Characterisation of urinary stones in the presence of iodinated contrast medium using dual-energy CT

A phantom study

Jia Wang, Mingliang Qu, Xinhui Duan, Naoki Takahashi, Akira Kawashima, Shuai Leng, Cynthia H. McCollough

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Objective: To develop a dual-energy CT (DECT) method for differentiating uric acid (UA) from non-UA stones in the presence of iodinated contrast medium. Methods: Thirty UA and 45 non-UA stones were selected after infra-red spectroscopic analysis and independently placed in a 1.5-ml vial, which was filled first with saline and then with increasing concentrations of iodine. For each condition, tubes were put in a 35-cm water phantom and examined using a dual-source CT system at 100 and 140 kV. Virtual unenhanced images created from CT data sets of the stones in iodine-containing solutions provided position and volume information. This map was used to calculate a CT number ratio to differentiate stone type. A region-growing method was developed to improve the ability to differentiate between UA and non-UA stones with iodinated contrast medium. Results: The sensitivity for detecting UA stones was 100 % for unenhanced images but fell to 18 % with 20 mgI/ml iodine solution and 0 % for higher concentrations. With region growing, the sensitivity for detecting UA stones was increased to 100 %, 82 %, 57 %, 50 % and 21 % for iodine solutions of 20, 40, 60, 80 and 100 mgI/ml. Conclusion: The region-growing method improves differentiation of UA from non-UA stones on contrast-enhanced DECT urograms. Key Points: • Computed tomography is widely used to assess renal tract calculi • Dual-energy CT can assess stone composition and provide virtual unenhanced images • However, iodinated contrast medium affects the volume estimation for urinary stones. • CTR of stones is altered by the surrounding iodine in CT urograms. • The region-growing method improves the identification of uric acid stones.

Original languageEnglish (US)
Pages (from-to)2589-2596
Number of pages8
JournalEuropean Radiology
Volume22
Issue number12
DOIs
StatePublished - Dec 2012

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Urinary Calculi
Uric Acid
Contrast Media
Iodine
Acids
Urography
Kidney Calculi
Tomography
Water

Keywords

  • CT Urogram
  • Dual-energy CT
  • Region growing method
  • Urinary stone compositions
  • Virtual unenhanced CT

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

Characterisation of urinary stones in the presence of iodinated contrast medium using dual-energy CT : A phantom study. / Wang, Jia; Qu, Mingliang; Duan, Xinhui; Takahashi, Naoki; Kawashima, Akira; Leng, Shuai; McCollough, Cynthia H.

In: European Radiology, Vol. 22, No. 12, 12.2012, p. 2589-2596.

Research output: Contribution to journalArticle

Wang, Jia ; Qu, Mingliang ; Duan, Xinhui ; Takahashi, Naoki ; Kawashima, Akira ; Leng, Shuai ; McCollough, Cynthia H. / Characterisation of urinary stones in the presence of iodinated contrast medium using dual-energy CT : A phantom study. In: European Radiology. 2012 ; Vol. 22, No. 12. pp. 2589-2596.
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abstract = "Objective: To develop a dual-energy CT (DECT) method for differentiating uric acid (UA) from non-UA stones in the presence of iodinated contrast medium. Methods: Thirty UA and 45 non-UA stones were selected after infra-red spectroscopic analysis and independently placed in a 1.5-ml vial, which was filled first with saline and then with increasing concentrations of iodine. For each condition, tubes were put in a 35-cm water phantom and examined using a dual-source CT system at 100 and 140 kV. Virtual unenhanced images created from CT data sets of the stones in iodine-containing solutions provided position and volume information. This map was used to calculate a CT number ratio to differentiate stone type. A region-growing method was developed to improve the ability to differentiate between UA and non-UA stones with iodinated contrast medium. Results: The sensitivity for detecting UA stones was 100 {\%} for unenhanced images but fell to 18 {\%} with 20 mgI/ml iodine solution and 0 {\%} for higher concentrations. With region growing, the sensitivity for detecting UA stones was increased to 100 {\%}, 82 {\%}, 57 {\%}, 50 {\%} and 21 {\%} for iodine solutions of 20, 40, 60, 80 and 100 mgI/ml. Conclusion: The region-growing method improves differentiation of UA from non-UA stones on contrast-enhanced DECT urograms. Key Points: • Computed tomography is widely used to assess renal tract calculi • Dual-energy CT can assess stone composition and provide virtual unenhanced images • However, iodinated contrast medium affects the volume estimation for urinary stones. • CTR of stones is altered by the surrounding iodine in CT urograms. • The region-growing method improves the identification of uric acid stones.",
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AU - Kawashima, Akira

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