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

Role of contrast-enhanced sonography in differentiation of subtypes of hepatocellular adenoma: correlation with MRI findings

OBJECTIVE

Hepatocellular adenomas (HCAs) are divided into three subtypes according to genotype and phenotype. The two main subgroups are hepatocyte nuclear factor 1α (HNF1α)-inactivated HCA and inflammatory HCA. Specific imaging features of these subgroups of adenoma have been delineated with MRI. The aim of this study was to document the contrast-enhanced sonographic (CEUS) features specific for adenoma subtypes and to correlate them with MRI findings.

MATERIALS AND METHODS

We retrospectively analyzed data on 38 patients with HCA confirmed at pathologic examination in all cases. All cases were classified with MRI.

RESULTS

HNF1α-inactivated HCA (n = 16) was found to have a homogeneous hyperechoic aspect at baseline gray-scale sonography, isovascularity or moderate hypervascularity with mixed filling in the arterial phase, and isoechogenicity in the portal and late portal venous phases. Homogeneous hyperechogenicity during B-mode sonography was the most specific pattern (sensitivity, 88%; specificity, 91%) and correlated with diffuse fat repartition observed on MR images obtained with chemical-shift sequences. In inflammatory HCA (n = 17) the association of arterial hypervascularity with centripetal filling, linear vascularities, peripheral rim of sustained enhancement, and central washout in the late venous phase was specific (sensitivity, 64%; specificity, 100%). Discrepancy between delayed washout during CEUS and sustained enhancement during MRI could be related to differences between gadolinium and microbubbles in diffusing in the interstitial spaces. In the five other HCA cases (four unclassified, one β-catenin activated) CEUS showed characteristics of benign hepatocellular tumors with no specific features.

CONCLUSION

HNF1α-inactivated HCA and inflammatory HCA had characteristic CEUS patterns. Delayed washout, an unusual finding in benign hepatic lesions, is of particular interest and was a characteristic of inflammatory HCA subtype.

Optical studies of vaporization and stability of fluorescently labelled perfluorocarbon droplets

Droplets of liquid perfluorocarbon (PFC) are under study as the next generation of contrast agents for ultrasound (US). These droplets can be selectively vaporized into echogenic gas bubbles in situ by externally applied US, with numerous applications to diagnosis and therapy. However, little is known about the mechanisms of droplet vaporization and the stability of the bubbles so produced. Here we observe optically the vaporization of fluorescent PFC droplets and the stability of the newly created bubbles. Fluorescent markers were used to label selectively either the liquid PFC core or the shell of the droplets. It was found that, following vaporization, the fluorescent marker is quickly expelled from the core of the newly created bubble and is retained on the gas-liquid interface. At the same time, it was shown that bubbles retain the original shells encapsulating their droplet precursors. The efficiency of encapsulation was found to depend strongly on the nature of the stabilizing material itself. These results provide direct evidence of droplet encapsulation post-vaporization, and suggest that the behaviour of the vaporized droplets is strongly dependent on the choice of the stabilizing material for the emulsion.

Comparison of allergic adverse effects and contrast enhancement between iodixanol and iopromide

Background

Iodinated X-ray contrast media are the most commonly used contrast agents in the world with an annual application of 40-50 million. New non-ionic contrast agents are subdivided into low osmolar agents such as iopromide and iso-osmolar agents such as iodixanol. Regarding different biochemical characteristics, these agents are different in the allergic reactions and contrast enhancement and final lesion conspicuity.

Objectives

This study was carried out to compare allergic adverse effects and contrast enhancement between iodixanol and iopromide.

Patients and Methods

One-hundred and twenty patients who were referred for abdominal CT scan to Besat Hospital were included in this study. Patients were randomly divided into two groups (A and B). Group A received 100 cc iodixanol (300 mgI/mL) and group B received 100 cc iopromide (300 mgI/ml) by power injector. CT examination was performed using Helical CT Scanner (Somatom, Siemens, Germany). Sixty seconds after injection, images were obtained and enhancement of port, liver and aorta were determined. Allergic adverse effects were recorded one hour and up to one week after injection.

Results

Iodixanol produced a significantly greater enhancement of the hepatic, aorta and portal vein than iopromide (P < 0.01). Sixty seconds after injection, associated pain and heat sensation were less frequent in iodixanol in comparison with iopromide (P = 0.03). Immediate reactions such as nausea and vomiting were less frequent in iodixanol (P = 0.01). Late skin reactions such as rash was more frequent in iodixanol (P < 0.01).

Conclusions

Iodixanol is safe and is better tolerated in the early phase of injection with better contrast enhancement and lesion conspicuity. Mild late skin rash is its disadvantage.

Contrast-enhanced ultrasound in abdominal imaging

The administration of a contrast agent is considered an essential tool to evaluate abdominal diseases using Ultrasound. The most targeted organ is the liver, especially to characterize focal liver lesions and to assess the response to percutaneous treatment. However, the expanding abdominal indications of contrast-enhanced ultrasound make this technique an important tool in the assessment of organ perfusion including the evaluation of ischemic, traumatic, and inflammatory diseases.

[Detection and characterization of liver metastases]

Since the advent of second generation ultrasound (US) contrast agents, ultrasound has caught up with other imaging modalities for the detection and characterization of liver metastases and as a result of its high temporal and spatial resolution it can in some cases even be superior to computed tomography (CT) and magnetic resonance imaging (MRI). Many studies have demonstrated a sensitivity and specificity of over 90%. Due to its high temporal resolution contrast-enhanced US (CEUS) is capable of detecting even a very short duration of hyper-enhancement during the arterial phase. Radiation protection and lack of adverse effects on renal or thyroid function are additional arguments why CEUS should be recommended as the first imaging modality in the evaluation of hepatic metastases in cases of favorable scanning conditions.

Value of contrast-enhanced sonography in the diagnosis of peripheral intrahepatic cholangiocarcinoma

BACKGROUND

To illustrate contrast-enhanced harmonic ultrasonography (CEUS) findings of peripheral intrahepatic cholangiocarcinoma (PICC) and to assess the usefulness of CEUS in the diagnosis of this disease.

METHODS

This study is a retrospective analysis of 46 patients (20 men, 26 women) with PICC who underwent both preoperative CEUS and pathologic examination. Sonographic examinations were performed with sonographic instruments equipped with low mechanical index contrast imaging software. The contrast agent SonoVue was used. The wash-in and wash-out features of the lesions were documented and the enhancement patterns were analyzed by visual inspection of the real-time cine loops.

RESULTS

During the hepatic arterial phase of CEUS, the majority of PICC lesions (43/46, 93.5%) showed hypervascularity compared with the liver parenchyma, whereas three lesions (3/46, 6.5%) showed hypovascularity. In the portal phases, all lesions were either isoechoic or hypoechoic, while they were all hypoechoic in the late phase. Of all the hypervascular lesions, 48.8% (21/43) showed diffuse enhancement and 51.2% (22/43) showed rim-like or thick, rim-like enhancement. In 62.8% (27/43) of cases, progressive dendritic and centripetal fill-in of the contrast agent was observed. There were 83.7% (36/43) of hypervascular nodules showing heterogeneous enhancement during peak contrast enhancement of the lesions. CEUS provided clearer visualization of lesion margins than did conventional sonography.

CONCLUSIONS

CEUS examination yields some specific findings that are useful in the diagnosis of PICC.

Investigation of vaporized submicron perfluorocarbon droplets as an ultrasound contrast agent

Acoustically activated submicron droplets of liquid perfluorocarbon are investigated as a new class of ultrasound contrast agent. In the liquid state, intravascular droplets can extravasate within tumours. Activation is then accomplished by using bursts of ultrasound to vaporize the droplets. We use acoustical and optical techniques to assess the characteristics of vaporized droplets and the resulting microbubbles in vitro, including size, conversion threshold, echogenicity and nonlinearity. Under exposure to single 5-50 cycle bursts of ultrasound at 7.5 MHz and mechanical index <1.0, droplets with mean diameter of 400 nm convert into microbubbles with mean diameter of 1.4 μm at 1 ms after vaporization, expanding to 5.6 μm by 1 s. The growth of microbubbles produced by vaporization causes a characteristic time-dependent increase in linear and nonlinear echogenicity, enabling selective detection with conventional bubble-specific imaging. These results suggest that submicron perfluorocarbon droplets, activated in situ, may be a candidate for an extravascular ultrasound contrast agent.

Differentiation of focal liver lesions: usefulness of parametric imaging with contrast-enhanced US

PURPOSE

To evaluate whether parametric imaging with contrast material-enhanced ultrasonography (US) is superior to visual assessment for the differential diagnosis of focal liver lesions (FLLs).

MATERIALS AND METHODS

This study had institutional review board approval, and verbal patient informed consent was obtained. Between August 2005 and October 2008, 146 FLLs in 145 patients (63 women, 82 men; mean age, 62.5 years; age range, 22-89 years) were imaged with real-time low-mechanical-index contrast-enhanced US after a bolus injection of 2.4 mL of a second-generation contrast agent. Clips showing contrast agent uptake kinetics (including arterial, portal, and late phases) were recorded and subsequently analyzed off-line with dedicated image processing software. Analysis of the dynamic vascular patterns (DVPs) of lesions with respect to adjacent parenchyma allowed mapping DVP signatures on a single parametric image. Cine loops of contrast-enhanced US and results from parametric imaging of DVP were assessed separately by three independent off-site readers who classified each lesion as benign, malignant, or indeterminate. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated for both techniques. Interobserver agreement (κ statistics) was determined.

RESULTS

Sensitivities for visual interpretation of cine loops for the three readers were 85.0%, 77.9%, and 87.6%, which improved significantly to 96.5%, 97.3%, and 96.5% for parametric imaging, respectively (P < .05, McNemar test), while retaining high specificity (90.9% for all three readers). Accuracy scores of parametric imaging were higher than those of conventional contrast-enhanced US for all three readers (P < .001, McNemar test). Interobserver agreement increased with DVP parametric imaging compared with conventional contrast-enhanced US (change of κ from 0.54 to 0.99).

CONCLUSION

Parametric imaging of DVP improves diagnostic performance of contrast-enhanced US in the differentiation between malignant and benign FLLs; it also provides excellent interobserver agreement.

Indeterminate focal liver lesions incidentally discovered at gray-scale US: role of contrast-enhanced sonography

OBJECTIVES

to assess the role of contrast-enhanced ultrasound (CEUS) in the characterization of focal liver lesions (FLLs) incidentally discovered but indeterminate at gray-scale ultrasound (US).

MATERIALS AND METHODS

one hundred forty-two consecutive patients with 174 FLLs (169 benign and 5 malignant) incidentally discovered but indeterminate at gray-scale US, underwent CEUS after the administration of SonoVue. Two readers independently reviewed CEUS scans and: (1) classified each lesion as malignant or benign on a 5-point scale of confidence by means of definite diagnostic criteria; (2) provided if possible a specific diagnosis; (3) were requested if further imaging was needed for lesion characterization. Sensitivity, specificity, and areas under the receiver-operating characteristic curve (Az) as well as interobserver agreement were calculated.

RESULTS

at CEUS, both readers correctly differentiated benign from malignant lesions in 168 of 174 (96.5%) cases (P < 0.0001). A specific correct diagnosis was provided in 123 of 174 (70.7%) and 127 of 174 (72.9%) cases for reader 1 and 2, respectively (P < 0.0001). A further imaging study to characterize the lesion after CEUS was requested in 67 cases (38.5%) for reader 1 (P < 0.001) and 46 cases (26.4%) for reader 2 (P < 0.001). Receiver-operating characteristic analysis after CEUS revealed Az value of 1 for both readers and sensitivity and specificity values of 100% and 97.04% for reader 1 and 100% and 96.45 for reader 2 respectively (P < 0.0001). Inter-reader agreement at CEUS was good (weighted k = 0.779).

CONCLUSION

CEUS improves the diagnostic performance of radiologists in the characterization of indeterminate FLLs incidentally discovered at US and reduces the need for further radiologic work-up.

Microbubble-enhanced US in body imaging: what role?

Contrast agents for ultrasonography (US) comprise microscopic bubbles of gas in an encapsulating shell. They are unique in that they interact with the imaging process, oscillating in response to a low-intensity ultrasound field and disrupting in response to a high-intensity field. New contrast-specific imaging modes allow US to show exquisite vascularity and tissue perfusion in real time and with excellent spatial resolution. In Europe, Asia, and Canada, to name only the most obvious, characterization of focal liver masses is the first and best established use of contrast-enhanced (CE) US, allowing for the noninvasive diagnosis of commonly encountered liver masses with comparable accuracy to that of computed tomography and magnetic resonance studies. CE US is a preferred modality for the difficult task of diagnosis of liver nodules detected on surveillance scans in those at risk for hepatocellular carcinoma. Newer body applications include the guidance of ablative intervention, monitoring activity of bowel inflammation in Crohn disease, characterization of kidney masses, especially cystic renal cell carcinoma, diagnosis of prostate cancer, and monitoring the response of tumors to antivascular drug therapies. Microbubble contrast agents are easy to use and robust; their use poses no risk of nephrotoxicity and requires no ionizing radiation. CE US plays a vital and expanding role that improves management and patient care.

Comparing enhancement and washout patterns of hepatic lesions between sonazoid-enhanced ultrasound and contrast-enhanced computed tomography

PURPOSE

To compare sonazoid-enhanced ultrasound (SEUS) and contrast-enhanced computed tomography (CECT) enhancement and washout patterns in hepatic lesions.

METHODS

Enhancement and washout patterns on SEUS were compared with those on CECT for 61 lesions. There were 36 hepatocellular carcinomas, three intrahepatic cholangiocarcinomas, three metastatic lesions, eight focal nodular hyperplasias, two angiomyolipomas, and nine undetermined benign lesions. Diagnosis was based on histopathology, or CECT and tumor markers, or findings on 2-year follow-up.

RESULTS

All 61 lesions (100%) showed arterial enhancement on both SEUS and CECT. The "washout/no washout" agreement between SEUS and CECT for the 61 lesions was 93.4% (κ coefficient: 0.816). Of the 42 malignant lesions, 38 lesions (90.5%) showed washout on both SEUS and CECT. The remaining four malignant lesions, of which three lesions contained fibrosis (two intrahepatic cholangiocarcinomas and one scirrhous hepatocellular carcinoma), showed washout on SEUS but not on CECT. For the 19 benign lesions, agreement between SEUS and CECT was 100% (κ coefficient: 1), with seven lesions showing washout with both methods and 12 lesions showing no washout with both methods.

CONCLUSION

The overall concordance rate between SEUS and CECT was good, but some differences were seen in the washout patterns of malignant lesions.

Intrahepatic peripheral cholangiocarcinoma in cirrhosis patients may display a vascular pattern similar to hepatocellular carcinoma on contrast-enhanced ultrasound

The aim of this study was to describe the imaging features by contrast-enhanced ultrasound (CEUS) of intrahepatic cholangiocarcinoma (ICC) in cirrhosis patients. We registered the CEUS images of cirrhosis patients with histologically confirmed ICC. In all cases magnetic resonance imaging (MRI) was done to confirm the diagnosis and/or staging purposes. A total of 21 patients met all the criteria to be included in the study. The median nodule size was 32 mm. All nodules showed contrast enhancement at arterial phase; in 10 cases it was homogeneous and in 11 cases peripheral (rim-like). All nodules displayed washout during the venous phases; it appeared during the first 60 seconds in 10 nodules, between 60-120 seconds in five cases, and in six cases after 2 minutes. Ten nodules (five larger than 2 cm) displayed homogeneous contrast uptake followed by washout and they correspond to the specific pattern of hepatocellular carcinoma according to the American Association for the Study of Liver Diseases criteria. However, none of these lesions displayed washout on MRI.

CONCLUSION

CEUS should not be used as the sole imaging technique for conclusive hepatocellular carcinoma diagnosis and if the MRI does not display the diagnostic vascular pattern, a confirmatory biopsy is mandatory.

Characterisation of focal liver lesions undetermined at grey-scale US: contrast-enhanced US versus 64-row MDCT and MRI with liver-specific contrast agent

PURPOSE

The aim of this study was to assess the role of contrast-enhanced ultrasonography (CEUS) in the characterisation of focal liver lesions in comparison with multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) with liver-specific contrast agent.

MATERIALS AND METHODS

One hundred and eighty-seven focal liver lesions, 91 malignant and 96 benign (mean size 3.2 cm) - proved by biopsy (n=12), histology (n=4), MDCT (n=108), MRI (n=44) MDCT/MRI (n=19) - in 159 patients were studied by CEUS. Two expert radiologists consensually evaluated the contrast-enhancement patterns at CEUS. For each lesion, they assessed: (a) nature (benign, malignant, not assessable), (b) specific diagnosis and (c) need for further radiological evaluation. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of CEUS were calculated.

RESULTS

A total of 167/187 (89.3%) lesions were correctly assessed as benign or malignant at CEUS, whereas 14/187 (7.5%) lesions remained undetermined and 6/187 (3.2%) were incorrectly assessed. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of CEUS were, respectively, 89%, 89.6%, 89%, 89.6% and 89.3%. The need for further radiological evaluation decreased to 46/187 (24.6%) lesions after CEUS (p<0.001).

CONCLUSIONS

In selected cases, CEUS can be considered an effective alternative to MDCT and MRI and reduce the need for further radiological workup.

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.

[Contrast-enhanced ultrasound and liver imaging: review of the literature]

The advent of second-generation microbubble ultrasound contrast agents and the development of contrast specific ultrasound techniques improved the ability of contrast enhanced ultrasound (CEUS) in detecting and characterizing focal liver lesions, opening new prospects in liver imaging. A Medline search in June 2008 identified 72 published studies that used CEUS in focal liver lesion detection, characterization, and follow-up to monitor tumor ablation procedures and antiangiogenic treatment. The purpose of this paper, based on literature review, is to describe the technical recommendations when using CEUS for liver imaging and to define the different vascular patterns of the most relevant benign and malignant lesions. Diagnostic performance of CEUS and the important clinical indications are also presented and discussed. CEUS is increasingly accepted in clinical use for diagnostic imaging and post-interventional workup liver imaging. It may replace many computed tomography and magnetic resonance imaging examinations in the near future, according to the European Federation of Societies for Ultrasound in Medicine and Biology guidelines.

Focal liver tumors: characterization with 3D perflubutane microbubble contrast agent-enhanced US versus 3D contrast-enhanced multidetector CT

PURPOSE

To investigate the potential application of contrast material-enhanced three-dimensional (3D) ultrasonography (US), as compared with contrast-enhanced 3D computed tomography (CT), for characterization of focal liver tumors.

MATERIALS AND METHODS

Institutional review board approval and informed patient consent were obtained. One hundred thirty-nine patients with focal liver tumors-77 hepatocellular carcinomas (HCCs), 33 metastases, 23 hemangiomas, and six focal nodular hyperplasias (FNHs)-who were examined at 3D US enhanced with a perflubutane microbubble contrast agent and at 3D contrast-enhanced multidetector CT were retrospectively identified. Two readers blindly reviewed the multiplanar images and angiograms reconstructed with both modalities and classified the depicted lesions according to diagnostic criteria based on their experience and published findings. Sensitivity, specificity, positive predictive value (PPV), area under the receiver operating characteristic curve (A(z)), intermodality agreement, and interreader agreement were assessed.

RESULTS

Readers 1 and 2 had concordant US and CT findings for 115 (83%) and 116 (83%) of the 139 lesions, respectively, with moderate to excellent (kappa = 0.55-0.81) intermodality agreement. There were no significant differences between the two modalities: Sensitivity was 83% or greater with both modalities, specificity was 87% or greater with contrast-enhanced US and 92% or greater with contrast-enhanced CT, the PPV was 71% or greater with both modalities, and the A(z) was at least 0.89 with US and at least 0.92 with CT. Interreader agreement was good to excellent (kappa > or = 0.76) with both modalities.

CONCLUSION

Contrast-enhanced 3D US potentially can be used to characterize focal liver tumors.

Does the echogenicity of focal liver lesions on baseline gray-scale ultrasound interfere with the diagnostic performance of contrast-enhanced ultrasound?

The objective was to evaluate whether the echogenicity of focal liver lesions (FLLs) on baseline gray-scale ultrasound (US) interferes with the diagnostic performance of contrast-enhanced US (CEUS) for small FLLs. Three-hundred and eighty-eight patients were examined by real-time CEUS using a sulfur hexafluoride-filled microbubble contrast agent. The images of 114 hyperechoic lesions, 30 isoechoic lesions and 244 hypoechoic lesions were reviewed by two blinded independent readers. A five-point confidence level was used to discriminate malignant from benign lesions, and specific diagnoses were made. The diagnostic performances were evaluated by receiver-operating characteristic (ROC) analysis. The diagnostic performances of CEUS on hyperechoic lesions in terms of the areas (Az) under the ROC curve were 0.987 (reader 1) and 0.981 (reader 2), and were 0.987 (reader 1) and 0.984 (reader 2) for iso- and hypoechoic lesions, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 87.0-95.9%, 93.1-100%, 88.6-100%, 70.0-97.1% and 90.0-95.1%, respectively. The echogenicity of FLLs on baseline gray-scale US does not appear to interfere with the diagnostic ability of CEUS for small FLLs.

Subcapsular liver tumors treated with percutaneous radiofrequency ablation: a prospective comparison with nonsubcapsular liver tumors for safety and effectiveness

PURPOSE

To assess the safety and effectiveness of percutaneous radiofrequency (RF) ablation of subcapsular liver tumors.

MATERIALS AND METHODS

The study protocol was approved by the institutional review board, and all patients gave written informed consent. One hundred eighty-one patients (79 men, 102 women; age range, 36-85 years) underwent ultrasonographically (US) guided percutaneous RF ablation of 361 primary or secondary (metastatic) liver tumors. Forty-four patients had one or more subcapsular nodules (group 1), and 137 had nonsubcapsular nodules only (group 2). Overall, 80 nodules were subcapsular and 281 were nonsubcapsular. The completeness of the ablation was assessed with contrast material-enhanced computed tomography (CT) 1 month after RF ablation. If residual tumor was documented, RF ablation was repeated. All patients in whom the ablation was complete after the first or second ablation session were monitored with CT or contrast-enhanced US every 3 months. Major complication, complete ablation, and local tumor progression rates were compared by using the chi(2) test or Fisher exact test.

RESULTS

Three (7%) major complications (intraperitoneal bleeding, skin burn, and tumor seeding) occurred in group 1, and two (1.5%) cases of tumor seeding occurred in group 2 (P = .093). No RF ablation-related deaths occurred. The complete ablation rate was 98% (43 of 44 patients) in group 1 and 98.5% (135 of 137 patients) in group 2 (P = .756). The local tumor progression rate after a median follow-up of 25 months (range, 13-54 months) was 16% (seven of 43 patients) in group 1 and 9.6% (13 of 135 patients) in group 2 (P = .355).

CONCLUSION

The difference in major complication rate between the subcapsular and nonsubcapsular liver tumors was not significant. The safety of RF ablation of subcapsular tumors seems acceptable, and the effectiveness is comparable to that of RF ablation of nonsubcapsular tumors.

Contrast-enhanced ultrasonography and spiral computed tomography in the detection and characterization of portal vein thrombosis complicating hepatocellular carcinoma

The aim was to compare the performances of contrast-enhanced (CE) ultrasonography (US) and spiral computed tomography (CT) in the detection and characterization of portal vein thrombosis complicating hepatocellular carcinoma (HCC). We studied 50 patients with HCC who had biopsy-proven portal vein thrombi that had been detected with US and color Doppler US. Thirteen of the thrombi involved the main portal trunk and 37 the segmental branches. CEUS and CT were performed within a week of thrombus biopsies. For each imaging technique, diagnoses of thrombosis (present/absent) and thrombus nature (malignancy/benignancy) were made by experienced readers under blinded conditions and compared with pathological findings to determine accuracy rates for thrombus detection and characterization. Forty-four of the 50 thrombi were pathologically diagnosed as malignant and the remaining six were benign. CEUS detected 50/50 (100%) thrombi and correctly characterized 49/50 (98%). CT detected 34/50 (68%) thrombi and correctly characterized 23 of these 34 (68%). CEUS outperformed CT in terms of both thrombus detection (P < 0.0001) and characterization (P = 0.0001). CEUS appears to be significantly superior to CT for detection and characterization of portal vein thrombosis complicating HCC, and it should be considered in the staging of these tumors.