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

Contrast-enhanced ultrasound in the detection and characterization of liver tumors

Contrast-enhanced ultrasound (CEUS) has unique advantages over contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) in the characterization of hepatic tumors. These include the capability of real-time dynamic imaging depicting the enhancement pattern of tumors regardless of its rapidity, purely intravascular properties of the microbubble contrast agents more consistently demonstrating washout of malignancy, and capability of repetitive observation of tumor vascularity with multiple injections of microbubbles with an excellent safety profile and no nephrotoxicity. For an indeterminate mass detected on an ultrasound scan, an immediate benign diagnosis reduces the necessity of costly further imaging as well as patients’ anxiety and an immediate malignant diagnosis prompts the proper work-up and management. CEUS is often served as a problem-solving tool for indeterminate lesions on prior CT or MRI scans, obviating further invasive steps. CEUS offers excellent visualization of peripheral nodular enhancement in even flash-filling or very slow-filling hemangiomas. Careful observation of early arterial filling pattern is helpful in the differentiation of focal nodular hyperplasia versus adenoma. Hepatocellular carcinoma is typically characterized by arterial hypervascularity and often late, partial washout. Metastasis shows brief arterial hypervascularity and complete rapid washout, which can improve its detection during a portal phase survey. The washout phenomenon of malignant tumors in general is useful to differentiate them from benign lesions.

Impact of contrast-enhanced ultrasonography in a tertiary clinical practice

OBJECTIVE

The purpose of this study was to assess the impact of contrast-enhanced ultrasonography (CEUS) of the liver in a tertiary clinical practice.

METHODS

One thousand forty consecutive CEUS examinations performed over 30 months for mass characterization were reviewed to determine their source, accuracy, and clinical impact.

RESULTS

Two hundred seventy-five (26.4%) of 1040 examinations were motivated by incidental detection of a mass at routine ultrasonography; 765 (73.6%) were clinical referrals, most often for characterization of a mass in a high-risk patient scanned for hepatoma surveillance or characterization of an indeterminate mass after prior imaging. Clinician referrals increased from 57 in the first 6 months after CEUS introduction to 158 in the last 6 months of the study. Surveillance scans yielded 78 confirmed hepatocellular carcinomas characterized on CEUS at the time of identification. Contrast-enhanced ultrasonography was accurate in 233 (89.2%) of 261 with histologic proof, including 208 malignant lesions. Clinical impact included reduced referrals for other imaging in 226 (21.7%) of 1040 patients, decreased time to diagnosis in 390 (37.5%), and successful guidance for ablation therapy in 26 (2.5%). A positive change in management occurred in 182 (17.5%) of 1040, including alteration of a previous diagnosis, a diagnosis made by CEUS after indeterminate prior imaging, and a diagnosis upstaged by CEUS. Negative impacts included delayed management in 8 (0.8%) small hepatocellular carcinomas misdiagnosed as benign lesions and wrong management of a solitary sclerotic hemangioma, in a high-risk patient for hepatoma, misdiagnosed as a malignant tumor on CEUS, computed tomography, and magnetic resonance imaging, leading to its surgical removal.

CONCLUSIONS

Contrast-enhanced ultrasonography has a positive impact on clinical management, providing rapid, accurate diagnosis of incidentally detected masses and resolving nodules on surveillance scans and indeterminate masses on other imaging.

Are metastases really hypovascular in the arterial phase? The perspective based on contrast-enhanced ultrasonography

OBJECTIVE

The purpose of this study was to describe enhancement and vascularity characteristics of liver metastases on real-time low-mechanical index contrast-enhanced ultrasonography.

METHODS

This retrospective study was approved for chart review by our Research Ethics Board. Informed consent was waived. Fifty metastases (colorectal [n = 28], neuroendocrine [n = 6], pancreatic [n = 6], melanoma [n = 3], and other [n = 7]) in 50 patients (38-84 years, 24 male and 26 female) were analyzed. Contrast-enhanced ultrasonography was performed after intravenous injection of a microbubble contrast agent. Two radiologists independently reviewed digital cine clips and static images for the arterial phase intensity and pattern of enhancement and the presence of dysmorphic vessels. Observations on wash-out included its presence and completeness. Disagreement was resolved by consensus. The interval to peak arterial enhancement and beginning of wash-out were determined. Reader agreement was estimated with the kappa statistic.

RESULTS

All but 6 metastases (44/50 [88%]) showed arterial hypervascularity, with dysmorphic vessels in 21 (42%) of 50. The pattern of enhancement was rim in 21 (42%) of 50 and diffuse in 29 (58%) of 50. The time to peak arterial enhancement ranged from 8 to 27 seconds (mean, 15.1 seconds), and the beginning of wash-out ranged from 13 to 50 seconds (mean, 25.2 seconds). Although a thin margin of residual enhancement was seen in 27 (54%) of 50 lesions in the early wash-out phase, all lesions (50/50) showed uniform complete wash-out in the portal phase.

CONCLUSIONS

Contrary to popular belief based on computed tomography and magnetic resonance imaging studies, most hepatic metastases, including those thought to be hypovascular, show transient arterial hypervascularity on contrast-enhanced ultrasonography, followed by rapid and complete wash-out initiated within the conventional arterial phase.

Application of percutaneous ultrasound-guided treatment for ultrasonically invisible hypervascular hepatocellular carcinoma using microbubble contrast agent

AIM

To evaluate the efficacy of contrast-enhanced ultrasound for the localization of ultrasonically invisible hypervascular lesions in the liver to facilitate percutaneous ultrasound-guided treatment.

MATERIALS AND METHODS

Forty patients with 47 ultrasonically invisible hypervascular lesions (5-20mm) diagnosed on contrast-enhanced computed tomography were enrolled in the retrospective study. Contrast-enhanced ultrasound (CEUS) with Levovist was performed to localize the lesions both in the early phase and liver-specific phase. Diagnosis of was confirmed by percutaneous needle biopsy where feasible, and on the basis of on treatment outcomes or changes in computed tomography findings in those not amenable to biopsy.

RESULTS

Thirty-two lesions were diagnosed as hepatocellular carcinoma (HCC). Contrast-enhanced ultrasound localized hepatocellular carcinoma in 24/32 (75%) lesions, the mean diameter (15.1+/-4.9mm), as measured using computed tomography, being significantly larger than that of the remaining eight lesions (10.5+/-2.1mm). Ultrasound-guided treatment was performed in 19 of the 24 lesions, and transarterial chemoembolization (TACE) was applied for the other five lesions because of difficult percutaneous access. Five of the eight non-visualised lesions were treated by transarterial chemoembolization, and the other three by surgical resection. The beneficial effect of CEUS was significantly greater when the reason for poor initial visualisation was the coarse liver architecture (17/17) than when it was due to adverse location (seven of 15, p<0.005). Fifteen of the CT-detected hypervascular lesions were considered to represent false positives for HCC, based on their behaviour during follow-up.

CONCLUSION

Contrast-enhanced ultrasound with Levovist facilitates the application of percutaneous ultrasound-guided treatment by improving localization of ultrasonically invisible hypervascular hepatocellular carcinomas in the liver.

Recent applications of ultrasound: diagnosis and treatment of hepatocellular carcinoma

Ultrasound (US) has the advantages of real-time observation, simple technique, and a noninvasive procedure compared to other imaging modalities. The recent development of digital technologies has enabled the observation of sonograms with improved signal-to-noise ratio, penetration, and spatial and contrast resolutions. Furthermore, microbubble contrast agents have increased the diagnostic ability of US examination, and the use of three-dimensional sonograms is now not unusual. These advances have furthered the usefulness of US for liver tumors in clinical practice. This article reviews the recent applications of US in the diagnosis and treatment of hepatocellular carcinoma.

Microbubble disappearance-time is the appropriate timing for liver-specific imaging after injection of Levovist

Contrast enhancement in the portal vein was repeatedly observed at 1 min intervals with wide-band Doppler ultrasonography in 152 consecutive patients (132 with liver cirrhosis and HCC, 20 controls), 5 min after the injection of Levovist. The duration time of contrast enhancement in the portal vein (microbubble disappearance-time; MD-T) was measured in all patients and contrast-enhanced appearances were compared between the 5 min phase and MD-T phase in 68 HCC nodules. MD-T in patients with liver cirrhosis (572.4 +/- 117.9 s) was significantly longer than in controls (481.6 +/- 89.3 s, p < 0.05). MD-T was prolonged in patients with Child B and C compared with Child A (p < 0.05). The contrast-enhanced appearances between the two phases were different in 30 of 68 HCC nodules (44.1%), showing positive enhancement in the 5 min phase and negative enhancement in the MD-T phase. The proposed MD-T may become an essential factor for the evaluation of liver-specific sonograms.

[Contrast ultrasound imaging in focal liver lesions: diagnostic value and guidelines]

The recent introduction of high quality scanners and contrast agents for ultrasound deeply modifies diagnosis strategy in focal liver lesions by using validated criteria. Non-linear imaging methods using low mechanical index (MI<0.2) and second generation contrast agents allow real-time continuous imaging with concomitant limitation in background tIssue signal and also in agent collapse for a high quality contrast imaging giving dramatic improvement in detection and characterization of lesions. Interpretation is based on the presence of contrast agent within the lesion or not (hyper-, hypo- or isosignal) and the delay after injection (arterial, portal or parenchymal or late phase) as previously used by non-ultrasound methods. This allows an easy differentiation of benign from malignant lesions. Moreover, this allows complete characterization in 85 to 95% of all focal liver lesions and 75% in hepatocellular carcinomas. Those results markedly improve ultrasound accuracy compared to conventional sonography and so put contrast-enhanced sonography among recommended non-invasive imaging methods for focal liver lesions with changes in diagnostic strategy according to the lesion type and actual place of US methods. It is recommended to use contrast ultrasound methods in cancer staging for an optimal detection of liver metastases as well as in characterization of lesions detected during conventional sonography with a consecutive decrease of cost-diagnosis ratio.

Apport de l’échographie de contraste et échographie conventionnelle simultanée en pathologie hépatique

PURPOSE

To assess the value of combined conventional and contrast-material enhanced sonography for the characterization of focal liver lesions.

MATERIALS AND METHODS

Simultaneous imaging with grey scale and contrast enhanced US was performed in 90 patients following Levovist injection (Schering, Berlin, Germany) using the "Agent Detection Imaging" method (ADI, Siemens-Acuson, Mountain View, USA). US scanning was performed at least 4 minutes after contrast injection with review of both grayscale and contrast enhanced modes. Results for detection and characterization of lesions were compared to the selected gold standard imaging modality (CT or MRI).

RESULTS

Final diagnoses included: 20 normal examinations, 41 patients with metastases, 6 patients with hepatocellular carcinoma, 13 patients with hemangioma, 6 patients with other benign lesions, 4 patients with cysts and 6 patients with two types of lesions. Delayed phase contrast enhanced US allowed diagnosis of all lesions except for one metastasis and all hepatocellular carcinomas. While the diagnosis of hepatoma could not be confirmed, the features suggested a malignant etiology. For 7 patients with metastases, more lesions were detected at ADI (4.9 lesions) than at conventional US (1.1 lesion). For 3 patients, CT showed more lesions than ADI US (3.3 versus 1.6 lesions). The accuracy of ADI US for differentiating between benign and malignant lesions was 98.7% compared to 49.6% for conventional US (p<0.001). The total number of lesions detected at ADI US was higher (p<0.01) than at conventional US and not significantly different from that obtained by the gold standard reference methods. Complete characterization was achieved in 92.2% of cases with ADI US compared to 59.2% with conventional US (p<0.001).

CONCLUSION

Contrast-material enhanced US combined with conventional US markedly improves the diagnostic accuracy of US in terms of lesion detection and characterization.

Pyogenic hepatic abscesses: distinctive features from hypovascular hepatic malignancies on contrast-enhanced ultrasound with SH U 508A; early experience

The aim of this study was to investigate the feasibility of contrast-enhanced US (conE US) in differentiating pyogenic hepatic abscesses (PyHAs) from hypovascular hepatic malignancies. conE US images of 16 PyHAs in 12 patients were evaluated retrospectively and were compared with those of 22 hypovascular hepatic malignancies in 12 patients. The conE US images were obtained at 30, 90, 150 and 270 s after a bolus injection of 4 g of SH U 508A (Levovist, Schering; 300 mg/mL). The images were specifically analyzed for the shape (round or ovoid, lobulating or coalescent according to the complexity), the margin (sharp or ill-defined), and the pattern of contrast agent enhancement of the lesion (internal and rim enhancement). In our experience, as to the shape of the lesion, PyHAs were usually coalescent (94%), and hepatic malignancies were more frequently round or ovoid (36%) or lobulating (50%) (p < 0.0001). The margin of the lesion was usually sharp in PyHAs (81%), whereas it was more commonly ill-defined (59%) in hepatic malignancies (p = 0.02). Whereas PYHAs usually produced no internal enhancement (94%), diffuse (73%) or peripheral (27%) hypoechoic intratumoral enhancement was seen in hepatic malignancies (p < 0.0001). This study shows that conE US is potentially useful in differentiation of PyHAs from hypovascular hepatic malignancies. PyHAs usually produce characteristic features, such as coalescent appearance, sharp boundary of necrotic cavity, and lack of internal enhancement on conE US.

[The role of contrast-enhanced ultrasonography for the detection of hepatocellular carcinoma]

The incidence of the hepatocellular carcinoma (HCC) is increasing in Occident, as well as in France. Primary prevention is the only solution for early detection. The combination of ultrasound (US) and alphaFP each 4 to 6 Months dosage has many limitations. The sensitivity of US examination is rather poor (less than 70% for lesions below 2 cm in diameter) and serum alphaFP values remain normal in almost 50% of HCC. US contrast agents (USCAs) with perfluorocarbon gases increase the backscattered signals during all phases of the liver transit, including arterial, portal and delayed phases. Hepatocellular lesions exhibit a specific kinetics with strong enhancement during arterial phase, and rapid wash-out during portal and delayed phases. USCAs increase the detection of HCCs and allow characterization of additional focal lesions found in cirrhotic livers (regenerative and dysplastic nodules, haemangiomas.). Indeed, regenerative nodules contrast uptake is synchronous to the surrounding parenchyma, and usually disappear during portal and delayed phases. However, US in cirrhosis remains a difficult examination, with limitations due to limited access to sub-diaphragmatic localization, attenuation of the ultrasound beam and shortness of the arterial phase.

Quantitative dynamic contrast-enhanced sonography of hepatic tumors

Liver tumors are defined using quantitative dynamic contrast-enhanced ultrasound compared to histological diagnosis, respectively, long-term follow-ups. Forty-two focal liver lesions in 39 patients were examined by contrast harmonic imaging over a period of 2 min after bolus injection of 10-ml galactose-based contrast agent. Vascular enhancement was quantified by using a dedicated software that allowed us to place representative regions of interest (ROI) in the center of the lesion, in the complete lesion, in regular liver parenchyma and in representative liver vessels (artery, vein and portal vein). Peak enhancement was judged to be either in the arterial, portal venous or in the late phase of liver perfusion. The lesion was described as hypovascular, isovascular and hypervascular compared to liver parenchyma. Contrast uptake was described as centrifugal or centripetal and peripheral or homogenous, respectively. Characterization of the lesions was performed unenhanced and after contrast by four independent specialists unaware of histology. Diagnosis of malignancy was evaluated by using a receiver operating characteristic (ROC) analysis, also overall accuracy, average sensitivity, specificity and negative and positive predictive values were calculated. Interobserver agreement was defined by the Kappa statistics. Histologic examination revealed 29 malignant [hepatocellular carcinoma (HCC), n=11; cholangiocellular carcinoma (CCC), n=1; lymphoma, n=1; metastases, n=16)] and 7 benign [hemangioma, n=1; focal nodular hyperplasia (FNH), n=4, adenoma, n=2)] lesions. Six benign lesions (hemangioma n=1; FNH n=5) were proved by long-term follow-up. ROC analysis regarding the diagnosis of malignancy showed values from 0.43 to 0.62 (mean 0.57) before and from 0.70 to 0.80 (mean 0.75) after contrast agent, respectively. The average values for sensitivity, specificity, accuracy and negative and positive predictive values were 66, 26, 62, 45 and 73% unenhanced and 83, 49, 73, 65 and 82% after contrast, respectively. The interobserver agreement was 0.54 and 0.65 for unenhanced and enhanced examinations, respectively. Quantitative dynamic contrast-enhanced sonography improves the diagnosis of malignancy in liver lesions.

Therapeutic response evaluation of malignant hepatic masses treated by interventional procedures with contrast-enhanced agent detection imaging

OBJECTIVE

To assess the usefulness of microbubble contrast-enhanced agent detection imaging in evaluating the therapeutic response of malignant hepatic masses to treatment with interventional procedures.

METHODS

Fifty-eight patients with 68 hepatocellular carcinomas and 6 metastases who were treated with interventional procedures were evaluated with SH U 508A-enhanced agent detection imaging and helical computed tomography. Helical computed tomography was also performed to help establish the outcome of therapy with unenhanced computed tomography 2 weeks after transcatheter arterial chemoembolization and with dynamic contrast-enhanced computed tomography 1 day after radio frequency ablation or percutaneous ethanol injection. The studies were reviewed separately and randomly, and the sensitivity and specificity of agent detection imaging for detection of viable tumor residue were determined by follow-up imaging performed at least 3 months later.

RESULTS

Follow-up computed tomography or magnetic resonance imaging revealed complete tumor responses in 44 (59.5%) of 74 cases after the therapeutic procedures. The sensitivity of agent detection imaging was 94.7% after transcatheter arterial chemoembolization and 72.7% after radio frequency ablation and percutaneous ethanol injection. The specificity of agent detection imaging for the detection of residual tumors was 80% after transcatheter arterial chemoembolization and 79.2% after radio frequency ablation and percutaneous ethanol injection. The false-positive rate for agent detection imaging in cases of radio frequency ablation or percutaneous ethanol injection was 20.8% (5 of 24), resulting from reactive hyperemia or vascularity within the safety margin. In the assessment of the therapeutic effects, the concordance of contrast-enhanced agent detection imaging with helical computed tomography was statistically significant after transcatheter arterial chemoembolization (P < .00001) and radio frequency ablation or percutaneous ethanol injection (P < .02).

CONCLUSIONS

Contrast-enhanced agent detection imaging proved useful and as effective as helical computed tomography for evaluating the therapeutic effects of interventional therapeutic procedures for malignant hepatic masses.

Evaluation of liver parenchymal blood flow with contrast-enhanced US: preliminary results in healthy and cirrhotic patients

RATIONALE AND OBJECTIVES

To determine whether changes in hepatic parenchymal blood flow in cirrhotic patients can be evaluated with contrast-enhanced ultrasound (US) after Levovist administration.

MATERIALS AND METHODS

Ten normal volunteers, 16 Child A and 16 Child C cirrhotic patients were evaluated with contrast-enhanced US. Frames obtained at progressively increasing pulse intervals of 2, 4, 7, and 10 seconds in the same scan plane during infusion of Levovist (300 mg/mL, 150 mL/h) have been digitally recorded. Pulse intervals versus signal intensity (PI-SI) plots were fitted to a straight line whose slope is proportional to the speed of blood in the liver parenchyma. Enhancement differences in late phase have been evaluated measuring the SI after 7 minutes from the beginning of the infusion.

RESULTS

The slope of the PI-SI plot of the Child A cirrhotic patients was significantly lower than the slope of the normal controls (P < 0.05); conversely, no significant differences were found between the slope of the patients with Child C cirrhosis and that of the normal controls. In comparison with the normal subjects, the average SI at late phase decreased significantly both in patients with Child A (P < 0.05) and Child C (P < 0.001) cirrhosis.

CONCLUSION

Microbubble contrast agents could provide a noninvasive tool to detect and monitor hemodynamic changes that occur in the cirrhotic liver. Changes in the hepatospecific properties at late phase have also been demonstrated.

Pulse-inversion harmonic imaging improves lesion conspicuity during US-guided biopsy

PURPOSE

To assess the feasibility of percutaneous biopsy of low-conspicuity focal liver lesions with use of pulse-inversion harmonic imaging (PIHI) guidance in the late phase after injection of microbubble contrast agent.

MATERIALS AND METHODS

Twelve patients referred for ultrasound (US)-guided biopsy had liver lesions lacking adequate conspicuity to undergo biopsy under conventional ultrasound (US) guidance. They underwent biopsy procedures performed with the use of PIHI guidance in the late phase after injection of Levovist. The conspicuity of lesions, procedure time, number of passes, and success and complication rates were documented and compared to a control group. The control group consisted of retrospective analysis of 19 patients who had undergone conventional US-guided biopsy procedures performed by the same radiologist.

RESULTS

After contrast material injection, all lesions had sufficient increases in conspicuity to be targeted under PIHI guidance. Procedure time was prolonged in the PIHI group (66 minutes; range, 30-120 min; vs control, 33 min; range, 15-77 min; P <.01, Wilcoxon signed-rank test). The number of passes was greater in the PIHI group (1.9 +/- 0.3; vs control, 1.4 +/- 0.6; P <.01, chi(2) test). No statistically significant difference was observed when comparing success and complication rates.

CONCLUSION

PIHI in the late phase after injection of Levovist generated clear delineation of focal liver lesions in all cases, allowing an accurate and safe sampling. This technique broadens the scope of US-guided biopsy to lesions lacking adequate conspicuity on conventional US.

Ultrasound contrast imaging research

This article is a review of the research on ultrasound contrast agents in general imaging. While general imaging contrast agent applications are still undergoing investigation and waiting FDA approval in the United States, they are approved for clinical use in Europe and other countries. The contrast microbubble properties are described, including their nonlinear behavior and destruction properties. Imaging techniques like harmonic imaging, pulse inversion, power pulse inversion, agent detection imaging, microvascular imaging, and flash contrast imaging are explained. A connection is made between the aforementioned imaging techniques and the different contrast agents available. The blood flow appearance of different liver tumors in the presence of contrast agents is demonstrated with examples.

Hilar biliary obstruction: preliminary results with Levovist-enhanced sonography

OBJECTIVE

The aim of this study was to investigate the value of using Levovist in the postvascular phase of sonography performed to assess hepatic hilar biliary obstruction.

SUBJECTS AND METHODS

In our prospective study, 50 patients underwent routine sonography followed by postvascular Levovist-enhanced pulse inversion imaging of the liver. Thirty-six patients had malignant disease (28 invasive parenchymal tumors and eight intraductal tumors), and 14 had benign disease. The 36 malignancies included 29 cholangiocarcinomas, six invasive gallbladder carcinomas, and one colon metastasis. Fourteen patients had benign disease: benign strictures (n = 5), primary sclerosing cholangitis (n = 5), chronic Mirizzi's syndrome (n = 1), varicosities of the parabiliary venous plexus (n = 1), and inflammatory liver lesions (n = 2). Sonographic findings in all 50 patients were correlated with findings from other imaging modalities (n = 50) as well as surgical specimens (n = 20), core biopsies (n = 3), and both clinical and imaging follow-ups (n = 24).

RESULTS

Seventeen (61%) of the 28 invasive intraparenchymal malignancies were visualized on routine sonograms, whereas all 28 (100%) were visualized on enhanced sonograms (p < 0.01). In 15 (88%) of 17 patients in whom tumor was seen on routine sonograms, contrast-enhanced sonography showed further mass extent, increased conspicuity, or satellite nodules not visualized on the baseline image. All eight noninvasive intraductal malignancies were correctly identified and staged on the routine sonography. In one of these patients, hepatic invasion was prospectively overcalled on the enhanced image. Of the 14 benign lesions, three had inflammatory periductal abnormalities seen exclusively or to advantage on the enhanced study. Correct prediction of resectability in the 16 patients with malignant disease who underwent surgery improved from 11 (69%) of 16 on unenhanced sonography to 15 (94%) of 16 on enhanced sonography (p = 0.13).

CONCLUSION

Detection and staging of malignant hilar obstructions are improved by the use of Levovist in the postvascular phase of sonography compared with routine sonography.

The sonographic evaluation of tubal patency with stimulated acoustic emission imaging

OBJECTIVES

Experimental and clinical data suggest that insonation of echo-enhancing contrast agents with high acoustic power produces disintegration of microbubbles, resulting in a phenomenon called stimulated acoustic emission (SAE). The purpose of this study was to investigate whether SAE might be detected by transvaginal sonography and whether this technique may be useful in the assessment of tubal patency by hysterosalpingo-contrast sonography (SAE-HyCoSy).

METHODS

Patients booked for X-ray hysterosalpingography (HSG) for infertility evaluation also received SAE-HyCoSy. The order of the two procedures was established in each patient by randomization after placement of a transcervical balloon catheter. For SAE-HyCoSy, the ultrasound contrast medium Levovist was injected, with the acoustic power set at the maximum level permitted on ultrasound machines employing dedicated algorithms. Conventional HSG was performed for comparison.

RESULTS

Seventy-seven Fallopian tubes were examined in 41 patients. In all cases it was possible to obtain the SAE phenomenon. In 10 tubes (13%) proximal filling was not observed by both SAE-HyCoSy and HSG. In the remaining 67 tubes, free spill from the distal end of the lumen was demonstrated in 96% of cases (64/67) with SAE-HyCoSy and in 97% of cases (65/67) with HSG. Disagreement between the two techniques was observed in five tubes only, with a Cohen's kappa coefficient of 0.76 (95% confidence interval, 0.56-0.96).

CONCLUSION

SAE techniques were successfully applied to HyCoSy and allowed the visualization of the free spill of contrast agent into the peritoneal cavity in the majority of cases. SAE-HyCoSy showed good agreement with HSG in this preliminary study.

Comparison of contrast-enhanced fundamental imaging, second-harmonic imaging, and pulse-inversion harmonic imaging

RATIONALE AND OBJECTIVES

To investigate the feasibility of recent contrast-specific ultrasound techniques in depicting vascular flow and the effects of changing the output power of the transducer and insonation mode on contrast enhancement, the authors performed an experimental study with a flow phantom.

METHODS

While changing the mechanical index and the sound insonation mode (continuous and intermittent), images were obtained with three contrast-enhanced ultrasound techniques: fundamental, second-harmonic, and pulse-inversion harmonic imaging (PIHI) after a bolus injection of microbubble contrast agent. The images were compared on a time-intensity curve.

RESULTS

In assessing fixed flow (10 cm/s), PIHI showed the best depiction of flow signal. In intermittent scanning, increases in the mechanical index caused stronger flow signals and longer enhancement duration in all techniques. However, continuous scanning revealed poor depiction of flow signal regardless of the technique or changes in the mechanical index because of significant bubble destruction.

CONCLUSIONS

Microbubble-enhanced PIHI with intermittent scanning at a high mechanical index can depict vascular flow highly effectively without shortening the duration of enhancement.