Relationship between multi-pool model-based chemical exchange saturation transfer imaging, intravoxel incoherent motion MRI, and 11C-methionine uptake on PET/CT in patients with gliomas

Abstract

Purpose

Magnetization transfer ratio asymmetry (MTRasym) analysis is used for chemical exchange saturation transfer (CEST) in patients with gliomas; however, this approach has limitations. CEST imaging using a multi-pool model (MPM) may allow a more detailed assessment of gliomas; however, its mechanism remains unknown. This study aimed to assess the relationship between CEST imaging by MPM, intravoxel incoherent motion (IVIM), and ¹¹C-methionine (¹¹C-MET) uptake on positron emission tomography/computed tomography (PET/CT) to clarify the clinical significance of CEST imaging using MPM in gliomas.

Methods

This retrospective study included 17 patients with gliomas who underwent ¹¹C-MET PET/CT at our institution between January 2020 and January 2022. Two-dimensional axial CEST imaging was conducted using single-shot fast-spin echo acquisition at 3 T. The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), f, MTRasym (3.5 ppm), parameters of MPM-based CEST imaging, and tumor-to-contralateral normal brain tissue (T/N) ratio were calculated using a region-of-interest analysis. Shapiro–Wilk test, weighted kappa coefficient, and Spearman's rank correlation coefficients were used for statistical analysis.

Results

Significant correlations were found between APT_T1 and T/N ratio (ρ = 0.87, p < 0.001), APT_T2 and T/N ratio (ρ = 0.47, p < 0.05), MTRasym and T/N ratio (ρ = 0.55, p < 0.01), and T2/T1 and T/N ratio (ρ = −0.36, p < 0.05). Furthermore, significant correlations were observed between APT_T1 and ADC (ρ = −0.67, p < 0.001), APT_T1 and D (ρ = −0.70, p < 0.001), APT_T2 and D* (ρ = −0.45, p < 0.05), and T2/T1 and D (ρ = 0.39, p < 0.05).

Conclusion

These preliminary findings indicate that MPM-based CEST imaging parameters correlate with IVIM and ¹¹C-MET uptake on PET/CT in patients with gliomas. In particular, the new parameter APT_T1 correlated more strongly with ¹¹C-MET uptake compared to the traditional CEST parameter MTRasym.