KEY POINTS
- This PRISMA-ScR scoping review searched PubMed, Embase, and references for studies published from January 2012 to February 2025; 8 studies met inclusion criteria.
- Eligible studies included adults with hepatocellular carcinoma treated with stereotactic, image-guided, highly conformal external-beam radiation therapy delivered in limited fractions with ablative intent.
- Post-treatment magnetic resonance imaging showed delayed evolution rather than immediate regression. In one cohort, non-progressing lesions transitioned to delayed enhancement in 71.9% and complete non-enhancement in 20.8%, typically stabilizing after 6–9 months.
- Early enhancement was a major pitfall: one responder series reported central arterial phase hyperenhancement in 40% and washout in 90% within the first year, despite response criteria and size reduction in 90%.
- Focal liver reaction was frequent and included ring-like or perilesional enhancement, T2 hyperintensity, hepatobiliary-phase hypointensity, capsular retraction, and dose-related parenchymal changes; no treatment-toxicity endpoint was assessed in this imaging-focused review.
CLINICAL TAKEAWAY
Response assessment after stereotactic body radiation therapy for hepatocellular carcinoma should be serial and multiparametric, not based on early arterial enhancement alone. Stable or regressing geographic/rim-like changes favor focal liver reaction, whereas new or increasing nodular or mass-like enhancement with washout, growth, rising T2 or diffusion-weighted signal, or absent apparent diffusion coefficient increase should raise concern. This is a useful review-level synthesis of a small, heterogeneous, mostly retrospective evidence base, so it supports cautious interpretation rather than a new response standard.