Spect Brain Imaging in Cognitively Impaired Subjects with A Neuroborreliosis; Watershed Abnormalities Suggest Cns Vasculitis.

1601 Objectives The objective of this study is to evaluate brain SPECT imaging in cognitively impaired subjects with a clinical diagnosis of neuroborreliosis. Methods 20 patients with cognitive impairment and Western blot positive borreliosis protein bands underwent SPECT brain imaging. All patients were scanned with a dual detector SPECT camera (Siemens ECam) 90min following 20 millicuries of Tc-99m ECD (Neurolite). Reconstructed images were warped to a standard stereotactic coordinate system and relative grey matter perfusion examined. Quantitative analysis was performed using a stereotactic surface projection (SSP) technique (Neurostat). A pixel wise two sample t-test was computed to create a Z-score between neuroborreliosis subjects and a normal SPECT database (SNM Brain Imaging Council). All subjects had reconstructed surface rendered images, axial, sagittal, and coronal views, and 3D-SSP quantitation. Results The 20 neuroborreliosis brain SPECT scans demonstrated a pattern of watershed hypoperfusion with strong statistical significance when compared to normal SPECT scans (p = 0.001). Diffuse involvement in the frontal watershed area was found, with a Z score of approximately 10 standard deviations (SD) below the mean for the normal group. Posterior watershed had a Z score averaging approximately 8.5 SD below the mean. The posterior watershed findings extend into the posterior and inferior parietal lobes and also extend anteriorly into the medial temporal lobe. Surface rendered images on all individuals confirmed the quantitative findings. Conclusions Visual and quantitative analysis of SPECT brain scans detected a pattern of severe hypoperfusion in the frontal and posterior watershed areas in the neuroborreliosis subgroup compared to normal subjects. To our knowledge this is the first demonstration of a pattern of watershed hypoperfusion in neuroborreliosis suggesting a vasculitis like process as a basis for cognitive impairment in patients with this disease.