CEREBRAL TOXOPLASMOSIS AND LYMPHOMA IN AIDS - PERFUSION MR-IMAGING EXPERIENCE IN 13 PATIENTS

PURPOSE: To evaluate the perfusion magnetic resonance (MR) imaging cha racteristics of cerebral toxoplasmosis and lymphoma in patients with a cquired immunodeficiency syndrome (AIDS). MATERIALS AND METHODS: Perfu sion MR imaging was performed prospectively in 13 patients with AIDS w ho had contrast material-enhancing focal brain lesions (six with activ e lymphoma, five with toxoplasmosis, one with treated lymphoma in remi ssion, and one with toxoplasmosis plus lymphomatoid granulomatosis). R egional cerebral blood volume (rCBV) was determined by using dynamic e cho-planar MR imaging during bolus injection of a gadolinium chelate. RESULTS: The rCBV was decreased (44% +/- 24 [standard deviation] of rC BV in contralateral regions) throughout the toxoplasmosis lesions and in the surrounding edema of both lesion types, whereas all active lymp homas displayed areas of increased rCBV (258% +/- 99). These differenc es were significant (P < .005) CONCLUSION: Reduced rCBV in toxoplasmos is lesions is probably due to a lack of vasculature within the abscess ; increased rCBV in lymphomas is probably due to hypervascularity in f oci of active tumor growth; and decreased rCBV in the edema is probabl y due to vasoconstriction associated with increased interstitial press ure. Perfusion MR imaging is a rapid, noninvasive tool that may allow differentiation between cerebral lymphoma and toxoplasmosis in patient s with AIDS.