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FIG 2. Patient 14. A 78-year-old woman with surgically proved pyogenic brain abscess and ventriculitis in the right temporal region secondary to Pseudomonas aeruginosa (aerobe) infection.
A, Axial contrast-enhanced T1-weighted MR image (500/30) shows a regular thin-walled ring-enhanced cystic lesion and adjacent temporal horn ventricular enhancement 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 spectra (TR/TE 1600/270 [B] and 1600/135 [C]) from the abscess cavity show spectral pattern B with only two resonance peaks identified; however, the phase reversal of the amino acid (AA) signal at 0.9 ppm is depicted on the MR spectrum obtained with a 135-msec TE (C), which is indicative of a pyogenic brain abscess. Lac inidcates lactate.
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 signals for lactate (Lac), amino acids (AA), alanine (Ala), glutamate/glutamine (Glx), leucine (leu), and lysine (lys). Alanine is present and more prominent 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.
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. The individual amino acids (e.g., leucine, isoleucine, and valine) can be identified only through 2D COSY. Ala indicates alanine; Glx, glutamate/glutamine; Lip, lipid; Lys, lysine; Tau, Taurine.
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