AJR:200, January 2013 W1 Lesions of the Corpus Callosum Residents’ Section • Pattern of the Month WEB This is a Web exclusive article. AJR 2013; 200:W1–W16 0361–803X/13/2001–W1 © American Roentgen Ray Society Mai-Lan Ho 1 Gul Moonis 1 Daniel T. Ginat 2 Ronald L. Eisenberg 1 Ho ML, Moonis G, Eisenberg RL 1 All authors: Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, 330 Brookline Ave, Boston, MA 02115. Address correspondence to R. L. Eisenberg ([email protected]). 2 Department of Radiology, Massachusetts General Hospital, Boston, MA. Keywords: brain, corpus callosum DOI:10.2214/AJR.11.8080 Received October 7, 2011; accepted after revision May 8, 2012. Residents inRadiology T his article reviews the causes and imaging appearances of lesions involving the cor- pus callosum (Table 1). The corpus callosum consists of densely bundled white mat- ter tracts connecting the two cerebral hemispheres, with a compact structure that largely blocks interstitial edema and tumor spread. Isolated lesions of the corpus callosum are rare and may represent transient responses to injury or myelination abnormalities. More common butterfly lesions involve the corpus callosum and both cerebral hemispheres—a pattern associated with aggressive tumors, demyelination, and traumatic brain injury. Unenhanced CT is a first-line neuroimaging modality. Although soft-tissue contrast enhance- ment is limited, CT can help characterize hemorrhage, edema, mass effect, calcification, and ne- crosis. MRI provides more detailed informa- tion regarding tissue structure and composi- tion, using various pulse excitation sequences, such as FLAIR, to distinguish abnormal signal in the corpus callosum from adjacent CSF in the lateral ventricles. Administration of IV contrast material is useful for characterization of neoplastic and vascular lesions, which may show characteristic patterns of enhancement. Neoplastic Lesions Glioma Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults, classified histologically as World Health Organization (WHO) grade IV, with a median survival time of 14 months. Tumors can involve both cerebral hemispheres, with extension across the corpus callosum produc- ing a classic butterfly appearance. On CT, GBM appears as an irregular, heterogeneous mass with peritumoral vasogenic edema or mass effect and possible internal areas of ne- crosis, calcification, and hemorrhage (Fig. 1A). On MRI, tumor is heterogeneously T1 hypoin- tense and T2 hyperintense, with possible foci of susceptibility, vascular flow voids, and ir- regular contrast enhancement (Fig. 1B). Gliomatosis cerebri is a slow-growing, diffuse form of glioma, classified as WHO grade III. By definition, it infiltrates two or more lobes and shows minimal contrast en- hancement (Fig. 2). The prognosis is slightly better than GBM, with a median survival time of 12 months. Ho et al. Lesions of the Corpus Callosum Residents’ Section Pattern of the Month TABLE 1: Lesions Involving the Corpus Callosum Neoplastic Glioma Lymphoma Meningioma Metastases Neurodystrophic Demyelinating diseases Hereditary leukoencephalopathies Wallerian degeneration Trauma or exposure Traumatic brain injury Hypoxic-ischemic encephalopathy Marchiafava-Bignami disease CSF shunting Congenital Callosal malformations Lipoma Vascular Infarct Aneurysm Arteriovenous malformation Callosal gliosis Periventricular leukomalacia Virchow-Robin spaces Infection or inflammation Downloaded from www.ajronline.org by 171.243.65.178 on 05/14/23 from IP address 171.243.65.178. Copyright ARRS. For personal use only; all rights reserved
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