MDCT urography for detecting recurrence after transurethral resection of bladder cancer: comparison of nephrographic phase with pyelographic phase

The purpose of this study was to prospectively compare nephrographic phase MDCT urography performed with oral hydration and a diuretic with standard pyelographic phase MDCT in the detection of recurrence after transurethral resection. The study included 140 MDCT urographic examinations of 121 patients (87 men, 34 women; age range, 46-88 years) at risk of urinary tract cancer recurrence. Acquisition was performed 60 seconds (nephrographic phase) and 420 seconds (pyelographic phase) after contrast injection. Two radiologists independently recorded the presence of recurrent lesions in each phase. The reference standard was histologic findings and prospective clinical decision. Distention and opacification were compared for each radiologist in each segment in each phase by kappa statistic and Spearman rank coefficient. Generalized estimating equations for logistic regression analysis were used to compare performance for each radiologist and phase and were adjusted for possibility within patient correlation. Urinary tract distention was rated significantly better at the pyelographic phase for all segments (p < 0.001). The degree of opacification provided by each radiologist for the same segment showed high correlation. There were 59 bladder recurrences in 38 patients and 19 upper tract recurrences in 13 patients. For recurrence detection in the bladder, the overall accuracy was significantly higher for the nephrographic phase than the pyelo-graphic phase (91.7% [354/386] vs 83.2% [321/386], p = 0.038). For recurrence detection in the upper tract, the overall accuracy was significantly higher in the nephrographic phase than in the pyelographic phase (86.7% [260/300] vs 80% [240/300], p = 0.028). Use of nephrographic phase MDCT urography is associated with a higher rate of detection of urinary tract recurrence than is pyelographic phase MDCT, which suggests the value of this technique for evaluating the urinary tract after transurethral resection.