Regarding “Brain Perfusion Alterations on 3D Pseudocontinuous Arterial Spin-Labeling MR Imaging in Patients with Autoimmune Encephalitis: A Case Series and Literature Review”

Abstract

W e read with interest the article by Li et al, "Brain Perfusion Alterations on 3D Pseudocontinuous Arterial Spin-Labeling MR Imaging in Patients with Autoimmune Encephalitis: A Case Series and Literature Review," recently published in the American Journal of Neuroradiology. In this retrospective case series, the authors found that all patients with autoimmune encephalitis (AE) had increased CBF in the inflammatory area. 1 Indeed, arterial spin-labeling (ASL) is critical in the diagnosis of AE and may serve as early evidence preceding conventional abnormal findings on MR imaging and laboratory diagnosis. Sachs et al 2 found cerebral hyperperfusion in anti-N-methyl-D-aspartate (NMDAR) encephalitis. Vallabhaneni et al 3 demonstrated increased CBF and CBV in the left parieto-occipital gray matter on CT perfusion. Sarria-Estrada et al 4 revealed ASL hyperperfusion overlapping the involved lesions, but they also found increased perfusion and increased metabolism on [ 18 F] FDG-PET/CT and SPECT in paraneoplastic autoimmune encephalitis.As mentioned above, 4 we have also encountered several cases of AE with hypoperfusion or without any visible changes on ASL perfusion in clinical practice. We retrospectively reviewed image data from 30 consecutive patients with AE in the most recent 2 years including major constituents of AE-covered anti-NMDAR (11 patients), anti-leucine-rich glioma inactivated-1 (5 patients), anti-G-protein coupled receptor for gamma-aminobutyric acid receptor (4 patients), anti-myelin oligodendrocyte glycoprotein antibody associated encephalitis (3 patients), anti-contactin-associated protein-like 2 antibody-associated disease (3 patients), Hashimoto encephalopathy (2 patients), anti-glutamic acid decarboxylase-65 AE (1 patient), and anti-CV2 AE (1 patient). All MR imaging of our patients was also performed on a 3T MR imaging scanner (Discovery 750; GE Healthcare) with a 3D ASL sequence. Seven patients had visible infected lesions with increased perfusion on ASL, 5 patients showed asymmetric changes across brain regions without intracranial lesions on T2 FLAIR, and 2 patients presented with decreased perfusion with visible infected focus, while the rest