Abnormalities in the Recirculation Phase of Contrast Agent Bolus Passage in Cerebral Gliomas: Comparison with Relative Blood Volume and Tumor Grade
Alan Jacksona,
Andrea Kassnerb,
Deborah Annesley-Williamsa,
Helen Reidc,
Xiau-Ping Zhua and
Kah-Loh Lia
a Imaging Science and Biomedical Engineering, University of Manchester, Manchester, United Kingdom
b Philips Medical Systems, Hammersmith, London, United Kingdom
c Department of Neuropathology, Hope Hospital, Salford, United Kingdom
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FIG 1. Parametric images of rCBV (left) and rR (right) in a patient with glioblastoma multiforme. The rCBV map is in color to aid interpretation. The color scale is nonlinear: black,  2%; blue, 2–5%; green, 5–10%; red, 10–30%; orange, 30–80%; and yellow,  80%. The image demonstrates large peripheral vessels (yellow) and a central area of high rCBV within the tumor core (red) and other central areas of poor perfusion or necrosis (black). The red areas in the rR map indicate pixels with values <0.46, which are seen in fewer than 2% of normal tissue. Single-pixel areas of elevated rR have been filtered out, and the pixel clusters have been filtered by using a 0.5-pixel gaussian filter. The underlying gray-scale image shows the rCBV map. This image demonstrates areas of elevated rR, which occur principally in the center of the tumor, adjacent to areas of necrosis and away from the central area of elevated rCBV.
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FIG 2. Plot of mean rCBV values against tumor grade shows increase in rCBV with increasing tumor grade. (AU indicates arbitrary units.)
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FIG 3. Pixel-by-pixel plots of rR versus rCBV for two examples of anaplastic astrocytoma (GIII) (top) and glioblastoma multiforme (GIV) (bottom). rR values show a relatively normal distribution in the grade III tumors and a more skewed distribution in the grade IV tumors. No evidence of correlation exists between rCBV and rR.
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FIG 4. Plot of skewness of rR against tumor grade shows increased skewness in grade IV tumors.
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FIG 5. Plot of rR values in one patient with a grade III tumor (left) and one patient with a grade IV tumor (right) shows loss of conformance of the pixel values to the normal distribution in the grade IV tumor. The optimal fitted normal distribution is illustrated.
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FIG 6. Plot of skewness of rR against mean rCBV values demonstrates the separation of grade IV tumors on the basis of both skewness of rR and rCBV and the separation of grade II and grade III tumors by rCBV. Grade II tumors are represented by triangles, grade III by diamonds, and grade IV by circles. (AU indicates arbitrary units.)
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