Multimodal imaging of tumor metabolism and microenvironment in feline sarcoma patients using hyperpolarized 13C MRI and PET

Motivation: Sarcomas are a rare but diverse cancer type with heterogeneous metabolic signatures. Their stratification is difficult, which limits treatment selection, therapy development and reliable patient prognosis. Goal(s): To demonstrate the feasibility of combined hyperpolarized 13C MRI and PET to differentiate sarcoma subtypes and to identify prognostic imaging biomarkers. Approach: Sarcoma cat patients were recruited, underwent PET/MR imaging and were followed-up several years post-surgery. Results: Hyperpolarized 13C MRI of pH and pyruvate metabolism allow subtype and tumor grade differentiation while [18F]FMISO-PET and DWI do not. Image-derived tumor acidification appears to be predictive for patient outcome. Correlations between parameters reveal hypoxia-driven metabolism and related acidification. Impact: Hyperpolarized 13C MRI allows sarcoma subtype and grade differentiation in cat patients in contrast to [18F]FMISO-PET and DWI. Acidification outperforms all other parameters as biomarker for cat patient prognosis, rendering hyperpolarized pH imaging a promising technique for clinical translation.