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 Table of Contents     
CASE REPORT
Year : 2011  |  Volume : 26  |  Issue : 2  |  Page : 94-95  

Unilateral thalamic hypometabolism on FDG brain PET in patient with temporal lobe epilepsy


Department of Nuclear Medicine, Istanbul University, Cerrahpasa Medical Faculty, Istanbul, Turkey

Date of Web Publication25-Nov-2011

Correspondence Address:
Sait Sager
Department of Nuclear Medicine, Istanbul University, Cerrahpasa Medical Faculty, Cerrahpasa, Fatih, Istanbul
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-3919.90260

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   Abstract 

Interictal Brain F-18 fluorodeoxyglucose (FDG) Positron Emission Tomography (PET) imaging has been widely used for localizing the focus of a seizure. Hypometabolism in the extratemporal cortex on FDG-PET study is an important finding to localize seizure focus, which might be seen as ipsilateral, contralateral or bilateral thalamus hypometabolism in epileptic patients. In this case report, it is aimed to show ipsilateral thalamus hypomethabolism on FDG PET brain study of a 24-year-old male patient with temporal lobe epilepsy.

Keywords: FDG PET, temporal lobe epilepsy, thalamus hypometabolism


How to cite this article:
Sager S, Asa S, Uslu L, Halac M. Unilateral thalamic hypometabolism on FDG brain PET in patient with temporal lobe epilepsy. Indian J Nucl Med 2011;26:94-5

How to cite this URL:
Sager S, Asa S, Uslu L, Halac M. Unilateral thalamic hypometabolism on FDG brain PET in patient with temporal lobe epilepsy. Indian J Nucl Med [serial online] 2011 [cited 2019 Dec 10];26:94-5. Available from: http://www.ijnm.in/text.asp?2011/26/2/94/90260


   Introduction Top


Positron emission tomography with Fluorine-18 fluorodeoxyglucose (F-18 FDG PET) has been widely used to examine epileptic patients. Interictal brain F18-FDG PET is a useful imaging technique for localizing the focus of a seizure. Temporal lobe hypometabolism is a characteristic finding for temporal lobe epilepsy (TLE) on FDG PET study. However, extratemporal hypometabolism can be seen and characteristics of the alteration of perfusion in the thalamus in epileptic patients have not been well-described. Thalamic hypometabolism has been observed in TLE. [1],[2] Thalamus has diffuse connections throughout the brain and its role in seizure activity is likely to be complex, so thalamic hypometabolism in patients with TLE is documented. [3] It is believed that thalamus plays a role in regulating or gating seizure activity. [4] The prevalence of thalamic hypometabolism suggests a pathophysiologic role in initiating temporal lobe seizures. Ipsilateral or contralateral thalamic hypometabolism is a supplementary finding on PET scan in TLE patients and can aid epileptic foci. [5]


   Case Report Top


A 24-year-old male patient with a history of TLE was referred to our Nuclear Medicine department for FDG PET Brain imaging. For Brain PET study , patient was injected 336,7 MBq (9,1mCi) F-18 FDG and after waiting 45 minutes in a silent room, he was imaged using an integrated PET/CT camera, which was 10 minutes for routine imaging and consists of a 6-slice CT gantry integrated on a LSO based full ring PET scanner (Siemens Biograph 6, IL, Chicago, USA). Axial PET [Figure 1]a, axial fusion [Figure 1]c and coronal fusion [Figure 1]d images showed hypometabolism in right thalamus [Figure 1]; arrow. In axial CT image, right thalamus can be seen in normal localization [Figure 1]b. Coronal PET image shows right temporal hypometabolism as a characteristic finding for TLE.
Figure 1: (a)Axial PET image shows hypometabolism in right thalamus (arrow)
Figure 1b: In axial CT image, right thalamus can be seen in normal localization
Figure 1c: Axial fusion image shows right thalamic hypometabolism (arrow)
Figure 1d: Coronal fusion image shows right thalamic hypometabolism


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   Discussion Top


F-18 FDG PET brain study often used to help localize the seizure focus in epileptic patients. In most studies, F-18 FDG is given in the interictal state to find epileptogenic focus. Interictal FDG-PET depicts hypometabolism in the epileptogenic region in 60-90% of patients with TLE. [6] On FDG-PET, hypometabolism in the extratemporal cortex is not an uncommon finding in patients with TLE.F-18 FDG-PET studies in patients suffering from TLE have shown hypometabolism of the affected temporal lobe. [7],[8] PET studies in patients with TLE investigating glucose utilization in the subcortical brain structures suggest a hypometabolism especially in the thalamus and caudate nucleus ipsilateral to the side of the epileptogenic focus. The mesial temporal lobe structures, i.e. amygdala and the hippocampus play a major role in the initiation of seizures in TLE. [9]

It is reported that thalamic hypometabolism may not be seen with TLE. Henry et al reported that 3 of their 27 patients had thalamic hypometabolism in the absence of temporal lobe hypometabolism. They suggested that any of the anatomic patterns of interictal hypometabolism can occur in individual patients with TLE. [10]

Yune et al reported thalamic hypoperfusion ipsilateral to temporal hypoperfusion in 12 (26%) of 46 patients with TLE who underwent interictal brain single-photon emission computed tomography (SPECT). The observation that contralateral thalamic hypometabolism may be associated with a poor postoperative seizure outcome may have a physiologic explanation. [11]

 
   References Top

1.Choi JY, Kim SJ, Hong SB, Seo DW, Hong SC, Kim BT, et al. Extratemporal hypometabolism on FDG PET in temporal lobe epilepsy as a predictor of seizure outcome after temporal lobectomy. Eur J Nucl Med Mol Imaging 2003;30:581-7.  Back to cited text no. 1
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2.Nelissen N, Van Paesschen W, Baete K, Van Laere K, Palmini A, Van Billoen H, et al. Correlations of interictal FDG-PET metabolism and ictal SPECT perfusion changes in human temporal lobe epilepsy with hippocampal sclerosis. Neuroimage 2006;32:684-95.  Back to cited text no. 2
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3.Petrucci M, Hoh C, Alksne JF. Thalamic hypometabolism in a patient undergoing vagal nerve stimulation seen on F-18 FDG PET imaging. Clin Nucl Med 2003;28:784-5.  Back to cited text no. 3
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4.Goffin K, Dedeurwaerdere S, Van Laere K, Van Paesschen W. Neuronuclear assessment of patients with epilepsy. Semin Nucl Med 2008;38:227-39.  Back to cited text no. 4
[PUBMED]  [FULLTEXT]  
5.Chang CP, Yen DJ, Yu SM, Liu RS, Chang HF, Hsieh HJ. et al. Unilateral thalamic hypometabolism in patients with temporal lobe epilepsy. J Formos Med Assoc 2008;107:567-71.  Back to cited text no. 5
    
6.Duncan JS. Imaging and epilepsy. Brain 1997;120:339-77.  Back to cited text no. 6
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7.Shih YH, Lirng JF, Yen DJ, Ho DM, Yiu CH. Surgery of intractable temporal lobe epilepsy presented with structural lesions. J Chin Med Assoc 2003;66:565-71.  Back to cited text no. 7
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8.Spencer SS. The relative contributions of MRI, SPECT, and PET imaging in epilepsy. Epilepsia 1994;35:S72-89.  Back to cited text no. 8
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9.Drzezga A, Arnold S, Minoshima S, Noachtar S, Szecsi J, Winkler P, et al. F18-FDG PET studies in patients with extratemporal and temporal epilepsy: Evaluation of an observer-independent analysis. J Nucl Med 1999;40:737-46.  Back to cited text no. 9
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10.Henry HR, Mazziotta JC, Engel J Jr. Interictal metabolic anatomy of mesial temporal lobe epilepsy. Arch Neurol 1993;50:582-9.  Back to cited text no. 10
    
11.Yune MJ, Lee JD, Ryu YH, Kim DI, Lee BI, Kim SJ. Ipsilateral thalamic hypoperfusion on interictal SPECT in temporal lobe epilepsy. J Nucl Med 1998;39:281-5.  Back to cited text no. 11
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