Is Volume Transfer Coefficient (Ktrans) Related to Histologic Grade in Human Gliomas?
Tufail F. Patankara,
Hamied A. Haroona,
Samantha J. Millsa,
Danielle Balériauxb,
David L. Buckleya,
Geoff J.M. Parkera and
Alan Jacksona
a Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom
b Service de Radiologie, Hôpital Erasme, Cliniques Universitaires de Bruxelles, Université Libre de Bruxelles, Brussels, Belgium
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FIG 1. Representative Ktrans maps from (A) a grade II fibrillary astrocytoma, (B) a grade III anaplastic astrocytoma, and (C) a grade IV glioblastoma multiforme. The white boxes enclose the tumor area in each image. Note that vasculature does not appear in these maps, and Ktrans values in normal brain are insignificant and consistent with noise. The Ktrans values in the grade II tumor (A) are insignificant corresponding to the lack of enhancement with contrast. The high-grade-defining necrotic core is clearly evident in the middle of the tumor in panel C. The heterogeneity of Ktrans is clearly evident in the enhancing tumor portion in panels B and C.
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FIG 2. Representative CBV maps from (A) a grade II fibrillary astrocytoma, (B) a grade III anaplastic astrocytoma, and (C) a grade IV glioblastoma multiforme. The white boxes enclose the tumor area in each image. The normal cerebral vasculature is clearly seen on these maps, particularly the superior sagittal sinus and other major vessels. The grade II tumor in panel A homogeneously shows very low blood volume, which is below the measurement accuracy of the technique. The necrotic core is clearly evident in the middle of the tumor in panel C. The heterogeneity of CBV is clearly evident in the enhancing tumor portion in panels B and C and shows very different distributions to those in Fig 1 (A and B).
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FIG 3. Scattergrams showing the relationships between histologic grade and median values of Ktrans, Ktrans (95%), CBV, and CBV (95%). Individual cases are indicated by circles, multiple cases are represented by the addition of "petals" to the glyph with the number of petals representing the number of cases. Lines indicate the optimal linear regression fit for the data and the 95th percentile confidence limits for the regression fit for the entire dataset. The correlation between grade and the median values of each of the parametric variables is significant (Ktrans, Ktrans [95%], CBV, and CBV [95%]; P < .01).
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FIG 4. Scattergram showing the relationship between values of median CBV and Ktrans (95%) for all individual cases. The grade II tumors show lower values of both CBV and Ktrans (95%). Higher values are seen in grade III and IV tumors, but there is a considerable overlap in these distributions.
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FIG 5. ROC analysis showing effect of using each individual variable or the discriminant function (C1) in differentiating between high- and low-grade tumors. The area under the ROC curve for high- versus low-grade is greatest for the discriminant function (0.993). Within the independent parametric variables the area was highest for Ktrans (95%) (0.986), though similarly high values were seen for Ktrans and CBV (0.979 and 0.966, respectively). (Areas under the ROC curves are shown in Table 7.)
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FIG 6. ROC analysis for separation of grade III and IV tumors. Areas under the ROC curves are shown in Table 7.
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