Research ArticleClinical Investigations

Clinical Evaluation of Zero-Echo-Time MR Imaging for the Segmentation of the Skull

Gaspar Delso, Florian Wiesinger, Laura I. Sacolick, Sandeep S. Kaushik, Dattesh D. Shanbhag, Martin Hüllner and Patrick Veit-Haibach
Journal of Nuclear Medicine March 2015, 56 (3) 417-422; DOI: https://doi.org/10.2967/jnumed.114.149997

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Axial (A and B) and sagittal views (C and D) of reconstructed ZTE dataset. Logarithmic intensity rescaling (B and D) was applied to enhance bone tissue and facilitate its separation from background and internal air cavities.

  • FIGURE 2.
    FIGURE 2.

    (A) Typical intensity histogram of ZTE dataset after logarithmic rescaling. Gaussian fitting result for soft-tissue and background peaks is indicated by dashed lines. Expected intensity range of bone tissue used in segmentation is indicated by dotted lines. (B) Axial view of corresponding ZTE volume. (C) Soft tissue (blue) and bone mask (green) obtained with segmentation.

  • FIGURE 3.
    FIGURE 3.

    Volume rendering (top) and sagittal views (bottom) of CT dataset (left) and corresponding segmented ZTE dataset (right). Dental artifacts on both images, minor misclassification of cartilage and auditory canal air, and oversegmentation around sinusal cavities exist.

  • FIGURE 4.
    FIGURE 4.

    Jaccard distance between CT and ZTE bone masks, as function of CT threshold value. Each line in plot corresponds to 1 of the patients.

  • FIGURE 5.
    FIGURE 5.

    Logarithmic rescaling of ZTE dataset (A and B) and corresponding map of agreement between ZTE and CT bone masks (C and D). Green pixels indicate true-positive bone identification, red pixels indicate false-negative (missed bone), and yellow pixels indicate false-positive. Residual misregistration can be perceived in, for example, occipital region. Notice surgical bone alteration.

Tables

  • TABLE 1

    Jaccard Overlap Distances Measured Between ZTE and CT Bone Masks

    Distance
    PatientWholeCranium
    159%46%
    250%37%
    353%38%
    451%40%
    546%33%
    638%32%
    757%36%
    854%39%
    963%40%
    1058%40%
    1146%41%
    1253%43%
    1350%38%
    1452%49%
    1546%40%
    Mean52%39%
    Maximum63%49%
    Minimum38%32%
    SD6%4%
  • TABLE 2

    Clinical Scoring of ZTE Bone Masks in Comparison with CT Gold Standard

    CalvariaCerebrospinal fluid space
    PatientFrontalParietalTemporalOccipitalInner earMastoidOrbitThird ventricleFourth ventricleChoroid plexus of lateral ventricle (calcification)Pineal gland (calcification)Artificial alteration
    110112111110NA
    2111021000101
    3011121120111
    4011111020101
    5110111220100
    6111111110002
    7201121121000
    8211121000011
    911112110100NA
    1011112112010NA
    11122221100102
    1211111100000NA
    13101121020101
    14222121120102
    15101121022101
    Mean1.10.91.11.01.71.00.71.20.30.70.11.1
    SD0.60.60.50.40.50.00.60.90.60.50.40.7

    • 1 = minor issue; 0 = no issue; 2 = major issue; NA = not applicable.

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