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Fractal Dimension (FD) is a parameter used widely for classification, analysis, and pattern recognition of images. In this work we explore the quantification of CT (computed tomography) lesions of the brain by using fractal theory. Five brain lesions, which are portions of CT images of diseased brains, are used for the study. These lesions exhibit self-similarity over a chosen range of scales, and are broadly characterized by their fractal dimensions.

The diagnosis of central nervous system sarcoidosis is uncertain without typical multisystem involvement. We describe two patients with isolated central nervous system mass lesions whose biopsy results were consistent with sarcoidosis. After a progressive clinical course, they were found to have diencephalic germinomas. Germ cell tumors, in particular, should be considered in the differential diagnosis of central nervous system sarcoidosis as they are potentially treatable, occur in intracranial locations favored by sarcoidosis mass lesions, and may be surrounded by granulomatous inflammation that can be mistaken for the noncaseating granulomas of sarcoidosis.

CT-guided stereotactic biopsy of lower brain stem lesions in 7 consecutive cases is discussed. A frontal transincisural approach was used. Five patients had astrocytomas histologically. The single patient who had undergone empirical radiation therapy prior to tissue diagnosis revealed only necrosis. One patient was found to have pathology suggestive of Leigh's disease. This patient was not radiated and is the first alive adult to have this diagnosis confirmed. Although controversy still exists in the management of brain stem lesions, we intend to demonstrate the value of tissue diagnosis in the management of such lesions.