Imaging Evaluation of Tumor Response

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.

Comparison between color power Doppler ultrasound with echo-enhancer and spiral computed tomography in the evaluation of hepatocellular carcinoma vascularization before and after ablation procedures

OBJECTIVE

Use of new echo enhancers capable of passing the lung filter has extended the clinical applications of color power Doppler flow imaging in many diseases and appears promising in the study of neoplasm vascularization. Levovist (Shering, Berlin Germany) is an ultrasound contrast agent containing galactose microbubbles suspended in palmitic oil. The sensitivity of Levovist-enhanced color power Doppler was compared to that of standard color power Doppler and contrast-enhanced spiral computed tomography (CT) in the detection of vascular signals in hepatocellular carcinoma.

METHODS

We examined 29 hepatocellular carcinoma nodules in cirrhotic livers that had appeared avascular on unenhanced color power Doppler. Color power Doppler studies were repeated with and without Levovist enhancement before (15 examinations) and/or after (23 examinations) percutaneous ablation procedures. Findings (vascularized vs nonvascularized) were compared to those obtained with contrast-enhanced spiral computed tomography (gold standard) performed no more than 24 h after each of the 38 Doppler examinations.

RESULTS

In pretreatment studies, Levovist-enhanced power Doppler correctly revealed vascularization in 12 of 15 lesions that had appeared avascular without echo enhancement and confirmed the avascularity of one other nodule; the remaining two, which appeared avascular on contrast-enhanced Doppler, displayed vascularization on the spiral CT examination. Levovist-enhanced power Doppler was fully concordant with spiral CT findings in all of the posttreatment examinations.

CONCLUSION

Considering the absence of false positive results in this study, echo-enhanced color power Doppler can be considered reliable in diagnosing incomplete necrosis of hepatocellular carcinomas after percutaenous ablation. Spiral computed tomography can thus be reserved for those cases in which the enhanced power Doppler examination reveals no evidence of vascularity.