Article Figures & Data
Figures
- 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.
- 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.
- Fig 3.
Patient 15. A 72-year-old man with Streptococcus mitis (aerobe) bacteremia, infective endocarditis, and multiple miliary pyogenic brain abscesses.
A, Axial contrast-enhanced T1-weighted MR image shows numerous miliary nodules with ring enhancement. The 2 x 2 x 2-cm voxel (box) in the lesion and adjacent brain tissue represents the 1H MR spectroscopic volume of interest.
B and C, In vivo 1H spectra (TR/TE 1600/270 [B] and 1600/135 [C]) show spectral pattern C with a lactate (Lac) peak (1.3 ppm) that is inverted at a TE of 135. The resonances of choline (Cho), creatine (Cr), and N-acetylaspartate (NAA) were interpreted to be caused by partial volume effects of the adjacent brain tissue. The phase reversal does not follow the classic pattern in this case because of the presence of some phase distortion, which presumably originated from the eddy current effect. Multiple small peaks at various frequencies are present; these peaks may represent noise or unassigned metabolites.
D, Axial contrast-enhanced T1-weighted MR image obtained 3 months later shows almost complete remission of the formation of diffuse abscesses after antibiotics.
Tables
- Table:
Clinical information and 1H MR spectroscopic findings in 15 patients with pyogenic brain abscesses
Patient No./Sex/ Age (y) Chief Complaint Location of Abscess Pus Culture Microorganisms Treatment Outcome Duration of Symptoms MR Spectroscopy before/after Starting Antibiotics MR Spectroscopic Findings Pattern NAA Cr Cho Succ Ace Ala AA Lac Lip 1/F/45 Fever, headache, unstable gait Left cerebellum Bacteroides fragilis Surgery/medical Cured 10 days 1 day after A + + ++ ++ +++ ++ ++ +++ ++ 2/M/74 Right hemiparesis Left parietal Streptococcus intermedius Surgery/medical Cured 30 days 1 day before A − − − − + + ++ ++ − 3/M/69 Fever, right hemiparesis Left parietal B fragilis Surgery/medical Died 7 days 1 day before A + + + ++ +++ + ++ ++ + 4/M/48 Headache Left frontal Negative Surgery/medical Cured 10 days 2 days before A − − − − +++ ++ +++ +++ + 5/M/45 Fever, headache Right temporal Streptococcus mitis, Enterococcus faecalis Surgery/medical Cured 12 days 2 days after A − − − ++ ++ + +++ +++ − 6/M/43 Consciousness change Right basal ganglion Eubacterium lentum Surgery/medical Cured 3 days 1 day after A − − − ++ ++ ++ ++ +++ − 7/M/47 Headache, left homonymous hemianopia Right occipital S intermedius Surgery/medical Cured 14 days 1 day after B − − − − − − + ++ − 8/F/28 Right homonymous hemianopia Left occipital S intermedius Surgery/medical Cured 21 days 2 days before B − − − − − − + ++ − 9/M/76 Fever, consciousness change Left temporal Negative Surgery/medical Cured 14 days 1 day after B + + + − − − + ++ − 10/F/69 Left hemiparesis Right frontal Staphylococcus aureus Surgery/medical Cured 3 days 1 day before B + + + − − − + ++ − 11/F/29 Fever, headache Left frontal Pseudomonas aeruginosa Surgery/medical Cured 2 wks 2 days after B − − − − − − + ++ + 12/M/72 Fever, left hemiparesis Right parietal S intermedius Surgery/medical Cured 10 days 2 days before B + + + − − − + ++ − 13/M/72 Left hemiparesis, infective endocarditis Multiple Streptococcus constellatus Surgery/medical Died 30 days 1 day after B − − − − − − + ++ − 14/F/78 Fever, consciousness change Right temporal P aeruginosa Surgery/medical Cured 10 days 2 days after B − − − − − − + ++ − 15/M/72 Consciousnes change, infective endocarditis Multiple military (<5 mm) S mitis (blood culture) Medical Cured 3 days 1 day after C ++ + ++ − − − − + − Notes.—Negative sign indicates no bacterial growth; +, small peak; ++, moderate peak; +++, large peak; Ace, acetate; Ala, alanine; AA, amino acids; Lac, lactate; Succ, succinate; NAA, N-acetylaspartate; Cho, choline; Cr, creatine-phosphocreatine; Lip, lipids.
