18F-FDG PET of Gliomas at Delayed Intervals: Improved Distinction Between Tumor and Normal Gray Matter
Alexander M. Spence, MD1,
Mark Muzi, MS2,
David A. Mankoff, MD, PhD2,
S. Finbarr O’Sullivan, PhD3,
Jeanne M. Link, PhD2,
Thomas K. Lewellen, PhD2,
Barbara Lewellen, MS2,
Pam Pham, BS2,
Satoshi Minoshima, MD, PhD2,
Kristin Swanson, PhD4 and
Kenneth A. Krohn, PhD2
1 Department of Neurology, University of Washington School of Medicine, Seattle, Washington
2 Department of Radiology, University of Washington School of Medicine, Seattle, Washington
3 Department of Statistics, University of Washington School of Medicine, Seattle, Washington
4 Department of Pathology, University of Washington School of Medicine, Seattle, Washington
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FIGURE 1. The 18F-FDG metabolism model, showing the compartments and parameters.
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FIGURE 2. A 45-y-old woman (patient 1, Table 1) with a recurrent right temporal glioblastoma multiforme shown on T1-weighted gadolinium-enhanced (T1Gd) MRI. Note the much more prominent tumor to gray matter (T/G) delineation at the later time point, 473 min, compared to 90 min.
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FIGURE 3. A 38-y-old man (patient 14, Table 1) with a recurrent left temporal astrocytoma. Coregistration of T1Gd MRI planes with the 18F-FDG PET planes and use of delayed imaging made evident that the small focus seen on MRI was tumor rather than radionecrosis, especially at 415 min. Subsequent MRI confirmed rapidly progressing disease.
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FIGURE 4. A 59-y-old woman (patient 6, Table 1) with a progressive memory disorder and seizures whose multiple MRI scans demonstrated an extensive intraaxial infiltrating mass predominantly in the right temporal lobe but also involving the splenium of the corpus callosum and contralateral temporal lobe. The initial clinical and radiographic diagnosis was low-grade glioma. She declined treatment. Gadolinium contrast enhancement appeared on T1-weighted MR images 2 y after presentation, at which time she underwent 18F-FDG PET. Autopsy 19 mo after PET showed a mixed glioma, WHO grade III. 18F-FDG uptake was decidedly more prominent at the later times, 82 and 315 min, than at 45 min.
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FIGURE 5. The plots for the images in Figure 4 show the time course of 18F-FDG SUV changes in tumor, brain, and gray matter. SUV is highest in tumor and remains so over the course of the study. Brain tissue and gray matter SUVs decline at later times.
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FIGURE 6. SUV data for all cases. On the left are plots of the SUV ratios of brain to gray matter, which do not change over time. On the right are similar plots of the T/G SUV ratios. These show enhancement of tumor uptake relative to gray matter over time.
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FIGURE 7. Kinetic modeling data. On the left are plots of the ratios of whole brain over gray matter (B/G) of k4 estimates, which over time remain flat. On the right are similar plots of T/G ratios, which decrease over time by –26% (n = 19, P < 0.002, paired t test).
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FIGURE 8. Plots of the gray matter SUV results for the first 90 min after injection. These show a continuous rise out to the 90-min time point.
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Copyright © 2004 by the Society of Nuclear Medicine.
