FDG-PET in Autoimmune Encephalitis: Utility, Pattern of Abnormalities, and Correlation with Autoantibodies

Overview

Journal Ann Indian Acad Neurol

Specialty Neurology

Date 2023 Mar 13

PMID 36911487

Authors

Shreyashi Jha

Chandana Nagaraj

R C Mundlamuri

Suvarna Alladi

Saraswati Nashi

Raghavendra Kenchaiah

Anita Mahadevan

Maya Bhat

Jitender Saini

M Netravathi

Affiliations

Soon will be listed here.

Abstract

Background: Fluorodeoxyglucose-positron emission tomography (FDG-PET) in autoimmune encephalitis (AE) as an adjunctive investigation helps in characterizing the type of AE based on characteristic metabolic patterns.

Objectives: We aimed to study the following: (i) the sensitivity of FDG-PET in the diagnosis of AE, (ii) describe abnormal patterns of metabolism of various subtypes of AE, and (iii) correlate serum serology with FDG-PET abnormalities.

Materials And Methods: This study was conducted at a tertiary university hospital in South India. The demographic profile, clinical features, and investigations (FDG-PET, magnetic resonance imaging (MRI) brain, electroencephalography (EEG), cerebrospinal fluid (CSF)) were reviewed. The nuclear medicine physician performed blinded qualitative visual and semi-quantitative analysis of the 18-FDG-PET (fluorine 18-FDG-PET) findings of these patients.

Results: Twenty-nine (M:F: 11:18) patients were recruited; among them, 22 (75.8%) patients had autoimmune antibodies; the rest seven (24.1%) patients were seronegative. Among the 22 seropositive patients, 9 (31%) patients were positive for anti-N-methyl-D-aspartate receptor (NMDAR), 8 (28%) for anti-leucine-rich glioma inactivated 1 (LGI-1), 4 (14%) for anti-contactin-associated protein 2 (CASPR2), 1 (3%) for anti-glutamic acid decarboxylase (GAD)-65, and rest 7 (24%) patients were seronegative. The patterns most commonly observed were isolated hypermetabolism (41%), isolated hypometabolism (41%), and combined hypermetabolism with hypometabolism (18%). The fraction of abnormalities was lower for MRI (17/22; 73.9%) than for FDG-PET (27/29; 93.1%). FDG-PET correlated with serology in 10 (34%) cases [NMDAR: 6 (60%) and LGI-1: 4 (40%)]. The sensitivity of FDG-PET was 94.1% when compared with MRI.

Discussion And Conclusion: FDG-PET correlated with serology in only one-third of patients. The most consistent pattern in both seropositive and seronegative AE is characterized by parieto-occipital hypometabolism and fronto-temporal with basal ganglia hypermetabolism.

Citing Articles

Antibody-Specific PET Finding in Autoimmune Encephalitis: How Accurate?.

Baishya J, Basher R Ann Indian Acad Neurol. 2024; 27(1):5-6.

PMID: 38495249 PMC: 10941909. DOI: 10.4103/aian.aian_338_23.

Autoimmune Encephalitis as a Rare Paraneoplastic Syndrome in Adrenocortical Carcinoma.

Mohapatra D, Tripathi M, Ojha S, Meena J, Chakrabarty B Indian J Nucl Med. 2024; 38(4):376-378.

PMID: 38390536 PMC: 10880859. DOI: 10.4103/ijnm.ijnm_26_23.

Anti-N-methyl-D-aspartate receptor-associated encephalitis: A review of clinicopathologic hallmarks and multimodal imaging manifestations.

Beutler B, Moody A, Thomas J, Sugar B, Ulanja M, Antwi-Amoabeng D World J Radiol. 2024; 16(1):1-8.

PMID: 38312349 PMC: 10835429. DOI: 10.4329/wjr.v16.i1.1.

References

Wegner F, Wilke F, Raab P, Tayeb S, Boeck A, Haense C . Anti-leucine rich glioma inactivated 1 protein and anti-N-methyl-D-aspartate receptor encephalitis show distinct patterns of brain glucose metabolism in 18F-fluoro-2-deoxy-d-glucose positron emission tomography. BMC Neurol. 2014; 14:136. PMC: 4076767. DOI: 10.1186/1471-2377-14-136. View

Lagarde S, Lepine A, Caietta E, Pelletier F, Boucraut J, Chabrol B . Cerebral (18)FluoroDeoxy-Glucose Positron Emission Tomography in paediatric anti N-methyl-D-aspartate receptor encephalitis: A case series. Brain Dev. 2015; 38(5):461-70. DOI: 10.1016/j.braindev.2015.10.013. View

Baumgartner A, Rauer S, Mader I, Meyer P . Cerebral FDG-PET and MRI findings in autoimmune limbic encephalitis: correlation with autoantibody types. J Neurol. 2013; 260(11):2744-53. DOI: 10.1007/s00415-013-7048-2. View

Probasco J, Solnes L, Nalluri A, Cohen J, Jones K, Zan E . Abnormal brain metabolism on FDG-PET/CT is a common early finding in autoimmune encephalitis. Neurol Neuroimmunol Neuroinflamm. 2017; 4(4):e352. PMC: 5442608. DOI: 10.1212/NXI.0000000000000352. View

Fisher R, Patel N, Lai E, Schulz P . Two different 18F-FDG brain PET metabolic patterns in autoimmune limbic encephalitis. Clin Nucl Med. 2012; 37(9):e213-8. DOI: 10.1097/RLU.0b013e31824852c7. View

Dalmau J, Tuzun E, Wu H, Masjuan J, Rossi J, Voloschin A . Paraneoplastic anti-N-methyl-D-aspartate receptor encephalitis associated with ovarian teratoma. Ann Neurol. 2007; 61(1):25-36. PMC: 2430743. DOI: 10.1002/ana.21050. View

Abboud H, Probasco J, Irani S, Ances B, Benavides D, Bradshaw M . Autoimmune encephalitis: proposed best practice recommendations for diagnosis and acute management. J Neurol Neurosurg Psychiatry. 2021; 92(7):757-768. PMC: 8223680. DOI: 10.1136/jnnp-2020-325300. View

Lee B, Newberg A, Liebeskind D, Kung J, Alavi A . FDG-PET findings in patients with suspected encephalitis. Clin Nucl Med. 2004; 29(10):620-5. DOI: 10.1097/00003072-200410000-00004. View

Solnes L, Jones K, Rowe S, Pattanayak P, Nalluri A, Venkatesan A . Diagnostic Value of F-FDG PET/CT Versus MRI in the Setting of Antibody-Specific Autoimmune Encephalitis. J Nucl Med. 2017; 58(8):1307-1313. PMC: 6944181. DOI: 10.2967/jnumed.116.184333. View

10.

Graus F, Titulaer M, Balu R, Benseler S, Bien C, Cellucci T . A clinical approach to diagnosis of autoimmune encephalitis. Lancet Neurol. 2016; 15(4):391-404. PMC: 5066574. DOI: 10.1016/S1474-4422(15)00401-9. View

11.

Leypoldt F, Buchert R, Kleiter I, Marienhagen J, Gelderblom M, Magnus T . Fluorodeoxyglucose positron emission tomography in anti-N-methyl-D-aspartate receptor encephalitis: distinct pattern of disease. J Neurol Neurosurg Psychiatry. 2012; 83(7):681-6. PMC: 3740122. DOI: 10.1136/jnnp-2011-301969. View

12.

Wei Y, Tseng J, Wu C, Su F, Weng W, Hsu C . Different FDG-PET metabolic patterns of anti-AMPAR and anti-NMDAR encephalitis: Case report and literature review. Brain Behav. 2020; 10(3):e01540. PMC: 7066351. DOI: 10.1002/brb3.1540. View

13.

Deuschl C, Ruber T, Ernst L, Fendler W, Kirchner J, Monninghoff C . 18F-FDG-PET/MRI in the diagnostic work-up of limbic encephalitis. PLoS One. 2020; 15(1):e0227906. PMC: 6968877. DOI: 10.1371/journal.pone.0227906. View

14.

Ances B, Vitaliani R, Taylor R, Liebeskind D, Voloschin A, Houghton D . Treatment-responsive limbic encephalitis identified by neuropil antibodies: MRI and PET correlates. Brain. 2005; 128(Pt 8):1764-77. PMC: 1939694. DOI: 10.1093/brain/awh526. View

15.

Bordonne M, Chawki M, Doyen M, Kas A, Guedj E, Tyvaert L . Brain F-FDG PET for the diagnosis of autoimmune encephalitis: a systematic review and a meta-analysis. Eur J Nucl Med Mol Imaging. 2021; 48(12):3847-3858. DOI: 10.1007/s00259-021-05299-y. View

16.

Macher S, Zimprich F, De Simoni D, Hoftberger R, Rommer P . Management of Autoimmune Encephalitis: An Observational Monocentric Study of 38 Patients. Front Immunol. 2018; 9:2708. PMC: 6262885. DOI: 10.3389/fimmu.2018.02708. View

17.

Kamble N, Netravathi M, Saini J, Mahadevan A, Yadav R, Nalini A . Clinical and imaging characteristics of 16 patients with autoimmune neuronal synaptic encephalitis. Neurol India. 2015; 63(5):687-96. DOI: 10.4103/0028-3886.166532. View

18.

Kelley B, Patel S, Marin H, Corrigan J, Mitsias P, Griffith B . Autoimmune Encephalitis: Pathophysiology and Imaging Review of an Overlooked Diagnosis. AJNR Am J Neuroradiol. 2017; 38(6):1070-1078. PMC: 7960083. DOI: 10.3174/ajnr.A5086. View

19.

Bradshaw M, Linnoila J . An Overview of Autoimmune and Paraneoplastic Encephalitides. Semin Neurol. 2018; 38(3):330-343. DOI: 10.1055/s-0038-1660821. View

20.

Yuan J, Guan H, Zhou X, Niu N, Li F, Cui L . Changing Brain Metabolism Patterns in Patients With ANMDARE: Serial 18F-FDG PET/CT Findings. Clin Nucl Med. 2016; 41(5):366-70. DOI: 10.1097/RLU.0000000000001164. View