Chin J Radiol 2001; 26: 51-60 51 Intracranial Meningeal Carcinomatosis and Non-neoplastic Meningeal Diseases: Evaluation with Contrast-Enhanced MR Imaging CHEN-PIN CHOU 1 PING-HONG LAI 1,2 WEI -LIANG CHEN 1 HUAY-BEN PAN 1,2 CLEMENT CHEN 1,2 CHIEN-FANG YANG 1,2 Department of Radiology, Veterans General Hospital-Kaohsiung 1 , and National Yang-Ming University 2 , Taipei, Taiwan, ROC This study was performed to correlate meningeal enhancement patterns with intracranial meningeal carcinomatosis and non- neoplastic meningeal diseases. From 1993 to 1998, 48 patients with a clinical diagnosis of meningeal carcinomatosis and non- neoplastic meningeal diseases with abnormal meningeal enhancement on MR imaging were reviewed. Two enhancement patterns of the meninges were characterized: pachymeningeal and leptomeningeal. The distribution and shape of the enhancement were also inspected. The meningeal enhancement was classified into six etiologic subgroups: carcinomatosis, infection, inflammation, cerebrovascular disease, reactive meningitis, and chemical meningitis. Nineteen of the 48 patients with enhanced meninges had carcinomatosis of the meninges. The other 29 patients without neoplasms included 10 with infectious meningitis, 5 with inflammatory disease, 8 with cerebrovascular disease (7 with early brain infarction and 1 with Sturge-Weber disease), 5 with reactive changes and 1 with chemical meningitis. Pachymeningeal enhancement occurred in 11 patients with meningeal metastasis, 1 with amebic meningitis, 4 with inflammatory meningeal disease, 7 with early infarction, 5 with reactive meningeal disease, and 1 with chemical meningitis while leptomeningeal enhancement was shown in 8 meningeal metastases, 9 with infectious meningitis, 2 with inflammatory changes and 2 with vascular disease (1 with early brain infarction and 1 with Sturge-Weber disease). Both enhancement patterns were noted in 1 with inflammatory changes (Wegener granulomatosis) and 1 with early brain infarction. Diffuse linear leptomeningeal enhancement favored non-neoplastic etiologies while enhanced leptomeningeal nodules indicated meningeal metastasis and some non-neoplastic disease such as tuberculosis and neuro- sarcoidosis. Focal nodular pachymeningeal enhancement presented mostly due to meningeal carcinomatosis. Diffuse linear pachymeningeal enhancement could be meningeal carcinomatosis or reactive meningeal change. Key words: Meninges, Magnetic resonance imaging, Meningitis, Meningeal metastasis. Clinical evaluation of meningeal disorders has limitations in nonspecific clinical presentations and confusing cerebrospinal fluid (CSF) analysis. ORIGINAL ARTICLE Reprint requests to: Ping-Hong Lai Department of Radiology, Veterans General Hospital- Kaohsiung, 386 Ta-Chung first Rd. Kaohsiung 813, Taiwan, ROC.