Byung Kwan Park MD, Presenter: Nothing to Disclose

Jung Jae Park MD, Abstract Co-Author: Nothing to Disclose

E-Ryung Choi MD, Abstract Co-Author: Nothing to Disclose

To retrospectively evaluate nephrographic dual energy CT (DECT) with virtual non-contrast CT (VNCT) compared to three-phase CT urography (CTU) in patients with hematuria.

A total of 296 consecutive patients (167 men and 129 women; mean age, 57.9±13.5 years) received three-phase (120 kvp non-contrast and 140/80 kvp nephrographic and excretory) CTU using DECT technique due to hematuria between September 2009 and August 2012. Two genitourinary radiologists independently evaluated three-phase CTU scans first and then, nephrographic DECT with VNCT. Sensitivity, specificity, and accuracy on three-phase CTU and nephrographic DECT were calculated and compared for detecting urothelial tumor. Stone detection rate and dose-length product (DLP) were compared between VNCT and three-phase CTU. Standard reference of urothelial tumor was biopsy or surgery and that of stone was 120 kvp unenhanced CT. DLP was automatically recorded on the patient protocol of each CT scan. McNemar test and paired t-test were used between DECT or VNCT and three-phase CTU for statistical analysis.

Of 296 patients, 27 tumors in 20 patients were pathologically confirmed. On three-phase CTU, 26 tumors in 19 patients and 148 stones in 64 patients were detected. On nephrographic DECT with VNCT, 24 tumors in 19 patients and 108 stones in 56 patients were detected. Sensitivity, specificity, and accuracy for tumor on three-phase CTU were 95% (19/20), 98.9% (273/276), and 98.6% (292/296); those on nephrographic DECT were 95% (19/20), 98.2% (271/276), and 98% (290/296), respectively (p>0.1). A total of 148 stones were detected on 120 kvp unenhanced CT. On VNCT images obtained from nephrographic DECT scan, 108 (73%) stones were detected, respectively. On VNCT from nephrographic DECT, mean sizes of detected and undetected stones were 5.0±3.5 mm and 1.5±0.5 mm, respectively (p<0.0001). Mean DLP of nephrographic (410±98 mGy•cm) was significantly lower than that (1076±248 mGy•cm) of three-phase CTU (p<0.0001).

Nephrographic DECT has potential to replace three-phase CTU for detection of urothelial tumor using much lower radiation dose. However, this single-phase DECT can miss a significant number of small stones that are detected on 120 kvp unenhanced CT.

Nephrographic contrast-enhanced DECT is recommended for evaluating hematuria in patients who are high risk for urothelial tumor.

Park, B, Park, J, Choi, E, Can Nephrographic Dual-energy CTU Replace Three-phase CTU?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007714.html