NIRA-11 [F18]FLUCICLOVINE PET AND DCE-MRI IN THE EVALUATION OF RECURRENCE VS TREATMENT EFFECT IN PREVIOUSLY RADIATED INTRACRANIAL METASTASES
Kate Rosen, Valentina Marulanda Corzo, Jana IvanidzeAbstract
Background
Discerning recurrence versus treatment effect in previously radiated brain metastases remains a clinically consequential challenge, as these entities demonstrate overlapping imaging features despite different management implications. MR perfusion is commonly used, but is limited by lack of specificity and heterogeneity in acquisition and analysis protocols. [F18]FDG PET is limited by high physiologic cortical uptake and low target‑to‑background contrast. [F18]Fluciclovine is an amino acid analog PET radiotracer with utility in brain neoplasms and metastases. We evaluated the added value of [F18]Fluciclovine PET combined with dynamic contrast‑enhanced perfusion MRI (DCE‑MRI) in patients with concern for recurrent CNS metastases.
Methods
Patients with CNS metastases who underwent [F18]Fluciclovine PET and contemporaneous DCE‑MRI were included in this retrospective study. PET maximum standardized uptake values (SUVmax) were compared with DCE‑MRI parameters including Ktrans (volume transfer constant) and Vp (plasma volume). Vp ratios referencing contralateral normal‑appearing parenchyma were obtained. Correlation analyses and descriptive statistics were performed.
Results
Nine patients with 36 lesions were evaluated. The most common pathology was breast (46%), followed by melanoma, renal cell carcinoma, and lung. Among perfusion metrics, median Ktrans, but not Vp ratio, was significantly higher in progressive disease compared with treatment effect/radiation necrosis (0.94 vs 0.14, p = 0.011). Median SUVmax was higher in progressive disease (4.2 vs 2.65), although the difference was not statistically significant (p = 0.24). In progressive disease, SUVmax and Ktrans demonstrated a moderate positive correlation (Pearson r = 0.43, p = 0.019), which was not observed among treatment effect/radiation necrosis lesions (Pearson r = 0.16, p = 0.42).
Conclusions
Combined [F18]Fluciclovine PET and DCE‑MRI provide complementary information for evaluating treated brain metastases, with permeability‑based perfusion metrics demonstrating the greatest discriminatory value. Larger prospective studies are warranted to further define pathology‑specific imaging patterns.