Abstract

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: Ten patients (18.5%) had CRS. The frequency of AD was higher in patients with CRS than in patients without CRS (p = 0.028). Compared with patients without CRS (n = 44), those with CRS showed significantly greater PCC hypoperfusion: eZIS severity (1.7 ± 0.5 vs. 1.2 ± 0.4, p = 0.026), extent (26.1 ± 13.4% vs. 15.1 ± 14.3%, p = 0.196), and ratio (5.0 ± 2.8 vs. 2.0 ± 1.7, p = 0.013). No differences were observed in the cingulate island sign score (CIScore; p = 0.215). Moreover, in the subgroup of patients clinically diagnosed with AD, those with CRS showed significantly greater PCC hypoperfusion than those without CRS (1.8 ± 0.3 vs. 1.4 ± 0.5; p = 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.

Keywords: Alzheimer's disease; SPECT; chronic rhinosinusitis; dementia; dementia clinics; posteriorcingulate cortex.

*Reproduced under the CC BY‑NC‑ND 4.0 license.