Fig. 4.

F58, healthy control. a T2WI/IDEAL showing the symmetrical bilateral nasopharyngeal mucosa thickening. b BF map showing relatively lower perfusion of tumor compared to surrounding tissues. c Merged image (image a and b) showing ROI of mucosa on ASL and acquired BF of nasopharyngeal mucosa as 32.37 mL/min/100 g. d IVIM image with b value = 1000 s/mm² showing the diffusion restriction in the tumor area. e-h ADC (1.06 × 10^− 3 mm²/s), D (0.80 × 10^− 3 mm²/s), D* (34.5 × 10^− 3 mm²/s), and f (0.30) were obtained