Cerebral toxoplasmosis and lymphoma in AIDS: perfusion MR imaging experience in 13 patients.

PURPOSE

To evaluate the perfusion magnetic resonance (MR) imaging characteristics of cerebral toxoplasmosis and lymphoma in patients with acquired immunodeficiency syndrome (AIDS).

MATERIALS AND METHODS

Perfusion MR imaging was performed prospectively in 13 patients with AIDS who had contrast material-enhancing focal brain lesions (six with active lymphoma, five with toxoplasmosis, one with treated lymphoma in remission, and one with toxoplasmosis plus lymphomatoid granulomatosis). Regional cerebral blood volume (rCBV) was determined by using dynamic echo-planar MR imaging during bolus injection of a gadolinium chelate.

RESULTS

The rCBV was decreased (44% +/- 24 [standard deviation] of rCBV in the contralateral regions) throughout the toxoplasmosis lesions and in the surrounding edema of both lesion types, whereas all active lymphomas displayed areas of increased rCBV (258% +/- 99). These differences were significant (P < .005).

CONCLUSION

Reduced rCBV i toxoplasmosis lesions is probably due to a lack of vasculature within the abscess; increased rCBV in lymphomas is probably due to hypervascularity in foci of active tumor growth; and decreased rCBV in the edema is probably due to vasoconstriction associated with increased interstitial pressure. Perfusion MR imaging is a rapid, noninvasive tool that may allow differentiation between cerebral lymphoma and toxoplasmosis in patients with AIDS.