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

Abstract

Autoimmune encephalitis is a heterogeneous group of newly identified disorders that are being diagnosed with increasing frequency. Early recognition and treatment of autoimmune encephalitis are crucial for patients, but diagnosis remains challenging and time-consuming. In this retrospective case series, we describe the findings of conventional MR imaging and 3D pseudocontinuous arterial spin-labeling in patients with autoimmune encephalitis confirmed by antibody testing. All patients with autoimmune encephalitis showed increased CBF in the affected area, even when some of them presented with normal or slightly abnormal findings on conventional MR imaging. Additionally, serial 3D pseudocontinuous arterial spin-labeling showed perfusion reduction in 1 patient after therapy. For patients with highly suspected autoimmune encephalitis, 3D pseudocontinuous arterial spin-labeling may be added to the clinical work-up. Further studies and longitudinal data are needed to corroborate whether and to what extent 3D pseudocontinuous arterial spin-labeling improves the diagnostic work-up in patients with autoimmune encephalitis compared with conventional MR imaging.

FIG 1.

MR imaging of case 1. Findings on axial T2WI (A) and axial T1WI (B) are unremarkable. C, Axial T2 FLAIR reveals hyperintensity in the right hippocampus (white arrow). D, 3D pCASL demonstrates marked hyperperfusion in the corresponding region (black arrow).

FIG 2.

MR imaging of case 3. Findings on axial T2WI (A) and axial T1WI (B) are unremarkable. C, Coronal T2 FLAIR demonstrates hyperintensity in the right hippocampus (white arrow), whereas there are normal findings in the left hippocampus (white arrowhead). D, 3D pCASL depicts hyperperfusion in the corresponding regions on the FLAIR image, more obvious on the right side (black arrows).

FIG 3.

MR imaging of case 5. Findings on axial T2WI (A) and axial T1WI (B) are unremarkable. C, Coronal T2 FLAIR shows subtle hyperintensity with mild swelling in the left hippocampus (white arrow), whereas it shows normal findings in the right hippocampus (white arrowhead). D, Increased CBF in the bilateral hippocampi could be detected on 3D pCASL, the left (black arrow) greater than the right (black arrowhead).

FIG 4.

Serial MR imaging of case 7. On hospital day 3, the first conventional MR imaging examination findings were normal (not shown). On the second MR imaging check (26 days after admission), MR imaging shows swelling and hyperintensities on axial T2WI (A) and hypointensities on axial T1WI (B) in the bilateral hippocampi. C, Coronal T2 FLAIR shows hyperintensities in the bilateral hippocampi (white arrows). D, 3D pCASL reveals marked hyperperfusion in the bilateral medial temporal lobes (black arrows), the left greater than the right. On the third MR imaging check (96 days after admission), including axial T2WI (E), axial T1WI (F), and coronal T2 FLAIR (G), complete resolution of the inflammation in the bilateral medial temporal areas is seen, with enlargement of the bilateral temporal horns (white arrows), and 3D pCASL (H) shows decreased perfusion in the bilateral hippocampi (black arrows). The patient’s condition markedly improved with the administration of high-dose glucocorticoids, intravenous immunoglobulin, and plasma exchange (3 times).

FIG 5.

Bar chart with the SD for the CBF (A) and rCBF (B) values of the lesions in the AE and control groups. The unit of CBF was mL/100 g/min.