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LETTER TO EDITOR |
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| Year : 2008 | Volume
: 3
| Issue : 2 | Page : 174-176 |
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Diagnosis of intracranial hydatid cyst by magnetic resonance spectroscopy
Kanchan Gupta1, Rangasami Rajeswaran1, Santosh Joseph1, Krishnamurthy Ganesh2
1 Department of Radiology and Imaging Sciences, Sri Ramachandra University, Chennai - 600 116, India
2 Department of Neurosurgery, Sri Ramachandra University, Chennai - 600 116, India
Correspondence Address:
Kanchan Gupta
Department of Radiology and Imaging Sciences, Sri Ramachandra Medical College and Research Institute, Chennai - 600 116
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/1817-1745.43655
How to cite this article:
Gupta K, Rajeswaran R, Joseph S, Ganesh K. Diagnosis of intracranial hydatid cyst by magnetic resonance spectroscopy. J Pediatr Neurosci 2008;3:174-6 |
Sir,
An eleven-year-old male child presented with the complaints of right-sided headache since three months. He had no papilloedema or any neurological deficit. MR imaging (MRI) of the brain performed on a 1.5 Tesla unit (GE, Signa HDx, Milwaukee) revealed a well-defined lesion measuring 8 x 8 x 7.3 cm, in right temporoparietal region with mass effect. The lesion was of cerebrospinal fluid (CSF) signal intensity on all sequences. A thin peripheral rim, hypointense to grey matter was seen on T2 weighted images (WI) [Figure 1A],[Figure 1B]. In addition, a thin layer of hyperintensity was noted on T1 WI in dependent portion of the cyst, which was hypointense on T2 WI. No restricted diffusion was seen on diffusion-WI [Figure 2A]. No enhancement was noted after administration of intravenous Gadolinium [Figure 2B]. Additional in vivo proton MR spectroscopy was performed by multivoxel chemicalshift imaging technique (TE 144 msec). MR spectroscopy spectrum showed reduced N-acetyl aspartate (NAA) peak, mildly elevated choline peak, markedly elevated pyruvate peak at 2.48 ppm, and succinate peak at 2.5 ppm. An inverted bifid lactate peak was noted at 1.3 ppm [Figure 3]. A smaller peak adjacent to lactate at 1.5 ppm was seen which might represent alanine. Mildly elevated myoinositol peak was also observed. Based on these radiological features, a diagnosis of hydatid cyst was made. The patient underwent right temporoparietal craniotomy and total excision of hydatid cyst. Histopathological examination of the cyst wall showed scolices and laminated membrane, confirming the diagnosis.
 Discussion | |  |
Hydatid cyst can now be confidently diagnosed based on the MRI and spectroscopy features. [1],[2] Although, the cysts can be found in any part of the brain, the disease is more common in cerebral hemispheres, particularly in the territory of middle cerebral artery. [3],[4],[5] MRI normally shows a well-defined rounded cystic lesion with attenuation or signal intensities similar to CSF. There is usually no evidence of any perilesional edema or contrast enhancement. Calcification of intracranial hydatid cyst is extremely rare. [3] MRI may show a thin hypointense peripheral rim on T2 WI, presence of which favors the diagnosis of hydatid cyst. [1],[3] Proton MR spectroscopy shows markedly elevated pyruvate, elevated succinate, acetate, and alanine peaks, [4],[5],[6] and lipid-lactate peak at 1.33 ppm. [4] Elevated myoinositol has been reported by Sreedhar et al . [5]
We found metabolites at 2.4 ppm and 2.5 ppm, representing pyruvate and succinate peaks, respectively. These are well-known metabolic endproducts arising from microorganisms. Succinate peak is nonspecific and can occur in hydatid disease, neurocysticercosis, and abscesses. [6] Presence of lactate, succinate, acetate, and other aminoacids can suggest infective etiology. [6] Pyruvate peak is more specific and has been mentioned as an in vivo marker of cestodal infestation, hydatid in particular. [2],[6],[7] Acetate and succinate peaks are seen in both parasitic cysts and bacterial abscesses. Acetate peak is noted at 1.9 ppm and succinate at 2.5 ppm. Acetate:succinate ratio is higher in abscesses, and succinate:acetate ratio is higher in hydatid and neurocysticercosis. [4],[6] Monika et al , have established presence of creatine peak in neurocysticercosis and absence of creatine peak in hydatid, thus differentiating the two. [8] Another study has been conducted by Garg et al , [9] where fertility assessment of hydatid cyst has been done ex-vivo by MR spectroscopy. This study showed presence of malate and fumarate in addition to other resonances in fertile cysts. Zoran et al , [10] described unusual appearance of the cyst on MRI which can be attributed to the layering of hydatid sand. This characteristic feature of hydatid disease was also documented in our case.
The differential diagnosis of an intracranial cyst includes neuroglial cyst, cystic glioma, and arachnoid cyst. Neuroglial cyst does not have the characteristic pericyst and the dependent layering due to hydatid sand. Cystic glioma may have solid component and does not show aminoacids (succinate, acetate, pyruvate) on MR spectroscopy. Arachnoid cyst is an extra axial lesion and may not produce significant mass effect. In conclusion, hydatid disease is rare in the brain and is characterized by well-defined peripheral rim and dependent layering. Though lactate, succinate, and acetate peaks signify infection, the presence of pyruvate peak is more specific for hydatid disease.
| References | | |
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| 3. | Pedrosa I, Saνz A, Arrazola J, Ferreirós J, Pedrosa CS. Hydatid disease: Radiologic and pathologic features and complications. Radiographics 2000;20:795-817. |
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| 8. | Garg M, Chawla S, Prasad KN, Roy R, Sikora SS, Kumar R, et al . Differentiation of hydatid cyst from cysticercus cyst by proton MR spectroscopy. NMR Biomed 2002;15:320-6. [PUBMED] [FULLTEXT] |
| 9. | Garg M, Gupta RK, Prasad KN, Sikora SS, Pal L, Chawla S, et al . Fertility assessment of hydatid cysts by proton MR spectroscopy. J Surg Res 2002;106:196-201. [PUBMED] [FULLTEXT] |
| 10. | Rumboldt Z, Jednacak H, Talan-Hraniloviζ J, Rumboldt T, Kalousek M. An unusual appearance of cisternal hydatid cyst. AJNR Am J Neuroradiol 2003;24:112-4. |
[Figure 1A], [Figure 1B], [Figure 2A], [Figure 2B], [Figure 3]
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