Slight hyperintensity of the left piriform cortex and amygdala on T2-weighted FLAIR images in older adults and patients with probable Alzheimer's disease.

BackgroundThe left piriform cortex and amygdala (PC&A) is an early target for deterioration due to aging and Alzheimer's disease (AD) in several neuropathological and magnetic resonance (MR) volumetric studies. We observed slight hyperintensity of the left PC&A in older adults and probable AD (pAD) patients on T2-weighted fluid-attenuated inversion recovery (T2W-FLAIR) images.PurposeTo quantitatively assess the validity of the left PC&A hyperintensity in older adults and pAD patients.Material and MethodsT2W-FLAIR images from three groups were retrospectively evaluated: (i) younger control (YC; n = 77): individuals aged 37.9 ± 8.4 years; (ii) older control (OC; n = 98): individuals aged 76.9 ± 5.3 years without cognitive impairment; and (iii) pAD (n = 35): individuals aged 80.5 ± 6.9 years with pAD. Signal intensity (SI) ratios of the left to right PC&A (L-PC&A/R-PC&A) were calculated for all groups. In the OC and pAD groups, SI ratios of the left PC&A to pons (L-PC&A/P) and the right PC&A to pons (R-PC&A/P) were calculated. The regions of interest were defined as large as possible on transaxial images in which the PC&As were most broadly depicted.ResultsThe mean L-PC&A/R-PC&A in the YC, OC, and pAD groups showed an increasing trend in that sequence < 0.001). The mean L-PC&A/P was higher in the pAD group than in the OC group (< 0.001). However, the mean R-PC&A/P was not significantly different between the OC and pAD groups (= 0.245).ConclusionThe SI of the left PC&A on T2W-FLAIR images significantly increased with age and in individuals with pAD, likely reflecting the deterioration of the left PC&A.