Where Should I Draw the Line: PET-Driven, Data-Driven, or Manufacturer Cut-Off?

Background: The optimal cut-off for Alzheimer's disease (AD) CSF biomarkers remains controversial. Objective: To analyze the performance of cut-off points standardized by three methods: one that optimized the agreement between 11C-Pittsburgh compound B PET (a-PET) and CSF biomarkers (Aß1-42, pTau, tTau, and Aß1-42/Aß1-40 ratio) in our population, called PET-driven; an unbiased cut-off using data from a healthy research cohort, called data-driven, and that provided by the manufacturer. We also compare changes in ATN classification. Methods: CSF biomarkers measured by the LUMIPULSE G600II platform and qualitative visualization of amyloid positron emission tomography (a-PET) were performed in all the patients. We established a cut-off for each single biomarker and Aß1-42/Aß1-40 ratio that optimized their agreement with a-PET using ROC curves. Sensitivity, Specificity, and Overall Percent of Agreement are assessed using a-PET or clinical diagnosis as gold standard for every cut-off. Also, we established a data-driven cut-off from our cognitively unimpaired cohort. We then analyzed changes in ATN classification. Results: One hundred and ten patients were recruited. Sixty-six (60%) were a-PET positive. PET-driven cut-offs were: pTau > 57, tTau > 362.62, Aß1-42/Aß1-40 < 0.069. For a single biomarker, pTau showed the highest accuracy (AUC 0.926). New PET-driven cut-offs classified patients similarly to manufacturer cut-offs (only two patients changed). However, 20 patients (18%) changed when data-driven cut-offs were used. Conclusions: We established our sample's best CSF biomarkers cut-offs using a-PET as the gold standard. These cut-offs categorize better symptomatic subjects than data-driven in ATN classification, but they are very similar to the manufacturer's.

Plasma Phosphorylated Tau 231 Increases at One-Year Intervals in Cognitively Unimpaired Subjects.

Background: Plasma biomarkers of Alzheimer's disease (AD) constitute a non-invasive tool for diagnosing and classifying subjects. They change even in preclinical stages, but it is necessary to understand their properties so they can be helpful in a clinical context. Objective: With this work we want to study the evolution of p-tau231 plasma levels in the preclinical stages of AD and its relationship with both cognitive and imaging parameters. Methods: We evaluated plasma phosphorylated (p)-tau231 levels in 146 cognitively unimpaired subjects in sequential visits. We performed a Linear Mixed-effects Model to analyze their rate of change. We also correlated their baseline levels with cognitive tests and structural and functional image values. ATN status was defined based on cerebrospinal fluid biomarkers. Results: Plasma p-tau231 showed a significant rate of change over time. It correlated negatively with memory tests only in amyloid-positive subjects. No significant correlations were found with any imaging measures. Conclusions: Increases in plasma p-tau231 can be detected at one-year intervals in cognitively healthy subjects. It could constitute a sensitive marker for detecting early signs of neuronal network impairment by amyloid.

Field-based molecular detection of Batrachochytrium dendrobatidis in critically endangered Atelopus toads and aquatic habitats in Ecuador.

Batrachochytrium dendrobatidis (Bd) is a lethal fungal species that parasitizes vertebrates and is associated with the worldwide decline of amphibian populations. The development of sensitive, rapid detection methods, particularly DNA-based techniques, is critical for effective management strategies. This study evaluates the efficacy of DNA extraction and a portable PCR device in a mountable field laboratory setup for detecting Bd near the habitats of three critically endangered Atelopus toad species in Ecuador. We collected skin swabs from Atelopus balios, A. nanay, and A. bomolochos, and environmental DNA (eDNA) samples from streams in Andean and coastal regions of Ecuador. For eDNA, a comparison was made with duplicates of the samples that were processed in the field and in a standard university laboratory. Our findings revealed Bd detection in eDNA and swabs from 6 of 12 water samples and 10 of 12 amphibian swab samples. The eDNA results obtained in the field laboratory were concordant with those obtained under campus laboratory conditions. These findings highlight the potential of field DNA-based monitoring techniques for detecting Bd in amphibian populations and their aquatic habitats, particularly in remote areas. Furthermore, this research aligns with the National Action Plan for the Conservation of Ecuadorian Amphibians and contributes to the global effort to control this invasive and deadly fungus.

Yaws elimination in Ecuador: Findings of a serological survey of children in Esmeraldas province to evaluate interruption of transmission.

BACKGROUND: The WHO roadmap for neglected tropical diseases includes yaws eradication requiring certification of elimination of transmission in all endemic and formerly endemic countries worldwide. A community-based programme for yaws control was considered to have achieved elimination of the infection in the endemic focus in Ecuador after 1993. We did a serosurvey of children in this focus to provide evidence for interruption of transmission. METHODS: Survey of serum samples collected from children aged 2 to 15 years living in the formerly endemic and in geographically contiguous areas. A convenience sample of sera collected between 2005 were 2017 from non-yaws studies, were analyzed using immunochromatic rapid tests to screen (OnSite Syphilis Ab Combo Rapid Test) for Treponema pallidum-specific antibodies and confirm (DPP Syphilis Screen and Confirm) seroreactivity based on the presence antibodies to treponemal and non-treponemal antigens. RESULTS: Seroreactivity was confirmed in 6 (0.14%, 95% CI 0.06-0.30) of 4,432 sera analyzed and was similar in formerly endemic (0.11%, (95% CI 0.01-0.75) and non-endemic (0.14%, 95% CI 0.06-0.34) communities. All seroreactors were of Afro-Ecuadorian ethnicity and most were male (4/6) and aged 10 or more years (5/6), the latter possibly indicating venereal syphilis. Only 1 seroreactor lived in a community in the Rio Santiago, that was formerly hyperendemic for yaws. CONCLUSION: We observed very low levels of treponemal transmission in both formerly endemic and non-endemic communities which might be indicative of congenital or venereal syphilis and, if yaws, would likely be insufficient to maintain transmission of this endemic childhood infection. Additional surveys of children aged 1 to 5 years are planned in Rio Santiago communities to exclude yaws transmission.

Prevalence of burnout syndrome in university students: A systematic review / Prevalencia del síndrome de burnout en estudiantes universitarios: Una revisión sistemática

Abstract Introdution Burnout syndrome is a social and health problem in college students. Objective To synthesize evidence from previous studies on the prevalence of burnout syndrome in university students in their three-dimensional approach. Method The search strategies followed the PRISMA guidelines and were based on the following descriptive terms: "burnout," "studies," "prevalence," "students." Pubmed, Web of Science Core Collection, PsicINFO, and Scielo were consulted. An evaluation of the quality of the information was carried out applying the STROBE positioning guidelines. Results We found 1,406 studies that were reduced to 46 studies for final analysis using the STROBE statement, eventually leaving 20 studies. One study (5%) was conducted in North America, five (25%) in Asia, nine (45%) in Latin America, and five (25%) in Europe. Of the 20 studies evaluated in the systematic review, those that had the best overall evaluation in the STROBE analysis were selected for discussion, corresponding to 10 (out of 75% of STROBE). Overall prevalence of each dimension of the syndrome was estimated at 55.4% for emotional exhaustion, 31.6% for cynicism, and 30.9% for academic efficacy. Discussion and conclusion Moderate levels of burnout syndrome prevail in the different populations of university students of different careers worldwide. In only a few studies is the prevalence low and this could be due to multiple evaluative variables.

Resumen Introducción El síndrome de burnout es un problema social y de salud en los estudiantes universitarios. Objetivo Sintetizar las pruebas de estudios anteriores sobre la prevalencia del síndrome de burnout en estudiantes universitarios en su enfoque tridimensional. Método Las estrategias de búsqueda siguieron las pautas de PRISMA y se basaron en los siguientes términos descriptivos: "burnout", "estudios", "prevalencia", "estudiantes". Se consultaron Pubmed, Web of Science Core Collection, PsicINFO y Scielo. Se llevó a cabo una evaluación de la calidad de la información aplicando las directrices de posicionamiento de STROBE. Resultados Se encontraron 1,406 estudios que se redujeron a 46 estudios para el análisis final utilizando la declaración STROBE, con lo que quedaron finalmente 20 estudios. Un estudio (5%) se llevó a cabo en América del Norte, cinco (25%) en Asia, nueve (45%) en América Latina y cinco (25%) en Europa. De los 20 estudios evaluados en la revisión sistemática, se seleccionaron para su discusión aquellos que tuvieron la mejor evaluación general en el análisis de la STROBE, correspondientes a 10 (de un 75% de la STROBE). La prevalencia general de cada dimensión del síndrome se estimó en un 55.4% para el agotamiento emocional, un 31.6% para el cinismo y un 30.9% para la eficacia académica. Discusión y conclusión Los niveles moderados del síndrome de burnout prevalecen en las diferentes poblaciones de estudiantes universitarios de distintas carreras en todo el mundo. En sólo unos pocos estudios la prevalencia es baja y esto podría deberse a múltiples variables evaluativas.

Evaluation of choroidal thickness in prodromal Alzheimer's disease defined by amyloid PET.

OBJECTIVE: To assess and compare the involvement of choroidal thickness (CT) in patients with mild cognitive impairment (MCI) and dementia due to Alzheimer's disease (AD) defined by amyloid PET and healthy controls (HC). METHODS: Sixty-three eyes from 34 AD patients [12 eyes (19.0%) with dementia and 51 eyes (80.9%) with MCI], positive to 11C-labelled Pittsburgh Compound-B with positron emission tomography (11C-PiB PET/CT), and the same number of sex- and age-paired HC were recruited. All participants underwent enhanced depth imaging optical coherence tomography (EDI-OCT) assessing CT at 14 measurements from 2 B-scans. Paired Student t-test was used to compare CT measurements between MCI, dementia and sex- and age-paired HC. A univariate generalized estimating equations model (GEE) test was performed to compare MCI and dementia individually with all HC included. RESULTS: Compared with HC, eyes from patients with positive 11C-PiB PET/CT showed a significant CT thinning in 5 selected locations (in foveal thickness in vertical scan, in temporal scan at 1500µm, in superior scan at 500µm and in inferior scan at 1000µm and 1500µm, p = 0.020-0.045) whilst few significant CT reduction data was reported in MCI or dementia individually versus HC. However, the GEE test identified significant CT thinning in AD compared with all HC included (p = 0.015-0.046). CONCLUSIONS: To our knowledge, the present study is the first measuring CT in eyes from MCI and dementia eyes positive to 11C-PiB PET/CT reporting a significant trend towards CT thinning in MCI patients which became more pronounced in dementia stage. We support further investigation involving larger and prospective OCT studies in AD population characterized with available biomarkers to describe whether choroidal vascular damage occurs specifically in prodromal stages of AD.

A snake that bites its own tail. Acquisition and loss of concepts in children and semantic dementia patients through the analysis of drawings.

OBJECTIVE: The structure of the semantic network is constructed and organized during childhood development. Previous publications have hypothesized that neurodegenerative diseases would lead to a disruption of this network reversing the steps acquired in childhood. Semantic Dementia (SD) is a subtype of frontotemporal lobe degeneration in which the main symptom is a specific loss of semantic memory. We aimed to describe the sequential acquisition of concepts in 3-8 years old children evaluated through the production of drawings and, in parallel, their progressive loss in SD patients. METHODS: 104 children between 40 and 96 months categorized into tertiles according to their age, 21 SD patients categorized into tertiles according to their score on a category fluency task and 34 healthy volunteers were asked to draw 12 items with, a priori, different age of acquisition and familiarity, belonging to four different semantic categories. We employed the drawings of the healthy volunteers to build a scoring scheme. We considered that a concept was acquired in children when 50% or more of its features were present in their drawings, and it was lost in patients when more than 50% were missing. RESULTS: Those concepts which the children were able to acquire earlier, according to our scoring scheme, tended to remain in patients with more advanced SD. While the items that children acquired later, were, in general, those that the SD patients lost at earlier disease stages. CONCLUSION: The patterns of concept acquisition in children were the mirror image of the loss in patients with SD. Our study supports the hypothesis that the sequence of concept acquisition in childhood is reversed in SD patients.

Distinctive Oculomotor Behaviors in Alzheimer's Disease and Frontotemporal Dementia.

Oculomotor behavior can provide insight into the integrity of widespread cortical networks, which may contribute to the differential diagnosis between Alzheimer's disease and frontotemporal dementia. Three groups of patients with Alzheimer's disease, behavioral variant of frontotemporal dementia (bvFTD) and semantic variant of primary progressive aphasia (svPPA) and a sample of cognitively unimpaired elders underwent an eye-tracking evaluation. All participants in the discovery sample, including controls, had a biomarker-supported diagnosis. Oculomotor correlates of neuropsychology and brain metabolism evaluated with 18F-FDG PET were explored. Machine-learning classification algorithms were trained for the differentiation between Alzheimer's disease, bvFTD and controls. A total of 93 subjects (33 Alzheimer's disease, 24 bvFTD, seven svPPA, and 29 controls) were included in the study. Alzheimer's disease was the most impaired group in all tests and displayed specific abnormalities in some visually-guided saccade parameters, as pursuit error and horizontal prosaccade latency, which are theoretically closely linked to posterior brain regions. BvFTD patients showed deficits especially in the most cognitively demanding tasks, the antisaccade and memory saccade tests, which require a fine control from frontal lobe regions. SvPPA patients performed similarly to controls in most parameters except for a lower number of correct memory saccades. Pursuit error was significantly correlated with cognitive measures of constructional praxis and executive function and metabolism in right posterior middle temporal gyrus. The classification algorithms yielded an area under the curve of 97.5% for the differentiation of Alzheimer's disease vs. controls, 96.7% for bvFTD vs. controls, and 92.5% for Alzheimer's disease vs. bvFTD. In conclusion, patients with Alzheimer's disease, bvFTD and svPPA exhibit differentiating oculomotor patterns which reflect the characteristic neuroanatomical distribution of pathology of each disease, and therefore its assessment can be useful in their diagnostic work-up. Machine learning approaches can facilitate the applicability of eye-tracking in clinical practice.

Cognitive and Behavioral Profiles of Left and Right Semantic Dementia: Differential Diagnosis with Behavioral Variant Frontotemporal Dementia and Alzheimer's Disease.

BACKGROUND: Semantic dementia (SD) is a subtype of frontotemporal dementia (FTD) characterized by semantic memory loss and preserved abilities of other cognitive functions. The clinical manifestations of SD require a differential diagnosis with Alzheimer's disease (AD), especially those with early onset, and behavioral variant FTD (bvFTD). OBJECTIVE: The present study aimed to compare cognitive performances and neuropsychiatric symptoms in a population of AD, bvFTD, and left and right SD defined with the support of molecular imaging (amyloid and 2-[18F] fluoro-2-deoxy-D-glucose positron emission tomography) and assessed the accuracy of different neuropsychological markers in distinguishing these neurodegenerative diseases. METHODS: Eighty-seven participants (32 AD, 20 bvFTD, and 35 SD (17 Left-SD and 18 Right-SD) completed a comprehensive neuropsychological battery that included memory, language, attention and executive functions, visuospatial function, visuoconstructional skills, and tasks designed specifically to evaluate prosopagnosia and facial emotions recognition. The Neuropsychiatric Inventory was administered to assess neuropsychiatric symptoms. RESULTS: An episodic memory test that included semantic cues, a visuospatial test (both impaired in AD), a naming test and a prosopagnosia task (both impaired in SD) were the four most valuable cognitive metrics for the differential diagnosis between groups. Several behavioral abnormalities were differentially present, of which aggression, self-care (both more frequent in bvFTD), and eating habits, specifically overeating and altered dietary preference (more frequent in SD), were the most valuable in group discrimination. CONCLUSION: Our study highlights the value of a comprehensive neuropsychological and neuropsychiatric evaluation for the differential diagnosis between FTD syndromes and AD.

Ganglion cell layer thinning in prodromal Alzheimer's disease defined by amyloid PET.

INTRODUCTION: The objective of this study was to investigate and compare optic nerve and retinal layers in eyes of patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) with paired control eyes using optical coherence tomography. METHODS: Sixty-three eyes of 34 subjects, 12 eyes with AD and 51 eyes with MCI, positive to 11C-labeled Pittsburgh Compound-B with positron emission tomography (11C-PiB PET/CT), and the same number of sex- and age-paired control eyes underwent optical coherence tomography scanning analyzing retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), Bruch's membrane opening-minimum rim width (BMO-MRW), inner plexiform layer (IPL), outer nuclear layer, and lamina cribrosa (LC). RESULTS: Compared with healthy controls, eyes of patients with positive 11C-PiB PET/CT showed a significant thinning of RNFL (P < .028) and GCL (P < .014). IPL and outer nuclear layer also showed significant thinning in two (P < .025) and one location (P < .010), respectively. No significant differences were found when optic nerve measurements BMO-MRW and LC were compared (P > .131 and P > .721, respectively). Temporal sector GCL, average RNFL, and temporal sector RNFL also exhibited significant thinning when MCI and control eyes were compared (P = .015, P = .005 and P = .050, respectively), and also the greatest area under the curve values (0.689, 0.647, and 0.659, respectively). GCL, IPL, and RNFL tend to be thinner in the AD group compared with healthy controls. DISCUSSION: Our study suggests that RNFL and GCL are useful for potential screening in the early diagnosis of AD. LC and BMO-MRW appear not to be affected by AD.

A Brief Drawing Task for the Differential Diagnosis of Semantic Dementia.

BACKGROUND: Semantic dementia (SD) is a subtype of frontotemporal lobe degeneration characterized by semantic loss, with other cognitive functions initially preserved. SD requires differential diagnosis with Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD). Semantic knowledge can be evaluated through different tests; however, most of them depend on language. OBJECTIVE: We describe the development of a brief drawing task that may be helpful for the differential diagnosis of SD. METHODS: Seventy-two patients, including 32 AD, 19 bvFTD, and 21 SD were asked to draw 12 items with different age of acquisition and familiarity, belonging to four different semantic categories. We employed the drawings of healthy volunteers to build a scoring scheme. RESULTS: Turtle, strawberry, train, and envelope were the items of each category that best discriminated between groups and were selected for the Brief drawing task. The discriminatory power of the Brief drawing task between SD versus AD and bvFTD patients, estimated through the area under the curve was 0.84 (95% CI = 0.72-0.96, p = 0.000007). In a logistic model, the Brief drawing task (p = 0.003) and VOSP "number location" subtest (p = 0.016) were significant predictors of the diagnosis of SD versus AD and bvFTD after adjustment by the main covariates. The Brief drawing task provided clinically useful qualitative information. SD drawings were characterized by loss of the distinctive features, intrusions, tendency to prototype, and answers like "I don't know what this is". CONCLUSION: The Brief drawing task appears to reveal deficits in semantic knowledge among patients with SD that may assist in the differential diagnosis with other neurodegenerative diseases.

A Rare PSEN1 (Leu85Pro) Mutation Causing Alzheimer's Disease in a 29-Year-Old Woman Presenting as Corticobasal Syndrome.

Dementia is not just a disease of old age. Early-onset dementia affects people younger than 65 and its differential diagnosis is broader than in older people. Nevertheless, although young people are considerably more liable to develop a rare form of dementia, Alzheimer's disease (AD) remains the most common diagnosis. The aim of this article is to report on an early-onset AD patient associated with the rare pathogenic variant PSEN1 (Leu85Pro) presenting as a possible corticobasal syndrome with asymmetric limb apraxia, parkinsonian signs, and myoclonus.

A 5-year longitudinal evaluation in patients with mild cognitive impairment by 11C-PIB PET/CT: a visual analysis.

OBJECTIVE: The aim of this study was to evaluate the cerebral amyloid distribution in patients with mild cognitive impairment (MCI), assessed by carbon-11-Pittsburgh compound B (C-PIB) PET/CT, after 5 years of follow-up. PATIENTS AND METHODS: Ten amnestic MCI (A-MCI) and four nonamnestic (NA-MCI) patients were studied by C-PIB PET/CT and re-evaluated 5 years later by a new C-PIB PET/CT. PET/CT scans were acquired 60-90 min after the administration of 555 MBq C-PIB and analyzed visually, to obtain a score of the cerebral cortical C-PIB retention in the frontal, basal ganglia (BG), temporoparietal (TP), occipital, posterior cingulate, and cerebellum areas. Initial and 5-year follow-up C-PIB retentions were compared. RESULTS: Initially, 9/10 A-MCI patients were C-PIB positive and one was C-PIB negative. All four NA-MCI patients were C-PIB negative. Of the C-PIB-positive A-MCI patients, seven progressed to Alzheimer's disease dementia (AD-D), one to mixed dementia and one remained as A-MCI. The C-PIB-negative A-MCI patient remained as A-MCI. Of the four C-PIB-negative NA-MCI, one progressed to semantic dementia. All changes in C-PIB retention were of low intensity. The A-MCI patients who progressed to AD-D (n=7) showed an increase in C-PIB retention in the frontal (5/7), BG (3/7), TP (3/7), occipital (1/7), and posterior cingulate (1/7) regions. The A-MCI patient who progressed to mix dementia showed an increase in C-PIB retention in the frontal region. The C-PIB-positive A-MCI patient who remained as A-MCI showed an increase in C-PIB retention in the frontal, BG, and TP areas. The amyloid deposition in the anterior part of the brain (frontal, TP, and BG) increased more than that in the posterior part (occipital and precuneus) (7/9 vs. 2/9; P<0.05). CONCLUSION: PIB retention increased predominantly in the frontal, BG, and TP areas. C-PIB-positive A-MCI patients mostly progressed to AD-D, showing similar topographic changes in their cerebral C-PIB pattern than the patient who remained as A-MCI.

Effect of positive carbon-11-choline PET/CT results in the therapeutic management of prostate cancer biochemical relapse.

OBJECTIVE: Carbon-11-(C)-choline PET/computed tomography (CT) has shown good results in re-staging of prostate cancer (PCa) with raised serum levels of prostate-specific antigen. Our aim was to evaluate the effect of positive C-choline PET/CT results in the therapeutic management of patients with PCa with biochemical relapse (BR) after curative intention treatment. PATIENTS AND METHODS: A total of 112 patients with PCa BR and positive C-choline PET/CT were retrospectively evaluated. PET/CT was acquired 20 min after intravenous administration of 555-740 MBq of C-choline. The therapeutic management after C-choline PET/CT was obtained from the clinical records. The minimum follow-up time was 18 months. RESULTS: In 80 (71.4%) of 112 patients, C-choline PET/CT showed local recurrence of PCa; in 17 (15.2%) patients, distant recurrence; and in 15 (13.4%) patients, local plus distant recurrence. A second malignancy was detected in five (4.5%) patients. The planned therapeutic management was changed as per positive C-choline PET/CT result in 74 (66.1%) patients and were treated as follows: 31 (27.7%) patients with HT, combined with other treatments in eight (7.1%), 17 (15.2%) with BT, 13 (11.6%) with external beam radiotherapy, one (0.9%) with RP, and four (3.6%) with chemotherapy. Treatment approach was not modified in 37 (33%) patients. No data was available from one (0.9%) patient. CONCLUSION: Positive C-choline PET/CT result had an important effect in the therapeutic management of patients with PCa and BR, leading to a change in the planned approach in two (66.1%) out of three patients. In addition, in 4.5% of the patients, the C-choline PET/CT allowed the detection of a second malignancy.

Utility of Amyloid and FDG-PET in Clinical Practice: Differences Between Secondary and Tertiary Care Memory Units.

The clinical utility of amyloid positron emission tomography (PET) has not been fully established. Our aim was to evaluate the effect of amyloid imaging on clinical decision making in a secondary care unit and compare our results with a previous study in a tertiary center following the same methods. We reviewed retrospectively 151 cognitively impaired patients who underwent amyloid (Pittsburgh compound B [PiB]) PET and were evaluated clinically before and after the scan in a secondary care unit. One hundred and fifty concurrently underwent fluorodeoxyglucose (FDG)-PET. We assessed changes between the pre- and post-PET clinical diagnosis and Alzheimer's disease treatment plan. The association between PiB/FDG results and changes in management was evaluated using χ2 and multivariate logistic regression. Concordance between classification based on scan readings and baseline diagnosis was 66% for PiB and 47% for FDG. The primary diagnosis changed after PET in 17.2% of cases. When examined independently, discordant PiB and discordant FDG were both associated with diagnostic change (p < 0.0001). However, when examined together in a multivariate logistic regression, only discordant PiB remained significant (p = 0.0002). Changes in treatment were associated with concordant PiB (p = 0.009) while FDG had no effect on treatment decisions. Based on our regression model, patients with diagnostic dilemmas, a suspected non-amyloid syndrome, and Clinical Dementia Rating <1 were more likely to benefit from amyloid PET due to a higher likelihood of diagnostic change. We found that changes in diagnosis after PET in our secondary center almost doubled those of our previous analysis of a tertiary unit (9% versus 17.2%). Our results offer some clues about the rational use of amyloid PET in a secondary care memory unit stressing its utility in mild cognitive impairment patients.

18F-FDG PET/CT in the follow-up of large-vessel vasculitis: A study of 37 consecutive patients.

OBJECTIVE: 18F-FDG PET/CT has proved to be of potential value for early diagnosis of large-vessel vasculitis (LVV), which frequently involves the aorta. However, its role in the follow-up of these patients has not been well established. Our aim was to evaluate the contribution of 18F-FDG PET/CT in this clinical situation. METHODS: This study included 37 consecutive patients (28 women, 66.5 ± 9.9 years) with an initial 18F-FDG PET/CT positive for LVV and a mean ± standard deviation follow-up PET/CT of 7.5 ± 2.9 months after the initial scan. A semiquantitative analysis of aortic wall uptake was performed calculating the target-to-background ratio (TBR: aortic wall uptake divided by blood pool uptake). The initial and follow-up TBR as well as the clinical and laboratory outcome were compared. RESULTS: Overall, the mean TBR decreased from 1.7 ± 0.5 at the initial scan to 1.5 ± 0.3 at the time of follow-up (p = 0.0001). In the 21 patients who experienced clinical improvement following therapy the TBR also decreased from 1.8 ± 0.6 to 1.5 ± 0.3 (p = 0.0002). However, in the other 16 patients, in whom the treating physician considered that there was no clinical improvement following therapy, no statistically significant differences in TBR were found when data from the first and the follow-up PET/CT scans were compared (1.6 ± 0.3 versus 1.5 ± 0.3, p = 0.1416). Patients who experienced clinical improvement following therapy showed a nonstatistically significant higher TBR at the time of disease diagnosis (1.8 ± 0.6 versus 1.6 ± 0.3; p = 0.12). CONCLUSIONS: The results obtained in the present study highlight the impact of 18F-FDG PET/CT on the management of patients with LVV.