detecting very small lesions, particularly those in the posterior fossa, and leptomeningeal spread.

Diagnostic screening and treatment planning benefit greatly from the sensitivity, specificity and anatomic resolution (particularly in the posterior fossa) of MRI. Most metastases are isointense on Tl-weighted images and hyperin-tense on T2-weighted images. Central necrosis, cysts and peripheral edema are all hypointense on Tl images and hyperintense on T2 images. The intensity pattern of hemorrhagic metastases varies with the age of the hematoma. Anomalies include melanomas that may be hyperintense on Tl images and adenocarcino-mas, highly cellular tumors, and calcified lesions that may be hypointense on T2 images.

Metastases usually enhance brightly and homogeneously with gadolinium, except in their necrotic, cystic or hemorrhagic portions. Rim-enhancing metastases have a center of fluid or necrosis; the rim is more irregular than that of benign cysts, abscesses and resolving hematomas [6]. Metastases may sometimes be distinguished from malignant gliomas that also have nodular rim-enhancement by multiplicity and a circumferential pattern of Tl hypointense, T2 hyperintense edema that is less likely to involve the cortex or corpus callosum [5]. Higher doses of contrast (0.3 mmol/kg) significantly increase the sensitivity of detecting small lesions. Diffuse leptomeningeal disease, carcinomatous meningitis, appears as sulcal enhancement on post-gadolinium Tl scans and as hyperintense linearities on flair sequences.

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Cure Your Yeast Infection For Good

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