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Indian Pediatr 2010;47:
803-804 |
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Magnetic Resonance Spectroscopy in Ring
Enhancing Lesions |
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R Seth, V Kalra, U Sharma* and N Jagannathan*
From Departments of Pediatrics and *Nuclear Magnetic
Resonance, All India Institute of Medical Sciences,
New Delhi, India.
Correspondence to: Dr Rachna Seth, Assistant Professor,
Department of Pediatrics, All India Institute of Medical Sciences, New
Delhi 110 029, India.
Email: [email protected]
Received: January 13, 2009;
Initial review: January 29, 2009;
Accepted: July 3, 2009.
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Abstract
We report a 4 year old girl with ring enhancing
lesions in brain CT, initially diagnosed as neurocysticercosis but did
not respond to cysticidal therapy. A Magnetic resonance spectropscopy (MRS)
revealed lipid peaks suggestive of tuberculoma which was successfully
treated with antituberculosis therapy. This report highlights the role
of MRS in the diagnosis of ring enhancing lesios.
Key words: Ring enhancing lesions, Magnetic Resonance
Spectroscopy, Neurometabolites.
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T
he two most common etiologies of
inflammatory granulomas encountered in clinical practice include
neurocysticercosis (NCC) and tuberculomas, the differentiation between the
two has defied conventional investigations. Clinical and radiological
criteria. We highlight the role of magnetic resonance spectroscopy (MRS)
in differentiating between these lesions.
Case Report
A 4 year old girl with normal development presented
with sudden onset multiple episodes of right sided complex partial
seizures. There was no history of fever, vomiting, weight loss, altered
sensorium or visual complaints. History of contact with a case of
tuberculosis was positive.
On examination the child was well built with stable
vitals. BCG scar was present. Systemic and neurological examination was
normal. Chest X ray was normal and mantoux test was not reactive. Serology
(IgG) for NCC was positive. CT scan revealed presence of three ring
enhancing lesions (9.6-13mm in size) with enhancing eccentric foci in left
frontal and both parietal regions with mild to moderate perilesional
edema. There was no evidence of midline shift. There was no evidence of
papilledema/intraocular cysticercosis on ophthalmological examination. The
child was given conventional antiepileptics and first course of cysticidal
(Albendazole for 28 days and steroids for 2 months).
However, The child continued to have multiple seizures
and also developed right lower limb paresis and papilledema while on
antiepileptics, cysticidal therapy and steroids. Repeat CT head done 12
weeks after completion of the first cysticidal course showed persistence
of the three ring enhancing lesions as in previous CT with increased
perilesional edema. The child was administered a course of praziquantal
and steroid. Seizures persisted even after this therapy and there was no
radiological improvement. A magnetic resonance imaging (MRI) confirmed the
CT findings. Magnetic resonance spectroscopy (MRS) identified a lipid peak
in all the lesions (Fig 1) and a diagnosis of tuberculoma
was considered. The choline/creatine ration was greater than 1, N-acetyl
aspartate (NA) was reduced.
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Fig.1 The arrow denotes the lipid
peak identified in the spectrum obtained during MRS. |
The patient was subsequently started on 4-drug
antitubercular drug therapy (2HRZE 10HR) with steroids 8 weeks. The child
responded to antituberculosis therapy. The headache, monoparesis and
papilledema also resolved. CT done 6 months after starting ATT showed
calcification of the left parietal lesion. A disc enhancing lesion was
seen in the left frontal region. The lesion in right parietal region
showed gliosis with reduction of perilesional edema. Perilesional edema
around the left sided lesions (frontal and parietal) had resolved.
Discussion
The diagnostic dilemma of inflammatory granulomas is
highlighted from the case history discussed. Common causes of inflammatory
granulomas include NCC (commonest) followed by tuberculosis,
toxoplasmosis, cerebral abscess and fungal lesions. This child presented
with seizures, showed a positive serological response towards NCC and CT
findings were compatible with NCC (<20mm, regular outline and no midline
shift)(1) yet the child was actually suffering from tuberculous
granulomatous lesions where we expect larger lesions (>20mm) with an
irregular outline and midline shifts(1). The patient was given two courses
of cysticidals with no clinical/radiologic improvement and this prompted
us to review our diagnosis.
MR spectroscopy identified lipid peaks in all the
lesions and raised the suspicion of tuberculoma. In a study by Pretell,
et al.(3) MR Spectroscopy was used to differentiate single enhancing
brain lesions as due to tuberculomas or neurocysticercosis. Tuberculomas (n=4)
had a high peak of lipids, more choline and less N acetylaspartate and
creatine. The choline/ creatine ratio was greater than 1 in all
tuberculomas but in none of the cysticerci (n=6)(2). Similar
findings in tuberculomas have been reported by Kumar, et al. and
Jayasunder, et al.(3-5). MRS findings of cysticercosis include a
combination of elevated levels of lactate, alanine, succinate and choline
and reduced levels of NAA and creatine(6).
To conclude, misdiagnosis of inflammatory granulomas
may occur. MRS could be a useful noninvasive alternative to determine
their etiology.
Contributors: RS: Concept, work up of patient and
manuscript; VK: Concept, design and contribution to manuscript; US and NJ:
MR spectroscopy and its analysis.
Funding: None.
Competing interests: None stated.
References
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