TACE is a standard treatment for patients with intermediate to advanced liver cancer, crucial for disease control, conversion therapy, and bridging to liver transplantation [24]. Given the variable responses and prognoses to TACE among liver cancer patients, predicting efficacy and prognosis post-TACE is essential for evaluating patient response and informing clinical decisions to enhance outcomes. Tumor heterogeneity is a significant prognostic factor in liver cancer [25],and radiomics technology can extract detailed tumor information from medical imaging, highlighting lesion heterogeneity often overlooked by visual inspection [11, 26], This technology can provide insights into tumor biology and microenvironment, serving as a valuable complement to current clinical prediction tools and aiding in treatment decisions.
A recent meta-analysis involving CT or MRI imaging demonstrated that combined imaging-genomic clinical models outperformed standalone imaging or clinical models in predicting survival outcomes [27]. These findings underscore the significant potential of radiomics for predicting the efficacy and prognosis of liver cancer. Moreover, the results of this study surpass those of the meta-analyses, suggesting that intra-TACE DSA radiomics may offer more precise predictions compared to CT or MRI.
DSA provides high-resolution, real-time imaging of tumor morphology and blood supply, which is valuable for both diagnosis and treatment. However, its application in imaging-genomic analyses for liver cancer has been limited due to challenges such as brief image storage durations and restricted accessibility [18, 20]. Several factors contribute to this scarcity of research: the short retention time of DSA images and the difficulty in obtaining DSA images generated by intraoperative CBCT during TACE procedures. Additionally, the field of radiomics research using DSA images from CBCT is still emerging, with no high-throughput studies yet utilizing intra-TACE DSA imaging to analyze liver tumor vascular characteristics for survival predictions. Our study addresses this gap in the literature by exploring the potential of intra-TACE DSA imaging in this context.
Previous research has employed deep learning methods to analyze intra-TACE DSA and pre-TACE CT images for predicting tumor response following the initial TACE treatment for liver cancer. In these studies, the first, which utilized intra-TACE DSA images, reported AUC values of 0.782 and 0.670, while the second, based on pre-TACE CT images, yielded AUC values of 0.981 and 0.972 [18, 28]. The disparity in predictive performance may be attributed to the focus of deep learning models using intra-TACE DSA images on overall tumor features rather than on detailed vascular characteristics. Further research is needed to enhance the deep analysis of DSA vascular features to improve predictions of TACE efficacy.
In this study, patients were categorized into high-risk and low-risk groups based on their radiomics scores. The findings indicated that the median progression-free survival (mPFS) for low-risk patients was significantly greater than that for high-risk patients, with Kaplan‒Meier analysis showing a notable difference in progression-free survival between the two groups. This demonstrates that radiomics scores are valuable for risk stratification and prognosis assessment in liver cancer patients.
A key challenge of the study was the segmentation of vascular images, which required focusing on tumor blood vessels rather than overall tumor features. Additionally, since DSA images obtained during TACE are two-dimensional, the study needed to account for various factors such as gastrointestinal visualization, as well as artifacts caused by heart and diaphragm motion [18]. To address this, we selected the slice with optimal visualization of tumor blood vessels and minimal motion interference around the liver for each patient. We used the gray-scale differences between the blood vessels and surrounding tissues to define intensity ranges, allowing us to delineate the tumor area and extract tumor vascular images directly. However, this method has limitations. For instance, in patients with prior TACE treatments, iodine oil deposition may be present in the DSA images, necessitating that ROI delineation physicians manually remove this interference from the extracted ROI.
This study has the following limitations: First, the study had a small sample size and lacked external validation, potentially limiting the results. Second, its retrospective nature may introduce selection bias, and there was variability in patient characteristics and TACE treatments that was not standardized. Third, most patients had hepatitis B-related liver cancer, which differs from the primary causes of liver cancer observed in Western countries [29]. Future research should focus on larger, multicenter, and prospective studies to address these limitations. Given that liver cancers with different etiologies may display variations in vascular features, it is essential to include a broader range of patients, including those with alcohol-related and hepatitis C-related liver cancer, to enhance the understanding of these differences.