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

mRECIST criteria and contrast-enhanced US for the assessment of the response of hepatocellular carcinoma to transarterial chemoembolization

PURPOSE

We aimed to evaluate the combination of the modified Response Evaluation Criteria In Solid Tumors (mRECIST) and contrast-enhanced ultrasonography (CEUS) as a tool for the assessment of hepatocellular carcinoma treated with transarterial chemoembolization.

MATERIALS AND METHODS

Forty-seven hepatocellular carcinoma patients (80 target tumors suitable for mRECIST measurements) were studied. They were treated with scheduled transarterial chemoembolization with doxorubicin-eluting microspheres every 5-7 weeks. Imaging follow-up (performed one month after each transarterial chemoembolization) included a standard, contrast-enhanced modality (computed tomography [CT] in 12 patients or magnetic resonance imaging [MRI] in 35 patients) and CEUS. The study focused on response evaluation after the third transarterial chemoembolization. CEUS required a bolus injection of an echo-enhancer and imaging with a dedicated, low mechanical index technique. The longest diameters of the enhancing target tumors were measured on the CEUS or CT/MRI, and mRECIST criteria were applied. Radiologic responses were correlated with overall survival and time to progression.

RESULTS

The measurements of longest diameters of the enhancing target tumors were easily performed in all patients. According to mRECIST-CEUS and mRECIST-CT/MRI, complete response was recorded in five and six patients, partial response in 22 and 21 patients, stable disease in 16 and 14 patients, and progressive disease in four and six patients, respectively. There was a high degree of concordance between CEUS and CT/MRI (kappa coefficient=0.84, P < 0.001). Responders (complete+partial response) according to mRECIST-CEUS had a significantly longer mean overall survival and time to progression compared to nonresponders (37.1 vs. 11.0 months, P < 0.001 and 24.6 vs. 10.9 months, P = 0.007, respectively).

CONCLUSION

The mRECIST-CEUS combination is feasible and has prognostic value in the assessment of hepatocellular carcinoma following transarterial chemoembolization.

Geometric optimization of a mathematical model of radiofrequency ablation in hepatic carcinoma

Radio frequency ablation (RFA) is an effective means of achieving local control of liver cancer. It is a particularly suitable mode of therapy for small and favorably located tumors. However, local progression rates are substantially higher for large tumors (>3.0 cm). In the current study, we report on a mathematical model based on geometric optimization to treat large liver tumors. A database of mathematical models relevant to the configuration of liver cancer was also established. The specific placement of electrodes and the frequency of ablation were also optimized. In addition, three types of liver cancer lesion were simulated by computer guidance incorporating mathematical models. This approach can be expected to provide a more effective and rationale mechanism for employing RFA in the therapy of hepatic carcinoma.

Sonographic features of placenta accreta after first-trimester abortion

We assessed 5 patients with histologically/clinically confirmed placenta accreta after first-trimester abortion. In 4 patients, sonography showed an unclear endometrium, absence of an endometrium-myometrium interface, a well-vascularized hyperechoic lesion in the uterine body with a low resistive index, and myometrial thinning near the lesion. In 2 patients, contrast-enhanced sonography showed rapid irregular lesion enhancement. Chemotherapy reduced the lesions in 3 patients, and a decreased blood supply increased the resistive index in all lesions. Two patients each underwent hysterectomy and uterine curettage. The fifth patient had a cervical pregnancy; sonography showed a well-vascularized hyperechoic lesion in an enlarged cervix. Methotrexate gradually reduced this lesion. Sonography, especially contrast-enhanced sonography, can detect placenta accreta and guide treatment.

Short-term evaluation of liver tumors after transarterial chemoembolization: limitations and feasibility of contrast-enhanced ultrasonography

PURPOSE

To evaluate the limitations and the feasibility of contrast-enhanced ultrasonography (CEUS) for the assessment of tumor response shortly after transarterial chemoembolization (TACE).

MATERIALS AND METHODS

Fifty seven patients (41 patients with hepatomas, 16 patients with metastases) were studied with CEUS before, 1 day after, and 30 days after TACE. A CEUS-efficiency score (CEUS-ES) was calculated, which evaluated: (a) the completeness of visualization of the target tumor(s) (2: good, 1: adequate, 0: poor) and (b) the quality of delineation of post-TACE necroses (2: good, 1: adequate, 0: poor). A CEUS study was considered as "diagnostic," if each of the aforementioned parameters was associated with grade 1 or 2.

RESULTS

CEUS studies were "diagnostic" in 36/57 patients (63.1%). Patients with hepatomas were more likely to undergo "diagnostic" CEUS than patients with metastases (70.7% vs. 43.7%, P = 0.0728). Lesions' multiplicity, deep location, hypoenhancement on pretreatment CEUS, and diffuse growth had a statistically significant (P < 0.05) negative impact on CEUS-ES. Hyperechogenicity on pre-treatment, unenhanced US had a non-statistically significant (P = 0.176) negative impact. Differences between "diagnostic" CEUS studies and CT/MR regarding detection of residual tumor were insignificant (P = 0.8178).

CONCLUSION

The percentage of lesions which are unsuitable for post-TACE evaluation with CEUS is not negligible. For the rest, the respective role of CEUS is promising.

Recurrent hepatocellular carcinoma after transcatheter arterial chemoembolization: planning sonography for radio frequency ablation

OBJECTIVES

The purposes of this study were to evaluate the sonographic findings of recurrent hepatocellular carcinoma after transcatheter arterial chemoembolization and to determine how often the lesion conspicuity of the recurrent hepatocellular carcinoma makes it suitable for percutaneous sonographically guided radio frequency ablation.

METHODS

A radiologist prospectively classified the echogenicity of recurrent hepatocellular carcinomas compared to that of the surrounding liver. In addition, the margin of the tumor was classified as follows: grade 1, absolutely indistinguishable; grade 2, less than 50%; grade 3, greater than 50%; and grade 4, clearly demarcated. The lesion conspicuity was also classified as follows: grade 1, absolutely invisible, thus ineligible for percutaneous sonographically guided radio frequency ablation; grade 2, poorly visible, thus unsuitable for ablation; and grade 3, visible and conspicuous, thus suitable for ablation.

RESULTS

A total of 37 consecutive patients (31 men and 6 women; mean age, 59.4 years) with 38 hepatocellular carcinomas were enrolled. The echogenicity of the recurrent hepatocellular carcinomas varied, with the most common finding being a heterogeneous hypoechoic lesion (31.6%), followed by an isoechoic lesion (23.7%), a heterogeneous hyperechoic lesion (18.4%), a homogeneous hypoechoic lesion (13.2%), a lesion with a hypoechoic halo (10.5%), and a homogeneous hyperechoic lesion (2.7%). The margin of the recurrent hepatocellular carcinomas was clearly demarcated in only 28.9% of tumors, whereas 23.7% of the tumors were absolutely indistinguishable from the surrounding liver. The lesion conspicuity was classified as grade 3 in only 60.5% of the recurrent hepatocellular carcinomas.

CONCLUSIONS

The echogenicity and margins of recurrent hepatocellular carcinomas after transcatheter arterial chemoembolization varied. The lesion conspicuity was suitable for sonographically guided radio frequency ablation in only 60.5% of cases.

Evaluation of local recurrence after treatment for hepatocellular carcinoma by contrast-enhanced ultrasonography using Sonazoid: comparison with dynamic computed tomography

PURPOSE

To evaluate the effectiveness of contrast-enhanced ultrasonography (CEUS) using Sonazoid for the diagnosis of the local recurrence after treatment for hepatocellular carcinoma (HCC) by comparing it with dynamic CT.

METHODS

Seventy-one patients with 87 HCC lesions (mean +/- SD; 19.5 +/- 9.6 mm) underwent CEUS using Sonazoid and dynamic CT after radiofrequency ablation (n = 55), transcatheter arterial chemoembolization (n = 22), or radiofrequency ablation combined with transcatheter arterial chemoembolization (n = 10). Two hepatologists (observer 1; 10 years of experience, and 2; 20 years of experience) reviewed the CEUS and dynamic CT images independently and evaluated presence or absence of the local recurrence. Diagnostic performance for the local recurrence was assessed using receiver operating characteristic curve analysis.

RESULTS

The Az value for dynamic CT was significantly lower in observer 1 than 2 (p < 0.05). The sensitivity of CEUS was 79% in observer 1 and 83.9% in observer 2, and that of dynamic CT was 83.9% and 90.3%, respectively. The specificity of CEUS was 96%, and that of dynamic CT was 92%, in both observers.

CONCLUSION

This study suggests that CEUS using Sonazoid is less affected by the observer's experience and is more accurate in the diagnosis of local recurrence after treatment for HCC than dynamic CT.

Double-contrast magnetic resonance imaging of hepatocellular carcinoma after transarterial chemoembolization

BACKGROUND

The purpose of this study was to assess the accuracy of double-contrast magnetic resonance (MR) imaging for the treatment response evaluation of hepatocellular carcinoma (HCC) in cirrhotic liver after transarterial chemoembolization (TACE).

METHODS

Twenty-two patients with 30 HCC nodules treated by TACE underwent double-contrast MR imaging 1 month after treatment. MR images were obtained before and after the sequential administration of superparamagnetic iron oxide (SPIO) and gadopentetate dimeglumine contrast agent within the same imaging session. Two observers retrospectively assessed all treated nodules for evidence of residual viable tumor after TACE. The diagnostic performance of gadolinium-enhanced, SPIO-enhanced, and double-contrast enhanced images was calculated. Histopathological and angiographical findings served as standard of reference. Receiver operating characteristic curves and areas under the curves (A (z)) were calculated.

RESULTS

Double-contrast technique (A (z) = 0.95) was significantly (p = 0.036) more accurate than SPIO-enhanced technique (A (z) = 0.92) and gadolinium-enhanced technique (p = 0.005) (A (z) = 0.81) in viable tumor detection after TACE. Double-contrast technique was significantly more sensitive (92%) than SPIO-enhanced technique (80%) and gadolinium-enhanced technique (68%). Kappa values for interobserver agreement ranged from 0.67 to 0.87 and were significantly different from zero (all p < 0.001).

CONCLUSIONS

Compared to gadolinium-enhanced and SPIO-enhanced techniques, double-contrast technique significantly improves the detection of viable tumor in HCC after TACE.

Therapeutic response assessment of high intensity focused ultrasound therapy for uterine fibroid: utility of contrast-enhanced ultrasonography

PURPOSE

To assess the utility of contrast-enhanced ultrasonography (ceUS) in the assessment of the therapeutic response to high intensity focused ultrasound (HIFU) ablation in patients with uterine fibroid.

MATERIALS AND METHODS

Sixty-four patients with a total of 64 uterine fibroids (mean: 5.3+/-1.2 cm; range: 3.2-8.9 cm) treated with HIFU ablation under the ultrasound guidance were evaluated with ceUS after receiving an intravenous bolus injection of a microbubble contrast agent (SonoVue) within 1 week after intervention. We obtained serial ceUS images during the time period from beginning to 5 min after the initiation of the bolus contrast injection. All of the patients underwent a contrast enhanced MRI (ceMRI) and ultrasound guided needle puncture biopsy within 1 week after HIFU ablation. And as a follow-up, all of the patients underwent US at 1, 3, 6 and 12 months after HIFU treatment. The volume change was observed and compared to pre- and post-HIFU ablation. The results of the ceUS were compared with those of the ceMRI in terms of the presence or absence of residual unablated tumor and pathologic change in the treated lesions.

RESULTS

On ceUS, diagnostic accuracy was 100%, while residual unablated tumors were found in three uterine fibroids (4.7%) and failed treatment was found in eight uterine fibroids (12.5%). All the 11 fibroids were subjected to additional HIFU ablation. Of the 58 ablated fibroids without residual tumors on both the ceUS and ceMRI after the HIFU ablation, the volumes of all the fibroids decreased in different degrees during the 1 year follow-up USs. And histologic examinations confirmed findings of necrotic and viable tumor tissue, respectively.

CONCLUSION

CEUS is potentially useful for evaluating the early therapeutic effect of percutaneous HIFU ablation for uterine fibroids.

Assessment of cystic renal masses based on Bosniak classification: comparison of CT and contrast-enhanced US

OBJECTIVES

To compare retrospectively the imaging features of computed tomography (CT) and contrast-enhanced US (CEUS) imaging for the assessment of cystic renal masses using the Bosniak classification system.

MATERIALS AND METHODS

The CT and CEUS images of 31 pathologically confirmed cystic renal masses in 31 patients were retrospectively analyzed for septa numbers, wall and/or septa thickness, enhancement degree, and for the presence of a solid component by consensus between two radiologists using the Bosniak classification. Diagnostic accuracies of CT and CEUS for malignant cystic tumor were calculated and compared using McNemar test.

RESULTS

Diagnostic accuracies of CT and CEUS for malignant renal tumor were 74% and 90%, respectively, but there were not statistically different (P>0.05). CEUS and CT images showed same Bosniak classification in 23 (74%) lesions and there were differences in 8 (26%) lesions, all of which were upgraded by CEUS; one lesion from I to IV, two lesions from II to IV, two lesions from IIF to III, and three lesions from III to IV. CEUS images depicted more septa in 10 (32%) lesions, more thickened wall and/or septa in 4 (13%) lesions, and stronger enhancement in 19 (61%) lesions. Moreover, for six lesions, solid component was detected by CEUS but not by CT.

CONCLUSION

CEUS might better visualize septa number, septa and/or wall thickness, solid component and the enhancement of some renal cystic masses than CT, resulting in upgrade of Bosniak classification and affecting their treatment plan.

State-of-the-art ultrasonography of hepatocellular carcinoma

Over the last few decades sonographic techniques have progressed remarkably. Recent advances in ultrasonography include harmonics, real-time spatial compound imaging, adaptive image processing, 3D power Doppler imaging and contrast-enhanced gray-scale harmonic ultrasonography. These advances have had positive effects on the diagnosis of hepatocellular carcinomas and on the evaluation of their responses to therapy. In this article, we review recent sonographic advances for the diagnosis and treatment of hepatocellular carcinomas and its typical imaging features.

Flash-echo contrast sonography in the evaluation of response of small hepatocellular carcinoma to percutaneous ablation

PURPOSE

To evaluate the use of flash-echo contrast sonography (FECS) in subtraction mode in assessing small hepatocellular carcinoma (HCC) after percutaneous local ablation therapy.

METHODS

Between March 2000 and February 2002, we prospectively assessed small HCCs after percutaneous local ablation therapy using FECS in subtraction mode. Thirty-three patients (22 men, 11 women) with 35 tumors ranging in size from 1.1 to 3.0 cm (mean +/- SD, 2.0 +/- 0.5) were enrolled. Twenty-one tumors received percutaneous ethanol injection only, 13 tumors received percutaneous microwave ablation therapy only, and the remaining tumor received both treatments. CT, hepatic angiography, and follow-up were used as gold standards in analyzing the accuracy of FECS in detecting residual tumors.

RESULTS

The agreements between FECS and CT, FECS and hepatic angiography, and all 3 imaging modalities were 80% (28/35), 85.7% (30/35), and 77.1% (27/35), respectively. Twenty-one patients with 23 completely ablated tumors were followed up for 5 to 39 months (mean +/- SD, 20.2 +/- 11.2). Recurrent disease was detected in 11 (52.4%) patients; local tumor recurrence occurred in 4 (17.4%) patients. The sensitivity, specificity, accuracy, and positive and negative predictive value of FECS in detecting viable tumors were 53.8% (7/13), 90.9% (20/22), 77.1% (27/35), 77.8% (7/9), and 76.9% (20/26), respectively.

CONCLUSIONS

FECS in subtraction mode shows good agreement with hepatic angiography and CT in the assessment of small HCC after percutaneous local ablation therapy. The sensitivity of FECS in detecting residual tumors is suboptimal.

Therapeutic response assessment of percutaneous radiofrequency ablation for hepatocellular carcinoma: utility of contrast-enhanced agent detection imaging

PURPOSE

To assess the utility of contrast-enhanced agent detection imaging (ADI) in the assessment of the therapeutic response to percutaneous radiofrequency (RF) ablation in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Ninety patients with a total of 97 nodular HCCs (mean, 2.1+/-1.3 cm; range, 1.0-5.0 cm) treated with percutaneous RF ablation under the ultrasound guidance were evaluated with contrast-enhanced ADI after receiving an intravenous bolus injection of a microbubble contrast agent (SH U 508A). We obtained serial contrast-enhanced ADI images during the time period from 15 to 90 s after the initiation of the bolus contrast injection. All of the patients underwent a follow-up four-phase helical CT at 1 month after RF ablation, which was then repeated at 2-4 month intervals during a period of at least 12 months. The results of the contrast-enhanced ADI were compared with those of the follow-up CT in terms of the presence or absence of residual unablated tumor and local tumor progression in the treated lesions.

RESULTS

On contrast-enhanced ADI, technical success was obtained in 94 (97%) of the 97 HCCs, while residual unablated tumors were found in three HCCs (3%). Two of the three tumors that were suspicious (was not proven) for incomplete ablation were subjected to additional RF ablation. The remaining one enhancing lesion that was suspicious of a residual tumor on contrast-enhanced ADI was revealed to be reactive hyperemia at the 1-month follow-up CT. Therefore; the diagnostic concordance between the contrast-enhanced ADI and 1-month follow-up CT was 99%. Of the 94 ablated HCCs without residual tumors on both the contrast-enhanced ADI and 1-month follow-up CT after the initial RF ablation, five (5%) had CT findings of local tumor progression at a subsequent follow-up CT.

CONCLUSION

Despite its limitations in predicting local tumor progression in the treated tumors, contrast-enhanced ADI is potentially useful for evaluating the early therapeutic effect of percutaneous RF ablation for HCCs.

Characterization of renal cell carcinoma using agent detection imaging: comparison with gray-scale US

Objective

We wanted to compare the imaging features of renal cell carcinoma (RCC) and their diagnostic accuracy on agent detection imaging (ADI) and gray-scale ultrasonography (US).

Materials and Methods

Thirty non-consecutive patients (age range; 32-80 years, mean age; 53.7 years) with 30 RCCs were examined with gray-scale US and with ADI in conjunction with using SH U 508A. We described the imaging features of the renal tumors obtained from ADI according to their enhancement pattern, the intratumoral anechoic areas and the presence of any pseudocapsule. The imaging features and diagnostic accuracy of ADI and gray-scale US were then compared.

Results

On the ADI exam, the RCCs were shown as being heterogeneous in 87% of the cases (26/30), homogeneous in 7% of the cases (2/30), and there was peripheral irregular enhancement in 7% of the cases (2/30). Intratumoral anechoic areas and pseudocapsule were seen in 87% and 77% of the RCCs on the ADI exam, whereas these features were seen in 53% and 17% of the cases on the gray-scale US, respectively. The diagnostic sensitivity, specificity, and accuracy for RCC with ADI were 97%, 93%, and 95%, respectively. However, those for RCC with using gray-scale US were 70%, 86%, and 78%, respectively. There was a significant difference for the diagnostic accuracy of RCC between ADI and gray-scale US (p < 0.05).

Conclusion

Agent detection imaging can help visualize the enhancement pattern of RCC and improve the diagnostic accuracy of this tumor by better displaying the intratumoral anechoic areas and the pseudocapsule than does the gray-scale US.

Contrast-enhanced gray-scale harmonic ultrasound in the efficacy assessment of ablation treatments for hepatocellular carcinoma

BACKGROUND

The aim of this study was to compare contrast-enhanced gray-scale harmonic ultrasound with multiphasic spiral computed tomography in the assessment of treatment efficacy of non-surgically treated HCC.

METHODS

We studied 56 HCCs treated by percutaneous ethanol injection (31 cases), radiofrequency ablation (three cases), trans-arterial chemoembolization (12 cases), and combined treatment (10 cases). The efficacy of therapies was blindly assessed by multiphasic computed tomography and gray-scale harmonic ultrasound with a second-generation contrast agent (sulfur hexafluoride).

RESULTS

On computed tomography 30 tumors (53.6%) showed complete necrosis, while 26 lesions (45.4%) were still viable. On contrast-enhanced ultrasound examination 33/56 nodules (58.9%) had no contrast enhancement in the arterial phase, while 23/56 lesions (41.1%) were still vascularized. All the nodules assessed as completely necrotic on computed tomography did not show arterial enhancement on contrast-enhanced ultrasound and diagnostic agreement was found in 53/56 cases (94.6%) (P<0.001). Contrast-enhanced ultrasound demonstrated relative sensitivity and specificity of 87.0% and 98.4%.

CONCLUSIONS

Contrast-enhanced harmonic ultrasound is promising in the efficacy evaluation of ablation treatments for HCC. Nodules vascularized in the arterial phase on contrast harmonic ultrasound should be considered still viable and addressed to additional treatment without further evaluation.

Value of contrast-enhanced sonography for the characterization of focal hepatic lesions in patients with diffuse liver disease: receiver operating characteristic analysis

OBJECTIVE

Our aim was to assess the diagnostic performance of contrast-enhanced agent detection sonographic imaging to characterize focal hepatic lesions in patients with diffuse liver disease in comparison with baseline sonographic images and to determine whether agent detection imaging can reduce the necessity of further diagnostic workup for lesion characterization.

MATERIALS AND METHODS

Contrast-enhanced sonography using 4 g of Levovist at a concentration of 300 mg/mL was performed on 75 focal hepatic lesions in 75 patients with diffuse liver disease. Interval reviews for both baseline without and with contrast-enhanced sonography were performed independently by two radiologists. They were requested to determine the malignity of focal hepatic lesions using a 5-point confidence level and to record the specific diagnoses and the necessity for further imaging for lesion characterization. Radiologists' performances for lesion differentiation using baseline and contrast-enhanced sonography were evaluated using receiver operating characteristic (ROC) analysis. Interobserver agreement was also analyzed.

RESULTS

When contrast-enhanced sonography was used, ROC analysis revealed a significant improvement for both reviewers (area under the receiver operating characteristic curve [A(z)] = 0.753 and 0.830 and 0.971 and 0.974 at baseline sonography and contrast-enhanced sonography, respectively; p < 0.002) for differentiating malignant and benign focal liver lesions. Contrast-enhanced sonography also improved specificity from 12% to 91% for reviewer 1 and from 26% to 85% for reviewer 2 compared with baseline sonography. Furthermore, excellent interobserver agreement was achieved for contrast-enhanced sonography (weighted kappa = 0.919), whereas only good agreement was achieved for baseline sonography (weighted kappa = 0.656). A better result for specific diagnosis was obtained by contrast-enhanced sonography (79% and 75%) than by baseline sonography (37% and 48%, p < 0.05). Contrast-enhanced sonography (72% and 63%) outperformed baseline sonography (35% and 28%, p < 0.05) as a confirmatory imaging technique.

CONCLUSION

Contrast-enhanced agent detection sonography can be used to characterize focal hepatic lesions in patients with diffuse liver disease reliably and with a higher diagnostic confidence than baseline sonography. Furthermore, contrast-enhanced sonography reduced the need for further diagnostic workups for focal hepatic lesion characterization.

Contrast-aided diagnostic ultrasound does not enhance lung metastasis in a mouse melanoma tumor model

OBJECTIVE

The purpose of this research was to test the hypothesis that contrast-aided diagnostic ultrasound (CADUS) could exacerbate the metastatic spread of mouse melanoma tumor cells to the lungs.

METHODS

The melanoma cell lines B16 and B16-D5 (metastatic specifically to lung) were implanted on a hind leg of female C57/bl6 mice. Growing tumors were scanned by 1.5-MHz diagnostic ultrasound in a 37 degrees C water bath. Four hundred image frames were triggered at a 1-Hz rate with 4 retro-orbital injections of an ultrasonographic contrast agent at dosage of 10 microL/kg at 100-second intervals. Sham-treated mice received 400 frames of ultrasonography followed by the contrast agent with the ultrasound off. The primary tumor was surgically removed 1 day after ultrasound administration. Lungs were removed and evaluated blind after 2 weeks of bleaching in Fekete solution.

RESULTS

Three experiments were performed. The first experiment involved scanning sham and CADUS groups of 20 mice each with B16 tumors; B16 metastasis was not enhanced. The second experiment repeated this test with the D5 cell line; the metastasis enhancement was marginally significant for average number (0.3 and 3.2; P = .06) and incidence (3 and 9 of 19; P = .08) in mice without tumor recurrence. Finally, a third experiment was performed to clarify ambiguous results in the second experiment and consisted of 2 groups of 40 mice each. In this larger experiment, the results were essentially equal for the sham and CADUS groups.

CONCLUSIONS

Overall, the results do not support the hypothesis of CADUS-enhanced metastasis.

Radiofrequency ablation of liver cancer: early evaluation of therapeutic response with contrast-enhanced ultrasonography

The early assessment of the therapeutic response after percutaneous radiofrequency (RF) ablation is important, in order to correctly decide whether further treatment is necessary. The residual unablated tumor is usually depicted on contrast-enhanced multiphase helical computed tomography (CT) as a focal enhancing structure during the arterial and portal venous phases. Contrast-enhanced color Doppler and power Doppler ultrasonography (US) have also been used to detect residual tumors. Contrast-enhanced gray-scale US, using a harmonic technology which has recently been introduced, allows for the detection of residual tumors after ablation, without any of the blooming or motion artifacts usually seen on contrast-enhanced color or power Doppler US. Based on our experience and reports in the literature, we consider that contrast-enhanced gray-scale harmonic US constitutes a reliable alternative to contrast-enhanced multiphase CT for the early evaluation of the therapeutic response to RF ablation for liver cancer. This technique was also useful in targeting any residual unablated tumors encountered during additional ablation.