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FIG 1. Patient 6. A 43-year-old man with surgically proved pyogenic brain abscess in the right basal ganglion secondary to Eubacterium lentum (obligate anaerobe) infection.
A, Axial contrast-enhanced T1-weighted MR image (500/30) shows a ring-shaped cystic lesion and surrounding edema. The 2 x 2 x 2-cm voxel (box) in the center of the lesion represents the 1H MR spectroscopic volume of interest.
B and C, In vivo 1H MR spectra (TR/TE 1600/270 [B] and 1600/135 [C]) from the abscess cavity show spectral pattern A, which represents succinate (Succ), acetate (Ac), alanine (Ala), lactate (Lac), and amino acids (AA). At a TE of 135 ms (C), the phase reversal resonances are well depicted at 1.5, 1.3, and 0.9 ppm, which confirms the assignment to alanine, lactate, and amino acids, respectively.
D and E, One-dimensional, in vitro, single-pulse (D) and spin-echo (TE = 135 ms; E) spectra of the pus removed from the abscess cavity show the prominent resonance for acetate (Ac), as well as signals for succinate (Succ), alanine (Ala), lactate (Lac), amino acids (AA) at 0.9 and 3.75 ppm, leucine (leu), lysine (lys) at 1.73 and 3.0 ppm, glutamate/glutamine (Glx) at 2.09–2.36 ppm, glycine (gly) at 3.55 ppm, and taurine (Tau) at 3.24 and 3.42 ppm. Alanine is equally prominent as lactate in vitro, compared with the in vivo study. Note the phase reversal at 1.5, 1.3, and 0.9 ppm, suggesting alanine, lactate, and amino acids, respectively, in the spin-echo (135 ms) spectrum (E).
F, In vitro 2D COSY spectrum of the pus obtained from the abscess cavity assigns leucine (L), isoleucine (I), valine (V), lipids (Lip), and lysine (Lys) unambiguously. COSY spectrum shows the J-couplings between amino acids and other metabolites, as well as the difference between the coupling values of amino acids and other metabolites. The individual amino acids (e.g., leucine, isoleucine, and valine) can be identified only through 2D COSY. Ala indicates alanine; Glx, glutamate/glutamine; Lac, lactate; Tau, Taurine.
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