Mediation and prognostic value of apparent diffusion coefficient in HCC patients receiving immune checkpoint inhibitors

OBJECTIVES: The study investigated the potential association between tumor size and inflammation from the standpoint of apparent diffusion coefficient (ADC) and the prognostic significance of ADC in hepatocellular carcinoma (HCC) patients treated with immune checkpoint inhibitors (ICIs). MATERIALS AND METHODS: This retrospective study ultimately included 255 HCC patients receiving ICIs, among whom 168 underwent posttreatment diffusion-weighted imaging at three months. The study analyzed the correlations among pretreatment tumor maximum diameter, inflammatory markers (neutrophil to lymphocyte ratio, NLR; platelet to lymphocyte ratio, PLR), and ADC (substantial tumor ADC, sADC; whole tumor ADC, wADC), as well as exploring the association between tumor maximum diameter and inflammatory markers regarding ADC. This study further focused on the prognostic value of baseline and relative change in ADC in HCC patients receiving ICIs. RESULTS: The study found a potential relationship between tumor maximum diameter and inflammatory markers regarding sADC. Multivariate Cox regression showed that higher sADC was associated with longer overall survival (OS) (HR: 0.63, 95% CI: 0.43-0.91, p = 0.015). Additionally, the relative change in sADC (ΔsADC) positive group exhibited better progression-free survival (12 vs 6.4 months, p < 0.001) and OS (20.5 vs 13.3 months, p < 0.001) compared to the ΔsADC non-positive group, serving as an independent prognostic factor for HCC patients receiving ICIs. CONCLUSIONS: The association between tumor burden and inflammatory markers was observed regarding sADC, with baseline sADC and relative change promising as prognostic imaging biomarkers in HCC patients receiving ICIs. CRITICAL RELEVANCE STATEMENT: The substantial tumor ADC is an important imaging feature revealing the potential association between tumor burden and inflammation, and its prognostic role for patients with HCC receiving ICIs. KEY POINTS: The sADC could indirectly reflect tumor microenvironment characteristics. The association between tumor burden and inflammatory markers was observed regarding sADC. Baseline sADC and its change predict prognosis in ICI-treated HCC patients.