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Noise reduction to decrease radiation dose and improve conspicuity of hepatic lesions at contrast-enhanced 80-kV hepatic CT using projection space denoising.

Abstract

OBJECTIVE
The purpose of this study was to investigate the combined potential of 80-kV CT and noise reduction using a projection space denoising algorithm to reduce radiation dose reduction or to improve the image quality of hepatic CT.
MATERIALS AND METHODS
Twenty patients with 56 liver lesions underwent dual-energy (80 and 140 kV) contrast-enhanced hepatic CT. Low-dose 80-kV-only images (comprising 26-54% of the total radiation dose), low-dose 80-kV projection space denoising images (routine and sharper reconstruction kernel), and full-dose mixed-kilovoltage with projection space denoising images were evaluated by three radiologists for lesion conspicuity, image noise, and sharpness. Lesions were compared with full-dose images using 5-point scales (0 = no change, +2 = markedly better, and -2 = markedly worse). Quantitative conspicuity in the form of lesion-to-liver contrast-to-noise ratio (CNR), image noise, and image sharpness were measured.
RESULTS
For all readers, the mean conspicuity rating of low-dose 80-kV projection space denoising images was better than that for full-dose images (mean conspicuity, 0.36-0.57; p < 0.001), with only 1.2% of lesions less conspicuous on 80-kV projection space denoising images. Eighty-kilovolt projection space denoising images reconstructed with a sharper kernel were subjectively similar to full-dose mixed-kilovoltage images comparing image noise (-0.054 to 0.018; p < 0.001 to p = 0.058) and sharpness (-0.64 to -0.09; p < 0.001 to p = 0.057). For 80-kV projection space denoising images with a sharper kernel, lesion-to-liver CNR was slightly higher than that for full-dose mixed-kilovoltage images (p < 0.001), whereas image sharpness and noise were unchanged (p = 0.74 and p = 0.02).
CONCLUSION
Eighty-kilovolt imaging with noise reduction can simultaneously increase lesion conspicuity and facilitate radiation dose reduction and image quality improvement at contrast-enhanced hepatic CT.

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  • Publisher Full Text
  • Authors

    Ehman EC, Guimarães LS, Fidler JL, Takahashi N, Ramirez-Giraldo JC, Yu L, Manduca A, Huprich JE, McCollough CH, Holmes D, Harmsen WS, Fletcher JG

    Source

    AJR. American journal of roentgenology 198:2 2012 Feb pg 405-11

    MeSH

    Aged
    Algorithms
    Contrast Media
    Female
    Humans
    Liver Diseases
    Male
    Middle Aged
    Pilot Projects
    Radiation Dosage
    Radiographic Image Interpretation, Computer-Assisted
    Retrospective Studies
    Signal-To-Noise Ratio
    Tomography, X-Ray Computed

    Pub Type(s)

    Journal Article
    Research Support, N.I.H., Extramural
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    22268185