Urinary bladder as an in vivo reference for quality assurance of apparent diffusion coefficient for prostate MRI

Motivation: Diagnostic accuracy for prostate cancer could be improved by quantitative assessment of apparent diffusion coefficient (ADC), but quality assurance would require an in vivo reference for each exam. Goal(s): Determine whether urinary bladder ADC is unbiased relative to normal saline across ADC fitting methods. Approach: In 103 prostate cancer patients, urinary bladder ADC was compared to ADC of normal saline in the balloon of an endorectal catheter. ADC fitting methods were compared across prostate regions. Results: Using weighted linear least-squares fitting and an intermediate range of b-values (100≤b≤600s/mm2), urinary bladder ADC is unbiased and fitting error is minimized. Impact: The urinary bladder serves as a reference sample for ADC, which will be necessary for quality assurance of ADC in prostate cancer diagnosis. Whether prostate ADC normalization by bladder ADC reduces interpatient variability can be investigated.