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FIGURE 3. Representative examples of tumor-bearing rat 10 d after implantation of F98 cells in left caudate putamen, as measured by 18F-CPFPX and high-resolution small-animal PET. (A) MRI depicting tumor (red arrows) as hypointense zone in coronal (left) and horizontal (right) sections. (B) Summed PET images of coronal (left) and horizontal (right) sections (frames 3–10, 48-min scan time). White tracing outlines outer brain contour based on individually coregistered MRI datasets depicted in A, which were subsequently superimposed onto PET datasets. Note significant tracer accumulation at tumor border (red arrows), coinciding with outer border of hypointense zone determined by MRI (red arrows in A). Other signals represent normal cerebral tracer accumulation and the tracer and its metabolites in blood vessels. (C) Ex vivo autoradiograph (left) taken from PET experiment shown in B confirms circumferential accumulation of 18F-CPFPX in tumor region at highest spatial resolution. Histogram (right) constructed from data measured along superimposed yellow line shows that accumulation of radiotracer at periphery of tumor (red arrows) clearly exceeds that in normal brain tissue. WW = wet weight. Scale bar in all panels = 10 mm.
