Baseline Tumor Lipiodol Uptake after Transarterial Chemoembolization for Hepatocellular Carcinoma: Identification of a Threshold Value Predicting Tumor Recurrence

Lipiodol accumulation patterns and their impact on survival outcomes in transarterial chemoembolization for hepatocellular carcinoma: a single institution retrospective analysis

Conventional Transarterial chemoembolization (TACE) using Lipiodol is a pivotal therapeutic modality for hepatocellular carcinoma (HCC). The link between Lipiodol accumulation patterns and patient survival outcomes remains underexplored. This study assesses the impact of these patterns on the prognosis of HCC patients undergoing TACE. We evaluated HCC patients treated with selective TACE between July 2015 and March 2020, classifying post-procedure Lipiodol accumulation observed on CT scans into four distinct patterns: homogeneous, heterogeneous, defective, and deficient. We analyzed cumulative local tumor recurrence (LTR), progression-free survival (PFS), and overall survival (OS) rates across these groups. Univariate and multivariate logistic regression analyses were performed to identify potential prognostic factors influencing PFS and OS. Among 124 HCC nodules, the distribution of Lipiodol patterns was: 65 homogeneous, 24 heterogeneous, 10 defective, and 25 deficient. Median PFS was 33.2, 9.1, 1.1, and 1.0 months, respectively, while median OS spanned 54.8, 44.5, 25.0, and 29.1 months for these groups. A significant difference in survival was found only between the homogeneous and defective patterns (hazard ratio, 2.33; confidence interval 1.25-4.36). Multivariate analyses revealed nonhomogeneous patterns as significant predictors of shorter PFS (HR 6.45, p < 0.001) and OS (HR 1.73, p = 0.033). Nonhomogeneous Lipiodol patterns in HCC following TACE significantly correlate with higher recurrence and decreased survival rates, especially with defective patterns. Early detection of these patterns may guide timely intervention strategies, potentially enhancing survival outcomes for patients with HCC.

Clinical impact and potential utility of non-enhanced computed tomography performed immediately after transarterial chemoembolization for hepatocellular carcinoma

Background

Intratumoral lipiodol deposition following transarterial chemoembolization (TACE) is associated with the prognosis of hepatocellular carcinoma (HCC) patients. However, there is insufficient evidence regarding the actual clinical significance of the imaging tests conducted to evaluate the lipiodol uptake after TACE. This study evaluates the clinical impact and potential utility of performing immediate post-TACE non-enhanced computed tomography (NECT) on the treatment of HCC.

Methods

This retrospective study at a tertiary referral center included patients undergoing their first session of conventional TACE for initial treatment of HCC from November 2021 to December 2022 with available immediate post-TACE NECT. Patients were categorized based on lipiodol uptake into Cohorts A (incomplete uptake with additional treatment before the first follow-up 1 month after TACE), B incomplete uptake without additional treatment before first follow-up), and C (complete uptake). Survival curves for the time to progression (TTP) were estimated using the Kaplan-Meier method and were compared by using the log-rank test.

Results

Out of 189 patients, 58 (29.6%) showed incomplete lipiodol uptake; 2 in Cohort A and 56 in Cohort B. Cohort C included 131 patients (69.3%). Cohort B had the highest rate of residual viable tumor (48.2%) 1 month after TACE, compared to the other cohorts (0% in Cohort A and 32.1% in Cohort C). The median TTP of Cohort B was 7.9 months [95% confidence interval (CI): 4.6-15.7 months], significantly shorter than the 15.4 months (95% CI: 10.9-20.9 months) for Cohort C (P=0.03). During follow-up, no progression occurred in Cohort A.

Conclusions

Assessment of lipiodol uptake by performing immediate post-TACE NECT can stratify HCC patients and facilitate early prediction of therapeutic response. Identifying suboptimal lipiodol uptake immediately after TACE can aid future treatment adjustments and potentially improving oncologic outcomes.

Ethiodized oil as an imaging biomarker after conventional transarterial chemoembolization

Conventional transarterial chemoembolization (cTACE) utilizing ethiodized oil as a chemotherapy carrier has become a standard treatment for intermediate-stage hepatocellular carcinoma (HCC) and has been adopted as a bridging and downstaging therapy for liver transplantation. Water-in-oil emulsion made up of ethiodized oil and chemotherapy solution is retained in tumor vasculature resulting in high tissue drug concentration and low systemic chemotherapy doses. The density and distribution pattern of ethiodized oil within the tumor on post-treatment imaging are predictive of the extent of tumor necrosis and duration of response to treatment. This review describes the multiple roles of ethiodized oil, particularly in its role as a biomarker of tumor response to cTACE. CLINICAL RELEVANCE: With the increasing complexity of locoregional therapy options, including the use of combination therapies, treatment response assessment has become challenging; Ethiodized oil deposition patterns can serve as an imaging biomarker for the prediction of treatment response, and perhaps predict post-treatment prognosis. KEY POINTS: • Treatment response assessment after locoregional therapy to hepatocellular carcinoma is fraught with multiple challenges given the varied post-treatment imaging appearance. • Ethiodized oil is unique in that its' radiopacity can serve as an imaging biomarker to help predict treatment response. • The pattern of deposition of ethiodozed oil has served as a mechanism to detect portions of tumor that are undertreated and can serve as an adjunct to enhancement in order to improve management in patients treated with intraarterial embolization with ethiodized oil.

Lipiodol as a Predictive Indicator for Therapy Response to Transarterial Chemoembolization of Hepatocellular Carcinoma

Background: The predictive value of Lipiodol was evaluated for response evaluation of hepatocellular carcinoma (HCC) treated with conventional transarterial chemoembolization (cTACE) by analysis of the enhancement pattern during angiography and in postinterventional computed tomography (CT). Materials and Methods: This retrospective study included 30 patients (mean age 63 years, range: 36 to 82 years, 22 males) with HCC. Patients received three Lipiodol-based cTACE sessions, each followed by an unenhanced CT within 24-h. Contrast-enhanced magnetic resonance imaging (MRI) was acquired before and after the treatment to determine tumor response. Lipiodol enhancement pattern, tumor vascularization, and density were evaluated by angiography and CT. Initial tumor size and response to cTACE were analyzed by MRI according to modified response evaluation criteria in solid tumors (mRECIST) in a 4-week follow-up. Results: Analysis of HCC lesions (68 lesions in 30 patients) during cTACE revealed clear visibility and hypervascularization in angiography as a potential independent parameter able to predict tumor response. A significant correlation was found for response measurements by volume (p = 0.012), diameter (p = 0.006), and according to mRECIST (p = 0.039). The amount of Lipiodol and enhancement pattern in postinterventional CT did not correlate with therapy response. Measurements of Hounsfield unit values after cTACE do not allow sufficient prediction of the tumor response. Conclusion: Hypervascularized HCC lesions with clear visibility after Lipiodol administration in the angiography respond significantly better to cTACE compared to hypo- or nonvascularized lesions.

Preoperative Balloon-Occluded Transcatheter Arterial Chemoembolization Followed by Surgical Resection: Pathological Evaluation of Necrosis

This study investigates the clinical and pathological outcomes of preoperative balloon-occluded transcatheter arterial chemoembolization (B-TACE) in patients with single hepatocellular carcinoma (HCC). The data are from 25 consecutive patients who underwent sequential treatment of subsegmental B-TACE and hepatic surgery for single HCC. Radiological and pathological evaluation of oily subsegmentectomy, defined as the iodized oil-laden necrotic area that includes the entire HCC and surrounding liver parenchyma, were performed. Subsegmental B-TACE was technically successful in all patients. The major and minor complication rates were 8% and 24%, respectively. On the first follow-up computed tomography (CT), oily subsegmentectomy was observed in 18 (72%) out of 25 patients. Apart from one patient showing a partial response, the remaining 24 (96%) patients showed a complete response. Pathological complete necrosis of the HCC was observed in 18 (72%) out of 25 patients with complete or extensive necrosis of the peritumoral liver parenchyma. The remaining seven patients without peritumoral parenchymal necrosis had extensive necrosis of the HCCs. In conclusion, preoperative B-TACE can be a safe and effective method for the treatment of single HCC and a good bridge treatment for subsequent surgical resection. In addition, oily subsegmentectomy itself on the CT can be a good predictor of pathological complete necrosis of the HCC. The findings obtained from this study would provide a potential role of B-TACE in the treatment strategy for single HCC.

Perspectives of Cone-beam Computed Tomography in Interventional Radiology: Techniques for Planning, Guidance, and Monitoring

Cone-beam computed tomography (CBCT) has emerged as a prominent imaging modality in interventional radiology that offers real-time visualization and precise guidance in various procedures. This article aims to provide an overview of the techniques used to guide and monitor interventions that use CBCT. It discusses the advantages of CBCT, its current applications, and potential future CBCT-related developments in the field of interventional radiology.

Quantitative Automated Segmentation of Lipiodol Deposits on Cone Beam CT Imaging acquired during Transarterial Chemoembolization for Liver Tumors: A Deep Learning Approach

PURPOSE

The purpose of this study was to show that a deep learning-based, automated model for Lipiodol segmentation on CBCT after cTACE performs closer to the "ground truth segmentation" than a conventional thresholding-based model.

MATERIALS & METHODS

This post-hoc analysis included 36 patients with a diagnosis of HCC or other solid liver tumor who underwent cTACE with an intra-procedural CBCT. Semi-automatic segmentation of Lipiodol were obtained. Then, a convolutional U-net model was used to output a binary mask that predicts Lipiodol deposition. A threshold value of signal intensity on CBCT was used to obtain a Lipiodol mask for comparison. Dice similarity coefficient (DSC), Mean-squared error (MSE), and Center of Mass (CM), and fractional volume ratios for both masks were obtained by comparing them to the ground truth (radiologist segmented Lipiodol deposits) to obtain accuracy metrics for the two masks. These results were used to compare the model vs. the threshold technique.

RESULTS

For all metrics, the U-net outperformed the threshold technique: DSC (0.65±0.17 vs. 0.45±0.22,p<0.001) and MSE (125.53±107.36 vs. 185.98±93.82,p=0.005). Difference between the CM predicted, and the actual CM was (15.31±14.63mm vs. 31.34±30.24mm,p<0.001), with lesser distance indicating higher accuracy. The fraction of volume present ([predicted Lipiodol volume]/[ground truth Lipiodol volume]) was 1.22±0.84vs.2.58±3.52,p=0.048 for our model's prediction and threshold technique, respectively.

CONCLUSION

This study showed that a deep learning framework could detect Lipiodol in CBCT imaging and was capable of outperforming the conventionally used thresholding technique over several metrics. Further optimization will allow for more accurate, quantitative predictions of Lipiodol depositions intra-procedurally.

Ultrasonic Heating Detects Lipiodol Deposition within Liver Tumors after Transarterial Embolization: An In Vivo Approach

Simple Summary

The accumulation of Lipiodol (ethiodized oil) after transarterial embolization is known to reflect tumor necrosis. In general, the treatment effect is evaluated by computed tomography; there has been no development in imaging modalities for several decades. A new technique, ultrasonic heating, can differentiate biological tissues based on the fact that tissues’ characteristic sound velocity varies depending on the temperature. This technique could have the potential to evaluate treatment effect after transarterial embolization as an alternative to computed tomography.

Abstract

Computed tomography (CT) is the standard method to evaluate Lipiodol deposition after transarterial embolization (TAE) for a long period. However, iodine but not Lipiodol can be observed on CT. A minimally invasive other method to detect Lipiodol has been needed to evaluate accurate evaluation after procedure. The purpose of this study was to evaluate the efficacy of using the rate of change in sound velocity caused by ultrasonic heating to reflect Lipiodol accumulation after TAE in a rat liver tumor model. We analyzed the association of this developed technique with CT images and histological findings. Eight rats bearing N1S1 cells were prepared. After confirmation of tumor development in a rat liver, Lipiodol was injected via the hepatic artery. Seven days after TAE, CT scan and sound velocity changes caused by ultrasonic heating were measured, and then the rats were sacrificed. An ultrasonic pulse-echo method was used to measure the sound velocity. The temperature coefficient of the sound velocity in each treated tumor was evaluated and compared with the mean CT value and the histological Lipiodol accumulation ratio. Pearson’s correlation coefficients were calculated to assess the correlation between the measured values. The correlation coefficient (r) of the mean CT value and histological Lipiodol accumulation ratio was 0.835 (p = 0.010), which was considered statistically significant. Also, those of the temperature coefficient of the sound velocity and the histological Lipiodol accumulation ratio were statistically significant (r = 0.804; p = 0.016). To our knowledge, this is the first study that reported the efficacy of ultrasonic heating to detect Lipiodol accumulation in rat liver tumors after TAE. Our results suggest that the rate of change in sound velocity caused by ultrasonic heating can be used to evaluate Lipiodol accumulation in liver tumors after TAE, and thus could represent an alternative to CT in this application. This new innovative technique is easy to treat and less invasive in terms of avoiding radiation compared with CT.

Spectral CT-Based Iodized Oil Quantification to Predict Tumor Response Following Chemoembolization of Hepatocellular Carcinoma

PURPOSE

To quantify iodized oil retention in tumors after transarterial chemoembolization using spectral computed tomography (CT) imaging in patients with hepatocellular carcinoma (HCC) and evaluate its performance in predicting 12-month tumor responses.

MATERIALS AND METHODS

From September 2017 to December 2018, 111 patients with HCC underwent initial conventional transarterial chemoembolization. Immediately after the procedure, unenhanced CT was performed using a spectral CT scanner, and the iodized oil densities in index tumors were measured. In tumor-level analyses, a threshold level of iodized oil density in the tumors was calculated using clustered receiver operating characteristic curve analyses to predict the 12-month tumor responses. In patient-level analyses, significant factors associated with a 12-month complete response, including the presence of tumors below the threshold value (ie, suspected residual tumors), were evaluated by logistic regression.

RESULTS

Forty-eight HCCs in 39 patients were included in the analyses. The lower 10th percentile of the iodine density was identified as the threshold for determining the 12-month nonviable responses. The area under the curve of the iodine density measurements in predicting the 12-month nonviable responses was 0.893 (95% confidence interval, 0.797-0.989). The threshold value of the iodine density of 10.68 mg/mL yielded a sensitivity of 82.76% and specificity of 94.74% (P < .001). In the patient-level analysis, the 12-month complete response was significantly associated with the presence of a suspected residual tumor, with an odds ratio of 72.0 (95% confidence interval, 7.273-712.770).

CONCLUSIONS

Spectral CT imaging using quantitative analysis of the iodized oil retention in target HCCs can predict tumor responses after a conventional transarterial chemoembolization procedure.

Occurrence of Vascular Lake Phenomenon Before Embolization for the Prediction of Lipiodol Uptake for Intermediate-Stage Hepatocellular Carcinoma Patients that Underwent cTACE

PURPOSE

To compare Lipiodol uptake and tumor response in intermediate-stage hepatocellular carcinoma (HCC) with and without pre-embolization vascular lake phenomenon (VLP) and to identify the incidence and predictive factors of this phenomenon, in patients treated by conventional transarterial chemoembolization (cTACE).

MATERIALS AND METHODS

This retrospective study included 151 consecutive patients with intermediate HCC totaling 232 nodules, who underwent cTACE from June 2015 to October 2018. Patients were divided into two groups according to the presence of VLP before embolization. Initial Lipiodol uptake was assessed using post-cTACE computed tomography (CT) within 1-1.5 months after cTACE. Enhanced CT or magnetic resonance imaging was performed at 6 months after the procedure to assess local recurrence and distant metastasis.

RESULTS

The VLP was demonstrated in 21.85% (33/151) patients and 16.81% (39/232) nodules on the super-selective angiography. On nodule-based analysis, significantly better Lipiodol uptake (p < 0.001) and higher ORR (60.61% vs. 26.49%, p < 0.001) and DCR (87.88% vs. 51.66%, p < 0.001) were observed in the VLP group compared to the non-VLP group. The multivariate logistic regression analysis showed that the presence of VLP (OR 6.431, 95% CI 2.495-16.579) might be a predictive factor for better Lipiodol uptake. Univariate and multivariate logistic regression analysis showed that poor differentiation of tumor (OR 6.397, 95% CI 2.804-19.635) remained predictive for the VLP.

CONCLUSION

The incidence of VLP before embolization is 21.19%. The presence of VLP is well correlated with tumor Lipiodol uptake after cTACE and may be a new predictive factor for evaluation of cTACE efficacy and prognosis of intermediate HCC.

Antitumor Effects of Intra-Arterial Delivery of Albumin-Doxorubicin Nanoparticle Conjugated Microbubbles Combined with Ultrasound-Targeted Microbubble Activation on VX2 Rabbit Liver Tumors

Image-guided intra-arterial therapies play a key role in the management of hepatic malignancies. However, limited clinical outcomes suggest the need for new multifunctional drug delivery systems to enhance local drug concentration while reducing systemic adverse reactions. Therefore, we developed the albumin-doxorubicin nanoparticle conjugated microbubble (ADMB) to enhance therapeutic efficiency by sonoporation under exposure to ultrasound. ADMB demonstrated a size distribution of 2.33 ± 1.34 µm and a doxorubicin loading efficiency of 82.7%. The echogenicity of ADMBs was sufficiently generated in the 2–9 MHz frequency range and cavitation depended on the strength of the irradiating ultrasound. In the VX2 rabbit tumor model, ADMB enhanced the therapeutic efficiency under ultrasound exposure, compared to free doxorubicin. The intra-arterial administration of ADMBs sufficiently reduced tumor growth by five times, compared to the control group. Changes in the ADC values and viable tumor fraction supported the fact that the antitumor effect of ADMBs were enhanced by evidence of necrosis ratio (over 70%) and survival tumor cell fraction (20%). Liver toxicity was comparable to that of conventional therapies. In conclusion, this study shows that tumor suppression can be sufficiently maximized by combining ultrasound exposure with intra-arterial ADMB administration.