Differentiation of Tuberculous from Pyogenic Brain Abscesses with In Vivo Proton MR Spectroscopy and Magnetization Transfer MR Imaging
Rakesh K. Guptaa,
Davender K. Vatsala,
Nuzat Husaina,
Sanjeev Chawlaa,
Kashi N. Prasada,
Raja Roya,
Rajesh Kumara,
Deepak Jhaa and
Mazhar Husaina
a From the Departments of Radiology (R.K.G., S.C., R.K.) and Microbiology (K.N.P.), Sanjay Gandhi Post-Graduate Institute of Medical Sciences; the Departments of Neurosurgery (D.K.V., D.J., M.H.) and Pathology (N.H.), King George's Medical College; and the Regional Sophisticated Instrumentation Center, CDRI (R.R.), Lucknow, India.
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FIG 1. Pyogenic brain abscess.
A, T2-weighted MR image through the temporal lobe shows a well-defined hyperintense lesion in the right temporal lobe with peripheral hypointense rim, perifocal edema, and mass effect on the ventricular system.
B, T1-weighted image shows the lesion as hypointense with isointense wall.
C, MT T1-weighted image shows minimal hyperintesity. The MT ratio from the wall is 31.25.
D, Postcontrast MT T1-weighted image shows enhancement of the rim of the lesion.
E and F, In vivo MR spectra obtained using STEAM (E) at 3000/20/30/128 (TR/TE/TM/excitations) and spin-echo (F) at 3000/135/128 (TR/TE/excitations) show presence of glycine (Gly) at 3.56 ppm; succinate (S) at 2.4 ppm; acetate (A) at 1.92 ppm; alanine (Al) at 1.5 ppm; lipid/lactate (Lip/L) at 1.3 ppm; and leucine, isoleucine, and valine (AA) at 0.9 ppm.
G and H, Ex vivo MR spectroscopy with single-pulse (G) and spin-echo (H) imaging confirm the assignments seen in vivo.
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FIG 2. Multiple tuberculous abscesses.
T2-weighted (A), T1-weighted (B), MT T1-weighted (C), and postcontrast MT T1-weighted (D) images through the third ventricle show abscesses in the right caudate nucleus, right frontal and left periventricular regions. The lesions show hyperintense core and peripheral hypointense rim along with perifocal edema on T2-weighted image (A). On T1-weighted (B) and MT T1-weighted images (C), these lesions shown hypointense core with hyperintense rim, more clearly visible on MT T1-weighted images. Postcontrast MT T1-weighted image shows enhancement of the peripheral rim. Note an additional lesion (arrow) visible on B, C, and D that is not visible in A. The MT ratio from the wall of these three abscesses varied from 18.3 to 20.4. In MR spectroscopy done from the large right caudate nucleus lesion using STEAM at 20 (TE) with a voxel of 1.5 cm3, only lipid and lactate (Lip/L) at 1.3 ppm are shown (E); on spin-echo spectrum at 135, phase reversal along with reduction in signal is seen (F). The presence of choline (Cho) in F results from the larger size of the voxel (2.0 cm3) selected on spin-echo sequences that included the wall of the lesion. Ex vivo high-resolution, single-pulse (G) and spin-echo (H) proton MR spectroscopy at 80 ms confirm the presence of Lip/L with no evidence of choline. Histopathology of the wall (I) shows dense mixed inflammatory infiltrate; no epitheloid granulomas were seen (hematoxylin and eosin stain; original magnification, x125). Ziehl-Neelsen stain of the wall (J) shows numerous acid-fast bacilli in clusters and individually (arrows) both in the intracellular and extracellular spaces (original magnification, x 1250).
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