Dual-energy CT iodine-subtraction virtual unenhanced technique to detect urinary stones in an iodine-filled collecting system: A phantom study

Naoki Takahashi, Robert P. Hartman, Terri J Vrtiska, Akira Kawashima, Andrew N. Primak, Oleksandr P. Dzyubak, Jayawant Mandrekar, Joel Garland Fletcher, Cynthia H McCollough

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Abstract

OBJECTIVE. The objective of our study was to evaluate the feasibility of virtual unenhanced images reconstructed from a dual-energy CT scan to depict urinary stones in an iodine solution in a phantom study. MATERIALS AND METHODS. Twenty urinary stones of different sizes (1.4-4.2 mm in short-axis diameter) were placed in plastic containers. The containers were consecutively filled with different concentrations of iodine solution (21, 43, 64, 85, and 107 mg/dL; CT attenuation value range, 510-2,310 H at 120 kVp). Dual-energy CT was repeated with 80-140 and 100-140 kVp pairs, two collimation-slice thickness combinations, and the presence or absence of a 4-cm-thick oil gel around the phantom. The iodine-subtraction virtual unenhanced images were reconstructed using commercial software. The images were evaluated by three radiologists in consensus for the visibility of the stones and the presence of residual nonsubtracted iodine. Stone visibility rates were compared between the 80-140 and 100-140 kVp pairs and the five different iodine concentrations. RESULTS. Stone visibility rates with the 80-140 kVp pair were 99%, 93%, 96%, 94%, and 3% and those with the 100-140 kVp pair were 98%, 95%, 99%, 94%, and 99% for an iodine concentration of 21, 43, 64, 85, and 107 mg/dL, respectively. The poor visibility rate with 80-140 kVp and 107 mg/dL iodine concentration was due to the failure of iodine subtraction. CONCLUSION. Dual-energy CT iodine-subtraction virtual unenhanced technique is capable of depicting urinary stones in iodine solutions of a diverse range of concentrations in a phantom study.

Original languageEnglish (US)
Pages (from-to)1169-1173
Number of pages5
JournalAmerican Journal of Roentgenology
Volume190
Issue number5
DOIs
StatePublished - May 2008

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Urinary Calculi
Iodine
Plastics
Oils
Software
Gels

Keywords

  • Dual-energy CT
  • Genitourinary imaging
  • Iodine-subtraction imaging technique
  • Reconstructed images
  • Urinary stones

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

@article{de95e45bf0744b27b72b3fa1144369ef,
title = "Dual-energy CT iodine-subtraction virtual unenhanced technique to detect urinary stones in an iodine-filled collecting system: A phantom study",
abstract = "OBJECTIVE. The objective of our study was to evaluate the feasibility of virtual unenhanced images reconstructed from a dual-energy CT scan to depict urinary stones in an iodine solution in a phantom study. MATERIALS AND METHODS. Twenty urinary stones of different sizes (1.4-4.2 mm in short-axis diameter) were placed in plastic containers. The containers were consecutively filled with different concentrations of iodine solution (21, 43, 64, 85, and 107 mg/dL; CT attenuation value range, 510-2,310 H at 120 kVp). Dual-energy CT was repeated with 80-140 and 100-140 kVp pairs, two collimation-slice thickness combinations, and the presence or absence of a 4-cm-thick oil gel around the phantom. The iodine-subtraction virtual unenhanced images were reconstructed using commercial software. The images were evaluated by three radiologists in consensus for the visibility of the stones and the presence of residual nonsubtracted iodine. Stone visibility rates were compared between the 80-140 and 100-140 kVp pairs and the five different iodine concentrations. RESULTS. Stone visibility rates with the 80-140 kVp pair were 99{\%}, 93{\%}, 96{\%}, 94{\%}, and 3{\%} and those with the 100-140 kVp pair were 98{\%}, 95{\%}, 99{\%}, 94{\%}, and 99{\%} for an iodine concentration of 21, 43, 64, 85, and 107 mg/dL, respectively. The poor visibility rate with 80-140 kVp and 107 mg/dL iodine concentration was due to the failure of iodine subtraction. CONCLUSION. Dual-energy CT iodine-subtraction virtual unenhanced technique is capable of depicting urinary stones in iodine solutions of a diverse range of concentrations in a phantom study.",
keywords = "Dual-energy CT, Genitourinary imaging, Iodine-subtraction imaging technique, Reconstructed images, Urinary stones",
author = "Naoki Takahashi and Hartman, {Robert P.} and Vrtiska, {Terri J} and Akira Kawashima and Primak, {Andrew N.} and Dzyubak, {Oleksandr P.} and Jayawant Mandrekar and Fletcher, {Joel Garland} and McCollough, {Cynthia H}",
year = "2008",
month = "5",
doi = "10.2214/AJR.07.3154",
language = "English (US)",
volume = "190",
pages = "1169--1173",
journal = "American Journal of Roentgenology",
issn = "0361-803X",
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TY - JOUR

T1 - Dual-energy CT iodine-subtraction virtual unenhanced technique to detect urinary stones in an iodine-filled collecting system

T2 - A phantom study

AU - Takahashi, Naoki

AU - Hartman, Robert P.

AU - Vrtiska, Terri J

AU - Kawashima, Akira

AU - Primak, Andrew N.

AU - Dzyubak, Oleksandr P.

AU - Mandrekar, Jayawant

AU - Fletcher, Joel Garland

AU - McCollough, Cynthia H

PY - 2008/5

Y1 - 2008/5

N2 - OBJECTIVE. The objective of our study was to evaluate the feasibility of virtual unenhanced images reconstructed from a dual-energy CT scan to depict urinary stones in an iodine solution in a phantom study. MATERIALS AND METHODS. Twenty urinary stones of different sizes (1.4-4.2 mm in short-axis diameter) were placed in plastic containers. The containers were consecutively filled with different concentrations of iodine solution (21, 43, 64, 85, and 107 mg/dL; CT attenuation value range, 510-2,310 H at 120 kVp). Dual-energy CT was repeated with 80-140 and 100-140 kVp pairs, two collimation-slice thickness combinations, and the presence or absence of a 4-cm-thick oil gel around the phantom. The iodine-subtraction virtual unenhanced images were reconstructed using commercial software. The images were evaluated by three radiologists in consensus for the visibility of the stones and the presence of residual nonsubtracted iodine. Stone visibility rates were compared between the 80-140 and 100-140 kVp pairs and the five different iodine concentrations. RESULTS. Stone visibility rates with the 80-140 kVp pair were 99%, 93%, 96%, 94%, and 3% and those with the 100-140 kVp pair were 98%, 95%, 99%, 94%, and 99% for an iodine concentration of 21, 43, 64, 85, and 107 mg/dL, respectively. The poor visibility rate with 80-140 kVp and 107 mg/dL iodine concentration was due to the failure of iodine subtraction. CONCLUSION. Dual-energy CT iodine-subtraction virtual unenhanced technique is capable of depicting urinary stones in iodine solutions of a diverse range of concentrations in a phantom study.

AB - OBJECTIVE. The objective of our study was to evaluate the feasibility of virtual unenhanced images reconstructed from a dual-energy CT scan to depict urinary stones in an iodine solution in a phantom study. MATERIALS AND METHODS. Twenty urinary stones of different sizes (1.4-4.2 mm in short-axis diameter) were placed in plastic containers. The containers were consecutively filled with different concentrations of iodine solution (21, 43, 64, 85, and 107 mg/dL; CT attenuation value range, 510-2,310 H at 120 kVp). Dual-energy CT was repeated with 80-140 and 100-140 kVp pairs, two collimation-slice thickness combinations, and the presence or absence of a 4-cm-thick oil gel around the phantom. The iodine-subtraction virtual unenhanced images were reconstructed using commercial software. The images were evaluated by three radiologists in consensus for the visibility of the stones and the presence of residual nonsubtracted iodine. Stone visibility rates were compared between the 80-140 and 100-140 kVp pairs and the five different iodine concentrations. RESULTS. Stone visibility rates with the 80-140 kVp pair were 99%, 93%, 96%, 94%, and 3% and those with the 100-140 kVp pair were 98%, 95%, 99%, 94%, and 99% for an iodine concentration of 21, 43, 64, 85, and 107 mg/dL, respectively. The poor visibility rate with 80-140 kVp and 107 mg/dL iodine concentration was due to the failure of iodine subtraction. CONCLUSION. Dual-energy CT iodine-subtraction virtual unenhanced technique is capable of depicting urinary stones in iodine solutions of a diverse range of concentrations in a phantom study.

KW - Dual-energy CT

KW - Genitourinary imaging

KW - Iodine-subtraction imaging technique

KW - Reconstructed images

KW - Urinary stones

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