Research ArticlePhysics/Instrumentation

PET/MRI for Oncologic Brain Imaging: A Comparison of Standard MR-Based Attenuation Corrections with a Model-Based Approach for the Siemens mMR PET/MR System

Ivo Rausch, Lucas Rischka, Claes N. Ladefoged, Julia Furtner, Matthias Fenchel, Andreas Hahn, Rupert Lanzenberger, Marius E. Mayerhoefer, Tatjana Traub-Weidinger and Thomas Beyer
Journal of Nuclear Medicine September 2017, 58 (9) 1519-1525; DOI: https://doi.org/10.2967/jnumed.116.186148

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    Example of artifact categories. Axial views at 2 main axial levels of same patient and different AC methods: CT—reference (A), DIXON—artificial filling of air cavities with tissue (B), UTE—overestimation of air cavities due to susceptibility artifacts (C), and BD-based MR-AC—translation of artifacts found in DIXON (D). Arrows indicate artifacts.

  • FIGURE 2.
    FIGURE 2.

    Axial views of patient with tumor recurrence imaged with 18F-FET (top) and patient with a meningeal tumor formation imaged with 68Ga-DOTANOC (bottom). PET images were reconstructed after AC using: CTref—reference (A), DIXON (B), UTE (C), and BD (D).

  • FIGURE 3.
    FIGURE 3.

    Box plots of RD of SUVmax and SUVmean, VOI70 (volume), and LBRs of SUVmax (LBRmax) and SUVmean (LBRmean) according to CTref for 18F-FET–avid lesions and 3 different AC methods.

  • FIGURE 4.
    FIGURE 4.

    Box plots of RD of SUVmax and SUVmean and VOI50 (volume) according to CTref for lesions in 68Ga-DOTANOC scans and 3 different AC methods. Data included 11 meningeal tumor formations and for 5 patients additionally pituitary gland (in 2 patients, pituitary gland could not be separated from tumor formation).

  • FIGURE 5.
    FIGURE 5.

    Box plots of RD of SUVmax and SUVmean and VOI50 (volume) according to CTref for evaluated lesions in 68Ga-DOTANOC scans and 3 different AC methods. (A) Findings for lesions and pituitary gland in skull base (n = 9). (B) Results for lesions attached to skull cap (n = 7).

  • FIGURE 6.
    FIGURE 6.

    Average RD of 10 reference regions within brain for 18F-FDG scans of healthy subjects. Error bars correspond to respective RD SD for each reference region. *Corresponding RDs of SUVmean for VOI70 of 18F-FET–avid lesions. Lesions were assigned to reference regions used in 18F-FDG evaluation by experienced nuclear medicine expert.

Tables

  • TABLE 1

    Mean RDs in Percentage (±SD) of All Investigated Values for 18F-FET and 68Ga-DOTANOC Scans

    18F-FET68Ga-DOTANOC
    ParameterDixonUTEBDDixonUTEBD
    SUVmax−10 ± 3−4 ± 3−3 ± 3−11 ± 8−11 ± 8−3 ± 6
    SUVmean−10 ± 4−4 ± 3−3 ± 3−11 ± 7−11 ± 8−3 ± 5
    Volume+1 ± 9+2 ± 8+7 ± 28*+1 ± 4−4 ± 12−3 ± 10
    LBRmax−2 ± 30 ± 30 ± 5———
    LBRmean−3 ± 30 ± 30 ± 2———

    • ↵* Includes 1 patient with a volume difference of +103%.

    • LBRmax = LBRs of SUVmax; LBRmean = LBRs of SUVmean.

    • Images of whole brain, segmented by threshold-based segmentation, were excluded from calculations.

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