Affiliations: [a] Department of Radiology, Mayo Clinic, Rochester, MN, USA
| [b] Department of Neurology, Mayo Clinic, Rochester, MN, USA
| [c] Department of Psychiatry and Psychology, Mayo Clinic, Rochester, MN, USA
Correspondence:
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Correspondence to: Jennifer L. Whitwell, PhD, Professor of Radiology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA. Tel.: +1 507 284 5576; Fax: +1 507 284 9778; E-mail:whitwell.jennifer@mayo.edu.
Abstract: Background:It has been hypothesized that medial temporal sparing may be related to preserved posterior cingulate metabolism and the cingulate island sign (CIS) on [18F]fluorodeoxyglucose (FDG) PET in posterior cortical atrophy (PCA). Objective:To assess the severity of medial temporal atrophy in PCA and determine whether the presence of a CIS is related to medial temporal sparing. Methods:Fifty-five PCA patients underwent MRI and FDG-PET. The degree and symmetry of medial temporal atrophy on MRI was visually assessed using a five-point scale for both hemispheres. Visual assessments of FDG-PET coded the presence/absence of a CIS and whether the CIS was symmetric or asymmetric. Hippocampal volumes and a quantitative CIS were also measured. Results:Medial temporal atrophy was most commonly mild or moderate, was symmetric in 55% of patients, and when asymmetric was most commonly worse on the right (76%). Older age and worse memory performance were associated with greater medial temporal atrophy. The CIS was observed in 44% of the PCA patients and was asymmetric in 50% of these. The patients with a CIS showed greater medial temporal asymmetry, but did not show lower medial temporal atrophy scores, compared to those without a CIS. Hippocampal volumes were not associated with quantitative CIS. Conclusion:Mild medial temporal atrophy is a common finding in PCA and is associated with memory impairment. However, medial temporal sparing was not related to the presence of a CIS in PCA.
Keywords: Cingulate island sign, FDG-PET, hippocampus, MRI, visual assessment
