PURPOSE: To determine the ability to differentiate brain abscess from
cystic or necrotic brain tumor with hydrogen-1 magnetic resonance (MR)
spectroscopy. MATERIALS AND METHODS: H-1 MR spectroscopy was prospect
ively performed in seven consecutive patients with pyogenic brain absc
ess and in seven consecutive patients with necrotic or cystic brain tu
mor (five patients with glioblastoma and one each with pilocytic astro
cytoma and metastasis from lung cancer) in whom radiologic images depi
cted ring-shaped areas of contrast material enhancement (indicative of
a cystic or necrotic mass). Assignment of resonance peaks to metaboli
tes was based on reports in the literature. RESULTS: In six of seven p
atients with abscess, there were various resonances attributed to lact
ate, valine, alanine, leucine, acetate, succinate, and unidentified me
tabolites (2.5, 2.9, 3.2, 3.4, and 3.8 ppm). In six of seven patients
with tumor, there was only a resonance attributed to lactate. One pati
ent with a tumor had an unidentified peak at 0.9 ppm (presumably attri
buted to lipid) in addition to the peak attributed to lactate. CONCLUS
ION: Spectral patterns from in vivo H-1 MR spectroscopy may permit dif
ferentiation of brain abscess from necrotic or cystic tumor.