Korean J Urol.  2014 Sep;55(9):581-586. 10.4111/kju.2014.55.9.581.

Pilot Study of Low-Dose Nonenhanced Computed Tomography With Iterative Reconstruction for Diagnosis of Urinary Stones

• Park SH
• Kim KD
• Moon YT
• Myung SC
• Kim TH
• Chang IH
• Kwon JK

• KMID: 2069775
• DOI: http://doi.org/10.4111/kju.2014.55.9.581

Abstract

PURPOSE
To evaluate the efficacy of low-dose computed tomography (LDCT) for detecting urinary stones with the use of an iterative reconstruction technique for reducing radiation dose and image noise.
MATERIALS AND METHODS
A total of 101 stones from 69 patients who underwent both conventional nonenhanced computed tomography (CCT) and LDCT were analyzed. Interpretations were made of the two scans according to stone characteristics (size, volume, location, Hounsfield unit [HU], and skin-to-stone distance [SSD]) and radiation dose by dose-length product (DLP), effective dose (ED), and image noise. Diagnostic performance for detecting urinary stones was assessed by statistical evaluation.
RESULTS
No statistical differences were found in stone characteristics between the two scans. The average DLP and ED were 384.60+/-132.15 mGy and 5.77+/-1.98 mSv in CCT and 90.08+/-31.80 mGy and 1.34+/-0.48 mSv in LDCT, respectively. The dose reduction rate of LDCT was nearly 77% for both DLP and ED (p<0.01). The mean objective noise (standard deviation) from three different areas was 23.0+/-2.5 in CCT and 29.2+/-3.1 in LDCT with a significant difference (p<0.05); the slight increase was 21.2%. For stones located throughout the kidney and ureter, the sensitivity and specificity of LDCT remained 96.0% and 100%, with positive and negative predictive values of 100% and 96.2%, respectively.
CONCLUSIONS
LDCT showed significant radiation reduction while maintaining high image quality. It is an attractive option in the diagnosis of urinary stones.

Keyword

Computer-assisted image processing; Radiation; Urinary calculi

MeSH Terms

Adult
Aged
Aged, 80 and over
Female
Humans
Male
Middle Aged
Pilot Projects
Radiation Dosage
Radiographic Image Interpretation, Computer-Assisted/*methods
Reproducibility of Results
Sensitivity and Specificity
Tomography, X-Ray Computed/*methods
Urinary Calculi/*radiography
Young Adult

Figure

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  FIG. 1 Comparison of conventional nonenhanced computed tomography with filtered back projection (A, C) and low-dose computed tomography with iterative reconstruction technique (B, D) on a left proximal ureter stone (arrow).

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  FIG. 2 Two tiny (<1 mm) right renal stones (arrow) were shown in conventional nonenhanced computed tomography (A, C) while not being detected in low-dose computed tomography (B, D).

• 

  FIG. 3 Image qualities were compared on conventional nonenhanced computed tomography (A) and low-dose filtered back projection (B) with iterative reconstruction low-dose computed tomography (C).

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