Value of normalized apparent diffusion coefficient for estimating histological grade of vesical urothelial carcinoma

•We use a new non-invasive method in bladder cancer preoperative pathological grade evaluation.•We first use the normalized ADC value in bladder cancer.•Normalized ADC value was confirmed to be more reliable than ADC value.

AimTo compare the efficacy of apparent diffusion coefficient (ADC) and normalized ADC (nADC) for estimating the histological grade of vesical urothelial carcinoma and to identify an optimal reference for nADC calculation.Materials and methodsThirty patients with histologically confirmed vesical urothelial carcinomas underwent preoperative diffusion-weighted magnetic resonance imaging (DW-MRI) of the pelvis. nADC of the tumour was calculated as ADC (tumour)/ADC (reference) using urine in the bladder lumen, and the obturator internus and gluteus maximus muscles as reference. Receiver operating characteristic (ROC) curves were constructed and compared to identify an optimal reference for nADC calculation.ResultsBoth ADC and nADC of low-grade tumours (1.112 ± 0.159 × 10−3 mm2/s, 0.403 ± 0.047 × 10−3 mm2/s) were significantly (p < 0.001) higher than those of high-grade tumours (0.772 ± 0.091 × 10−3 mm2/s, 0.276 ± 0.033 × 10−3 mm2/s). The area under the nADC ROC curve using urine as reference was significantly (p = 0.000) larger (0.995) than those using obturator internus (0.960) and gluteus maximus (0.945).ConclusionsnADC is superior to ADC for estimating the histological grade of bladder carcinoma using urine in the bladder lumen as an optimal reference for nADC calculation.