Fig. 3
Pre-therapy, two-week and 12-week post-therapy images for a 43-year-old male patient from the responder group with abdominal metastatic gastrointestinal stromal tumor (GIST) lesions treated with imatinib mesylate. a-c Axial fast spin-echo T2-weighted MR images at three time points. The maximum tumor diameters were 7.5 cm before therapy (a), 7.2 cm at two weeks post-therapy (b) and 3.6 cm at 12 weeks post-therapy (c). The tumor-to-muscle CNRs were 47 before therapy (a), 43 at two weeks post-therapy (b) and 55 at 12 weeks post-therapy (c). d-f Axial diffusion-weighted MR images (DWI) with b = 1000 s/mm2 at three time points. The tumors ADCs were 0.86 × 10− 3 mm2/s before therapy (g), 1.36 × 10− 3 mm2/s at two weeks post-therapy (h) and 2.43 × 10− 3 mm2/s at 12 weeks post-therapy (i). The tumor ADC was significantly increased at two weeks after the targeted therapy (%ΔADC = 58.1%), whereas the changes in tumor size and the T2WI-CNR were not obvious (%ΔLD = − 4.0%, %ΔCNR = − 8.5%)