BACKGROUND AND PURPOSE:Noninvasive diagnosis of brain lesions is important for the correct choice of treatment. Our aims were to investigate whether 1) proton MR spectroscopic imaging ( 1 H-MRSI) can aid in differentiating between tumors and nonneoplastic brain lesions, and 2) perfusion MR imaging can improve the classification.

Object. The natural history of Modic changes (MCs) in the lumbar spine is often marked by conversion from one type to another, but their course following lumbar discectomy remains unknown. The authors sought to study the impact of surgery on the natural history of these lesions.Methods. Forty-one patients treated with lumbar microdiscectomy between 2004 and 2005 were enrolled in this study and underwent clinical evaluation and repeat MR imaging after a median follow-up of 41 months (range 32-59 months). Preoperative and follow-up MR images were reviewed and the type, location, and extent of MCs at the operated level were recorded and compared.Results. The study population consisted of 27 men and 14 women with a mean age of 54 years (range 24-78 years). During the follow-up period, the prevalence of MCs increased from 46.3% to 78%, and 26 patients (63.4%) had Type 2 lesions at the operated level. Of the 22 patients without MCs, 4 (18.2%) converted to Type 1 and 9 (40.9%) to Type 2. Of the 5 Type 1 lesions, 3 (60%) converted to Type 2, and 2 (40%) remained Type 1 but increased in size. In contrast, none of the 14 Type 2 changes converted to another type, although 10 (71.4%) increased in extent. There were no reverse conversions to Type 0.

The authors report the case of a 14-month-old baby boy with an epidermoid cyst located entirely within the pons and medulla, without an exophytic component. The lesion was examined by computed tomography and magnetic resonance imaging. The child was operated upon three times after two recurrences of the lesion. A suboccipital, subtonsillar approach was used for the first and second procedures and a transtemporal approach for the last one. Excision was thought to be complete the first time, since a solid tumor was found and removed in a large cyst. The cyst wall was not identified. No tumor was found during the second procedure despite recurrence of the cyst, which was drained without an attempt to remove the cyst wall. Finally the cyst recurred with a large tumor in the cyst wall which was again totally removed. Consistent with the high mortality of brain stem epidermoid cysts in the literature, the child eventually died. The therapeutic problems, surgical options, and consequences are discussed.

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