Cerebral Amebiasis: MRI,DWI,Perfusion and MRS Features

Abstract

Entamoeba histolytica brain abscess is a rare clinical entity. Here we present a case with magnetic resonance imaging, diffusion weighted imaging (DWI), magnetic resonance perfusion imaging and magnetic resonance spectroscopy (MRS) findings of a patient with pathologically proven E. Histolytica brain abscess. To our knowledge, these findings have not been described before in a patient with E. Histolytica brain abscess. MRI examination revealed multiple mass lesions with vasogenic edema and prominent contrast enhancement located at both gray and white matter of the right temporal, left parietooccipital, and bilateral frontal regions. T2-weighted images demonstrated hypointense foci within the lesions thought to be consistent with hemorrhage. Despite the large size and the radiologically aggressive appearance of the lesions, the gyral configuration seems to be relatively well preserved. DWI study revealed increased diffusion particularly in the central portion of the lesions. Perfusion imaging of the lesions demonstrated decreased perfusion compared with normal brain parenchyma. MRS examination of the left frontal lesion showed decreased N-acetylaspartate (NAA)/choline (Cho) ratio, and increased Cho/creatine (Cr) ratio at the peripheral thick enhancing rim. A resonance peak for Cho (3.2 ppm), lipid (1.2 ppm), and negative lactate (1.3 ppm) was detected at the central non-enhancing part of the frontal mass lesion. Nearly all patients with amebic intracranial abscess reported in the medical literature died despite aggressive medical and surgical treatment. It is likely that intense pharmacologic treatment or early neurosurgical intervention in single lesions may be life-saving in these patients and late diagnosis may be a contributory factor in the high mortality rate. Although it is not at the top of the differential diagnosis list, we think that amebic encephalitis must be entertained in a patient with ancillary radiological and clinical findings.