The Role of PET-CT Scans in the Diagnosis and Outcome in Autoimmune Encephalitis
Laxmi Khanna1, Mandaville Gourie-Devi2, Ritu Verma3
1Neurophysiology, Sir Ganga Ram Hospital, 2Neurophysiology, 3Nuclear Medicine, Sir Ganga Ram hospital
Objective:
To evaluate the role of FDG PET-CT scans in 30 hospitalized patients with a diagnosis of autoimmune encephalitis and to compare their clinical picture, antibodies, outcome after treatment and quality of life with a control group of similar patients without FDG PET-CT scans.
Background:
FDG PET-CT scans are invaluable in the early diagnosis of autoimmune encephalitis when autoantibody assays are inconclusive. Coexisting neoplasms can be detected and response to treatment can be evaluated. Thus FDG PET-CT scans are biomarkers of the disease.
Design/Methods:
Two cohorts of thirty inpatients, with and without PET-CT scans were included in a retrospective study that spanned five years from 2018 to 2023. PET-CT scans were not done in the second group due to delayed presentation or lack of resources. These subjects were admitted, investigated and treated during hospitalization and evaluated after one month follow-up to assess the outcome after treatment.
Results:
The clinical features, hospital course and outcome were severe in those whose diagnosis was delayed due to lack of FDG PET-CT scans. 53.33% recovered, 40% had sequel and 6.67% died in the PET-CT group while 13.33% recovered, 73.33% had sequel and 13.33% died in the no PET-CT group [p value < 0.001]. FDG PET-CT scans were abnormal in 3.33% in the first, 20% in the second, 33.33% in the third week, 26.67% in the first month and 16.67% after one month of illness. Sequelae like personality and behavior disorders, impaired memory, cognitive decline, refractory epilepsy, focal motor seizures and impaired quality of life were common in the non FDG-PET-CT scan group [p value <0.001].
Conclusions:
Thus FDG PET-CT scans are invaluable in the early diagnosis of autoimmune encephalitis. PET-CT scan aided in better outcome, less sequelae and improved quality of life [p value < 0.001].