Author |
김상은(Sang Eun Kim),나덕렬(Duk Lyul Na),이정림(Jeong Rim Lee),최용(Yong Choi),이경한(Kyung Han Lee),최연성(Yearn Seong Choe),김도관(Doh Kwan Kim),김병태(Byung Tae Kim),이광호(Kwang Ho Lee),김승태(Seung Tai Kim), |
Abstract |
The purpose of the present study was to validate the
use of tissue radioactivity ratios instead of regional
metabolic rates for the assessment of regional
metabolic changes in Alzheimer's disease(AD) with
[18F]FDG PET and to examine the correlation of ratio
indices with the severity of cognitive impairment in
AD. Thirty-seven AD patients(age 68±9 yrs, mean±s.d.;
36 probable and 1 definite AD), 28 patients with
dementia of non-Alzheimer type(age 66±7 yrs), and 17
healthy controls(age 66±4 yrs) underwent [18F]FDG PET
imaging. Two simplified radioactivity ratio indices
were calculated from 37-66 min image: region-to-
cerebellar radioactivity-ratio(RCR) and a composite
radioactivity ratio(a ratio of radioactivity in the
most typically affected regions over the least
typically affected regions: CRR). Local cerebral
metabolic rate for glucose(LCMRglu) was also measured
using a three-compartment, five-parameter tracer
kinetic model. The ratio indices were significantly
lower in AD patients than in controls(RCR in
temporoparietal cortex, 0.949±8.136 vs. 1.238±0.129,
p=0.0004; PCR in frontal cortex, 1.027±0.128 vs.
1.361±0.151, p〈0.0001; CRR, 0.886±0.096 vs.
1.032±0.042: p=0.0024). On the RCR analysis, 86% of AD
patients showed a pattern of bilateral temporoparietal
hypometabolism with or without frontal involvement;
hypometabolism was unilateral in 11% of the patients.
When bilateral temporoparietal hypometabolism was
considered to be suggestive of AD, the sensitivity and
specificity of the RCR was analysis for the
differential diagnosis of AD were 86% and 73%,
respectively. The RCR was correlated significantly with
the macroparameter K [K1k3/(k2+k3)] (r=0.775, p
〈0.0001) and LCMRglu(r=0.633, p=0.0002) measured using
the kinetic model. In patients with AD, both average
RCR of cortical association areas and CRR were
correlated with Mini-Mental Status Examination(r=0.565,
p=0.0145; r=0.642, p=0.0031, respectively), Clinical
Dementia Rating(r=-0.576, p=0.0124; r=-0.591,
p=0.0077), and total score of Mattis Dementia Rating
Scale (r=0.574, p=0.0648; r=0.737, p=0.0096). There
were also significant correlations between memory and
language impairments and corresponding regionl RCRs.
The results suggest that the [18F]FDG PET ratio
indices, RCR and CRR, reflect global and regional
metabolic rates and correlate with the severity of
cognitive impairment in AD. The simplified ratio
analysis may be clinically useful for the differential
diagnosis and seral monitoring of the disease. |