Conventional Doppler Sonography Research Articles

Intraoperative Cardiac Ultrasound Examination Using Vector Flow Imaging

Conventional ultrasound (US) methods for blood velocity estimation only provide one-dimensional and angle-dependent velocity estimates; thus, the complexity of cardiac flow has been difficult to measure. To circumvent these limitations, the Transverse Oscillation (TO) vector flow method has been proposed. The vector flow method implemented on a commercial scanner provided real-time, angle-independent estimates of cardiac blood flow. Epicardiac and epiaortic, intraoperative US examinations were performed on three patients with stenosed coronary arteries scheduled for bypass surgery. Repeating cyclic beat-to-beat flow patterns were seen in the ascending aorta and pulmonary artery of each patient, but these patterns varied between patients. Early systolic retrograde flow filling the aortic sinuses was seen in the ascending aorta as well as early systolic retrograde flow in the pulmonary artery. In diastole, stable vortices in aortic sinuses of the ascending aorta created central antegrade flow. A stable vortex in the right atrium was seen during the entire heart cycle. The measurements were compared with estimates obtained intraoperatively with conventional spectral Doppler US using a transesophageal and an epiaortic approach. Mean differences in peak systole velocity of 11% and 26% were observed when TO was compared with transesophageal echocardiography and epiaortic US, respectively. In one patient, the cardiac output derived from vector velocities was compared with pulmonary artery catheter thermodilution technique and showed a difference of 16%. Vector flow provides real-time, angle-independent vector velocities of cardiac blood flow. The technique can potentially reveal new information of cardiovascular physiology and give insight into blood flow dynamics.

Prospective evaluation in 123 patients of strain ratio as provided by quantitative elastosonography and multiparametric ultrasound evaluation (ultrasound score) for the characterisation of thyroid nodules

This study was done to compare quantitative elastosonography and ultrasound analysis in the characterisation of thyroid nodules. From July 2009 to September 2011, 123 patients with 147 thyroid nodules were included in our study. All patients enrolled had to undergo thyroidectomy because of nodular thyroid disease (goitre or nodules). After preliminary examination with conventional ultrasound (US) and colour Doppler US, the patients were examined with elastosonography, using high-level equipment (Toshiba Aplio XG) and quantitative software (Elasto-Q). Each lesion was characterised using an US score (echogenicity, borders, microcalcifications and colour Doppler pattern), and then by elastosonographic strain ratio. Each patient subsequently underwent thyroidectomy. Histological results were used as the gold standard. Histological examination demonstrated 89 benign and 58 malignant lesions. On average, the strain ratio value was 2.84±2.69 (range, 0.05-14.5; p=0.001). Sensitivity and specificity of the US score were about 56% and 72%, respectively, whereas those of the strain ratio were 93% and 89%, using a cut-off of 2 obtained with receiver operating characteristic (ROC) curve analysis. Elastosonography was more accurate than US and colour Doppler US in characterising thyroid nodules (p=0.002). Quantitative elastosonography is a useful diagnostic tool in the evaluation of thyroid lesions, and can be used to limit fine-needle aspiration cytology and improve the selection of patients for thyroidectomy.

Quantitative assessment of spinal cord perfusion by using contrast-enhanced ultrasound in a porcine model with acute spinal cord contusion

To quantify spinal cord perfusion by using contrast-enhanced ultrasound (CEUS) in a porcine model with acute spinal cord injury. Microcirculatory changes of acute spinal cord injury were shown by CEUS in a porcine model with spinal cord contusion at three selected time points, coupling with conventional ultrasound (US) and Color Doppler US (CDFI). Time-intensity curves and perfusion parameters were also obtained by autotracking contrast quantification (ACQ) software in the epicenter of contusion site, adjacent region and distant region, respectively. Neurologic and histologic examinations were used to confirm the severity of injury. Conventional US revealed the spinal cord was hypoechoic and homogeneous, whereas the dura mater, pia mater and cerebral aqueduct were hyperechoic. On CDFI intramedullary blood vessels were displayed as segmental and columnar. It was homogeneous on CEUS. After spinal cord contusion, the injured region on gray scale US was hyperechoic. CDFI demonstrated intramedullary blood vessels of adjacent region had increased and dilated during the observation period. On CEUS the epicenter of contusion site was hypoperfusion, whereas its adjacent region was hyperperfusion compared with the distant region. Quantitative analysis showed that peak intensity decreased in epicenters of contusion but increased in adjacent regions significantly at all time points (P<0.05). Evaluation of neurological function for post-contusion demonstrated significantly deterioration in comparison before injury (P<0.05). CEUS is a practical technique that provides overall views for evaluating microcirculatory pattern in spinal cord injury. Quantitative analysis shows the efficacy in assessment of perfusion changes after spinal cord injury.

Mo2077 A New Paradigm in the Noninvasive Assessment of Portal Hypertension: A Single Ultrasound Procedure Incorporating Acoustic Radiation Force Impulse Elastography Predicts >90% of Esophagogastric Varices and Portal Gastropathy

Introduction Accurate non-invasive techniques for imaging portal hypertension (PHT) have long been the goal of hepatologists. However the sensitivity of standard ultrasound (US) alone is too low to achieve this. The combined use of elastography with US to detect PHT has not been investigated. ARFI (Virtual Touch © ) elastography is a novel validated technique for measuring liver stiffness (LS), with practical advantages over transient elastography including real-time scanning. We report our experience of this technique in assessing PHT in a consecutive secondary care cohort. Aims To establish whether the addition of LS estimation by ARFI to conventional US Doppler assessment of the spleno-portal venous system can reliably predict the presence of significant endoscopic PHT. Methods Conventional US and elastography were performed simultaneously at one session by a single radiologist, using a Siemens Acuson S2000 TM and 4C1 probe 4 MHz transducer and a standard, validated 10 observation right lobe ARFI technique. Within the study period, 82/108 chronic liver disease (CLD) patients (60 hospitalised and 48 outpatients) underwent both elastography and upper GI endoscopy. Standard US data collected included spleen size, portal vein Doppler flow velocity, direction and waveform, presence of collaterals, and platelet count. Results Significant endoscopic PHT, defined as oesophageal/gastric varices and/or moderate to severe portal hypertensive gastropathy, was seen in 34/82 patients (41%). Median LS measured by shear velocity was significantly higher in the PHT group (2.9 vs 2.2 m/s, p Conclusion In this retrospective “real world” study the addition of ARFI to standard US parameters using a combined scoring system achieved high (>90%) predictive value for the non-invasive detection of endoscopic PHT. A further prospective study, with refinement of US Doppler technique, is now in progress to confirm these promising results. Single session ARFI+US may accurately guide PHT diagnosis and selection for endoscopic surveillance in CLD. Competing interests None declared.

PP055. Preliminary results of the more prepared study (microparticle orientated risk evaluation in the prediction of preeclampsia among risk gravidas): A multicenter prospective prognostic marker study

Preeclampsia (PE) is a potentially dangerous pregnancy pathology contributing to a higher worldwide mortality and morbidity. The negative influence of syncytiotrophoblastic microparticles (STBMs) on the placenta and maternal endothelia is thought to play a key role in generating the inflammatory effects that lead to PE symptoms. Doppler sonography of the uterine arteries assists in identifying a risk population, however, the positive predictive value for this method is low. Aim of this study is to evaluate whether STBMs can serve as an accessory marker to conventional Doppler sonography to better identify pregnant women who will actually develop PE. Pregnant women between 19-21 gestational weeks (GW) with abnormal uterine perfusion were enrolled into this prospective study. Plasma samples were taken at inclusion (baseline) and at two further visits at 8 week intervals to follow STBM concentration alterations during pregnancy. The primary endpoint assessed is PE and/or hemolysis, elevated liver, low platelets (HELLP) syndrome. Other PE-associated pathologies (intrauterine growth retardation [IUGR], intrauterine fetal demise [IUFD], placental abruption, premature delivery) constitute the secondary endpoints. Maternal STBM concentrations were measured using a home made Enzyme Linked Sorbent Assay (ELSA) which specifically measures STBMs. The receiver operating characteristics (ROC) for baseline measures are graphically displayed and area under curve (AUC) is estimated including 95% confidence levels. Of the 73 women included in the study, 16 developed PE (cases) and 56 did not (control). After analyses of mid-gestational probes, the ROC curve was in close proximity to the line of no-discrimination. Our preliminary results indicate that the maternal STBM concentration at mid-gestation does not predict the development of PE or associated pregnancy pathologies. Further analysis is underway to assess whether STBM measurements at later gestational time points can predict PE shortly before onset of disease.

PTU-025 A new paradigm in the non-invasive assessment of portal hypertension: a single ultrasound procedure incorporating acoustic radiation force impulse (ARFI) elastography predicts over 90% of oesophago-gastric varices and portal gastropathy

IntroductionAccurate non-invasive techniques for imaging portal hypertension (PHT) have long been the goal of hepatologists. However the sensitivity of standard ultrasound (US) alone is too low to achieve this. The...

Two-Dimensional Flow Index Mapping for Hemodynamic Imaging: A Feasibility Study

The resistive index (RI) is a functional hemodynamic index used to measure flow resistance within an organ, such as the kidney, to assess if there is any vascular disease associated with that organ. Currently, the measurement of RI values using spectral Doppler ultrasound (US) is performed in one location at a time. As a result, RI values are typically obtained only from a few locations. To visualize the entire two-dimensional distribution of RI values, we developed a method called two-dimensional flow index mapping (2D-FIM). To evaluate this method, we performed a feasibility study using 16 kidney data sets, with eight from healthy volunteers with normal native kidneys and eight from kidney transplant recipients. Quadrature-demodulated baseband Doppler data were used to calculate the spatial distribution of RI values using 2D-FIM. For comparison, the intrarenal RI values at different levels of renal arterial branches were measured with conventional spectral Doppler US. The RI values determined from 2D-FIM were compared with those from spectral Doppler US, which led to a Pearson correlation coefficient of 0.84. There was no significant difference between 2D-FIM– and spectral Doppler US–produced RI values. With the ability to visualize RI in more than one dimension, 2D-FIM could help guide placement of the spectral Doppler range gate to regions of abnormal RI, thus potentially reducing exam times. (E-mail: ykim@u.washington.edu)

Clinical utility of microbubble contrast-enhanced ultrasound in the diagnosis of hepatic artery occlusion after liver transplantation

To evaluate the frequency of use and the diagnostic accuracy of real-time contrast-enhanced ultrasound (CEUS) in the diagnosis of hepatic artery occlusion after liver transplantation. One hundred and fifty-two liver transplantations in 142 adult subjects, comprising 80 male patients and 62 female patients, were studied. After surgery, liver circulation was routinely assessed by conventional Doppler ultrasound (US). Wherever the examiners were not confident about the state of the circulation, CEUS was performed with one or more doses of a sulfur hexafluoride (SF-6)-containing second-generation contrast agent intravenously. Clinical follow up including repeat Doppler US, computed tomographic angiography (CTA) or magnetic resonance angiography (MRA) of the liver vasculature were used as reference standards. During the first month after transplantation, Doppler US was inconclusive with regard to patency of the hepatic artery (HA) circulation in 20 (13 %) of 152 transplantations. CEUS was performed in these patients, and detected six cases of HA thrombosis (HAT) in five transplants. CEUS correctly ruled out HA occlusion in 15 transplants. All HA occlusions occurred during the first 14 days after transplantation. In the subset of transplantations examined with CEUS, the sensitivity, specificity and accuracy of CEUS were 100%. In approximately 13% of cases, conventional Doppler US did not provide sufficient visualization of the HA after liver transplantation. In these cases, correct diagnosis was achieved by supplementary CEUS.

High-Definition Flow Doppler Ultrasonographic Technique to Assess Hepatic Vasculature Compared With Color or Power Doppler Ultrasonography

The purpose of this study was to introduce a new high-definition flow (HDF) Doppler technique and to compare its performance with those of color Doppler ultrasonography (CDU) and power Doppler ultrasonography (PDU) for assessment of hepatic vasculature in native and transplanted livers. High-definition flow was invented as a high-resolution bidirectional PDU technique. We obtained CDU, PDU, and HDF images of the hepatic artery (HA), portal vein (PV), and hepatic vein from 60 patients. They were divided into 2 groups: a liver transplantation group (group 1, n = 10) and a native liver group (group 2, n = 50). Two radiologists independently reviewed the cine images and graded them using a 4-point scale in terms of the clarity of the vessel margin and degree of depiction of the HA, flow filling, and flash artifacts. The degree of differentiation between the HA and PV was also evaluated. Flow directionality was recorded, and interobserver agreement was finally analyzed. Moderate to almost perfect agreement was achieved between radiologists for all parameters of each ultrasonographic technique. High-definition flow was significantly superior to both CDU and PDU with respect to all analyzed items except the degree of flash artifacts (P < .05). With regard to flash artifacts, CDU was significantly better than either PDU or HDF. High-definition flow provided directional information, as did CDU. The HDF technique provides better resolution for depicting hepatic vessels as well as their margins with less blooming compared with conventional Doppler ultrasonography in both native and transplanted liver. It also provides solid directional flow information. One point of concern, however, is the frequency of flash artifacts compared with that on CDU.

Vaskuläre Raumforderungen der Arteria carotis - Nachweis mit der farbkodierten Dopplersonographie

Nine patients with a cervical tumour, diagnosed by duplex Doppler sonography were additionally evaluated by colour-coded Doppler sonography (CCDS). The duplex Doppler diagnosis of three internal carotid artery aneurysm was confirmed by CCDS in only one patient. In the remaining two cases CCDS identified a marked coiling of the internal carotid artery. Three low echogenic lesions, interpreted as cervical lymphomas by conventional Doppler sonography were identified as two internal carotid aneurysm with partial thrombosis and a carotid body tumour in the third patient by CCDS. Duplex-Doppler sonography and CCDS agreed in the diagnosis of two AV-malformations and one carotid body tumour. Angiography confirmed the CCDS-diagnosis in 7 patients. In the two patients with coiling of the ICA angiographic evaluation was not performed. Thus, CCDS was superior to duplex Doppler sonography in the evaluation of vascular lesions of the extracranial section of the carotid artery and provided additional diagnostic information.

Does Three-Dimensional Power Doppler Ultrasound Help in Discrimination Between Benign and Malignant Ovarian Masses?

Gray-scale ultrasonography is a reliable and reproducible means of distinguishing between benign and malignant ovarian tumors. New blood vessel formation is a key factor in tumor growth and spread, but conventional Doppler ultrasonography has not appreciably improved the assessment of tumor vascularization. The advent of three-dimensional (3D) power Doppler ultrasound raises the possibility of objectively studying vascularization in a whole organ or tumor. The value of this modality was studied in 106 women scheduled to have surgery for an ovarian mass, which was assessed by transvaginal gray-scale ultrasound as well as two-dimensional (2D) and 3D power Doppler ultrasound. The examiner rated the color content of the tumor scan using a visual analog scale. The whole tumor and a sample taken from the most vascular area of the tumor were analyzed to determine the vascularization index (VI), flow index (FI), and vascularization flow index. An attempt was made to include the entire tumor in the 3D power Doppler studies. The series included 79 women with benign tumors, 6 with borderline lesions, and 21 with invasive tumors. A logistic regression model incorporating only gray-scale variables (size of the largest solid component, wall irregularity, lesion size) had an area under the receiver-operating characteristics (ROC) curve of 0.98, was 100% sensitive, had a false-positive rate of 10%, and had a positive likelihood ratio of 10 when using the mathematically best cutoff value for risk of malignancy. The 3D FI in the most vascular part of the tumor—the 3D parameter that performed best diagnostically—was superior to the color content of the tumor scan, with an area under the ROC curve of 0.92, sensitivity of 93%, and a false-positive rate of 16% using the mathematically best cutoff value. Adding the color content of the tumor scan or FI in the vascular tumor sample to the logistic regression model improved its diagnostic performance only marginally. There were no systematic differences between the first and second measurements of one observer or between measurements made by two observers. An experienced ultrasound examiner is able to correctly classify most adnexal tumors as benign or malignant using only gray-scale ultrasonography. Approximately 10% of tumors, however, are very problematic even for expert sonographers; it is for these cases that newer diagnostic methods, possibly including 3D power Doppler ultrasound, may prove to be helpful.

Prospective Evaluation of Vascular Complications after Liver Transplantation: Comparison of Conventional and Microbubble Contrast-enhanced US

To prospectively compare diagnostic performance of conventional Doppler ultrasonography (US) and microbubble contrast material-enhanced US for assessment of vascular complications after liver transplantation, with clinical follow-up or angiography as reference standard. This study was approved by institutional review board and was HIPAA compliant. Written informed consent was obtained. Seventy-two patients (49 men, 23 women; average age, 52.3 years) were included in this study. Patients who had undergone liver transplantation underwent conventional color Doppler and contrast-enhanced US of the liver. Quality of hepatic artery (HA) and portal vein (PV) visualization, contrast material arrival time, and time for complete evaluation of vasculature were compared for both techniques. McNemar test was used to compare vascular flow visualization scores; Student t test was used to compare mean study times with both techniques. Patients without HA flow at Doppler US underwent angiography; those with flow were followed up clinically. McNemar test was used to compare sensitivity of both techniques. Contrast-enhanced US helped significantly improve flow visualization in hepatic vessels (P < .001). Mean contrast material arrival time was 13.7 seconds +/- 3.8 (standard deviation) in proper HA and 20.7 seconds +/- 6.3 in PV. Mean study time decreased from 27.4 minutes +/- 13.9 to 9.3 minutes +/- 4.5 (P < .01). Doppler US failed to depict HA flow in eight patients; contrast-enhanced US showed flow in six and no flow in two of these patients. Follow-up results confirmed contrast-enhanced US findings. Sensitivity, specificity, and accuracy for Doppler US were 91.3%, 100%, and 91.5%, respectively. Sensitivity, specificity, and accuracy of contrast-enhanced US were all 100%. Sensitivity and accuracy values of the two techniques were significantly different (P < .014); there was no significant difference in specificity (P > .99) Contrast-enhanced US helped improve flow visualization in the HA and PV, decrease scanning time, and correctly differentiate between thrombosis and a patent artery in patients without HA flow at conventional Doppler US.

1003: Use of first generation ultrasound contrast agent in the abdomen

Diagnostic imaging techniques are used for assessment of morphological structures and vascularity of pathologic entity. Different technical approaches and imaging protocols are required for the evaluation of lesion character, Traditionally, B-mode ultrasound (US) is used to demonstrate structures, and Doppler methods are for assessment of vascularity and blood flow. The value of conventional Doppler US in demonstrating tumoral vascularity in abdominal organ has been described by many investigators.

Pulse-Inversion US Imaging of Testicular Ischemia: Quantitative and Qualitative Analyses in a Rabbit Model

To quantitatively and qualitatively assess perfusion with pulse-inversion (PI) ultrasonography (US) in rabbit model of acute testicular ischemia. Institutional animal care committee approval was obtained. After 35 rabbits underwent unilateral spermatic cord occlusion, testicular Doppler US and contrast material-enhanced PI imaging were performed. Enhancement data yielded perfusion measurements including mean value during the first 10 seconds, mean value over entire recorded replenishment curve, and curve slope during the first 5 seconds. Calculated perfusion ratios were compared with radiolabeled microsphere-derived perfusion ratios. Two readers assessed testicular perfusion as none, possible, or definite and relative perfusion as greater to the right testis than to the left, greater to the left testis than to the right, or as equal to both testes. With kappa statistics, interobserver agreement for all imaging methods was determined. Association between qualitative perfusion categories and radiolabeled microsphere-based perfusion measurements was assessed. Quantitative and qualitative determinations of relative perfusion were compared with radiolabeled microsphere-based measurements. Correlations between calculated and radiolabeled microsphere-based perfusion ratios were determined (r=0.49-0.64). Interobserver agreement for presence of perfusion was excellent (kappa=0.76), and that for relative perfusion assessment was good (kappa=0.55). Neither kappa value varied significantly with imaging method. The percentage of times a testis classified as having definite perfusion had greater perfusion as measured with radiolabeled microspheres than a testis classified as having no perfusion or possible perfusion was higher with PI imaging than with Doppler US (85%-98% vs 72%-89%). Identification of the testis with less perfusion was better with quantitative methods than with qualitative assessment of images by the readers (75%-79% vs 34%-60%, P<.004). PI imaging, compared with conventional Doppler US methods, provides superior assessment of perfusion in the setting of acute testicular ischemia.

Ultrasonic vibration dectection with wavelets: Preliminary results

Several arterial disorders are known to cause systolic audio vibrations in tissue: they include stenoses, vasospasm, aneurysms, bleeds and arteriovenous fistulas. High-amplitude vibrations can be discovered with conventional Doppler ultrasound (US) instruments; however, differentiating brief, low-amplitude vibrations from other nonstationary echo sources is difficult. Further, characterizing the frequency and amplitude of vibrations is not feasible with conventional Doppler US. The automated detection and estimation of both the frequency and amplitude of vibrations with durations less than 100 ms and amplitudes of a micrometer or less have remained a signal-processing challenge. These vibrations may be associated with both nonstationary colored noise and strong low-frequency clutter. The normalized continuous Morlet wavelet power-spectrum analysis of quadrature Doppler echoes, followed by a binary hypothesis test for noise, results in simulated detection rates above 99.9%, with 0.1% false alarms for signal-on signal-to-noise ratios (SNRs) as low as one. Two clinical examples are included. (E-mail: mplett@spu.edu)

In vitro investigation of turbulence intensity in the carotid bifurcation

Objective: A clinical Doppler ultrasound (DUS) machine is an appealing modality to prescribe carotid endarterectomy for prophylaxis against stroke because it is non-invasive and widely available. Doppler ultrasound diagnosis based on peak systolic velocities alone may not have sufficient sensitivity and specificity to diagnose carotid artery disease. Additional information may be obtained from parameters such as turbulence intensity, providing a more accurate view of the hemodynamic factors produced by a stenosed carotid artery. We hypothesize that quantification of turbulence intensity (TI) distal to a severely stenosed carotid bifurcation is possible with conventional DUS, even in the presence of normal physiological cycle-to-cycle cardiac variability.

Renal parenchymal diseases: is characterization feasible with ultrasound?

Ultrasound (US) imaging of the kidneys has greatly improved in recent years with introduction of wideband transducers and advances is beamformer technology. US is often the first imaging technique to be employed in patients with renal failure, haematuria or proteinuria, after clinical and laboratory evaluation. After conventional US evaluation, Doppler US (DUS) and resistive indices (RIs) analysis provide renal functional evaluation. Anyway, both sensitivity and specificity of conventional US and DUS in renal parenchymal disease evaluation remains low. In the initial or mild clinical stages of renal parenchymal diseases, kidneys may present normal US morphological appearance and normal RIs values, whereas different renal parenchymal diseases may reveal similar appearance on US and DUS evaluation. Besides, different renal parenchymal diseases may present some distinct features on conventional US and DUS with colour Doppler (CD) and power Doppler (PD) evaluation, even though percutaneous renal biopsy is often necessary to reach definite diagnosis. Renal vasculitides and tubular-interstitial nephropathies are more frequently identified by conventional US and DUS than glomerular nephropathies, since glomerular component accounts only for 8% of the renal parenchyma, whereas the highest percentage is occupied by vascular and tubulo-interstitial component. Follow-up of acute renal failure, during and after medical treatment, is the most useful field of employment of conventional US and DUS techniques, since a progressive lowering of RIs is correlated to a progressive recovery of renal function.

Color Doppler energy--a new technique to study tissue perfusion in renal transplants.

Information on renal tissue perfusion after transplantation remains important for renal allograft monitoring. Findings obtained by conventional Doppler sonography are limited to vascular resistance (RI). The new technique color Doppler energy (CDE) is Doppler angle independent, omits flow velocity and direction, and is proportional to the returning signal strength. The aim of our study was to standardize the application of this technique and to analyze the information obtained. Forty-six CDE studies were performed with an Acuson 128XP in 28 children (mean age 12.4+/-5.3 years) between 4 days and 10 years after renal transplantation. The most-reproducible information was obtained with a 5-MHz linear probe and a constant area of 2x3 cm (log compression 40 dB, filter 3). CDE provided a high-resolution cross-sectional display of perfused cortical tissue vessels. According to the density of signals, the perfusion could be grouped into six perfusion scores (PS). The interobserver concordance was more than 85%. No correlation was found between PS and RI or blood pressure. However, there was a significant correlation between PS and glomerular filtration rate (r=-0.78, P<0. 001). These first results demonstrate a significant relationship between PS and chronic rejection. Non-rejection-related functional impairment exhibited no decrease in PS. We conclude that our proposed standardized CDE renal study is observer independent. CDE is a promising new technique that provides information on renal allograft dysfunction that is different from classical color Doppler findings. Further studies will clarify its role in renal transplant monitoring and its ability to replace more-invasive techniques.

Improved investigation of portal-hepatic veins by echo-enhanced Doppler sonography

Microbubbles of air released from a galactose vehicle (Levovist ®) amplify the intensity of Doppler signals. They survive both pulmonary and systemic capillary passage, leading to echo enhancement in the entire vascular system. The aim of this study was to investigate this agent in patients with liver disease and insufficient Doppler signals. A total of 275 Doppler examinations were performed in 176 patients; 20 of these patients could not be studied conventionally due to bowel gas, obesity or noncompliance. They received Levovist ® to examine portal or hepatic veins or TIPS patency. Angiography, computed tomography (CT) scan or magnetic resonance tomographic angiography (MRTA) was performed subsequently as a control. After administration of Levovist ®, portal or hepatic veins and TIPS patency could be unequivocally assessed in 18 of the 20 patients. In two patients, suspected occlusion of the portal vein was disproved because the diagnosis was not confirmed later. Only minor adverse effects were encountered. Echo-enhanced Doppler sonography with Levovist ® is well tolerated. Further study of the value of Levovist ® for the assessment of portal-hepatic vessels not amenable to conventional Doppler sonography is justified.

Hepatic hemangioma: quantitative color power US angiography--facts and fallacies.

To explore the origin of signals detected with color power ultrasound (US) angiography (CPA) and evaluate a semiquantitative method to assess signals in hepatic hemangiomas. Twenty-four adult patients with 27 hepatic hemangiomas (< 2 cm in diameter) and five patients with five hyperechoic hepatic metastases underwent CPA and conventional color Doppler US in this prospective study. A sponge phantom was studied to determine whether the origin of CPA signals was related to architecture. The mean number of signals and the signal density in each lesion were scored. A "diffuse blush" was seen in all capillary hemangiomas at CPA, whereas no signal was seen at color Doppler US. The sponge phantom test produced a CPA appearance similar to that of capillary hemangiomas. Quantitative analysis of CPA images of hepatic hemangiomas showed a mean of 16.1 signals per cubic centimeter and a mean signal area of 25%. Hyperechoic avascular hepatic metastases resulted in CPA images similar to those of hepatic hemangiomas, with no quantitative difference in signal count, despite a mild qualitative difference at CPA. CPA signals in hepatic hemangiomas appear to be related more to architecture than to true capillary flow. There is a qualitative difference in the strength of the blush at CPA between hepatic hemangiomas and metastases, which may be the only possible differentiating factor.