RESUMO
Prostatic artery embolization (PAE) has gained acceptance as a minimally invasive, safe and effective treatment of symptomatic benign prostatic hyperplasia. Radiologic imaging is an indispensable part of post-interventional evaluation of PAE and serves both clinical and investigational purposes. In this context, ultrasonography (US) has a central and multifaceted role. Gray-scale US is routinely utilized for measurement of significant outcome parameters (prostatic volume, intra-vesical prostatic protrusion and post-void residual volume) before and after PAE. Improvement of these parameters may become more obvious one-month post-PAE, or later. Contrast-enhanced US (CEUS) with intravenous administration of a second-generation echo-enhancer can demonstrate prostatic infarcts (as enhancement defects) immediately post-PAE and monitor their resolution over time. The volume of prostatic infarcts can also be measured and compared to prostatic volume. Prostatic infarction is a definite sign of the local efficacy of PAE and a predictor of prostate shrinkage and (at least in some patients) of clinical success. CEUS can also be performed intraoperatively in the angio-suite, for on-site evaluation of the ischemic effect; a variation of this technique, with intraarterial (instead of intravenous) administration of diluted echo enhancer, can also be applied intraoperatively, to map the embolized territory and to prevent non-target embolization. Initial experience with US-elastographic techniques (shear-wave and strain elastography) has shown that they can detect and quantify the improvement of tissue elasticity post-PAE, thus providing new insights into the therapeutic mechanisms of this treatment. With utilization of high-end equipment, experience and standardized imaging protocols, US could be the primary modality for imaging evaluation of PAE.
RESUMO
PURPOSE: To assess the diagnostic performance of computed tomography (CT), and of the combination of CT with contrast-enhanced ultrasonography (CT + CEUS), for the early evaluation of local response of hepatocellular carcinoma (HCC) treated with transarterial chemoembolization (TACE) with radiopaque drug-eluting microspheres (RO-DEMs). MATERIALS AND METHODS: 30 HCC patients (55 target tumors) were treated with TACE with RO-DEMs (diameter: 70-150 µm) preloaded with 75 mg doxorubicin/2 ml of microspheres. Unenhanced and contrast-enhanced CT, followed by CEUS, were performed 1-3 days post-RO-DEMs-TACE. Contrast-enhanced magnetic resonance (MR) performed 1 month later served as the reference standard. Local tumor response was evaluated with modified Response Evaluation Criteria in Solid Tumors (mRECIST). RESULTS: MR diagnosed 9 tumors with complete response and 46 with residual disease. Compared to MR, CT had 9 false negative and 1 false positive diagnosis for residual tumor. Potential causes for these misdiagnoses were the hyperdensities and associated artifacts (caused by the accumulation of RO-DEMs in the target tumors) and the small size of residual tumor. CT + CEUS had 3 false negative and no false positive diagnosis for residual tumor. The sensitivity, specificity and diagnostic accuracy of CT for detection of residual tumor were, respectively: 80.4%, 88.9% and 81.8%, and for CT + CEUS: 93.5%, 100% and 94.5%, respectively. Agreement (kappa coefficient) in application of mRECIST between MR and CT was lower than between MR and CT + CEUS (0.508 vs. 0.757). CONCLUSION: CT evaluation of TACE with RO-DEMs is associated with limitations which can be partially overcome by combining CT with CEUS.
