Follow-Up 18F-FDG PET/CT versus Contrast-Enhanced CT after Ablation of Liver Metastases of Colorectal Carcinoma-A Cost-Effectiveness Analysis

Abstract

Purpose: After a percutaneous ablation of colorectal liver metastases (CRLM), follow-up investigations to evaluate potential tumor recurrence are necessary. The aim of this study was to analyze whether a combined 18F-Fluordesoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) scan is cost-effective compared to a contrast-enhanced computed tomography (CE-CT) scan for detecting local tumor progression.

Materials and methods: A decision model based on Markov simulations that estimated lifetime costs and quality-adjusted life years (QALYs) was developed. Model input parameters were obtained from the recent literature. Deterministic sensitivity analysis of diagnostic parameters based on a Monte-Carlo simulation with 30,000 iterations was performed. The willingness-to-pay (WTP) was set to $100,000/QALY.

Results: In the base-case scenario, CE-CT resulted in total costs of $28,625.08 and an efficacy of 0.755 QALYs, whereas 18F-FDG PET/CT resulted in total costs of $29,239.97 with an efficacy of 0.767. Therefore, the corresponding incremental cost-effectiveness ratio (ICER) of 18F-FDG PET/CT was $50,338.96 per QALY indicating cost-effectiveness based on the WTP threshold set above. The results were stable in deterministic and probabilistic sensitivity analyses.

Conclusion: Based on our model, 18F-FDG PET/CT can be considered as a cost-effective imaging alternative for follow-up investigations after percutaneous ablation of colorectal liver metastases.

Keywords: 18F-FDG PET/CT; cost-effectiveness; liver metastases; nuclear imaging; oncologic imaging.

Figure 1

Markov simulation for two years. (a). Outcomes for patients receiving a timely reablation (true positive). (b). Outcomes of patients without initially needed reablation (true negative and false positive). (c). Outcomes of patients with delayed reablation (false negative).

Figure 1

Markov simulation for two years. (a). Outcomes for patients receiving a timely reablation (true positive). (b). Outcomes of patients without initially needed reablation (true negative and false positive). (c). Outcomes of patients with delayed reablation (false negative).

Figure 2

Deterministic sensitivity analysis. (a). Tornado diagram showing the impact of input parameters on incremental cost-effectiveness ratio (ICER) starting from expected value (EV) in base case scenario. For every parameter range investigated, the ICER of 18F-FDG PET/CT remained below the willingness-to-pay threshold of $100,000 per QALY (quality of life year) indicating cost-effectiveness of 18F-FDG PET/CT in this setting. (b). Analysis investigating the impact of probability of complete ablation on cost-effectiveness. Especially in patients with high risk of incomplete ablation, 18F-FDG PET-CT is the cost-effective strategy in comparison to CE-CT. ICER, incremental cost-effectiveness ratio; WTP, willingness-to-pay.

Figure 2

Deterministic sensitivity analysis. (a). Tornado diagram showing the impact of input parameters on incremental cost-effectiveness ratio (ICER) starting from expected value (EV) in base case scenario. For every parameter range investigated, the ICER of 18F-FDG PET/CT remained below the willingness-to-pay threshold of $100,000 per QALY (quality of life year) indicating cost-effectiveness of 18F-FDG PET/CT in this setting. (b). Analysis investigating the impact of probability of complete ablation on cost-effectiveness. Especially in patients with high risk of incomplete ablation, 18F-FDG PET-CT is the cost-effective strategy in comparison to CE-CT. ICER, incremental cost-effectiveness ratio; WTP, willingness-to-pay.

Figure 3

Probabilistic sensitivity analysis utilizing Monte-Carlo simulations with 30,000 iterations. (a). Incremental cost-effectiveness scatterplot (18F-FDG PET-CT vs. CE-CT). (b). Cost-effectiveness acceptability curve dependent on willingness-to-pay (WTP). 18F-FDG PET-CT is cost-effective in the majority of iterations above a WTP-threshold of $45,000.

Figure 3

Probabilistic sensitivity analysis utilizing Monte-Carlo simulations with 30,000 iterations. (a). Incremental cost-effectiveness scatterplot (18F-FDG PET-CT vs. CE-CT). (b). Cost-effectiveness acceptability curve dependent on willingness-to-pay (WTP). 18F-FDG PET-CT is cost-effective in the majority of iterations above a WTP-threshold of $45,000.

Figure 4

Patient from our institution undergoing microwave ablation (MWA) for oligometastatic liver disease. (a). Pre-interventional CT in portal-venous phase shows contrast-enhancing metastasis in segment VIII. (b). Pre-interventional MRI in hepatocyte-specific phase. (c). Interventional imaging during MWA. (d). CT in portal-venous phase acquired immediately after intervention without evidence of complication or residual tumor. (e). Four-month follow-up F-18 FDG PET/CT without morphological evidence of recurrence in CT component. (f). PET-component acquired at same scan 4-month after MWA with tracer accumulation at the margins of the previous ablation in line with recurrence. Additional metastases without morphological evidence in the CT component can also be depicted.

Figure 5

Model overview. (a). Decision model for both strategies incorporating CE-CT and 18F-FDG PET/CT. For each outcome, a Markov model analysis was performed; (b). Markov model with potential states “No recurrence”, “Hepatic recurrence only”, “Any other recurrence” and “Death”. The first state was determined depending on the outcomes in the decision model.

Figure 5

Model overview. (a). Decision model for both strategies incorporating CE-CT and 18F-FDG PET/CT. For each outcome, a Markov model analysis was performed; (b). Markov model with potential states “No recurrence”, “Hepatic recurrence only”, “Any other recurrence” and “Death”. The first state was determined depending on the outcomes in the decision model.