PET reveals inflammation around calcified Taenia solium granulomas with perilesional edema.
OBJECTIVE
Neurocysticercosis, an infection with the larval form of the tapeworm, Taeniasolium, is the cause of 29% of epilepsy in endemic regions. Epilepsy in this population is mostly associated with calcified granulomas; at the time of seizure recurrence 50% of those with calcifications demonstrate transient surrounding perilesional edema. Whether edema is consequence of the seizure, or a result of host inflammation directed against parasite antigens or other processes is unknown. To investigate whether perilesional edema is due to inflammation, we imaged a marker of neuroinflammation, translocater protein (TSPO), using positron emission tomography (PET) and the selective ligand (11)C-PBR28.


METHODS
In nine patients with perilesional edema, degenerating cyst or both, PET findings were compared to the corresponding magnetic resonance images. Degenerating cysts were also studied because unlike perilesional edema, degenerating cysts are known to have inflammation. In three of the nine patients, changes in (11)C-PBR28 binding were also studied over time. (11)C-PBR28 binding was compared to the contralateral un-affected region.


RESULTS
(11)C-PBR28 binding increased by a mean of 13% in perilesional edema or degenerating cysts (P = 0.0005, n = 13 in nine patients). Among these 13 lesions, perilesional edema (n=10) showed a slightly smaller increase of 10% compared to the contralateral side (P = 0.005) than the three degenerating cysts. In five lesions with perilesional edema in which repeated measurements of (11)C-PBR28 binding were done, increased binding lasted for 2-9 months.


CONCLUSIONS
Increased TSPO in perilesional edema indicates an inflammatory etiology. The long duration of increased TSPO binding after resolution of the original perilesional edema and the pattern of periodic episodes is consistent with intermittent exacerbation from a continued baseline presence of low level inflammation. Novel anti-inflammatory measures may be useful in the prevention or treatment of seizures in this population.
Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health. Bethesda, Maryland, United States of America.
Masahiro
M
Fujita
Siddhartha
S
Mahanty
Sami S
SS
Zoghbi
Maria Desiree
MD
Ferraris Araneta
Jinsoo
J
Hong
Victor W
VW
Pike
Robert B
RB
Innis
Theodore E
TE
Nash
D000328:Adult; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology*; D001929:Brain Edema / Q000150:complications / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology*; D002114:Calcinosis / Q000150:complications / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology*; D002250:Carbon Radioisotopes; D005260:Female; D006099:Granuloma / Q000150:complications / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology*; D006801:Humans; D007249:Inflammation / Q000150:complications / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology; D008024:Ligands; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020019:Neurocysticercosis / Q000150:complications / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology*; D049268:Positron-Emission Tomography; D011485:Protein Binding; D011743:Pyrimidines / Q000008:administration & dosage / Q000378:metabolism; D011859:Radiography; D018079:Receptors, GABA / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D012640:Seizures / Q000150:complications / Q000000981:diagnostic imaging / Q000469:parasitology / Q000473:pathology*; D041201:Taenia solium / Q000472:pathogenicity / Q000502:physiology
C526315:(methyl-(11)C)N-acetyl-N-(2-methoxybenzyl)-2-phenoxy-5-pyridinamine; D015415:Biomarkers; D002250:Carbon Radioisotopes; D008024:Ligands; D011743:Pyrimidines; D018079:Receptors, GABA; C499229:TSPO protein, human