Focused dual-energy CT maintains diagnostic & compositional accuracy for urolithiasis using ultra-low dose non-contrast CT

To evaluate the diagnostic accuracy of a new energy and radiation dose reduced protocol for non-contrast computer tomography (NCCT) with dual energy (DE) analysis (DECT) and its potential for the compositional analysis of uric (UA) or non-uric acid (N-UA) containing calculi.

A retrospective evaluation was carried out in 61 patients who underwent dose-reduced DECT (tube A: 140 kV/55 mAs; tube B: 80 kV/303 mAs) with a tube current 38. 8% lower than those set by the manufacturer. A protocol combining low-dose CT and targeted DE scans was used. Urinary stones were detected and classified as UA- or N-UA-containing, or mixed based on DE software results. The accuracy of the compositional analysis was controlled by correlation with conventional infrared-based analysis.

The compositional stone differentiation was correct in 58 out of 61 (95. 1%). The sensitivity of detecting pure UA-containing and pure N-UA- containing stones was 100%. The specificity of detecting UA- and pure N-UA-containing stones was 100% and 78. 57%, respectively, as 3 out of 7 mixed urinary stones (small fragments <4mm) were classified as N-UA calculi. The total radiation dose in patients with BMI < 25 and > 25 kg/m² was 1. 2 and 2. 5 mSv, respectively.

Lowering the DECT tube current by up to 38% of the manufacturer's recommendations allows a reduced radiation dose without impairing detection accuracy and stone compositional analysis. Compared with previous studies, this protocol might significantly decrease patient radiation exposure without affecting results quality.

Urology. 2015 Sep 14 [Epub ahead of print]

Konrad Wilhelm, Martin Schoenthaler, Simon Hein, Fabian Adams, Daniel Schlager, Franklin Emmanuel Kuehhas, Sabina Sevcenco, Gregor Pache, Mathias Langer, Stefan Bulla, Arkadiusz Miernik

University Medical Center, Department of Urology, Hugstetterstr. 55, D-79106 Freiburg, Germany.  University Medical Center, Department of Urology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , University Medical Center, Department of Urology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , University Medical Center, Department of Urology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , University Medical Center, Department of Urology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , Medical University of Vienna, Department of Urology, Währinger Gürtel 18-20, A-1090 Wien, Austria. , Medical University of Vienna, Department of Urology, Währinger Gürtel 18-20, A-1090 Wien, Austria. , University Medical Center, Department of Radiology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , University Medical Center, Department of Radiology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , University Medical Center, Department of Radiology, Hugstetterstr. 55, D-79106 Freiburg, Germany. , University Medical Center, Department of Urology, Hugstetterstr. 55, D-79106 Freiburg, Germany.

PubMed

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