When it comes to predicting the cognitive-impairment course Alzheimer’s disease will take in a mildly stricken patient, neither of two tracers commonly used with PET—18F-FDG (for assessing glucose metabolism) and 11C-PiB (for assessing amyloid deposits)—brings much to the table. And that’s so regardless of automated vs. visual analysis.
However, for ruling Alzheimer’s out, amyloid (11C-PiB) PET is a pillar of the neuroimaging community, one that performs best when paired with automated analysis.
Those are the main takeaways from a small German study published in the February edition of the Journal of Nuclear Medicine.
Timo Grimmer, MD, of the Technical University of Munich and colleagues examined 28 patients with mild cognitive impairment, first performing a baseline examination combining clinical and imaging assessments.
At two-year followup, nine of the 28 had developed Alzheimer’s-associated dementia, two had frontotemporal dementia and one had moderate dementia of unknown etiology.
Measuring these outcomes against the baseline testing data, the researchers found that for the prediction of progression of dementia due to Alzheimer’s, the positive and negative predictive values and the accuracy of 11C-PiB were 0.50, 1.00 and 0.68, respectively, for the visual analyses, and 0.53, 1.00, and 0.71, respectively, for the automated.
Meanwhile, positive predictive value, negative predictive value and accuracy of fully automated analyses of 18F-FDG PET were 0.37, 0.78, and 0.50, respectively.
Grimmer et al. additionally found that results of visual analyses were highly variable between raters but were superior to automated analyses.
“The results of this study show that amyloid PET scans and 18F-FDG scans are of limited benefit in terms of their ability to predict conversion to dementia due to Alzheimer disease in patients with mild cognitive impairment at short-term follow-up, but amyloid PET is extremely useful to rule out a risk of underlying Alzheimer disease,” conclude Grimmer et al.
The authors add that their study “favors a fully automated method of analysis for 11C-PiB assessments and a visual analysis by experts for 18F-FDG assessments.”
Dave P. has worked in journalism, marketing and public relations for more than 30 years, frequently concentrating on hospitals, healthcare technology and Catholic communications. He has also specialized in fundraising communications, ghostwriting for CEOs of local, national and global charities, nonprofits and foundations.