European Radiology

, Volume 22, Issue 1, pp 251–258

Targeted dual-energy single-source CT for characterisation of urinary calculi: experimental and clinical experience

  • Matthias Eiber
  • Konstantin Holzapfel
  • Markus Frimberger
  • Michael Straub
  • Heike Schneider
  • Ernst J. Rummeny
  • Martin Dobritz
  • Armin Huber
Urogenital

DOI: 10.1007/s00330-011-2231-2

Cite this article as:
Eiber, M., Holzapfel, K., Frimberger, M. et al. Eur Radiol (2012) 22: 251. doi:10.1007/s00330-011-2231-2

Abstract

Objective

To assess the accuracy of targeted dual-energy single-source multi-detector CT (MDCT) for characterisation of urinary calculi.

Methods

For proof of principle, 71 ex-vivo calculi underwent single-source 256-slice MDCT. Low-dose CT was performed in 154 patients with suspected urinary calculi. In 104 patients with urinary calculi targeted dual-energy imaging within one breath-hold was added. 46 patients with sufficient material for infrared-spectroscopy were analysed. Potential anatomical misregistrations between 80- and 140-kVp-images and HU-values were measured. DEIs (dual-energy-indices) were compared with the standard of reference. Effective doses were calculated.

Results

In 26 of 46 patients no misregistration was present. Mean deviations were 2.7 mm in the z-axis (16 patients) and 4.3 mm in the axial plane (10 patients). The DEIs were 0.018 ± 0.016 for uric acid (UA), 0.035 ± 0.015 for mixed UA and 0.102 ± 0.015 for calcified stones in-vitro and 0.017 ± 0.002 for UA, 0.050 ± 0.019 for mixed UA and 0.122 ± 0.024 for calcified calculi in-vivo. Significant differences were noted among calcium, mixed UA and UA stones (p < 0.05). For the low-dose examination mean effective dose was 3.11 mSv. Targed dual-energy resulted in an extra dose of 1.84 mSv (additional 59.1%).

Conclusion

Targeted dual-energy imaging within one breath-hold is feasible for characterisation of urinary calculi using single-source MDCT allowing minimal anatomical discordance.

Key Points

• Targeted dual-energy single-source CT is feasible for characterizing urinary calculi

Dual Energy Index discriminates between uric-acid and non-uric-acid containing stones

It provides ancillary for decisions about stone removal or metaphylaxis

Keywords

Urinary calculiSingle-source multi-detector CTTargeted dual-energy imagingDual energy indexAnatomical misregistration

Copyright information

© European Society of Radiology 2011

Authors and Affiliations

  • Matthias Eiber
    • 1
  • Konstantin Holzapfel
    • 1
  • Markus Frimberger
    • 2
  • Michael Straub
    • 2
  • Heike Schneider
    • 3
  • Ernst J. Rummeny
    • 1
  • Martin Dobritz
    • 1
  • Armin Huber
    • 1
  1. 1.Institute of Radiology, Klinikum rechts der IsarTechnische Universität MünchenMunichGermany
  2. 2.Department of UrologyTechnische Universität MünchenMunichGermany
  3. 3.Institute of Clinical Chemistry and PathobiochemistryTechnische Universität MünchenMunichGermany