The therapeutic effect of transcatheter arterial thromboembolization of hepatocellular carcinoma as for residual viable tumors related to lipiodol density areas and detected by 18F-FDG PET/CT and CT

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide and causes about one million deaths annually [1, 2], however, most patients are diagnosed at an advanced stage, Transcatheter arterial chemoembolization (TACE) is one of the most common and effective palliative treatments and meta-analysis of a randomized controlled trial has shown that survival is improved after treatment [3]. Despite documented survival benefits, TACE can also induce the up-regulation of proangiogenic and growth factors, which might contribute to accelerate the progression of HCC in patients with incomplete response. Therefore, it is clinically important to analyse the therapeutic effect of TACE as soon as possible [4]. Conventional imaging modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI), cannot satisfy clinicians in that context, because treatment evaluation by these anatomical imaging modalities requires a sufficient period of time in order to confirm tumor shrinkage. Additionally, the ability of contrast CT to determine tumor viability after TACE is limited, because the retained hyperattenuating lipiodol makes it difficult to detect contrast enhancement within a viable tumor. The 18F-fluoro-2-deoxy-D-glucose positron-emission-tomography (18F-FDG PET) is a functional imaging tool that provides metabolic information of the lesion. It is effective for diagnosis, monitoring treatment and detection of recurrent tumors of various cancers because of its high sensitivity and specificity [5]. In contrast to morphological imaging techniques such as CT, the 18F-FDG PET evaluates tumor viability based on glucose metabolism; it is not influenced by tumor morphology or lipiodol deposition. Therefore, as several investigators have previously reported 18F-FDG PET might be useful for monitoring response and for being a guide in following treatment [6]. Our present report and a previous study of ours have shown that increased 18F-FDG uptake was not correlated with lipiodol dense distribution [7]. Researchers have also found that 18FDG PET was valuable to reveal recurrent tumor or residual tumor in HCC patients after TACE [8]. Jinpeng Li1 MD, Wenbo Shao1MD, PhD, Jinlong Song1 MD, Congcong Shi2, Hua Chen1 MD, Ning Cong1 MD. (Jinpeng Li and Wenbo Shao contributed equally to this study)