Advanced Hyperpolarized ¹³C Metabolic Imaging Protocol for Patients with Gliomas: A Comprehensive Multimodal MRI...

This study aimed to implement a multimodal ¹H/HP-¹³C imaging protocol to augment the serial monitoring of patients with glioma, while simultaneously pursuing methods for improving the robustness of HP-¹³C metabolic data. A total of 100 ¹H/HP [1-¹³C]-pyruvate MR examinations (104 HP-¹³C datasets) were acquired from 42 patients according to the comprehensive multimodal glioma imaging protocol. Serial data coverage, accuracy of frequency reference, and acquisition delay were evaluated using a mixed-effects model to account for multiple exams per patient. Serial atlas-based HP-¹³C MRI demonstrated consistency in volumetric coverage measured by inter-exam dice coefficients (0.977 ± 0.008, mean ± SD; four patients/11 exams). The atlas-derived prescription provided significantly improved data quality compared to manually prescribed acquisitions (n = 26/78; p = 0.04). The water-based method for referencing [1-¹³C]-pyruvate center frequency significantly reduced off-resonance excitation relative to the coil-embedded [¹³C]-urea phantom (4.1 ± 3.7 Hz vs. 9.9 ± 10.7 Hz; p = 0.0007). Significantly improved capture of tracer inflow was achieved with the 2-s versus 5-s HP-¹³C MRI acquisition delay (p = 0.007). This study demonstrated the implementation of a comprehensive multimodal ¹H/HP-¹³C MR protocol emphasizing the monitoring of steady-state/dynamic metabolism in patients with glioma.