An Algorithm for the Diagnosis of Focal Liver Masses Using Microbubble Contrast-Enhanced Pulse-Inversion Sonography

SURF imaging: in vivo demonstration of an ultrasound contrast agent detection technique

A dual-band method for ultrasound contrast agent detection is demonstrated in vivo in an animal experiment using pigs. The method is named Second -order UltRasound Field Imaging, abbreviated SURF Imaging. It relies on simultaneously transmitting two ultrasound pulses with a large separation in frequency. Here, a low-frequency pulse of 0.9 MHz is combined with a high-frequency pulse of 7.5 MHz. The low-frequency pulse is used to manipulate the properties of the contrast agent, and the high frequency pulse is used for high-resolution contrast detection and imaging. An annular array capable of transmitting the low- and high-frequency pulses simultaneously was constructed and fitted to a mechanically scanned probe used in a GE Vingmed System 5 ultrasound scanner. The scanner was modified and adapted for the dual-band transmit technique. In-house software was written for post-processing of recorded IQ-data. Contrast-processed B-mode images of pig kidneys after bolus injections of 1 mL of Sonovuer are presented. The images display contrast detection with contrast-to-tissue ratios ranging from 15-40 dB. The results demonstrate the potential of SURF Imaging as an ultrasound contrast detection technique for clinically high ultrasound frequencies. This may allow ultrasound contrast imaging to be available for a wide range of applications.

Real-time temporal maximum-intensity-projection imaging of hepatic lesions with contrast-enhanced sonography

OBJECTIVE

We sought to perform a preliminary evaluation of temporal maximum intensity projection (MIP) of focal hepatic masses in selected patients. The technique processes real-time contrast-enhanced sonography images by integrating the path of moving bubbles to depict vascular morphology. Following a high-intensity ultrasound pulse that disrupts bubbles within the scan plane, MIP images the trajectories of fresh bubbles replenishing the plane and revealing their course.

CONCLUSION

Vascular morphology is depicted at a level or detail not seen before with sonography. High-frame-rate sequences of less than one second uniquely show arterial structure in liver lesions.

Use of second generation contrast-enhanced ultrasound in the assessment of focal liver lesions

Ultrasound (US) is often the first imaging modality employed in patients with suspected focal liver lesions. The role of US in the characterisation of focal liver lesions has been transformed with the introduction of specific contrast media and the development of specialized imaging techniques. Ultrasound now can fully characterise the enhancement pattern of hepatic lesions, similar to that achieved with contrast enhanced multiphasic computed tomography (CT) and magnetic resonance imaging (MRI). US contrast agents are safe, well-tolerated and have very few contraindications. Furthermore, real-time evaluation of the vascularity of focal liver lesions has become possible with the use of the newer microbubble contrast agents. This article reviews the enhancement pattern of the most frequent liver lesions seen, using the second generation US contrast media. The common pitfalls for each type of lesion are discussed. The recent developments in US contrast media and specific imaging techniques have been a major advance and this technique, in view of the intrinsic advantages of US, will undoubtedly gain popularity in the years to come.

Use of second generation contrast-enhanced ultrasound in the assessment of focal liver lesions

Ultrasound (US) is often the first imaging modality employed in patients with suspected focal liver lesions. The role of US in the characterisation of focal liver lesions has been transformed with the introduction of specific contrast media and the development of specialized imaging techniques. Ultrasound now can fully characterise the enhancement pattern of hepatic lesions, similar to that achieved with contrast enhanced multiphasic computed tomography (CT) and magnetic resonance imaging (MRI). US contrast agents are safe, well-tolerated and have very few contraindications. Furthermore, real-time evaluation of the vascularity of focal liver lesions has become possible with the use of the newer microbubble contrast agents. This article reviews the enhancement pattern of the most frequent liver lesions seen, using the second generation US contrast media. The common pitfalls for each type of lesion are discussed. The recent developments in US contrast media and specific imaging techniques have been a major advance and this technique, in view of the intrinsic advantages of US, will undoubtedly gain popularity in the years to come.

Early hepatocellular carcinoma: pathology, imaging, and therapy

BACKGROUND

In 1987, Japanese researchers proposed to define the pathological concept of early hepatocellular carcinoma (HCC). However, there are some conceptual differences between the East and the West in the diagnosis and treatment of early HCC.

METHODS

To provide up-to-date data for making a worldwide consensus, this article has collected six papers focused on the management of early HCC, which were presented in the Fifth International Meeting of "Hepatocellular Carcinoma: Eastern and Western Experiences" in Houston in January 2007.

RESULTS

In the pathological perspective, the common criteria to discriminate early HCC from dysplastic nodule included hepatocytic invasion of portal triads and septa (stromal invasion). The current imaging modalities such as contrast-enhanced ultrasound (CEUS), computed tomography (CT), and magnetic resonance imaging (MRI) with the use of intravenous contrast material with multiphasic imaging could enhance their ability to accurately characterize early HCC. From the treatment perspective, a single early HCC had a high chance for cure by resection, ablation, or transplantation, which proved to be the earliest clinical entity (Stage 0 HCC).

CONCLUSIONS

Early HCC is characterized by its incipient malignant nature and by an extremely favorable clinical outcome, thereby justifying its definition.

Focal nodular hyperplasia and hepatic adenoma: differentiation with low-mechanical-index contrast-enhanced sonography

OBJECTIVE

The purpose of our study was to determine the differentiating features of focal nodular hyperplasia (FNH) and hepatic adenoma on contrast-enhanced sonography.

MATERIALS AND METHODS

Sixty-two patients who underwent contrast-enhanced sonography and were confirmed to have FNH (n = 43) or hepatic adenoma (n = 19) were assessed retrospectively for arterial phase enhancement, filling direction, stellate arteries, and portal phase enhancement. An algorithm was applied to these interpreted features to determine the contrast-enhanced sonography diagnosis.

RESULTS

All lesions were hypervascular in the arterial phase. Centrifugal filling was more common in FNH (39 and 32 of 43, 91% and 74% [reader 1 and reader 2]) than in adenoma (3 and 3 of 19, 16%). Centripetal or mixed filling was more common in adenoma (16 and 16 of 19, 84%) than in FNH (4 and 11 of 43, 9% and 26%) (p < 0.001, kappa = 0.61). Stellate arteries characterized FNH (29 and 26 of 43, 67% and 60%) but not adenoma (3 and 2 of 19, 16% and 11%) (p < 0.001, kappa = 0.36). Sustained portal phase enhancement was more common in FNH (37 and 39 of 43, 86% and 91%) than in adenoma (9 and 12 of 19, 47% and 63%) (p < 0.02, kappa = 0.79). The sensitivity, specificity, positive predictive value, and negative predictive value of sonography for diagnosing FNH were 95% and 86%, 74% and 79%, 89% and 90%, and 88% and 71%, (reader 1 and reader 2, respectively).

CONCLUSION

FNH is predicted on the basis of arterial phase centrifugal filling and stellate vascularity on contrast-enhanced sonography. Adenoma is less reliably predicted on the basis of centripetal or mixed filling without stellate vascularity. Sustained portal phase enhancement is more common in FNH than in adenoma but contributes less to the differentiation of these lesions.

[Diagnostic imaging of liver tumours. Current status]

Nowadays, contrast enhanced ultrasound (CEUS) is an imaging technique equivalent to multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection and characterization of focal liver lesions. These methods have comparable sensitivity and specificity in differentiating a liver lesion as "benign" or "malignant". For benign lesions, CEUS is the recommended method of the choice. In unclear cases, or if CEUS is not available, MRI or CT are the methods of the second choice. If a benign tumor remains unclear, then a needle biopsy is recommended. In the case of a malignant tumor, it is necessary to use a second imaging technique besides CEUS. In addition to the detection and characterization of a liver tumor, CT and MRI provide information on the extrahepatic spread of a tumor, particularly into the lung or retroperitoneum. The rapid development of surgical and interventional approaches requires accurate information on the character and number of malignant liver lesions. Therefore, the combined use of CEUS and MDCT or MRI currently represents the most modern and optimal standard of imaging. The standardization of CT and MRI protocols has increased the general diagnostic level of these images. Adequate training and a certificate for the use of CEUS is recommended in order to maintain the high diagnostic level of this method (EFSUMB guide lines). An optimal interdisciplinary imaging strategy for focal liver lesions minimises unnecessary invasive or potentially harmful imaging and reduces health costs.

Use of second generation contrast-enhanced ultrasound in the assessment of focal liver lesions

Ultrasound (US) is often the first imaging modality employed in patients with suspected focal liver lesions. The role of US in the characterisation of focal liver lesions has been transformed with the introduction of specific contrast media and the development of specialized imaging techniques. Ultrasound now can fully characterise the enhancement pattern of hepatic lesions, similar to that achieved with contrast enhanced multiphasic computed tomography (CT) and magnetic resonance imaging (MRI). US contrast agents are safe, well-tolerated and have very few contraindications. Furthermore, real-time evaluation of the vascularity of focal liver lesions has become possible with the use of the newer microbubble contrast agents. This article reviews the enhancement pattern of the most frequent liver lesions seen, using the second generation US contrast media. The common pitfalls for each type of lesion are discussed. The recent developments in US contrast media and specific imaging techniques have been a major advance and this technique, in view of the intrinsic advantages of US, will undoubtedly gain popularity in the years to come.

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.

[Incidentalomas of the liver and gallbladder. Evaluation and therapeutic procedure]

The expanding use of ultrasound in general practice is leading to an ever increasing rate of detection of true hepatic incidentaloma. The correct diagnosis of hepatic incidentaloma may be made in over 90% with non-invasive means. The questionable diagnosis of "symptomatic" incidentaloma should undergo close scrutiny prior to a decision in favour of surgery. With regard to more recent literature, the former "absolute" requirement for surgical resection in all cases of liver cell adenoma may have to be reappraised. Final inability to rule out malignancy represents an unquestionable indication for surgery in the light of low rates of morbidity and lack of mortality in this otherwise healthy patient group. Percutaneous biopsies should not be performed due to oncological hazards, indeterminate results and potential for acute complications.The stage-oriented radical re-resection following diagnosis of an incidentally detected gallbladder cancer may lead to significantly improved long-term survival, especially in the early tumour stages T1b and T2, which represents the most common stage of gallbladder cancer in incidentaloma. Patients at elevated risk for incidental gallbladder cancer should undergo thorough instruction with regard to the potential hazards of laparoscopic cholecystectomy. Multimodal therapeutic strategies directed at advanced stages of incidentally detected gallbladder cancer should be evaluated in prospective multicentre studies.

Enhancement patterns and signal-intensity characteristics of small hepatocellular carcinoma in cirrhosis: pathologic basis and diagnostic challenges

Recent pathologic studies of hepatic resection and transplantation specimens have elucidated the morphologic features of the precancerous lesions and small hepatocellular carcinomas (HCCs) arising in cirrhotic livers. Small HCCs measuring less than 2 cm in diameter are of two types: vaguely nodular, well-differentiated tumors, also known as "early" HCCs, and distinctly nodular tumors, with histologic features of "classic" HCC. The precancerous lesions include dysplastic foci and dysplastic nodules. "Classic" small HCCs are supplied by nontriadal arteries, whereas early HCCs and dysplastic nodules may receive blood supply from both portal tracts and nontriadal arteries. The similarities in blood supply of these three types of nodular lesions result in significant overlap of findings on dynamic imaging. Nevertheless, small HCCs sometimes display characteristic radiologic features, such as "nodule-in-nodule" configuration and "corona enhancement" pattern. Moreover, various histologic features of these nodular lesions may also be related to a variety of signal intensities and attenuation coefficients, while the presence of cirrhosis is known to limit the sensitivity and specificity of any imaging modality, due to liver inhomogeneity. Because of these reasons, imaging findings of nodular lesions in cirrhotic livers are often inconclusive, emphasizing the need for a better understanding of these imaging features.

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.

Enhancement patterns of hepatocellular carcinoma at contrast-enhanced US: comparison with histologic differentiation

PURPOSE

To retrospectively compare the arterial and portal venous phase enhancement patterns of hepatocellular carcinoma (HCC) at contrast material-enhanced ultrasonography (US) with the degree of HCC histologic differentiation.

MATERIALS AND METHODS

This study was approved by the research ethics board, and informed consent was obtained. The study population included 112 consecutive patients (91 men, 21 women; aged 25-86 years) with 112 histologically proved HCCs: 23 well differentiated, 77 moderately differentiated, and 12 poorly differentiated. All underwent continuous real-time low-mechanical-index contrast-enhanced US from wash-in of contrast material to 300 seconds by using a blood-pool microbubble agent. Initial image interpretation included arterial enhancement, dysmorphic intratumor arteries, and presence and time of negative enhancement (washout). Enhancement patterns were compared with histologic differentiation by using the Fisher exact test.

RESULTS

In the arterial phase, 97 of 112 (87%) HCCs showed hypervascularity, with a significantly higher proportion in moderately differentiated HCCs (74 of 77, 96%) when compared with well- (14 of 23, 61%; P<.001) and poorly differentiated HCC (nine of 12, 75%; P<.004). Eight of 112 (7%) were isovascular and seven (6%) were hypovascular. Dysmorphic arteries were seen in 81 (72%) HCCs. Of 97 hypervascular tumors, only 42 (43%) showed typical washout by 90 seconds. Late washout appeared in 25 (26%) HCCs in the 91-180 seconds phase and in 21 (22%) in the 181-300 seconds phase. The remaining nine showed no washout up to 300 seconds and seven (78%) were well-differentiated HCCs.

CONCLUSION

Moderately differentiated HCC generally shows classic enhancement features, while well- and poorly differentiated tumors account for most atypical variations. Extended observation in the portal phase is important as late washout occurs with slightly more frequency than washout in the conventionally defined portal venous phase.

Focal liver lesions: role of contrast-enhanced ultrasound

The introduction of microbubble contrast agents and the development of contrast-specific techniques have opened new possibilities in liver imaging. Initially, only intermittent imaging with Doppler detection was available. Second-generation contrast agents and low mechanical index real-time scanning techniques are decisive advances that enable convenient liver examinations with high sensitivity and specificity. Hepatic lesions usually show typical perfusion and enhancement patterns through the various contrast phases, which help their characterization. Several published studies and the daily clinical routine show that, as opposed to conventional ultrasound (US), contrast-enhanced US can substantially improve detection and differentiation of focal liver lesions. Today, contrast-enhanced US is the dynamic imaging modality of choice for differentiation of focal liver lesions. Contrast uptake patterns of the most relevant liver lesions, as well as important clinical indications are presented and discussed.

Focal nodular hyperplasia: Spoke-wheel arterial pattern and other signs on dynamic contrast-enhanced ultrasonography

OBJECTIVE

To evaluate the prevalence of spoke-wheel pattern and typical symptoms of focal nodular hyperplasia (FNH) by means of dynamic contrast-enhanced ultrasonography (CEUS) in relation to lesion size.

METHODS

Twenty-eight patients were included in the trial, in whom, based on the CEUS, we raised suspicion of hypervascularized liver lesion; there were 30 lesions altogether. The final diagnosis of FNH was verified by means of CT, MRI or lesion biopsy. Majority of patients (26) were females, compared to 2 male, with average age of 33.3 years. Average lesion size was 45.6 mm. Besides the ultrasound examination, we used also "blood pool" ultrasound contrast agent of second generation, sulphur hexafluoride (BR1); we evaluated enhancement of the lesion until the late stage-within 5 min from application.

RESULTS

In lesions larger than 3 cm (n=20), stellate vascular enhancement was found in 19 cases (95.0%) early in arterial phase. As for lesions smaller than 3 cm (n=10), spoke-wheel pattern was observed only in 3 cases (30%) and lesions smaller than 2 cm practically did not show this phenomenon at all (n=1; 17%). Generally, symptom of spoke-wheel pattern was observed in 22 cases, i.e. in 73.3%. In total, central scar was present in 63.3% (n=19) of cases. In lesions larger than 3 cm, it was present in 85.0% (n=17), in lesions smaller than 3 cm in 20% (n=2).

CONCLUSION

Contrast-enhanced ultrasonography can be the final diagnostic method for FNH larger than 3 cm which has typical spoke-wheel vessel structure on CEUS. If this phenomenon is not present and the central scar is not visible, specific diagnosis of FNH cannot be based solely on CEUS findings.

Enhancement patterns of focal liver masses: discordance between contrast-enhanced sonography and contrast-enhanced CT and MRI

OBJECTIVE

The purpose of this study was to investigate the origin of the infrequent discordance between the contrast enhancement patterns of liver lesions on sonography and those on CT and MRI. Forty-four discordant cases were reviewed retrospectively.

CONCLUSION

Four categories of discordance were identified, one of which is unexplained. Contrast agent diffusion caused portal venous phase discordance in malignant tumors (n = 6) whereby CT and MRI contrast material diffused through the vascular endothelium into the tumor interstitium, concealing washout. Sonographic microbubbles were purely intravascular and showed washout. Arterial phase timing discordance occurred in metastatic lesions (n = 10) with hypervascularity and rapid washout on contrast-enhanced sonography. CT arterial imaging performed later showed hypovascularity. Rapidly enhancing hemangiomas (n = 7) exhibited hypervascularity on CT when contrast-enhanced sonography also showed peripheral nodules and fast centripetal progression. Discordance caused by fat in lesions (n = 4) or liver (n = 10) reflected the inherent echogenicity of fat on sonography compared with its low attenuation on CT and low signal intensity on MRI. Infrequent cases of discordance remain unexplained. Recognition of the cause of the infrequent disagreement in enhancement patterns on contrast-enhanced sonography with those on CT and MRI improves diagnostic interpretation.

Terminology for contrast-enhanced sonography: a practical glossary

OBJECTIVE

The purpose of this glossary is to offer an updated guide to the correct terminology for contrast-enhanced sonography.

METHODS

This report was prepared by a panel of radiologists from the Sonography Section of the Italian Association of Medical Radiology. A leading author prepared a list of terms based on a comprehensive literature survey. The draft was analyzed by 3 experts on the topic of contrast-enhanced sonography. These reviewers reached a consensus and prepared the final version.

RESULTS

A list of 137 terms is included. These terms are briefly defined. Their proper application is discussed, with special reference to potential misleading uses.

CONCLUSIONS

Contrast-enhanced sonography is a relatively new diagnostic tool, now entering clinical practice in several countries. Use of appropriate, universal terminology is mandatory in the scientific setting to allow comparison between different published experiences. Additionally, use of clear, standardized terminology is necessary in the clinical setting to facilitate report understanding by the referring physician. Standardized, nonequivocal nomenclature may also help future diffusion of sonographic contrast media in countries where their application is still not approved.

Diagnosis of focal liver masses on ultrasonography: comparison of unenhanced and contrast-enhanced scans

OBJECTIVE

The purpose of this study was to compare the diagnostic accuracy, confidence level, and recommended management of focal liver masses after contrast-enhanced ultrasonography (CEUS) compared with unenhanced ultrasonography alone.

METHODS

One hundred sixty-seven patients were referred for CEUS to characterize a focal liver mass. A 2-person blind read determined benignancy or malignancy, comparative diagnosis, and accuracy on both ultrasonography and CEUS. Results were compared with the final diagnoses.

RESULTS

The 2 readers could not determine benignancy or malignancy in 77 (46.1%) and 46 (27.5%) of 167 unenhanced scans compared with 2 (1.2%) and 1 (0.6%) of 167 CEUS scans. The confidence level increased from 0 responses in the 2 highest grades (4 and 5) on the unenhanced scans to 135 (81.8%) and 132 (79.5%) of 167 at level 5 for CEUS. Regarding the diagnosis, the confidence level was lowest (grade 1) on the unenhanced scans in 128 (82.1%) and 79 (65.3%) of 167 for the 2 readers and improved to the highest (grade 5) in 110 (65.9%) and 113 (68.1%) of 167. Regarding diagnostic accuracy, the unenhanced scans agreed with the correct diagnosis in 85 (50.9%) and 63 (37.7%) of 167, and CEUS agreed with the correct diagnosis in 133 (79.6%) and 142 (85%) of 167 for readers 1 and 2, respectively. Recommendations for further imaging decreased from 166 (99.4%) and 147 (88%) of 167 on the unenhanced scans to 30 (18%) and 5 (3%) of 167 on CEUS for readers 1 and 2.

CONCLUSIONS

Contrast-enhanced ultrasonography improves the accuracy and confidence of diagnosis of focal liver lesions and reduces recommendations for further investigations.

Rupture of liver metastasis: report of a case with an emphasis on contrast-enhanced US

We present a case of liver metastasis from an uterine leiomyosarcoma in which contrast-enhanced ultrasonography (CEUS) helped determine the bleeding point and prevented a delay in devising diagnostic and therapeutic strategies. CEUS allowed us to differentiate active from nonactive bleeding on the basis of presence or absence of contrast extravasation in the ascites. CEUS is the first examination performed when liver tumor rupture is suspected. Reference to the preangiographic CEUS results is expected to provide a road map for angiography.

Differential diagnosis of gallbladder diseases with contrast-enhanced harmonic gray scale ultrasonography

OBJECTIVES

We evaluated the usefulness of contrast-enhanced harmonic gray scale ultrasonographic findings for differential diagnosis of gallbladder diseases.

METHODS

We evaluated contrast-enhanced harmonic gray scale ultrasonographic images from 33 patients with 35 polypoid gallbladder disease lesions larger than 10 mm in diameter, consisting of 12 biliary sludge lesions, 8 cholesterol polyps, 1 inflammatory polyp, 2 adenomas, and 12 carcinomas. After a galactosepalmitic acid contrast agent was injected, lesions were scanned by contrast-enhanced harmonic gray scale ultrasonography in 2 phases: early vascular and late vascular.

RESULTS

None of the biliary sludge lesions (n = 12) showed either tumor vessels or tumor enhancement. Lesions showing tumor vessels and tumor enhancement on contrast-enhanced harmonic gray scale ultrasonography were diagnosed as cholesterol polyp, inflammatory polyp, adenoma, or carcinoma. Three (38%) of the 8 cholesterol polyps showed dotted-type tumor vessels. Branched-type tumor vessels were observed in 5 (62%) of the 8 cholesterol polyps, the 1 (100%) inflammatory polyp, both (100%) adenomas, and 3 (25%) of the 12 carcinomas. Tortuous-type tumor vessels were observed in 9 (75%) of the 12 carcinomas. Lesions with tumor enhancement and tortuous-type tumor vessels on contrast-enhanced harmonic gray scale ultrasonography were diagnosed as carcinomas, and the sensitivity, specificity, and accuracy of this diagnosis with the current modality were 75% (9/12), 100% (23/23), and 91% (32/35), respectively.

CONCLUSIONS

Evaluation of tumor vessels on contrast-enhanced harmonic gray scale ultrasonography may be a useful modality for differentiating gallbladder carcinoma from other polypoid gallbladder disease lesions.

Microbubble ultrasound contrast agents: an update

Microbubble contrast agents for ultrasound (US) have gained increasing interest in recent years, and contrast-enhanced US (CEUS) is a rapidly evolving field with applications now extending far beyond the initial improvements achieved in Doppler US. This has been achieved as a result of the safe profile and the increased stability of microbubbles persisting in the bloodstream for several minutes, and also by the availability of specialized contrast-specific US techniques, which allow a definite improvement in the contrast resolution and suppression of signal from stationary tissues. CEUS with low transmit power allows real-time scanning with the possibility of prolonged organ insonation. Several reports have described the effectiveness of microbubble contrast agents in many clinical applications and particularly in the liver, spleen, and kidneys. CEUS allows the assessment of the macrovasculature and microvasculature in different parenchymas, the identification and characterization of hepatic and splenic lesions, the depiction of septal enhancement in cystic renal masses, and the quantification of organ perfusion by the quantitative analysis of the echo-signal intensity. Other fields of application include the assessment of abdominal organs after traumas and the assessment of vesico-ureteral reflux in children. Finally, tumor-targeted microbubbles make possible the depiction of specific biologic processes.

Transient hepatic echogenicity difference on contrast-enhanced ultrasonography: sonographic sign and pitfall

OBJECTIVE

The purpose of this study was to report and analyze a new contrast-enhanced ultrasonographic (CEUS) imaging finding, the transient hepatic echogenicity difference due to perfusion changes, using computed tomography (CT) as a reference standard.

METHODS

We retrospectively investigated the records of patients evaluated in a 2-year period, selecting those who had undergone both CT and CEUS within 15 days, who had CT evidence of a perfusion abnormality, and who had had a CEUS study that included the malperfused parenchymal area.

RESULTS

There were 30 patients with 44 hepatic perfusion changes on CT scans (28 around liver focal lesions and 16 unrelated to focal lesions). Retrospectively, CEUS allowed recognition of 21 of 28 perifocal transient hepatic attenuation differences (THADs), 6 of 10 subsegmental THADs, 2 of 3 segmental THADs, and 1 of 3 lobar THADs. Only some of these abnormalities had been identified at the original CEUS examinations: 0 of 3 lobar THADs, 1 of 3 segmental THADs, 2 of 10 subsegmental THADs, and 16 of 28 perifocal THADs.

CONCLUSIONS

Contrast-enhanced ultrasonography can show hepatic perfusion abnormalities similar to those well known from CT literature, although with a lower sensitivity. Knowledge of this transient hepatic echogenicity difference phenomenon may be relevant for avoiding incorrect image interpretation or incorrect tumor size measurement and for eventually identifying occult vascular disorders such as venous thrombosis or fistulas.

Focal liver masses: enhancement patterns on contrast-enhanced images--concordance of US scans with CT scans and MR images

PURPOSE

To assess prospectively the concordance of enhancement patterns of focal liver masses on contrast material-enhanced ultrasonographic (US) scans with patterns on contrast-enhanced computed tomographic (CT) scans or magnetic resonance (MR) images.

MATERIALS AND METHODS

This study was approved by the institutional review board; patients gave informed consent. Contrast-enhanced US and contrast-enhanced CT or MR imaging were performed in 135 patients (62 men, 73 women; mean age, 51 years) with 144 confirmed liver masses. Masses included 49 hepatocellular carcinomas, 13 metastases, 30 hemangiomas, 41 lesions of focal nodular hyperplasia, and 11 others. Randomized image sets from each modality were shown independently to three blinded readers, who answered identical questions about enhancement of the lesion and liver in the arterial and portal venous phases and changes with time. Concordance for modalities was calculated from answers of readers and consensus answers between readers, with 95% confidence intervals (CIs). The kappa values were calculated for interreader agreement.

RESULTS

Features of arterial phase enhancement showed concordance of more than 76% for modalities. The highest concordance of 92% (132 of 144), with 95% CI of 86% and 95% (kappa>0.84), was for the presence of peripheral pools and centripetal progression. Concordance in the portal venous phase was lower, with agreement for predominant enhancement of the lesion in 61% (86 of 142), with 95% CI of 52% and 68% (kappa>0.83). Portal venous phase washout occurred in 75% (106 of 142), with 95% CI of 67% and 81% (kappa>0.81). The majority of discordances were for malignancies for which only US depicted no sustained enhancement in the portal venous phase.

CONCLUSION

US shows high concordance with CT or MR imaging, especially for the arterial phase. Discordance in the portal venous phase may reflect the tendency of CT and MR contrast agents, unlike microbubbles, to diffuse into interstitium.

Prospective study of differential diagnosis of hepatic tumors by pattern-based classification of contrast-enhanced sonography

AIM: To prospectively evaluate the usefulness of a pattern-based classification of contrast-enhanced sonographic findings for differential diagnosis of hepatic tumors.

METHODS: We evaluated the enhancement pattern of the contrast-enhanced sonography images in 586 patients with 586 hepatic lesions, consisting of 383 hepatocellular carcinomas, 89 metastases, and 114 hemangiomas. After injecting a galactose-palmitic acid contrast agent, lesions were scanned by contrast-enhanced harmonic gray-scale sonography in three phases: arterial, portal, and late. The enhancement patterns of the initial 303 lesions were classified retrospectively, and multiple logistic regression analysis was used to identify enhancement patterns that allowed differentiation between hepatic tumors. We then used the pattern-based classification of enhancement we had retrospectively devised to prospectively diagnose 283 liver tumors.

RESULTS: Seven enhancement patterns were found to be significant predictors of different hepatic tumors. The presence of homogeneous or heterogeneous enhancement both in the arterial and portal phase was the typical enhancement pattern for hepatocellular carcinoma, while the presence of peritumoral vessels in the arterial phase and ring enhancement or a perfusion defect in the portal phase was the typical enhancement pattern for metastases, and the presence of peripheral nodular enhancement both in the arterial and portal phase was the typical enhancement pattern for hemangioma. The sensitivity, specificity, and accuracy of prospective diagnosis based on the combinations of enhancement patterns, respectively, were 93.2%, 96.2%, and 94.0% for hepatocellular carcinoma, 87.9%, 99.6%, and 98.2% for metastasis, and 95.6%, 94.1%, and 94.3% for hemangioma.

CONCLUSION: The pattern-based classification of the contrast-enhanced sonographic findings is useful for differentiating among hepatic tumors.