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LETTER TO EDITOR
Year : 2011  |  Volume : 59  |  Issue : 6  |  Page : 913-914

Magnetic resonance perfusion and spectroscopy in a giant tuberculoma


Department of Radiology, Seven Hills Hospital, Mumbai, India

Date of Submission20-Oct-2011
Date of Decision26-Oct-2011
Date of Acceptance27-Oct-2011
Date of Web Publication2-Jan-2012

Correspondence Address:
Prashant S Naphade
Department of Radiology, Seven Hills Hospital, Mumbai
India
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DOI: 10.4103/0028-3886.91382

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How to cite this article:
Naphade PS, Raut AA, Pai BU. Magnetic resonance perfusion and spectroscopy in a giant tuberculoma. Neurol India 2011;59:913-4

How to cite this URL:
Naphade PS, Raut AA, Pai BU. Magnetic resonance perfusion and spectroscopy in a giant tuberculoma. Neurol India [serial online] 2011 [cited 2014 Apr 24];59:913-4. Available from: http://www.neurologyindia.com/text.asp?2011/59/6/913/91382


Sir,

A 24-year-old man presented with repeated episodes of giddiness of four days' duration. Magnetic resonance imaging (MRI) of the brain revealed a lobulated T2-weighted hypointense mass lesion in the right cerebellar hemisphere with adjacent vasogenic edema causing mass effect on the fourth ventricle with resultant supratentorial hydrocephalus and periventricular cerebrospinal fluid (CSF) ooze [Figure 1]a and b. The mass appeared isointense on T1-weighted images with thick irregular peripheral enhancement [Figure 1]c and d. Dynamic contrast-enhanced MRI perfusion revealed the mass to be homogenously hypoperfused as compared to normal reference cerebellar white matter [Figure 2]a. MR-spectroscopy (TE135) revealed absent N-acetyl aspartate (NAA) within the mass lesion with a large lipid peak at 1.2 ppm [Figure 2]b. Multivoxel spectroscopy (TE30) revealed reduction of NAA without significant elevation of choline in the mass lesion [Figure 3]. These classical findings on spectroscopy and perfusion are very useful in the correct diagnosis of giant tuberculoma.
Figure 1: T2 axial (a) and coronal (b) images reveal hypointense tuberculoma in the right cerebellar hemisphere with obstructive hydrocephalus. Pre (c)- and post (d)-contrast T1 images reveal peripheral enhancement of tuberculoma

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Figure 2: CBV map (a) shows the tuberculoma to be hypoperfused with relative increased CBV along its wall. Single-voxel spectroscopy at 135TE (b) reveals a large lipid peak at 1.2 ppm

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Figure 3: Multivoxel spectroscopy at 30TE - Color maps of Choline (a), NAA (b) reveal no significant elevation in choline with significant decrease in NAA. Spectral map (c) reveals a lipid lactate peak throughout the tuberculoma

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Tuberculomas appear hypointense on T2-weighted images. However, giant tuberculomas display mixed signal intensity on T2-weighted images and may be confused with neoplastic lesions. On perfusion imaging, the tuberculoma reveals low or mildly increased cerebral blood volume (CBV) as compared to normal reference white matter. The wall of the tuberculoma may reveal significantly increased CBV due to upregulated expression of vascular endothelial growth factor. [1] Further therapeutic response to antitubercular therapy can be assessed with serial perfusion imaging. [2] The common differential for ring-enhancing mass lesion in the cerebellum would be metastasis and dynamic contrast-enhanced MR perfusion is especially useful in their differentiation. The mean rCBV ratio of periphery of mass and normal reference white matter is around one in cases of tuberculoma while mean rCBV ratio is more than five in case of metastasis. [3] MR-spectroscopy usually reveals a large lipid lactate peak at 0.9 to 1.33 ppm and reduced NAA. The lipid peak in tuberculoma is primarily due to the predominant lipid content in the cell wall of tubercle bacillus. Presence of lactate indicates anaerobic glycolysis and necrosis within the tuberculoma. However, lipid lactate peak is not specific for tuberculoma and can be seen in high-grade tumors and metastasis. [4] Elevated choline peak can be seen in tuberculoma due to inflammatory cellular infiltrates with resultant increased cellularity. [5] In conclusion, MR spectroscopy and perfusion play an important role in the accurate diagnosis of giant tuberculoma.

 
  References Top

1.Gupta RK, Haris M, Husain N, Husain M, Prasad KN, Pauliah M, et al. Relative cerebral blood volume is a measure of angiogenesis in brain tuberculoma. J Comput Assist Tomogr 2007;31:335-41.  Back to cited text no. 1
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2.Haris M, Gupta RK, Husain M, Srivastava C, Singh A, Singh Rathore RK, et al. Assessment of therapeutic response in brain tuberculomas using serial dynamic contrast-enhanced MRI. Clin Radiol 2008;63:562-74.   Back to cited text no. 2
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3.Chatterjee S, Saini J, Kesavadas C, Arvinda HR, Jolappara M, Gupta AK. Differentiation of tubercular infection and metastasis presenting as ring enhancing lesion by diffusion and perfusion magnetic resonance imaging. J Neuroradiol 2010;37:167-71.  Back to cited text no. 3
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4.Poptani H, Gupta RK, Roy R, Pandey R, Jain VK, Chhabra DK. Characterization of intracranial mass lesions with in vivo proton MR spectroscopy. AJNR Am J Neuroradiol 1995;16:1593-603.  Back to cited text no. 4
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5.Venkatesh SK, Gupta RK, Pal L, Husain N, Husain M. Spectroscopic increase in choline signal is a nonspecific marker for differentiation of infective/inflammatory from neoplastic lesions of the brain. J Magn Reson Imaging 2001;14:8-15.  Back to cited text no. 5
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