Dysmyelinating diseases, or leukodystrophies, encompass a wide spectrum of inherited neurodegenerative disorders affecting the integrity of myelin in the brain and peripheral nerves. Most of these disorders fall into one of three categories-lysosomal storage diseases, peroxisomal disorders, and diseases caused by mitochondrial dysfunction-and each leukodystrophy has distinctive clinical, biochemical, pathologic, and radiologic features. Magnetic resonance (MR) imaging has become the primary imaging modality in patients with leukodystrophy and plays an important role in the identification, localization, and characterization of underlying white matter abnormalities in affected patients. MR imaging has also been extensively used to monitor the natural progression of various white matter disorders and the response to therapy. Although the MR imaging features of leukodystrophy are often nonspecific, systematic analysis of the finer details of disease involvement may permit a narrower differential diagnosis, which the clinician can then further refine with knowledge of patient history, clinical testing, and metabolic analysis.

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Germinoma in the basal ganglia (BG) is notorious for its diagnostic difficulty. Clinical and radiological features of this disease are quite diverse, but have not been well characterized with respect to prognosis. We retrospectively reviewed the clinical course and treatment outcomes of 17 patients with a BG germinoma. The initial magnetic resonance imaging (MRI) features were classified. Clinical features and treatment outcomes were then analyzed with this classification scheme. A Type 1 lesion was defined as a subtle lesion with faint or no contrast enhancement (six patients). Type 2, 3, and 4 lesions were defined as contrast-enhancing lesions and were differentiated by the lesion size and the presence of subependymal seeding (11 patients). Type 1 lesions were distinct from the other lesions. Patients with a Type 1 lesion had a significantly longer time from the initial MRI to diagnosis than patients with Type 2, 3, and 4 lesions (P = 0.012). The actuarial progression-free survival and overall survival of patients 5 years after diagnosis were 66 and 77%, respectively. The presence of a Type 1 lesion (P = 0.004), a longer time delay in the diagnosis (P = 0.038), and radiation therapy without complete ventricular coverage (P = 0.010) were significantly associated with tumor progression. Profound motor deficits at diagnosis were associated with deterioration in motor function after tumor remission (P = 0.035). Early diagnosis of BG germinomas could affect the ability to control a tumor and neurological outcomes. In particular, high clinical suspicion and active diagnostic procedures are recommended. For optimal treatment, radiation fields should include entire ventricles even if there is no subependymal seeding.

Synthetic T1- and T2-weighted images were diagnostically acceptable, but synthetic FLAIR images were not. Lesion conspicuity and gray/white matter differentiation were comparable to conventional MRI.