PPIG and hypertrophy: Using the formula described in the method section, we calculated the bladder mass in vivo based on the MRI results and demonstrated an increase in the CYP groups and a reduction in LY294002 treated groups (Fig. 6A); these numbers were very similar to the wet weight of the urinary bladder measured ex vivo (Fig. 6B) suggesting that MRI is reliable in the measurement of bladder hypertrophy in situ.