Fluorodeoxyglucose positron emission tomography of mild cognitive impairment with clinical follow‐up at 3 years

Abstract

Background-Alzheimer's disease (AD) is the most common dementing illness. Development of effective treatments directed at AD requires an early diagnosis. Mild cognitive impairment (MCI) often heralds AD. Thus, characterizing MCI is fundamental to the early diagnosis of AD.Participants-Nineteen MCI patients referred from a memory loss clinic and 27 healthy subjects, all followed for 3 years.Method-Metabolism scans (MCI minus controls) were compared voxel-wise after anatomical normalization and were examined both visually and with a computerized classifier.Results-Agreement between raters as to whether the individual scans were normal or abnormal was high. Agreement between raters of the eventual clinical diagnosis and baseline metabolic pattern was poor. A computerized classifier was unsuccessful at classifying MCI from normal; however, its performance improved when using only prototypic AD-like MCI scans, indicating the classifier worked well when shared patterns existed in the data. Outcomes on follow-up were 9/19 AD; 5/19 remained MCI; and 5/19 developed dementias other than AD. Both cases of early Lewy body dementia (LBD) showed an AD-like metabolic pattern.Conclusions-Visual inspection proved reliable in determining normal from abnormal scans; but it proved unreliable at predicting diagnosis on follow-up. Computerized classification of MCI using an AD-like metabolic template (such as derived from the averaged MCI images) showed Corresponding author: José V. Pardo, M.D., Ph.D.; VAMC; One Veterans Drive; Minneapolis, MN, 55417,

Prodromal dementia with Lewy bodies

“…This may not be representative of all prodromal DLB. Pardo et al (2010) followed 19 army veterans with MCI for 3 years following baseline FDG-PET scans. Two developed DLB; both had an 'AD-like' pattern of hypometabolism (hypometabolism in medial parietal and lateral parietal regions) on visual inspection.…”

“…Surprisingly, the typical DLB pattern of occipital hypometabolism was not found in the few patients who had FDG-PET scans in the prodromal stage of the illness (Clerici et al 2009;Pardo et al 2010).…”

A Cochrane review on brain [18F]FDG PET in dementia: limitations and future perspectives

“…In the latter case, [ 18 F]FDG PET identified patients with AD with a sensitivity of 94 % and a specificity of 73 % [21]. In addition, it has to be noted that sensitivity and specificity values at the lower end of the range given above were derived (1) from studies performed using stand-alone PET scanners with poorer sensitivity and lower spatial resolution than available PET/CT scanners, and/or (2) using a very small group of oncological patients without evidence of brain lesions as controls [22,23]. All these limitations were clearly discussed by the original authors and these articles represent a proof of past efforts to develop and define the specific pattern of AD at the stage of MCI.…”

A preliminary study of resting brain metabolism in treatment-resistant depression before and after treatment with olanzapine-fluoxetine combination

“…Patients’ polypharmacy was tapered with washout for two weeks before the baseline measurement of glucose uptake using FDG PET as described previously [42]. They were then titrated to the maximal tolerated dose of fluoxetine (≤ 60 mg) and olanzapine (≤ 30 mg).…”