Deuterium Metabolic MRI and [18F]FDG PET for Assessment of Treatment Response Following Radioembolization

Radioembolization, also known as Selective Internal Radiation Therapy (SIRT), is a liver-directed therapy for patients suffering from hepatic metastases. As SIRT is a liver-directed treatment, only patients with liver-only or liver-dominant disease are eligible for treatment. FDG-PET/CT is known to outperform conventional anatomical imaging modalities (CT or MRI) for treatment response assessment, also being of prognostic value. Subsequently following SIRT, patients are restaged with FDG-PET/CT. However, optimal timing of restaging following treatment is unknown (most commonly after 1 or 3 months, according to local institutional guidelines). More importantly, intrinsic resolution of FDG-PET/CT limits its utility in patients with small metastases, as image quality is worsened by high background noise, due to physiologic FDG uptake / metabolism in normal liver parenchyma. Additionally, FDG as radiopharmaceutical increases additional radiation burden to patients. This study will investigate the potential of metabolic MRI (7T MRI), non-invasively imaging metabolites using X-nuclei (e.g. 31P MRSI) and more importantly, the application of Deuterium Metabolic Imaging (DMI) with non-radioactive deuterated glucose, as a potential alternative over FDG-PET/CT.