| J Nucl Med 2000 Nov;41(11):1920-1928 |
FDG PET imaging in patients with pathologically verified dementia.
Hoffman JM, Welsh-Bohmer KA, Hanson M, Crain B, Hulette C, Earl N, Coleman RE.
The purpose of this study was to confirm with pathologic verification 2 beliefs related to
Alzheimer's disease (AD): (a) the long-standing impression that bilateral temporo-parietal
hypometabolism, as noted on FDG PET imaging, is the metabolic abnormality associated with
Alzheimer's disease (AD) and (b) that the sensitivity, specificity, and diagnostic
accuracy of the metabolic pattern of bilateral temporo-parietal hypometabolism allows
differentiation between other degenerative causes of dementia. METHODS: Twenty two
individuals (8 women, 14 men) with difficult-to-characterize memory loss or dementia
(using standard clinical criteria), and who eventually received pathologic confirmation of
diagnosis, were evaluated. FDG PET brain scans were obtained and visually graded by an
experienced nuclear medicine physician as to the presence of classic bilateral
temporo-parietal hypometabolism as seen in Alzheimer's type dementia. Sensitivity,
specificity, positive predictive value, negative predictive value, and diagnostic accuracy
of the metabolic pattern of bilateral temporo-parietal hypometabolism were determined
using pathologic diagnosis as the gold standard. RESULTS: The clinical diagnosis of
possible or probable AD was determined as the primary cause of dementia in 12 patients.
The sensitivity and specificity of the clinical diagnosis for probable AD were 63% and
100%, respectively. The sensitivity and specificity of the clinical diagnosis for possible
and probable AD were 75% and 100%, respectively. The sensitivity, specificity, and
diagnostic accuracy of bilateral temporo-parietal hypometabolism being associated with AD
were 93%, 63%, and 82%, respectively. CONCLUSION: This study confirms that bilateral
temporo-parietal hypometabolism is indeed the classic metabolic abnormality associated
with AD. Furthermore, in individuals with dementia whose FDG PET scans indicated a
metabolic pattern other than bilateral temporo-parietal hypometabolism, a cause of
dementia other than AD should be suspected. These observations may be of clinical
importance in differentiating dementia syndromes. The sensitivity, specificity, and
diagnostic accuracy of FDG PET are acceptable as tests to be used in the evaluation of
dementia and particularly to confirm the clinical suspicion of AD.
