***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: An 18F-labeled PET amyloid-β ( Aβ ) imaging agent could facilitate the clinical evaluation of late-life cognitive impairment by providing an objective measure for Alzheimer disease ( AD ) pathology . Here we present the results of a clinical trial with (E)-4-(2-(6-(2-(2-(2 - 18F-fluoroethoxy)ethoxy)ethoxy)pyridin-3-yl)vinyl)-N-methyl benzenamine ( 18F-AV-45 or flobetapir F 18 ) . Methods : An open-label , multicenter brain imaging , metabolism , and safety study of 18F-AV-45 was performed on 16 patients with AD ( Mini-Mental State Examination score , 19.3 ± 3.1 ; mean age ± SD , 75.8 ± 9.2 y ) and 16 cognitively healthy controls ( HCs ) ( Mini-Mental State Examination score , 29.8 ± 0.45 ; mean age ± SD , 72.5 ± 11.6 y ) .  Dynamic PET was performed over a period of approximately 90 min after injection of the tracer ( 370 MBq [ 10 mCi ] ) . St and ardized uptake values and cortical-to-cerebellum st and ardized uptake value ratios ( SUVRs ) were calculated . A simplified reference tissue method was used to generate distribution volume ratio ( DVR ) parametric maps for a subset of subjects . Results : Valid PET data were available for 11 AD patients and 15 HCs . 18F-AV-45 accumulated in cortical regions expected to be high in Aβ deposition ( e.g. , precuneus and frontal and temporal cortices ) in AD patients ; minimal accumulation of the tracer was seen in cortical regions of HCs . The cortical-to-cerebellar SUVRs in AD patients showed continual substantial increases through 30 min after administration , reaching a plateau within 50 min . The 10-min period from 50 to 60 min after administration was taken as a representative sample for further analysis . The cortical average SUVR for this period was 1.67 ± 0.175 for patients with AD versus 1.25 ± 0.177 for HCs . Spatially normalized DVRs generated from PET dynamic scans were highly correlated with SUVR ( r = 0.58–0.88 , P < 0.005 ) and were significantly greater for AD patients than for HCs in cortical regions but not in subcortical white matter or cerebellar regions . No clinical ly significant changes in vital signs , electrocardiogram , or laboratory values were observed . Conclusion : 18F-AV-45 was well tolerated , and PET showed significant discrimination between AD patients and HCs , using either a parametric reference region method ( DVR ) or a simplified SUVR calculated from 10 min of scanning 50–60 min after 18F-AV-45 administration BACKGROUND Subjects with a mild cognitive impairment ( MCI ) have a memory impairment beyond that expected for age and education yet are not demented . These subjects are becoming the focus of many prediction studies and early intervention trials . OBJECTIVE To characterize clinical ly subjects with MCI  cross-sectionally and longitudinally . DESIGN A prospect i ve , longitudinal inception cohort . SETTING General community clinic . PARTICIPANTS A sample of 76 consecutively evaluated subjects with MCI were compared with 234 healthy control subjects and 106 patients with mild Alzheimer disease ( AD ) , all from a community setting as part of the Mayo Clinic Alzheimer 's Disease Center/Alzheimer 's Disease Patient Registry , Rochester , Minn. MAIN OUTCOME MEASURES The 3 groups of individuals were compared on demographic factors and measures of cognitive function including the  Mini-Mental State Examination , Wechsler Adult Intelligence Scale-Revised , Wechsler Memory Scale-Revised , Dementia Rating Scale , Free and Cued Selective Reminding Test , and Auditory Verbal Learning Test .  Clinical classifications of dementia and AD were determined according to the Diagnostic and Statistical Manual of Mental Disorders , Revised Third Edition and the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer 's Disease and Related Disorders Association criteria , respectively . RESULTS The primary distinction between control subjects and subjects with MCI was in the area of memory , while other cognitive functions were comparable . However , when the subjects with MCI were compared with the patients with very mild AD , memory performance was similar , but patients with AD were more impaired in other cognitive domains as well . Longitudinal performance demonstrated that the subjects with MCI declined at a rate greater than that of the controls but less rapidly than the patients with mild AD . CONCLUSIONS Patients who meet the criteria for MCI can be differentiated from healthy control subjects and those with very mild AD . They appear to constitute a clinical entity that can be characterized for treatment interventions BACKGROUND Results of previous studies have shown associations between PET imaging of amyloid plaques and amyloid-β pathology measured at autopsy . However , these studies were small and not design ed to prospect ively measure sensitivity or specificity of amyloid PET imaging against a reference st and ard . We therefore prospect ively compared the sensitivity and specificity of amyloid PET imaging with neuropathology at autopsy . METHODS This study was an extension of our previous imaging-to-autopsy study of participants recruited at 22 centres in the USA who had a life expectancy of less than 6 months at enrolment . Participants had autopsy within 2 years of PET imaging with florbetapir ( (18)F ) . For one of the primary analyses , the interpretation of the florbetapir scans ( majority interpretation of five nuclear medicine physicians , who classified each scan as amyloid positive or amyloid negative ) was compared with amyloid pathology ( assessed according to the Consortium to Establish a Registry for Alzheimer 's Disease st and ards , and classed as amyloid positive for moderate or frequent plaques or amyloid negative for no or sparse plaques ) ; correlation of the image analysis results with amyloid burden was tested as a co primary endpoint . Correlation , sensitivity , and specificity analyses were also done in the subset of participants who had autopsy within 1 year of imaging as secondary endpoints . The study is registered with Clinical Trials.gov , number NCT 01447719 ( original study NCT 00857415 ) . FINDINGS We included 59 participants ( aged 47 - 103 years ; cognitive status ranging from normal to advanced dementia ) .  The sensitivity and specificity of florbetapir PET imaging  for detection of moderate to frequent plaques were 92 % ( 36 of 39 ; 95 % CI 78 - 98 ) and 100 % ( 20 of 20 ; 80 - 100 % ) , respectively , in people who had autopsy within 2 years of PET imaging , and 96 % ( 27 of 28 ; 80 - 100 % ) and 100 % ( 18 of 18 ; 78 - 100 % ) , respectively , for those who had autopsy within 1 year . Amyloid assessed semiquantitatively with florbetapir PET was correlated with the post-mortem amyloid burden in the participants who had an autopsy within 2 years ( Spearman ρ=0·76 ; p<0·0001 ) and within 12 months between imaging and autopsy ( 0·79 ; p<0·0001 ) . INTERPRETATION The results of this study vali date the binary visual reading method approved in the USA for clinical use with florbetapir and suggest that florbetapir could be used to distinguish individuals with no or sparse amyloid plaques from those with moderate to frequent plaques . Additional research is needed to underst and the prognostic implication s of moderate to frequent plaque density . FUNDING Avid Radiopharmaceuticals Objective : To investigate the 10-year risk of dementia in subjects with mild cognitive impairment ( MCI ) ages 40 to 85 years . Methods : We selected subjects from a memory clinic if they met one of the following definitions of MCI : cognitive complaints ( n = 181 ) , aging-associated cognitive decline ( AACD ) ( n = 163 ) , mild functional impairment ( n = 86 ) , or amnestic MCI ( n = 64 ) . Subjects were reassessed after 2 , 5 , and 10 years . The risk of dementia was calculated with Kaplan-Meier statistics . Analyses were conducted in the entire sample and in subgroups of subjects aged 40 to 54 years , 55 to 69 years , and 70 to 85 years . Results : The 10-year risk of dementia was 0.27 ( 95 % CI 0.20 to 0.34 ) in subjects with cognitive complaints , 0.28 ( 95 % CI 0.21 to 0.35 ) in subjects with AACD , 0.44 ( 95 % CI 0.32 to 0.56 ) in subjects with mild functional impairment , and 0.48 ( 95 % CI 0.35 to 0.61 ) in subjects with amnestic MCI . Ninety-one percent of the demented subjects had probable AD . The risk of dementia increased with increasing age for all MCI definitions ( p < 0.001 ) . Depending on the MCI definition used , the risk for dementia ranged from 0 to 0.06 in subjects aged 40 to 54 years , from 0.37 to 0.52 in subjects aged 55 to 69 years , and from 0.77 to 1.0 in subjects aged 70 to 85 years . Conclusions : The majority of subjects with MCI  do not progress to dementia at the long term . Age strongly influences the dementia risk . MCI often represents the predementia stage of a neurodegenerative disorder in elderly subjects but rarely in younger subjects CONTEXT Small single-center studies have shown that cerebrospinal fluid ( CSF ) biomarkers may be useful to identify incipient Alzheimer disease ( AD ) in patients with mild cognitive impairment ( MCI ) , but large-scale multicenter studies have not been conducted . OBJECTIVE To determine the diagnostic accuracy of CSF beta-amyloid(1 - 42 ) ( Abeta42 ) , total tau protein ( T-tau ) , and tau phosphorylated at position threonine 181 ( P-tau ) for predicting incipient AD in patients with MCI . DESIGN , SETTING , AND PARTICIPANTS The study had 2 parts : a cross-sectional study involving patients with AD and controls to identify cut points , followed by a prospect i ve cohort study involving patients with MCI  , conducted 1990 - 2007 . A total of 750 individuals with MCI , 529 with AD , and 304 controls were recruited by 12 centers in Europe and the United States . Individuals with MCI  were followed up for at least 2 years or until symptoms had progressed to clinical dementia . MAIN OUTCOME MEASURES Sensitivity , specificity , positive and negative likelihood ratios ( LRs ) of CSF Abeta42 , T-tau , and P-tau for identifying incipient AD . RESULTS During follow-up , 271 participants with MCI were diagnosed with AD and 59 with other dementias . The Abeta42 assay in particular had considerable intersite variability . Patients who developed AD had lower median Abeta42 ( 356 ; range , 96 - 1075 ng/L ) and higher P-tau ( 81 ; range , 15 - 183 ng/L ) and T-tau ( 582 ; range , 83 - 2174 ng/L ) levels than MCI patients who did not develop AD during follow-up ( 579 ; range , 121 - 1420 ng/L for Abeta42 ; 53 ; range , 15 - 163 ng/L for P-tau ; and 294 ; range , 31 - 2483 ng/L for T-tau , P < .001 ) . The area under the receiver operating characteristic curve was 0.78 ( 95 % confidence interval [ CI ] , 0.75 - 0.82 ) for Abeta42 , 0.76 ( 95 % CI , 0.72 - 0.80 ) for P-tau , and 0.79 ( 95 % CI , 0.76 - 0.83 ) for T-tau . Cut-offs with sensitivity set to 85 % were defined in the AD and control groups and tested in the MCI group , where the combination of Abeta42/P-tau ratio and T-tau identified incipient AD with a sensitivity of 83 % ( 95 % CI , 78%-88 % ) , specificity 72 % ( 95 % CI , 68%-76 % ) , positive LR , 3.0 ( 95 % CI , 2.5 - 3.4 ) , and negative LR , 0.24 ( 95 % CI , 0.21 - 0.28 ) . The positive predictive value was 62 % and the negative predictive value was 88 % . CONCLUSIONS This multicenter study found that CSF Abeta42 , T-tau , and P-tau identify incipient AD with good accuracy , but less accurately than reported from single 
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Although sensitivity was good in one included study , considering the poor specificity and the limited data available in the literature , we can not recommend routine use of 18F-florbetapir PET in clinical practice to predict the progression from MCI to ADD.Because of the poor sensitivity and specificity , limited number of included participants , and the limited data available in the literature , we can not recommend its routine use in clinical practice to predict the progression from MCI to any form of dementia .