[The value of split-bolus 2-phase with virtual non-enhanced scan in CT urography].

OBJECTIVE: To investigate the value of split-bolus 2-phase with virtual non-enhanced scan in CT urography. METHODS: Eighty (80) patients with urinary obstruction were divided into two groups, group A was traditional CT urography scan, group B was split-bolus 2-phase with virtual non-enhanced scan. The scan sequence of group A included conventional scan first, then enhanced scan in arterial phase, parenchyma phase and excretion delayed phase after the injection of 100 mL contrast agent. The scan sequence of group B included conventional scan and enhanced scan following two bolus injection of contrast; the first injection of contrast was 40 mL, the second injection was 60 mL with 15-30 minutes delay, then enhanced scan was conducted in arterial and parenchymal phase, the parenchymal phase scan was performed with dual energy scanning sequence. The image quality of urinary collecting system, the detection of urinary obstructive lesion, and radiation dose were compared between the two groups. RESULTS: Between the two imaging methods, the imaging quality of urinary system did not show significant difference, but radiation dose was statistically significant difference. The radiation dose of split-bolus 2-phase with virtual non-enhanced scan was only 55% of traditional CTU scan. CONCLUSION: Split-bolus2 phase with virtual non-enhanced scan could obtain the same image quality as tranditional CTU, while reducing the approximately half the radiation dose.