Contrast-enhanced power Doppler sonography and helical computed tomography for assessment of vascularity of small hepatocellular carcinomas before and after percutaneous ablation

Meta-analysis and systematic review of contrast-enhanced ultrasound in evaluating the treatment response after locoregional therapy of hepatocellular carcinoma

PURPOSE

Contrast-enhanced ultrasound (CEUS) is a useful tool to assess treatment response after percutaneous ablation or transarterial chemoembolization (TACE) of hepatocellular carcinoma (HCC). Here, we performed a systematic review and meta-analysis to evaluate the usefulness of CEUS in identifying residual tumor after locoregional therapy.

METHODS

PubMed, Scopus, and Cochrane library databases were searched from their inception until March 8, 2021, for diagnostic test accuracy studies comparing CEUS to a reference standard for identifying residual tumors after locoregional therapy of HCC. The pooled sensitivity, specificity, accuracy, and diagnostic odds ratio (DOR) were obtained using a bivariate random effects model. Subgroup analyses were performed by stratifying the studies based on study design, type of locoregional therapy, CEUS criteria for residual tumor, timing of CEUS follow up, and type of standard reference.

RESULTS

Two reviewers independently evaluated 1479 publications. After full-text review, 142 studies were found to be relevant, and 43 publications (50 cohorts) were finally included. The overall sensitivity of CEUS in detection of residual disease estimated from the bivariate random effects model was 0.85 (95% CI 0.80-0.89). Similarly, the overall specificity was 0.94 (95% CI 0.91-0.96). The diagnostic accuracy was 93.5%. The DOR was 70.1 (95% CI 62.2-148), and the AUROC was 0.95. Importantly, subgroup analysis showed no apparent differences in the diagnostic performance between locoregional therapy (TACE vs. ablation) and criteria used to define residual enhancement, timing of performing CEUS, study design, or type of reference standard.

CONCLUSION

CEUS is a highly accurate method to identify HCC residual tumor after TACE or percutaneous ablation.

Comparison of elastography, contrast-enhanced ultrasonography, and computed tomography for assessment of lesion margin after radiofrequency ablation in livers of healthy dogs

OBJECTIVE To assess by use of various diagnostic imaging modalities acute changes in livers of healthy dogs after radiofrequency ablation (RFA) and determine the capability of each imaging modality to monitor ablation lesion changes.

ANIMALS 6 healthy Beagles.

PROCEDURES 12 ablation lesions were created in the liver of the dogs (2 lesions/dog). Ablation lesions were evaluated by use of conventional ultrasonography, strain elastography, and contrast-enhanced ultrasonography immediately after (time 0), 30 to 60 minutes after, and 3 days after RFA, and by use of CT 30 minutes and 3 days after RFA. Three dogs were euthanized shortly after RFA, and the other 3 dogs were euthanized on day 3. Lesion size measured by each imaging modality was compared with necropsy findings.

RESULTS Immediately after RFA, clear margins were more visible with elastography and contrast-enhanced ultrasonography than with conventional ultrasonography, which had acoustic shadowing. On triphasic contrast CT, the ablation zone, which indicated necrosis and hemorrhage, was not enhanced and could be measured. Marked enhancement of the periablation rim was observed during the venous phase and was identified as granulation tissue. Size of the ablation area measured on enhanced CT images was strongly correlated with actual lesion size.

CONCLUSIONS AND CLINICAL RELEVANCE For dogs of this study, CT was the most reliable method for lesion size determination. Although ultrasonographic imaging measurements underestimated lesion size, all modalities could be used to provide additional real-time guidance for RFA procedures of the liver as well as for other RFA procedures.

Contrast-enhanced ultrasound (CEUS) follow-up after radiofrequency ablation or cryoablation of focal liver lesions: treated-area patterns and their changes over time

OBJECTIVES

To describe the early patterns of liver lesions successfully treated with radiofrequency ablation (RFA) or cryoablation (CA) and their changes over time.

METHODS

Twenty-two RFA-treated and 17 CA-treated patients underwent CEUS from week 1 to year 3 post-ablation. Patterns, margins and volumes of RF-induced and cryolesions were evaluated and compared over time.

RESULTS

After contrast enhancement, shortly after ablation, undefined margins with persistent enhancing small vessels penetrating >2 mm into the treated zone were significantly more frequent after CA (67 %) than RFA (22 %) (P < 0.02). During the arterial phase, a thin, enhancing marginal rim was seen during week 1 (T1) in around 28 % of RF lesions, while 75 % of cryolesions had thick enhancing rims (P < 0.02). The mean RF-induced lesion volume, maximum at T1 (44.1 ± 37.5 ml), shrank slowly over time, remaining clearly visible at 1 year (8.3 ± 7.4 ml). Cryolesions shrank faster (P = 0.009), from an average of 16.6 ± 7.1 ml at T1 to 1.7 ± 1.3 ml 1-year post-ablation.

CONCLUSION

RF-induced and cryolesions differ, particularly their margins and shrinkage rates. Knowing these differences allows avoidance of incomplete treatment or falsely diagnosed recurrence, especially after CA.

KEY POINTS

• Contrast-enhanced ultrasound (CEUS) provides new follow-up information following hepatic radiological inyervention. • CEUS provides good visualisation of vascular modifications after thermoablation. • RFA-induced lesions and cryoablated lesions differ. • Knowledge about RF and cryolesion patterns is essential for correct CEUS follow-up. • Cryolesions have thicker peripheral inflammatory reactions and shrink faster than RFA-induced lesions.

Imaging of liver cancer

Improvements in imaging technology allow exploitation of the dual blood supply of the liver to aid in the identification and characterisation of both malignant and benign liver lesions. Imaging techniques available include contrast enhanced ultrasound, computed tomography and magnetic resonance imaging. This review discusses the application of several imaging techniques in the diagnosis and staging of both hepatocellular carcinoma and cholangiocarcinoma and outlines certain characteristics of benign liver lesions. The advantages of each imaging technique are highlighted, while underscoring the potential pitfalls and limitations of each imaging modality.

How to characterize non-hypervascular hepatic nodules on contrast-enhanced computed tomography in chronic liver disease: feasibility of contrast-enhanced ultrasound with a microbubble contrast agent

BACKGROUND AND AIM

Although hypervascular appearance is characteristic in hepatocellular carcinoma (HCC), hepatic nodules without hypervascular appearance are sometimes found in patients with chronic liver disease (CLD). The aim of the present study was to clarify the efficacy of contrast-enhanced ultrasound (CEUS) with Levovist to characterize small, non-hypervascular hepatic nodules on contrast-enhanced computed tomography (CECT) in patients with CLD.

METHODS

The subject was 41 hepatic nodules (<30 mm, 18.5 +/- 5.6 mm) which showed non-hypervascular appearance on CECT in 35 patients with CLD; their histological results were 31 HCC (15 well, 14 moderate, and two poor) and 10 regenerative nodules (RN). CEUS with Levovist was performed under intermittent scanning (1-s interval) using APLIO at the early phase and the liver-specific phase, and the contrast enhancement of the nodule was assessed in comparison to that of the surrounding liver parenchyma. The contrast-enhanced findings with the time-intensity analysis were compared with the histological results.

RESULTS

Twelve nodules with weak enhancement in the liver-specific phase were HCC, regardless of their early-phase appearances. The other 29 nodules with equivalent or weak enhancement in the early phase and equivalent enhancement in the liver-specific phase were 19 HCC and 10 RN. Among them, the maximum-intensity ratio of tumor to non-tumor in the early phase was significantly higher in HCC than in RN (P < 0.01, n = 16), and the receiver-operating characteristic analysis showed a sensitivity of 1.0 and a specificity of 0.83 for their characterization.

CONCLUSION

CEUS with Levovist may be an alternative to biopsy to characterize small, non-hypervascular hepatic nodules on CECT in patients with CLD.

Imaging appearances following thermal ablation

Radiofrequency ablation (RFA) has an increasingly important role in the management of a number of solid tumours. Treatments usually take place at specialist centres that draw patients from a wide geographical area, but follow-up imaging is often undertaken at the referring institution. This review aims to describe and illustrate the range of normal and abnormal post-ablative appearances encountered in the most commonly treated organs, i.e. liver, lung, and kidney, to equip radiologists with the necessary knowledge for confident interpretation of post-ablation imaging in this diverse patient group.

Radiofrequency ablation of hepatocellular carcinoma: predicting success using contrast-enhanced sonography

OBJECTIVE

This pilot study compared the utility of immediate postprocedural contrast-enhanced sonography with that of delayed enhanced sonography and CT or MRI in assessing the success of radiofrequency ablation of hepatocellular carcinoma.

SUBJECTS AND METHODS

Twenty-two lesions (1.5-3.7 cm) were studied in 19 patients. Enhanced sonography was performed before and within 1 hr after radiofrequency ablation. At routine 2-week follow-up CT or MRI, additional enhanced sonography was performed. The findings of preablation CT or MRI and enhanced sonography were compared with those of postprocedural and follow-up enhanced sonography by three radiologists experienced in these techniques. The reviewers were unaware of the follow-up CT or MRI results (reference standard). Technical adequacy, ablation zone targeting, and identification of residual disease were assessed by each reviewer, and the results were analyzed by consensus.

RESULTS

One postprocedural sonographic study was considered technically inadequate. Postprocedural sonography predicted the follow-up CT or MRI results in 76% (16/21) of subjects (sensitivity, 88%; specificity, 40%; positive predictive value [PPV], 82%; negative predictive value, [NPV] 50%). Follow-up CT or MRI identified accurate targeting in 17 of 22 subjects. Follow-up sonography agreed with CT or MRI in 82% (18/22) of subjects (sensitivity, 88%; specificity, 67%; PPV, 88%; NPV, 67%). Postprocedural sonography predicted the follow-up CT or MRI results in 81% (17/21) of subjects (sensitivity, 40%; specificity, 94%; PPV, 66%; NPV, 83%). Follow-up CT or MRI detected residual disease in six subjects. Follow-up sonography agreed with CT or MRI in 91% (20/22) of subjects (sensitivity, 83%; specificity, 94%; PPV, 83%; NPV, 94%).

CONCLUSION

Postprocedural enhanced sonography has the potential to guide completion of radiofrequency ablation at the time of initial therapy when residual disease is detected. The procedure is less accurate in detection of residual disease than is either delayed enhanced sonography or CT or MRI.

Treatment of small hepatocellular carcinoma: a comparison of techniques and long-term results

OBJECTIVE

The aim of this study was to compare the results over time of transcatheter arterial chemoembolization (TACE), percutaneous ethanol injection (PEI), laser thermal ablation (LTA) and combined therapy in the treatment of small hepatocellular carcinoma.

METHODS

Between 1998 and 2004, 131 cirrhosis patients (99 Child-Pugh class A, 32 Child-Pugh class B) with a small hepatocellular carcinoma were included in the study; 34 were treated with PEI, 46 with LTA, 18 with TACE and 33 with combined therapy.

RESULTS

No major complication occurred during any procedure. Computed tomography scan showed that complete necrosis was achieved in 81% of treated nodules (120 out of 148); as a whole, the disease relapsed in 42 (32.0%) patients (with a disease-free interval of 17.0+/-13.7 months). The cumulative survival rates were 81.9, 35.7 and 20.8% at 12, 36 and 60 months respectively. A univariate analysis of survival showed statistically significant differences in the comparison between Child-Pugh class A with respect to Child-Pugh class B (P<0.0001) and between nodules with a diameter of 20 mm or less as opposed to larger than 20 mm (P=0.001). Patients subjected to LTA showed a statistically significant longer survival than those treated with TACE and PEI.

CONCLUSIONS

LTA proves to be the most effective treatment, affording reduced invasiveness, a limited number of sessions, complete necrosis in almost all cases and better total survival in the treated patients.

Is microbubble-enhanced ultrasonography sufficient for assessment of response to percutaneous treatment in patients with early hepatocellular carcinoma?

The objective of this study was to assess the efficacy of contrast-enhanced ultrasonography (CEUS) with SonoVue to evaluate the response to percutaneous treatment (ethanol injection/radiofrequency) of hepatocellular carcinoma in comparison with spiral computed tomography (CT) immediately and 1 month after treatment. Forty-one consecutive cirrhotic patients with early stage tumor (not suitable for resection) were included. Spiral CT and CEUS were performed in all patients before treatment, in the following 24 h, and 1 month later. The results of each examination were compared with the 1-month spiral CT, considered the gold standard technique. The 24-h CEUS and the 24-h spiral CT sensitivity to detect residual disease were 27% and 20%, respectively. The 24-h CEUS and the 24-h spiral CT positive predictive value of persistent vascularization detection were 75% and 66%, respectively. The 1-month CEUS detected partial responses in ten out of 11 cases (91% sensitivity, 97% specificity, 95% accuracy). Spiral CT and CEUS performed in the 24 h following treatment are slightly useful to evaluate therapeutic efficacy. The 1-month CEUS has a high diagnostic accuracy compared with spiral-CT in the usual assessment of percutaneous treatment response.

Radiofrequency ablation has a valuable therapeutic role in metastatic VIPoma

BACKGROUND

Vasoactive intestinal peptide-secreting tumours (VIPomas) are rare islet cell tumours of the pancreas that can result in life-threatening biochemical abnormalities. The optimal intervention for metastatic VIPoma remains undecided. This case history documents the clinical role of radiofrequency (RF) ablation in the treatment of metastatic VIPoma.

CASE HISTORY

A primary pancreatic VIPoma was diagnosed in a 61-year-old female in 1998 and a distal pancreatectomy and splenectomy were performed. She remained disease-free for 44 months when she presented as an emergency with watery diarrhoea, hypokalaemia, renal failure and an elevated serum VIP level. CT scanning showed a liver metastasis and open RF ablation was performed with complete resolution of symptoms and biochemistry within 48 h. Post-ablation imaging confirmed complete ablation of the metastasis. She remained disease-free until 22 months later when watery diarrhoea resumed and a new hepatic metastasis was seen on CT. Percutaneous RF ablation was performed and follow-up CT scan showed complete ablation of the metastasis. The patient remains disease- and symptom-free 10 months after the second RF ablation.

CONCLUSION

This case illustrates that the pronounced clinical and biochemical upset caused by metastatic VIPoma can be resolved safely, quickly and repeatedly by RF ablation.

MR diffusion-weighed imaging of rabbit liver

AIM: To study the techniques of MR diffusion-weighed imaging (DWI) for normal rabbit liver.

METHODS: After 15 normal New Zealand white rabbits and one New Zealand white rabbit implanted with VX-2 tumor were anesthetized with 3% soluble pentobarbitone, DWI was performed respectively for different b values, repetition times (TR) or thicknesses, when other parameters were the same and magnetic resonance imaging (MRI) was performed respectively, or with different field of views (FOV) or coil when other parameters were the same. The distinction between groups was analyzed by SPSS10.0 with apparent diffusion coefficient (ADC), quality index (QI) or signal-noise ratio (SNR).

RESULTS: As b value increased, liver ADC, QI and SNR of DWI became smaller and simultaneously (F = 292.87, 156.1, 88.23, P<0.01). QI of DWI was high, when b value was 10, 50 or 100 respectively, but the distinction between them was insignificant; when b value was 800, QI and SNR of DWI were low. QI and SNR of DWI had no significant difference between TR = 4 000, 6 000 and 8 000. QI of DWI with 2 mm thickness was bigger than that with 5 mm thickness (t = 3.04, P<0.01), but SNR of DWI with 2 mm thickness was significantly smaller (t = -17.86, P<0.01). SNR of MRI with knee joint coil was obviously bigger than that with cranium coil [t = -5.77 (T1WI) or -4.02 (T2WI), P<0.01], but QI of MRI was smaller on the contrary [t = 7.10 (T1WI) or 3.97 (T2WI), P<0.01]. When FOV was enlarged gradually, SNR of MRI increased [F = 85.81 (T1WI) or 221.96 (T2WI), P<0.01], but QI firstly increased, then decreased [F = 68.67 (T1WI) or 69.46 (T2WI), P<0.01] and QI of MRI was the biggest when FOV was 20 cm×15 cm.

CONCLUSION: The scanning technique is very important in DWI of rabbit liver and the overall quality of DWI with b (100 s/mm2), thickness (2 mm), cranium coils and FOV (20 cm×15 cm) was best in our study, when other parameters were the same.

MR diffusion-weighted imaging of rabbit liver VX-2 tumor

AIM: To investigate the implanting method of rabbit liver VX-2 tumor and its MR diffusion-weighted imaging (DWI) characteristics.

METHODS: Thirty-five New Zealand rabbits were included in the study. VX-2 tumor was implanted subcutaneously in 14 rabbits and intrahepatically in 6 for pre-experiments. VX-2 tumor was implanted intrahepatically in 12 rabbits for experiment and three were used as the control group. DWI, T1- and T2-weighted of MRI were performed periodically in 15 rabbits for experiment before and after implantation. The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values. The statistical significance was calculated by analysis of variance (ANOVA) of the randomized block design using SPSS10.0 software.

RESULTS: The successful rate of subcutaneous implantation of VX-2 tumor was 29% (4/14) while that of intrahepatic implantation of it was 33% (2/6) in the preexperiment. The successful rate of intrahepatic implantation of VX-2 tumor in the experiment was 83% (10/12) and 15 tumors grew in 10 successfully implanted rabbits. The DWI signal of VX-2 tumor was high and became lower when the b value increased step by step. The signal of VX-2 tumor on the map of ADC was low. When the b value was 100 or 300 s/mm², the ADC value of normal group and VX-2 tumor group was respectively 2.57±0.26, 1.73±0.31, 1.87±0.25 and 1.57±0.23 mm²/s. Their distinction was significant (F = 43.26, P<0.01), the tumor ADC value between b values 100 and 300 s/mm² was significant (Tukey HSP, P<0.05) and the ADC value between VX-2 tumor and normal liver was also significant (Tukey HSP, P<0.01). VX-2 tumor developed quickly and metastasized early to all body, especially to the lung, liver, lymph nodes of mediastinum, etc.

CONCLUSION: The DWI signal of rabbit VX-2 tumor has its characteristics on MR DWI and DWI plays an important role in diagnosing and discovering VX-2 tumor.

Effect of thalidomide in hepatocellular carcinoma: assessment with power doppler US and analysis of circulating angiogenic factors

PURPOSE

To prospectively evaluate the feasibility of using power Doppler ultrasonography (US) and measurement of circulating angiogenic factors to assess the antiangiogenic effect of thalidomide in hepatocellular carcinoma.

MATERIALS AND METHODS

The Ethics Committee of the National Taiwan University Hospital approved the study, and all patients gave prior written informed consent. Evaluation of response to thalidomide treatment was based on findings at computed tomography (CT) and change in serum alpha-fetoprotein level. Tumor vascularity index was evaluated with power Doppler US in patients with advanced hepatocellular carcinoma treated with 200-300 mg/d thalidomide. Serum levels of vascular endothelial growth factor, basic fibroblast growth factor, and placental growth factor were measured with enzyme-linked immunoassay. The chi(2) test or Fisher exact test was used for categorical variables, and the nonparametric Mann-Whitney test was used for numeric variables. A P value of less than .05 was considered to indicate a statistically significant difference.

RESULTS

Of 47 patients enrolled in the study who had disease that was bidimensionally assessable on CT scans, 44 were assessable for tumor response. Of the 44 evaluated, five were classified as showing objective response (responders): One each showed a complete and a partial response according to World Health Organization criteria, and three had a decrease in alpha-fetoprotein level by more than 50% and stable disease for 10.4, 5.3, or 3.5 months. The pretreatment vascularity index was significantly higher in responders (median, 7.42; range, 2.99-13.90) than in nonresponders (median, 2.15; range, 0-25.36) (P = .03). Four of five responders had a significant decrease in vascularity index with thalidomide. Serum levels of angiogenic factors did not differ significantly between responders and nonresponders.

CONCLUSION

Higher vascularity index may be associated with a better chance of response to thalidomide in patients with advanced hepatocellular carcinoma. Serum levels of circulating angiogenic factors do not appear to be clinically useful as an indicator of response.

Abdominal virtual ultrasonographic images reconstructed by multi-detector row helical computed tomography

BACKGROUND

Three-dimensional (3D) images can be generated using thin sections from multi-detector row computed tomography (CT) and computer software, simulating images obtained using conventional ultrasonography (US). This software allows easy diagnosis of abdominal lesions and subsequent treatment of focal liver lesions such as hepatocellular carcinoma (HCC). The present study used newly developed virtual US software for diagnose and treatment of hepatobiliary disease.

METHODS

The software was used to create virtual US images in 10 subjects. Radiofrequency ablation (RFA) was performed by virtual US in seven patients with HCC.

RESULTS

Slices were easily reconstructed from various angles, and each slice was continuously animated as with conventional US in all subjects. Moreover, when seven patients with HCC were examined using virtual US, HCC nodules were visualized and could be treated with RFA.

CONCLUSIONS

Virtual US should prove useful for visualization of HCC nodules that cannot be seen under conventional US. Virtual US is a useful tool for US-guided treatment of HCC.

Contrast enhanced ultrasound in liver imaging

Ultrasound contrast agents were originally introduced to enhance the Doppler signals when detecting vessels with low velocity flow or when imaging conditions were sub-optimal. Contrast agents showed additional properties, it was discovered that a parenchymal enhancement phase in the liver followed the enhancement of the blood pool. Contrast agents have made ultrasound scanning more accurate in detection and characterization of focal hepatic lesions and the sensitivity is now comparable with CT and MRI scanning. Further, analysis of the transit time of contrast agent through the liver seems to give information on possible hepatic involvement, not only from focal lesions but also from diffuse benign parenchymal disease. The first ultrasound contrast agents were easily destroyed by the energy from the sound waves but newer agents have proved to last for longer time and hereby enable real-time scanning and make contrast enhancement suitable for interventional procedures such as biopsies and tissue ablation. Also, in monitoring the effect of tumour treatment contrast agents have been useful. A brief overview is given on some possible applications and on different techniques using ultrasound contrast agents in liver imaging. At present, the use of an ultrasound contrast agent that allows real-time scanning with low mechanical index is to be preferred.

Evaluation of hepatocellular carcinoma using SonoVue, a second generation ultrasound contrast agent: correlation with cellular differentiation

The appearance of hepatocellular carcinoma (HCC) with contrast-enhanced ultrasound (CEUS) in the vascular phase is described and evaluated as to whether the enhancement pattern correlates with the degree of cellular differentiation. One hundred four HCCs were prospectively evaluated with CEUS using coherent-contrast imaging (CCI) and SonoVue with a low mechanical index (<0.2). The enhancement of HCCs in the vascular phase was analyzed according to the degree of pathological differentiation obtained by fine-needle biopsy. In the arterial phase, all HCCs except for four well differentiated ones (96.2%) showed enhancement ( P<0.05). Histological differentiation of hypoechoic lesions in the early portal phase (7 HCCs; 16%) significantly differed from hyperechoic (1 HCC; 1%) or isoechoic lesions (87 HCCs; 83.6%) ( P<0.05), with a significant probability of a worse differentiation in hypoechoic lesions. Histological differentiation of isoechoic lesions in the late phase (30 HCCs; 28.8%) significantly differed from hypoechoic lesions (74 HCCs; 71.2%) ( P<0.05), with a significant probability of a better differentiation in isoechoic lesions. CEUS using CCI and SonoVue revealed enhancement in the arterial phase in >95% of HCCs, with a few well-differentiated cases not being diagnosed due to the absence of enhancement. Echogenicity in the portal and late phases correlated with cellular differentiation.

MRI angiography is superior to helical CT for detection of HCC prior to liver transplantation: an explant correlation

Helical computerized tomography (CT) and magnetic resonance imaging (MRI) are used for staging of hepatocellular carcinoma (HCC) prior to curative treatments but underestimate tumor extension in 30% to 50% of cases when compared with pathologic explants. This study compares a new technology, MRI angiography (MRA), with triphasic helical CT in detection of HCC. Fifty cirrhotic patients, 29 with HCC, undergoing liver transplantation were analyzed. MRA was performed with a 3-D breath-hold fast spoiled gradient-echo sequence by using an effective section thickness of 2 to 2.5 mm. The gold standard was the pathologic examination (liver cut into 5-mm slices). One hundred twenty-seven lesions were identified at the explant: 76 HCC, 13 high-grade dysplastic nodules, 31 macroregenerative nodules, 7 hemangiomas. Diameter of the main HCC nodules was 29 +/- 14 mm and 11 +/- 7 mm for the 47 additional nodules. On a per nodule basis, sensitivity of MRA was superior to CT (58/76 [76%] vs. 43/70 [61%], respectively, P =.001). Sensitivity of MRA for detection of additional nodules decreased with size (>20 mm: 6/6 [100%]; 10-20 mm: 16/19 [84%]; <10 mm: 7/22 [32%]) and was superior to CT for nodules 10 to 20 mm (84% vs. 47%, P =.016). Nonspecific hypervascular nodules >5 mm at MRA were HCC in two thirds of the cases. In conclusion, MRA has a high diagnostic accuracy for HCC > or =10 mm and is more sensitive than triphasic helical CT in nodules sized 10 to 20 mm. MRA is the optimal technique for HCC staging prior to curative therapies.