Correlations between intravoxel incoherent motion diffusion-weighted MR imaging parameters and ¹⁸F-FDG PET/CT...

To investigate the relationship between intravoxel incoherent motion (IVIM) diffusion-weighted MRI (DW MRI) parameters and ¹⁸F-fluodeoxyglucose (FDG) (PET/CT) metabolic parameters in patients with vertebral bone metastases.

19 patients with vertebral bone metastases were retrospectively included in this institutional review board-approved study. All patients underwent IVIM DW-MRI and ¹⁸F-FDG PET/CT before treatment. The IVIM parameters [molecular diffusion coefficient (D), perfusion fraction (f), and perfusion-related D (D*)] and apparent diffusion coefficient were acquired using 11 b-values (0, 10, 15, 20, 25, 50, 80, 120, 200, 300, and 800 s mm^-2). Maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), metabolic tumor volume, and total lesion glycolysis derived from ¹⁸F-FDG PET/CT were calculated using thresholds of 3.0 SUV. The associations among parameters were evaluated by Spearman's correlation analysis.

A total of 19 patients and 41 regions of interest were included in this study. The IVIM parameter f was positively correlated with the metabolic parameters SUVmean and SUVmax [ρ = 0.499 (p < 0.01) and ρ = 0.413 (p < 0.01), respectively]. There was a weak positive correlation between D* and SUVmean (ρ = 0.321, p = 0.041).

IVIM perfusion-related parameters, especially f, were correlated with ¹⁸F-FDG PET/CT metabolic parameters in patients with vertebral bone metastases. IVIM DW-MRI, used to evaluate metabolic activity, appears to have diagnostic potential for bone metastasis and may also have utility in monitoring the post-treatment response. Advances in knowledge: The use of IVIM for vertebral bone metastasis is demonstrated. f may be more suitable to reflect the metabolic activity and may facilitate another diagnostic potential for monitoring the posttreatment response.