Pittsburgh Compound B (11C-PIB) and Fluorodeoxyglucose (18 F-FDG) PET in Patients With Alzheimer Disease, Mild Cognitive Impairment, and Healthy Controls

Abstract

Amyloid load in the brain using 11C-PIB PET and cerebral glucose metabolism using 18F-FDG PET were evaluated in patients with mild Alzheimer’s disease (AD, n=18), mild cognitive impairment (MCI, n=24) and controls (CTR, n=18). 11C-PIB binding potential (BPND) was higher in prefrontal cortex, cingulate, parietal cortex, and precuneus in AD compared to CTR or MCI, and in prefrontal cortex for MCI compared to CTR. For 18F-FDG, rCMRGlu was decreased in precuneus and parietal cortex in AD compared to CTR and MCI, with no MCI-CTR differences. For the AD-CTR comparison, precuneus BPND area under the ROC curve (AUC) was 0.938 and parietal cortex rCMRGlu AUC was 0.915; for the combination AUC was 0.989. 11C-PIB PET BPND clearly distinguished diagnostic groups, and combined with 18F-FDG PET rCMRGlu this effect was stronger. These PET techniques provide complementary information in strongly distinguishing diagnostic groups in cross-sectional comparisons that need testing in longitudinal studies.

Plasma Aβ and PET PiB binding are inversely related in mild cognitive impairment

“…3,4 The relative sparing of the parahippocampal gyrus is consistent with the literature showing low binding in the medial temporal lobe with amyloid brain imaging. [2][3][4]19 Increased PiB binding in the cingulate and parietal cortex, and total brain, was associated with decreased plasma A␤42 and the A␤42/A␤40 ratio, and these associations remained significant even after controlling for age, sex, and cognitive test scores. The resilience of this finding in this sample supports the hypothesis that increased amyloid deposition in the brain is accompanied by lower peripheral A␤ levels in plasma.…”

“…[16][17][18][19][20][21] 11 C-PiB kinetic analysis. The cerebellum is nearly devoid of amyloid plaques in patients with AD 22 and cerebellar gray matter shows little 11 C-PiB binding in healthy controls and AD.…”

“…DISCUSSION The plasma A␤42/A␤40 ratio, and to a lesser extent plasma A␤42, were decreased in patients with MCI compared to cognitively intact control subjects, consistent with the literature. [3][4][5]19 Increased PiB binding in the cingulate and parietal cortex, as well as increased total brain PiB binding, have been shown to occur in MCI compared to controls. 3,4 The increase in prefrontal cortex binding was not as strong as in the initial PiB report 2 but is consistent with subsequent reports which showed that the precuneus or parietal cortex rather than prefrontal cortex manifests the greatest differences between AD and controls.…”

Quantification of Task-Specific Glucose Metabolism with Constant Infusion of18F-FDG

“…First, application of the Patlak plot does not take into account the fact that k 4 may actually be higher than 0, resulting in a known underestimation of CMRGlu (here, ;27%) (3,29). Although this is important to keep in mind when different studies are compared, the underestimation is a scaling factor and may thus be less problematic if applied consistently across subjects.…”

“…These include tumor imaging (1), neurologic diseases such as epilepsy (2) and Alzheimer disease (3)(4)(5), and psychiatric disorders such as major depression (6). Hence, PET using the radiolabeled glucose analog 18 F-FDG offers an excellent opportunity for imaging and quantification of glucose metabolism.…”