Chronic rhinosinusitis and posterior cingulate hypoperfusion on SPECT in dementia diagnosis

Introduction: Single-photon emission computed tomography (SPECT) is widely used in dementia clinics to evaluate regional cerebral blood flow (rCBF). Posterior cingulate cortex (PCC) hypoperfusion is a supportive, though not definitive, marker for Alzheimer's disease (AD). Magnetic resonance imaging (MRI)-defined sinus inflammation has been associated with systemic inflammation and altered brain connectivity; therefore, we aimed to determine whether MRI-defined chronic rhinosinusitis (CRS) is associated with differences in PCC perfusion patterns on SPECT among patients with cognitive impairment. Methods: We retrospectively reviewed 54 patients with cognitive impairment who had undergone brain MRI and SPECT. CRS was defined using MRI-based modified Lund-Mackay scores. SPECT findings were analyzed using the easy Z-score Imaging System (eZIS), focusing on PCC severity, extent, and ratio. Comparisons were performed between patients with and without CRS. Results: = 0.023). PCC hypoperfusion in CRS overlapped with canonical AD patterns but was not observed in non-AD dementias. Conclusion: Our exploratory findings suggest that MRI-defined CRS may be associated with differences in SPECT-derived PCC perfusion patterns in patients with cognitive impairment. Awareness of CRS as a common incidental MRI finding may help neurologists interpret SPECT results more cautiously in memory clinic settings.