Single-phase DECT with VNCT compared with three-phase CTU in patients with haematuria.

OBJECTIVE

To retrospectively evaluate the diagnostic performance of single-phase dual-energy CT (DECT) with virtual non-contrast CT (VNCT) compared with three-phase CT urography (CTU) in patients with haematuria.

METHODS

A total of 296 patients underwent three-phase CTU (NCT at 120 kVp; nephrographic phase and excretory phase DECTs at 140 kVp and 80 kVp) owing to haematuria. Diagnostic performances of CT scans were compared for detecting urothelial tumours and urinary stones. Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU.

RESULTS

Sensitivity and specificity for tumour were 95 % (19/20) and 98.9 % (273/276) on CTU, 95 % (19/20) and 98.2 % (271/276) on nephrographic phase DECT, and 90 % (18/20) and 98.2 % (271/276) on excretory phase DECT (P > 0.1). Of the 148 stones detected on NCT, 108 (73 %) and 100 (67.6 %) were detected on nephrographic phase and excretory phase VNCTs, respectively. The mean size of stones undetected on nephrographic and excretory VNCTs was measured as 1.5 ± 0.5 mm and 1.6 ± 0.6 mm, respectively. The mean DLPs of three-phase CTU, nephrographic phase DECT and excretory phase DECT were 1076 ± 248 mGy · cm, 410 ± 98 mGy · cm, and 360 ± 87 mGy · cm, respectively (P < 0.001).

CONCLUSIONS

Single-phase DECT has a potential to replace three-phase CTU for detecting tumours with a lower radiation dose.

KEY POINTS

• Single-phase DECT with virtual NCT may replace three-phase CTU for detecting tumours. • Virtual NCT cannot replace NCT for detecting small urinary stones. • Single-phase DECT may reduce the radiation dose by 62-67 % compared to three-phase CTU. • Nephrographic phase DECT is superior to excretory phase DECT for assessing haematuria.