Focal hepatic lesions: evaluation with contrast-enhanced gray-scale harmonic US

Intratumor Heterogeneity in Hepatocellular Carcinoma: Challenges and Opportunities

Hepatocellular carcinoma (HCC) represents a leading cause of cancer-related death, but it remains difficult to treat. Intratumor genetic and phenotypic heterogeneity are inherent properties of breast, skin, lung, prostate, and brain tumors, and intratumor heterogeneity (ITH) helps define prognosis and therapeutic response in these cancers. Several recent studies estimate that ITH is inherent to HCC and attribute the clinical intractability of HCC to this heterogeneity. In this review, we examine the evidence for genomic, phenotypic, and tumor microenvironment ITH in HCC, with a focus on two of the top molecular drivers of HCC: β-catenin (CTNNB1) and Telomerase reverse transcriptase (TERT). We discuss the influence of ITH on HCC diagnosis, prognosis, and therapy, while highlighting the gaps in knowledge and possible future directions.

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.

Use of accumulation images obtained by arterial-phase contrast-enhanced harmonic grayscale ultrasonography to evaluate tumor vessels in focal nodular hyperplasia and other hepatic tumors

PURPOSE

To evaluate the usefulness of accumulation images obtained by arterial-phase contrast-enhanced harmonic grayscale ultrasonography for examining tumor vessels in focal nodular hyperplasia and other hepatic lesions.

METHODS

After injecting a galactose-palmitic acid contrast agent, we used conventional contrast-enhanced harmonic grayscale ultrasonography to scan 8 focal nodular hyperplasia lesions, 21 hepatocellular carcinomas, 2 cholangiocellular carcinomas, 12 hepatic metastases, 17 hemangiomas, and 2 angiomyolipomas. We then accumulated and superimposed consecutive conventional images (accumulation images) and compared them with corresponding conventional images to evaluate serial images of hepatic tumor vessels.

RESULTS

Serial tumor vessel findings obtained from accumulation images were superior to those obtained from conventional images in 51 (77%) of the 66 various hepatic lesions examined. Evidence of the spoke-wheel artery pattern in 2 of the 8 focal nodular hyperplasia lesions was equivocal in the conventional images, but accumulation images clearly depicted serial images of spoke-wheel arteries, clearly indicating a diagnosis of focal nodular hyperplasia. Accumulation images allowed the diagnosis of two additional focal nodular hyperplasia lesions that had not been correctly diagnosed as focal nodular hyperplasia from conventional images.

CONCLUSION

Accumulation images obtained by arterial-phase contrast-enhanced harmonic grayscale ultrasonography are useful in evaluating hepatic tumor vessels, especially spoke-wheel arteries, which specifically indicate focal nodular hyperplasia.

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.

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.

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.

Contrast-enhanced ultrasonographic imaging diagnosis on assessment of vascularity in liver metastatic lesions

AIM: To investigate the vasculature of rabbit liver metastatic lesions by color Doppler imaging and power Doppler imaging (PDI) techniques.

METHODS: Eight New Zealand rabbits with implanted VX2 liver tumors were used. All ultrasound examinations were performed with a HP 5500 color Doppler ultrasound scanner. Before and after the injection of contrast agent, the changes of gray scale and the periphery and intralesional blood flow of the liver metastatic lesion were carefully observed by B mode ultrasound, color Doppler flow imaging (CDFI) and PDI.

RESULTS: Twelve lesions were found in the eight rabbits with implanted VX2 liver tumors, whose diameter ranged from 1.6 to 4.8 cm. Echoes of these lesions were not characterized and has lack of specificity. After the injection of contrast agent, the numbers of dot or strip-like flow messages increased both at the periphery and inside of these lesions under the mode of CDFI and PDI, and were more pronounced under PDI. Morphology of intralesional vessels extended, even branched and some signals were clearly found encircling the lesion. And some vessels were found penetrating into the center of the lesion.

CONCLUSION: PDI after injection of self-made echo contrast agent can show a pronounced sensitivity than that of B mode ultrasound and CDFI in diagnosis of vascularity of a metastatic lesion.

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.

Imaging diagnosis of hepatocellular carcinoma with differentiation from other pathology

Recent advances in liver imaging techniques and better understanding of imaging findings have facilitated the detection and characterization of hepatocellular nodules in a cirrhotic liver. It is important to recognize that various types of benign nodules and pseudolesions are identified on all imaging scans performed for the diagnosis of hepatocellular carcinoma. An accurate differentiation between them is critical for adequate management of cirrhotic patients. Unfortunately, any of the imaging tests and even percutaneous biopsy are not diagnostic for borderline lesions. Intimate collaboration of hepatologists, pathologists, surgeons, and radiologists with reasonable imaging and clinical criteria estimating the degree of malignancy is imperative.

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.

Focal hepatic lesions: contrast-enhancement patterns at pulse-inversion harmonic US using a microbubble contrast agent

Objective

To analyze the contrast-enhancement patterns obtained at pulse-inversion harmonic imaging (PIHI) of focal hepatic lesions, and to thus determine tumor vascularity and the acoustic emission effect.

Materials and Methods

We reviewed pulse-inversion images in 90 consecutive patients with focal hepatic lesions, namely hepatocellular carcinoma (HCC) (n=43), metastases (n=30), and hemangioma (n=17). Vascular and delayed phase images were obtained immediately and five minutes following the injection of a microbubble contrast agent. Tumoral vascularity at vascular phase imaging and the acoustic emission effect at delayed phase imaging were each classified as one of four patterns.

Results

Vascular phase images depicted internal vessels in 93% of HCCs, marginal vessels in 83% of metastases, and peripheral nodular enhancement in 71% of hemangiomas. Delayed phase images showed inhomogeneous enhancement in 86% of HCCs; hypoechoic, decreased enhancement in 93% of metastases; and hypoechoic and reversed echogenicity in 65% of hemangiomas. Vascular and delayed phase enhancement patterns were associated with a specificity of 91% or greater, and 92% or greater, respectively, and with positive predictive values of 71% or greater, and 85% or greater, respectively.

Conclusion

Contrast-enhancement patterns depicting tumoral vascularity and the acoustic emission effect at PIHI can help differentiate focal hepatic lesions.

[Ultrasound imaging of focal liver lesions with contrast agents: which clinical applications?]

The contrast-enhanced ultrasonography is a promising technique for the diagnosis of focal liver lesion with an increased sensitivity for the tumour detection and a direct visualization of the tumour vascularity. The future applications of this technique will probably depend on the clinical context: in case of suspicion of benign tumour, contrast injection should be able to facilitate the characterization of hemangiomas and focal nodular hyperplasia, when hepatic metastases are researched, it may improve the detection of small lesions in cirrhotic patients, it may facilitate the detection of small hepatocellular carcinomas and find a place in the systematic screening for these tumours. The recently published data are encouraging, but a confirmation of the clinical interest of this technique, and its place within the imaging diagnostic strategies still have to be performed.

Evaluation of hepatic focal nodular hyperplasia with contrast-enhanced gray scale harmonic sonography: initial experience

OBJECTIVE

To assess the potential of contrast-enhanced gray scale harmonic sonography in the evaluation of the typical vascular and enhancement patterns of hepatic focal nodular hyperplasia.

METHODS

Thirteen patients with 13 lesions of hepatic focal nodular hyperplasia underwent contrast-enhanced gray scale harmonic sonography. After the injection of a microbubble contrast agent (SH U 508A), gray scale harmonic sonographic studies using a Coded Harmonic Angio technique were performed with a combination of a period of continuous scanning to assess the vascular pattern (vascular imaging) and interval delay scanning to determine the sequential enhancement pattern (acoustic emission imaging). Each imaging pattern was categorized and analyzed by consensus of 2 experienced radiologists.

RESULTS

In 12 (92%) of 13 lesions, vascular imaging during the arterial phase showed central arteries of a spoked wheel pattern, whereas the remaining lesion had stippled vascularity. On acoustic emission imaging, 11 (85%) of 13 lesions were hyperechoic during the early phase, and the remaining 2 (15%) were isoechoic compared with surrounding parenchyma. Ten (77%) of 13 lesions remained either hyperechoic (5 of 13) or isoechoic (5 of 13) during the delay phase, whereas the remaining 3 lesions (23%) were hypoechoic.

CONCLUSIONS

Contrast-enhanced gray scale harmonic sonography showed the typical vascularity of a spoked wheel pattern during the vascular phase and persistent enhancement on serial acoustic emission imaging in most cases of hepatic focal nodular hyperplasia, and thereby it can be a promising technique in noninvasive diagnosis of this entity.