Fig 1. Comparison of the signal intensity of 26 metastatic brain tumors on diffusion-weighted images. All 6 well differentiated adenocarcinomas (Well diff. AC) were classified as grade –2, –1, or 0. All 3 small-cell carcinomas (Small cell ca.) and 1 large-cell neuroendocrine carcinoma (LCNC) were graded as +2. A malignant melanoma was grade –1; all other tumors were grade 0 or +1. Poorly diff. AC, indicates poorly differentiated adenocarcinomas; Large cell ca., large cell carcinoma; SCC, squamous cell carcinoma; Papillotubular ca., papillotubular carcinoma; Mucoepidermoid ca., mucoepidermoid carcinoma; Mod. diff. AC, moderately differentiated adenocarcinoma. The signal intensity was graded on a point scale: –2 = hypointense relative to the normal-appearing white matter; –1 = isointense relative to the normal-appearing white matter; 0 = isointense relative to the normal-appearing cortical gray matter; +1 = slightly hyperintense relative to the normal-appearing cortical gray matter; and +2 = hyperintense relative to the normal-appearing cortical gray matter.