Objective: We assessed structural abnormalities of optic radiation (OR) in healthy subjects (HS) and dementia with lewy body (DLB) patients (with visual hallucination) (VH) on phase difference enhanced imaging (PADRE). Then, we evaluated the correlation with abnormal findings in OR and VH in lewy body disease (LBD) patients including Parkinson disease (PD), PD with dementia (PDD) and dementia with lewy bodies (DLB), and observe the newly appearance of VH in LBD patients without VH during one-year follow-up.

Background: Structural abnormalities in visual association areas including OR have been reported to be associated with VH, which occurs frequently in PDD/DLB patients, often in the early stages of the condition.1 A recently developed, phase-weighted magnetic resonance imaging (MRI) technique “PADRE” can delineate the OR clearly due to the difference in myelin concentration of nerve fiber.2 Therefore, the OR changes on PADRE may represent a useful marker to help diagnosis or early identification of LBD patients with VH.

Methods: Coronal PADRE images were obtained with a 3D multi-echo spoiled gradient echo sequence at a 3T MRI system. First, two radiologists reviewed OR appearances in HS and DLB patients on PADRE in a non-blinded manner, and deviations from the appearance of the normal OR were recorded as OR abnormalities. Next, based on the OR abnormalities, two reviewers assessed PADRE images from 26 LBD with VH patients (10 PDD, 16 DLB), LBD without 41 VH (36 PD, 4 PDD and 1 DLB) and 18 HS in blinded manner. Subjects were considered to have been affected when abnormal findings were observed on at least one side of OR. Kappa values were calculated for inter-observer agreement. Finally, all LBD without VH patients were followed for one year after MRI to determine whether the VH would be appeared.

Results: On the PADRE, the two radiologists identified two layers (internal and external sagittal stratum) of the normal OR, and they were able to consensually define the OR as abnormal when the two layers was obscured at the cranial side of the OR in DLB patitets. The observer study by the two reviewers demonstrated the sensitivity/specificity of abnormal findings of the OR were 69% / 83% (LBD with VH vs. LBD without VH) and no HS showed abnormal OR findings. The κ values for the interobserver variability between two reviewers were 0.81 with excellent interobserver agreement. During a one-year follow-up observation period in LBD patients without VH, the VH was newly appeared in 4 of 7 LBD with abnormal OR findings, but no LBD patients without abnormal OR findings showed the VH.

Conclusions: The abnormal OR findings on PADRE can be associated with VH in LBD patients, and to might be useful to predict the newly appearance of VH.

References: 1. Pizzi SD, Franciotti R, Tartaro A, et al. Structural alteration of the dorsal visual network in DLB patients with visual hallucinations: a cortical thickness MRI study. PloS one 2014;9(1):e86624. 2. Ide S, Kakeda S, Korogi Y, et al. Delineation of optic radiation and stria of.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/lewy-body-disease-with-visual-hallucination-optic-radiation-abnormalities-on-phase-difference-enhanced-imaging-padre/