Objective: This retrospective study investigated the specificity of restricted water diffusion for the diagnosis of brain abscess. Two of five rim-enhancing brain masses with restricted water diffusion (apparent diffusion coefficient of 0.79 [10(-3) mm(2)/sec] or less) were brain abscesses, but diagnoses in the other cases were metastatic squamous cell carcinoma (two cases) and radiation necrosis.
Conclusion: Although an important diagnostic sign, restricted water diffusion is not specific for brain abscess.