Magnetic resonance cystometry: accurate assessment of bladder volume with magnetic resonance imaging.

OBJECTIVES: To evaluate magnetic resonance hydrometry for the calculation of bladder volume. The reference standard to assess bladder volume is urethral catheterization, which may be linked with the risk of trauma and infection. Hence, ultrasonography is the preferred diagnostic method. However, ultrasonography is investigator dependent and inaccurate in the hands of an inexperienced operator.

METHODS: Investigations were performed in a 1.0-Tesla clinical scanner with a manufacturer-provided single-shot turbo spin-echo sequence. We examined 30 healthy volunteers (21 males and 9 females) with a mean age of 26.4 years. To quantify the volume of fluid in a magnetic resonance image, a histogram algorithm was used and a calibration phantom applied. Prevoid and postvoid images were acquired. The bladder volume was calculated as the difference between the prevoid and postvoid image fluid volumes. The magnetic resonance-calculated data were compared with the actually voided volumes.

RESULTS: The measured voided bladder volume was 400 +/- 33 mL, whereas magnetic resonance hydrometry yielded 390 +/- 31 mL. The difference between both measurements was not statistically significant. The 95% confidence interval for the difference of both measurements ranged from -22.6 to 2.4 mL. The regression had an r2 of 0.97.

CONCLUSIONS: The feasibility of magnetic resonance hydrometry to quantify the bladder volume noninvasively was demonstrated.