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Fig 9. A, Toxoplasmosis on ASL. Decreased perfusion to a toxoplasmosis abscess. Ring-enhancing lesion is demonstrated on corresponding postgadolinium T1-weighted image (arrow). The edema surrounding the abscess decreases the perfusion of the white matter, accentuating the normal perfusion of the adjacent gyri. The area of high signal intensity on ASL surrounding the abscess (arrowhead) represents the normal adjacent gray matter. B, Toxoplasmosis on ASL. Axial T2-weighted image (left) shows a mass with vasogenic edema in the left frontal lobe (arrow). Corresponding ASL image (right) shows diffusely decreased perfusion in the lesion and adjacent white matter (arrow).
