Document Detail


Urinary calculi composed of uric acid, cystine, and mineral salts: differentiation with dual-energy CT at a radiation dose comparable to that of intravenous pyelography.
MedLine Citation:
PMID:  20807847     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: To retrospectively evaluate radiation dose, image quality, and the ability to differentiate urinary calculi of differing compositions by using low-dose dual-energy computed tomography (CT).
MATERIALS AND METHODS: The institutional review board approved this retrospective study; informed consent was waived. A low-dose dual-energy CT protocol (tube voltage and reference effective tube current-time product, 140 kV and 23 mAs and 80 kV and 105 mAs; collimation, 64 × 0.6 mm; pitch, 0.7) for the detection of urinary calculi was implemented into routine clinical care. All patients (n = 112) who were examined with this protocol from July 2008 to August 2009 were included. The composition of urinary calculi was assessed by using commercially available postprocessing software and was compared with results of the reference standard (ex vivo infrared spectroscopy) in 40 patients for whom the reference standard was available. Effective doses were calculated. Image quality was rated subjectively and objectively and was correlated with patient size expressed as body cross-sectional area at the level of acquisition by using Spearman correlation coefficients.
RESULTS: One calcified concrement in the distal ureter of an obese patient was mistakenly interpreted as mixed calcified and uric acid. One struvite calculus was falsely interpreted as cystine. All other uric acid, cystine, and calcium-containing calculi were correctly identified by using dual-energy CT. The mean radiation dose was 2.7 mSv. The average image quality was rated as acceptable, with a decrease in image quality in larger patients.
CONCLUSION: Low-dose unenhanced dual-source dual-energy CT can help differentiate between calcified, uric acid, and cystine calculi at a radiation dose comparable to that of conventional intravenous pyelography. Because of decreased image quality in obese patients, only nonobese patients should be examined with this protocol.
Authors:
Christoph Thomas; Martin Heuschmid; David Schilling; Dominik Ketelsen; Ilias Tsiflikas; Arnulf Stenzl; Claus D Claussen; Heinz-Peter Schlemmer
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Publication Detail:
Type:  Journal Article     Date:  2010-08-31
Journal Detail:
Title:  Radiology     Volume:  257     ISSN:  1527-1315     ISO Abbreviation:  Radiology     Publication Date:  2010 Nov 
Date Detail:
Created Date:  2010-10-20     Completed Date:  2010-12-02     Revised Date:  2011-02-01    
Medline Journal Info:
Nlm Unique ID:  0401260     Medline TA:  Radiology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  402-9     Citation Subset:  AIM; IM    
Copyright Information:
© RSNA, 2010.
Affiliation:
Department of Diagnostic and Interventional Radiology, University of Tübingen, Hoppe-Seyler-Strasse 3, 72076 Tübingen, Germany. christoph.thomas@med .uni-tuebingen.de
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Aged
Aged, 80 and over
Child
Diagnosis, Differential
Diagnostic Errors
Female
Humans
Male
Middle Aged
Predictive Value of Tests
Radiation Dosage
Radiographic Image Interpretation, Computer-Assisted
Retrospective Studies
Sensitivity and Specificity
Tomography, X-Ray Computed / methods*
Urinary Calculi / chemistry*,  radiography*
Urography
Comments/Corrections
Comment In:
Nat Rev Urol. 2011 Jan;8(1):7

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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