Fig. 4
M50, NPC with right metastatic RLN, and left non-metastatic RLN. Axial T2WI before treatment (a) showed bilateral RLNs with slightly high heterogeneous signal intensity and size as long axis × short axis of 19 × 11 mm (right, curved arrow) and 7 × 5 mm (left, straight arrow), respectively. Both lymph nodes demonstrated higher perfusion than the surrounding tissue on the fused image by T2WI and ASL (b), and the map of BF (c), especially the right one with remarkable pseudo-color contrast. On the fused image (b), the high perfusion area behind the right lymph node (arrowhead) was the internal carotid. ROI of the lymph nodes were delineated on the map of BF (c) and multi-b-value DWI with b value = 800 s/mm2 (d), acquiring at BF value of 89.64 mL/100 g/min, 49.50 mL/100 g/min, and ADC value of 0.715 × 10−3 mm2/s, 0.893 × 10−3 mm2/s on ADC map (e), respectively. Axial T2WI at three months after radiotherapy (f) showed the size was remarkably reduced to 6 × 3 mm on the right lymph node (curved arrow) and was reduced (but not significantly) to 7 × 4 mm on the left lymph node (straight arrow)