Feasibility of discriminating uric acid from non-uric acid renal stones using consecutive spatially registered low-and high-energy scans obtained on a conventional CT scanner

Shuai Leng, Maria Shiung, Songtao Ai, Mingliang Qu, Terri J Vrtiska, Katharine L. Grant, Bernhard Krauss, Bernhard Schmidt, John C Lieske, Cynthia H McCollough

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21 Scopus citations

Abstract

OBJECTIVE The objective of our study was to show the feasibility of distinguishing between uric acid (UA) and non-UA renal stones using two consecutive spatially registered low-and high-energy scans acquired on a conventional CT system. SUBJECTS AND METHODS. A total of 33 patients undergoing clinically indicated dual-source dual-energy CT examinations to differentiate UA from non-UA renal stones were enrolled in this study. Immediately after patients underwent clinically indicated dual-source dual-energy CT, two consecutive scans (one at 80 kV and one at 140 kV) were obtained on a conventional CT scanner over the region limited to the stones identified on the dual-source scans. After 3D deformable registration of the 80-and 140-kV images, UA and non-UA stones were identified using commercial software. The sensitivity, specificity, and accuracy of stone classification were calculated using the dual-source results as the reference standard. RESULTS. A total of 469 stones were identified in the dual-source examinations (26 UA and 443 non-UA stones). The average in-plane stone diameter was 4.4 ± 2.5 (SD) mm (range, 2.0-18.9 mm). The overall sensitivity, specificity, and accuracy for identifying UA stones were 73.1%, 90.1%, and 89.1%, respectively. The sensitivity, specificity, and accuracy were 94.7%, 96.9%, and 96.8% for stones 3 mm or larger (n = 341[19 UA and 322 non-UA]). CONCLUSION. Accurate differentiation of UA from non-UA renal stones is feasible using two consecutively acquired and spatially registered conventional CT scans.

Original languageEnglish (US)
Pages (from-to)92-97
Number of pages6
JournalAmerican Journal of Roentgenology
Volume204
Issue number1
DOIs
StatePublished - Jan 1 2015

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Keywords

  • CT
  • Deformable registration
  • Dual-energy CT
  • Renal stone
  • Stone composition

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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