Fig. 5

Comparison of lymph node staging (N-stage) on pre-transurethral resection (a, b, c) and post-chemotherapy ¹¹C-acetate PET/MRI (d, e, f) in patient number 12, the same patient as in Fig. 4. 17 mm right obturator lymph node (a - white arrow on T2-weighted image) demonstrated increased diffusion signal restriction (b - b value 800 s/mm² trace diffusion weighted image) and increased ¹¹C-acetate uptake (c - PET fused with T2-weighted image, SUV is scaled from 0.0 to 3.5) suggestive of lymph node metastasis. On post-chemotherapy ¹¹C-acetate PET/MRI, lymph node decreased in size and measured 4 mm (d - green arrow on T2-weighted image) with increased diffusion signal (e - b value 800 s/mm² trace diffusion weighted image) and increased ¹¹C-acetate uptake (f - PET fused with T2-weighted image, SUV is scaled from 0.0 to 3.0). SUVmax values of the lymph node on the pre-transurethral resection (c) and post-chemotherapy ¹¹C-acetate PET/MRI (f) were 3.4 and 2.8, respectively. The lymph node was confirmed to be lymph node metastasis measuring 3 mm on extended pelvic lymph node dissection, thus the findings of ¹¹C-acetate PET/MRI were considered as true positive