgroups of the collective. Results: Acoustic shadowing causes diagnostic problems in morphological and haemodynamic evaluation of stenoses. Mirror image artefacts simulate flow in cases of actual vessel occlusion or mimic vessel wall ulceration in carotid plaques and stenoses. Insonation angle artefacts inhibit detection of flow or mimic flow reversal. Problems of spatial resolution lead to incorrect demonstration of the vessel lumen in stenotic findings. Aliasing, perivascular colour artefacts, and ghosting do not cause any diagnostic problems. Relevant shadowing artefacts occurred in 14.7%, and relevant mirror image artefacts in 2.5% of the pathological cases. Insonation angle artefacts occurred in 17.3% of the cases (when using standard apparatus setting). However, with an exact knowledge of the artefact phenomena, insonation angle artefacts could be eliminated and mirror image artefacts were recognized in all cases. Resolution artefacts resulted in underestimation of carotid stenoses by on average 13.3% of the degree of stenosis. Conclusion: In principle, four artefact phenomena give rise to diagnostic problems; however, with a good knowledge of the phenomena, only artefacts due to acoustic shadowing and limited spatial resolution are of diagnostic significance.

Nasal bone evaluation with ultrasonography: a marker for fetal aneuploidy.

Nasal bone evaluation with ultrasonography: a marker for fetal aneuploidy.

Evolução dos índices dopplervelocimétricos da artéria cerebral média em fetos de gestantes normais

OBJETIVO: observar a evolução dos índices de resistência, pulsatilidade, velocidade máxima, velocidade diastólica final e tempo de aceleração da artéria cerebral média fetal entre a 22ª e a 38ª semana de gestação. MÉTODOS: foi feito estudo observacional prospectivo e longitudinal no qual 33 fetos de gestantes normais foram avaliados entre a 22ª e a 38ª semana de gestação. A idade gestacional foi determinada pela data da última menstruação e/ou pelo exame ultra-sonográfico do primeiro trimestre. Os exames ultra-sonográficos com Doppler foram feitos por um único observador, que utilizou aparelho modelo Image Point 1800 (Hewlett Packard), com transdutor multifreqüencial. Para a aquisição do traçado Doppler da artéria cerebral média, o indicador de amostra foi calibrado para um volume de amostra de 1 mm³ e colocado na artéria cerebral média anterior o mais próximo da calota craniana. O ângulo de insonação foi mantido entre 5º e 19º e o filtro foi ajustado na freqüência de 50-100 Hz. Os recém-nascidos foram avaliados no intuito de comprovar que os fetos eram vigorosos e adequados para a idade gestacional. RESULTADOS: os resultados obtidos para o índice de resistência e pulsatilidade revelaram que a evolução dos valores no período entre a 22ª e a 38ª semana é descrita por uma equação do 2O grau, representando uma parábola. Os valores medianos para o índice de resistência foram de 0,81 na 22ª semana e 0,75 na 38ª semana. O índice de pulsatilidade foi de 1,59 na 22ª semana e 1,45 na 38ª semana. A velocidade sistólica máxima aumentou progressivamente ao longo da gestação, com valores de 26,3 cm/s na 22ª semana e 57,7 cm/s na 38ª semana. A velocidade diastólica final teve aumento progressivo a partir de 26 semanas (5,21 cm/s) até o termo (14,6 cm/s). O tempo de aceleração mostrou aumento significativo apenas entre 26 e 30 semanas, cujos valores foram de 0,04 s na 26ª semana e 0,05 s na 30ª semana. CONCLUSÃO: concluiu-se que os índices de resistência, pulsatilidade e velocidade sistólica máxima apresentaram valores variáveis de acordo com a idade gestacional e são semelhantes ao observado na maioria dos estudos anteriores. O tempo de aceleração apresentou pequenas modificações nas semanas gestacionais avaliadas.

Limits of uncertainty in measured values of embolus-to-blood ratio due to Doppler sample volume shape and location

Measurements of the relative Doppler power scattered by an embolus and the surrounding blood are widely used to infer the composition of the embolus. For a given embolus, measured embolus-to-blood ratio (MEBR) is affected by the Doppler sample volume shape, the geometrical relationship between the sample volume and the vessel, and the embolus trajectory through the blood vessel. The likely magnitudes of such effects were quantified using a model that allowed calculation of theoretical values of MEBR as a function of the geometrical relationship between a blood vessel and a defined sample volume. Overall, the effects of embolus trajectory, likely insonation angles, and plausible vessel misalignments introduced uncertainties in MEBR values of approximately 10 to 12 dB for a given vessel size. In practice, the only operator-controlled factors are the position and orientation of the transcranial Doppler probe on the patients' heads. Probe positioning can significantly affect MEBR and suboptimal positioning may result in the reduced detection of emboli.

Modeling the frequency dependence (5-120 MHz) of ultrasound backscattering by red cell aggregates in shear flow at a normal hematocrit.

The frequency dependence of the ultrasound signal backscattered by blood in shear flow was studied using a simulation model. The ultrasound backscattered signal was computed with a linear model that considers the characteristics of the ultrasound system and tissue acoustic properties. The tissue scattering properties were related to the position and shape of the red blood cells (RBCs). A 2D microrheological model simulated the RBC dynamics in a Couette shear flow system. This iterative model, described earlier [Biophys. J. 82, 1696-1710 (2002)], integrates the hydrodynamic effect of the flow, as well as adhesive and repulsive forces between RBCs. RBC aggregation was simulated at 40% hematocrit and shear rates of 0.05-2 s(-1). The RBC aggregate sizes ranged, on average, from 3.3 RBCs at 2 s(-1) to 33.5 cells at 0.05 s(-1). The ultrasound backscattered power was studied at frequencies between 5-120 MHz and insonification angles between 0-180 degrees. At frequencies below approximately 30 MHz, the ultrasound backscattered power increased as the shear rate was decreased and the size of the aggregates was raised. A totally different scattering behavior was noted above 30 MHz. Typical spectral slopes of the backscattered power (log-log scale) between 5-25 MHz equaled 3.8, whereas slopes down to 0.6 were measured at 0.05 s(-1), between 40-60 MHz. The ultrasound backscattered power was shown to be angle dependent at low frequencies (5-25 MHz). The anisotropy persisted at high frequencies (>25 MHz) for small aggregates (at 2 s(-1)). In conclusion, this study sheds some light on the blood backscattering behavior with an emphasis on the non-Rayleigh regime. Additional experimental studies may be necessary to validate the simulation results, and to fully understand the relation between the ultrasound backscattered power, level of RBC aggregation, shear rate, frequency, and insonification angle.

The snuffbox technique: A reliable color Doppler method to assess hand circulation

Objective: Although the Allen test is crude and subjective, an objective color Doppler method has yet to be established in the assessment of hand circulation before radial artery harvesting. Doppler studies so far have neglected the Doppler principle that the insonation angles should be less than 30° and have not been compared with any standard except the crude Allen test. We therefore introduced the snuffbox technique, measuring the radial artery at the anatomic snuffbox, which is the most distal area after harvesting. Color Doppler methods were compared with the stump pressure as a criterion standard. Methods: Maximal flow velocity and Doppler angles of the snuffbox, palmar artery, and ulnar artery were measured in 20 hands before and after radial artery harvesting. Stump pressure was measured during surgery. Results: Maximal flow velocity in the snuffbox decreased with radial artery compression and after radial artery harvesting. All the flow patterns in the snuffbox technique showed simultaneous reversal. Maximal flow velocity in the ulnar artery increased with radial artery compression and after radial artery harvesting. Maximal flow velocity in the palmar artery did not change significantly with radial artery compression or after radial artery harvesting. Doppler angles were 20.9° ± 6.0° in the radial artery of the snuffbox, 82.5° ± 6.1° at the palmar artery, and 81.0° ± 7.6° at the ulnar artery. The changes in the snuffbox technique were highly correlated with the stump pressure ratio (P <.001). Conclusions: Among various color Doppler methods, the snuffbox technique was precise and reliable.J Thorac Cardiovasc Surg 2003;125:821-5

Circumferential resonance modes of solid elastic cylinders excited by obliquely incident acoustic waves.

When an immersed solid elastic cylinder is insonified by an obliquely incident plane acoustic wave, some of the resonance modes of the cylinder are excited. These modes are directly related to the incidence angle of the insonifying wave. In this paper, the circumferential resonance modes of such immersed elastic cylinders are studied over a large range of incidence angles and frequencies and physical explanations are presented for singular features of the frequency-incidence angle plots. These features include the pairing of one axially guided mode with each transverse whispering gallery mode, the appearance of an anomalous pseudo-Rayleigh in the cylinder at incidence angles greater than the Rayleigh angle, and distortional effects of the longitudinal whispering gallery modes on the entire resonance spectrum of the cylinder. The physical explanations are derived from Resonance Scattering Theory (RST), which is employed to determine the interior displacement field of the cylinder and its dependence on insonification angle.

Automatic flow angle correction by ultrasonic vector

An ultrasound system produces an image including a blood vessel. A blood flow direction indicator is displayed over the blood vessel to indicate the direction of blood flow within the vessel. The direction of blood flow is used to correct the Doppler estimate for angle of insonation. The orientation of the blood flow direction indicator is set automatically by a vector processor. The automatically calculated angle is used to display the correct flow velocity without user intervention.

P220: Middle cerebral artery peak systolic velocity in normal and high risk pregnancies: the impact of Doppler-gate-placement and correction of the angle of insonation

and the Doppler-gate was placed at the origin of the MCA and in the distal, visualized part of the vessel. Measurements were performed with and without angle-correction and compared. We constructed new reference ranges for the PSV-values of the total population (N = 146) with angle correction. Results: There was a significant difference between the PSV-values at the proximal and the distal part of the MCA with higher velocities proximal. The measurements with angle correction also showed significantly higher velocities as those without. Between the normal and complicated pregnancies we couldn’t find a significant difference. Discussion: As we couldn’t show significant difference of the PSVACM between normal and complicated pregnancies the reference ranges can be applied also in complicated pregnancies. Our data show that placement and angle correction are relevant for a standardisized measurement, especially important because the decision for invasive testing for fetal anaemia depends on it.

Perioperative tissue Doppler echocardiography and bypass graft flowmetry in patients undergoing coronary revascularization: Predictive power for late recovery of regional myocardial function

To assess if recovery of regional myocardial function can be predicted by perioperative Doppler tissue echocariography, 20 patients undergoing coronary artery bypass graft surgery (mean 4.1 grafts) had serial transthoracic and transesophageal echocardiography. Systolic velocities were lower in basal posterior and anterior segments, and higher in the midanterior septum, at intraoperative transesophageal echocardiography compared with preoperative transthoracic echocardiography (−45%, −30%, +18%, respectively), but comparable elsewhere. After bypass, velocities were increased in midposterior, basal lateral, basal anterior, and midanterior septal segments (+41%, 25%, 27%, 44%, respectively, P < .05). Increased velocities in circumflex segments at 6 weeks (midposterior, basal lateral, and midlateral +54%, 45%, 39%, respectively, P < .05) were not predicted by perioperative changes or related to graft flow (transit-time flowmetry; R −0.09, −0.14, and −0.32, respectively, not significant). Myocardial velocities measured by transthoracic and transesophageal echocardiography are not comparable in segments with different angles of insonation. Perioperative changes in resting myocardial systolic velocity are highly variable and do not predict late recovery. (J Am Soc Echocardiogr 2002;15:1202-10.)

Reference ranges for Doppler-assessed pulmonary venous blood flow velocities and pulsatility indices in normal human fetuses.

To establish reference ranges with gestation for Doppler parameters of fetal pulmonary venous blood flow during the second half of pregnancy, including not only peak velocities, but also relative indices reflecting left atrial pressure changes. In this cross-sectional study, 114 normal singleton pregnancies between 19 and 37 weeks' gestation were examined by Doppler echocardiography. In 98 fetuses, peak systolic velocity (S), peak diastolic velocity (D), end-diastolic velocity (A), and time velocity integral (TVI) were measured, and S/D ratio, pulsatility index for veins (PIV), as well as peak velocity index for veins (PVIV), were calculated. Regression analysis was used to determine reference ranges with gestation. With advancing gestation, a significant increase in S, D and A velocities as well as in TVI, was observed. Whereas the S/D ratio remained constant, PVIV and PIV decreased significantly during the second half of pregnancy. During the second half of pregnancy the increase in left atrial and ventricular compliance is reflected by the observed decrease in PIV and PVIV, which could be mainly due to the increased flow during atrial contraction. Such relative Doppler indices are better comparable than absolute values and are independent from the insonation angle. Potential clinical applications for such Doppler indices are conditions with possibly impaired left atrial function, like heart defects with left atrial obstruction or late stages of severe intrauterine growth retardation.

Effects of the Ultrasound Contrast-Enhancing Agent Levovist® on the Detection of Intracranial Arteries and Stenoses in Chinese by Transcranial Doppler Ultrasound

Proper assessment of intracranial arteries by transcranial Doppler sonography (TCD) in patients with intracranial stenoses is occasionally made difficult by an insufficient temporal bone window, an unfavourable insonation angle, or low flow velocity or volume. This condition is frequently found in Chinese. In these cases, echocontrast could be helpful. We investigated 48 temporal windows of 24 acute Chinese stroke patients with insufficient native transtemporal insonation conditions before and after the application of the echo enhancer Levovist^® (galactose/palmitic acid) by an injection pump. We classified the signal quality from four segments of the main intracranial arteries: anterior cerebral artery (A1), main stem of the middle cerebral artery (MCA, M1), intracranial segment of the carotid artery (C1), and posterior cerebral artery (P1). The signal quality was classified as follows: 0 = no signal, 1 = poor, envelope curve does not follow spectrum, 2 = adequate, envelope curve follows spectrum. As compared to the pre-contrast scans, echocontrast allowed for more segments to be evaluated by pulsed Doppler sonography. Before Levovist, only 12% of the segments could be detected, after Levovist 63%. For all arteries, signal quality was better after Levovist, p between 0.0180 and 0.0003. In 3 patients, MCA stenoses with peak systolic Doppler flow velocities above 160 cm/s were found only after Levovist. In patients with poor pre-contrast detection, echocontrast-enhanced TCD allows for more arterial segments to be insonated and for the detection of stenoses unnoted during the non-enhanced investigation.

Accuracy of Duplex Scan of Internal Carotid Arteries

In a prospective study, 65 consecutive patients with suspected symptomatic high grade ICA stenosis were examined during a 12 months period 1998±99. Using a Siemens Sonoline Elegra, Siemens Medical System, Washington, U.S.A., and an angle of insonation of below 60%, flow velocities within the common carotid artery (CCA) and the ICA were obtained bilaterally. The degree of stenosis was determined using a modification of the criterias developed by Zwiebel. Hence, a 70% stenosis was characterised by an ICA peak systolic velocity 150 cm sy1, an ICA end diastolic velocity 90 cm sy1, and a PSV ratio 4 2.8. No flow indicated occlusion. From selective carotid angiography the degree of stenosis was calculated using the NASCET method.

SonoVue® (BR1), a New Long-Acting Echocontrast Agent, Improves Transcranial Colour-Coded Duplex Ultrasonic Imaging

Background and Purpose: Visualization of normal or pathological flow in the intracranial arteries using transcranial colour-coded duplex sonography (TCCS) is occasionally obstructed by insufficient temporal bone windows, unfavourable insonation angles, or low flow velocities or volumes. SonoVue^® (BR1) is a new, long-acting echocontrast agent, which could be helpful in these instances. Methods: SonoVue was studied in two separate multicentre investigations of patients with insufficient bone windows (BR1-014 with 73 patients and BR1-017 with 40 patients) using an identical protocol. The agent was given intravenously as a bolus in four different doses (0.3, 0.6, 1.2 and 2.4 ml). Evaluation was performed on-site and off-site with video clips. Results: The contrast agent was well tolerated. As compared to the precontrast scans, SonoVue facilitated the visualization of vessel patency, stenosis, occlusion, and collateral flow, decreased the need for additional tests, and had an impact on the patient’s treatment. In 66–74%, a non-diagnostic investigation was converted into a diagnostic investigation. The highest dose (2.4 ml) allowed for a clinically useful signal enhancement of a median 1.9–6.3 min. Conclusions: SonoVue at a single dose of 1.2 or 2.4 ml is effective in increasing the detection of normal or pathological flow in the intracerebral arteries in patients who do not have a fully diagnostic unenhanced TCCS examination.