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Background: The prediction of Alzheimer's disease (AD) progression from its early stages is a research priority. In this context, the use of Artificial Intelligence (AI) in AD has experienced a notable surge in recent years. However, existing investigations predominantly concentrate on distinguishing clinical phenotypes through cross-sectional approaches. This study aims to investigate the potential of modeling additional dimensions of the disease, such as variations in brain metabolism assessed via [ 18 F]-fluorodeoxyglucose positron emission tomography (FDG-PET), and utilize this information to identify patients with mild cognitive impairment (MCI) who will progress to dementia (pMCI)., Methods: We analyzed data from 1,617 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) who had undergone at least one FDG-PET scan. We identified the brain regions with the most significant hypometabolism in AD and used Deep Learning (DL) models to predict future changes in brain metabolism. The best-performing model was then adapted under a multi-task learning framework to identify pMCI individuals. Finally, this model underwent further analysis using eXplainable AI (XAI) techniques., Results: Our results confirm a strong association between hypometabolism, disease progression, and cognitive decline. Furthermore, we demonstrated that integrating data on changes in brain metabolism during training enhanced the models' ability to detect pMCI individuals (sensitivity=88.4%, specificity=86.9%). Lastly, the application of XAI techniques enabled us to delve into the brain regions with the most significant impact on model predictions, highlighting the importance of the hippocampus, cingulate cortex, and some subcortical structures., Conclusion: This study introduces a novel dimension to predictive modeling in AD, emphasizing the importance of projecting variations in brain metabolism under a multi-task learning paradigm., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest regarding the publication of this research article., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Although the novel coronavirus disease 2019 (COVID-19) can present as nonspecific clinical forms, subclinical cases represent an important route of transmission and a significant source of mortality, mainly in high-risk subpopulations such as cancer patients. A deeper knowledge of the metabolic shift in cells infected with severe acute respiratory syndrome coronavirus 2 could provide new insights about its pathogenic and host response and help to diagnose pulmonary involvement. We explored the potential added diagnostic value of 18 F-FDG PET/CT scans in asymptomatic cancer patients with suspected COVID-19 pneumonia by investigating the association between metabolic and structural changes in the lung parenchyma. Methods: 18 F-FDG PET/CT studies acquired between February 19 and May 29, 2020, were reviewed to identify those cancer patients with incidental findings suggestive of COVID-19 pneumonia. PET studies were interpreted through qualitative (visual) and semiquantitative (measurement of SUV max ) analysis evaluating lung findings. Several characteristic signs of COVID-19 pneumonia on CT were described as COVID-19 Reporting and Data System (CO-RADS) categories ( 1 -6). After comparing the SUV max of pulmonary infiltrates among different CO-RADS categories, we explored the best potential cutoffs for pulmonary SUV max against CO-RADS categories as the gold standard result to eliminate the possibility that the diagnosis of COVID-19 pneumonia exists. Results: On multimodal PET/CT imaging, CT signs classified as CO-RADS category 5 or 6 were found in 16 of 41 (39%) oncologic patients. SUV max was higher in patients with categories 5 and 6 than in patients with category 4 (6.17 ± 0.82 vs. 3.78 ± 0.50, P = 0.04) or categories 2 and 3 (3.59 ± 0.41, P = 0.01). A specificity of 93.8% (95% CI, 71.7%-99.7%) and an accuracy of 92.9% were obtained when combining a CO-RADS score of 5 or 6 with an SUV max of 2.45 in pulmonary infiltrates. Conclusion: In asymptomatic cancer patients, the metabolic activity in lung infiltrates is closely associated with several combined tomographic changes characteristic of COVID-19 pneumonia. Multimodal 18 F-FDG PET/CT imaging could provide additional information during early diagnosis in selected predisposed patients during the pandemic. The prognostic implications of simultaneous radiologic and molecular findings in cancer patients and other subpopulations at high risk for COVID-19 pneumonia deserve further evaluation in prospective research., (© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)

Background: Primary progressive aphasia (PPA) is a clinical syndrome characterized by gradual loss of language skills. This study aimed to evaluate the diagnostic capacity of a connected speech task for the diagnosis of PPA and its variants, to determine the main components of spontaneous speech, and to examine their neural correlates., Methods: A total of 118 participants (31 patients with nfvPPA, 11 with svPPA, 45 with lvPPA, and 31 healthy controls) were evaluated with the Cookie Theft picture description task and a comprehensive language assessment protocol. Patients also underwent 18 F-fluorodeoxyglucose positron emission tomography and magnetic resonance imaging studies. Principal component analysis and machine learning were used to evaluate the main components of connected speech and the accuracy of connected speech parameters for diagnosing PPA. Voxel-based analyses were conducted to evaluate the correlation between spontaneous speech components and brain metabolism, brain volumes, and white matter microstructure., Results: Discrimination between patients with PPA and controls was 91.67%, with 77.78% discrimination between PPA variants. Parameters related to speech rate and lexical variables were the most discriminative for classification. Three main components were identified: lexical features, fluency, and syntax. The lexical component was associated with ventrolateral frontal regions, while the fluency component was associated with the medial superior prefrontal cortex. Number of pauses was more related with the left parietotemporal region, while pauses duration with the bilateral frontal lobe. The lexical component was correlated with several tracts in the language network (left frontal aslant tract, left superior longitudinal fasciculus I, II, and III, left arcuate fasciculus, and left uncinate fasciculus), and fluency was linked to the frontal aslant tract., Conclusion: Spontaneous speech assessment is a useful, brief approach for the diagnosis of PPA and its variants. Neuroimaging correlates suggested a subspecialization within the left frontal lobe, with ventrolateral regions being more associated with lexical production and the medial superior prefrontal cortex with speech rate., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background: Lung involvement in patients with coronavirus disease 2019 (COVID-19) undergoing PET-CT has been previously reported. However, FDG uptake outside lung parenchyma was poorly characterized in detail. We evaluated the extra-parenchymal lung involvement in asymptomatic cancer patients with COVID-19 pneumonia through 18 F-FDG PET-CT., Methods: A total of 1079 oncologic 18 F-FDG PET-CT were performed between February 2 and May 18, 2020. Confirmed COVID-19 pneumonia was defined as characteristic ground-glass bilateral CT infiltrates and positive genetic/serologic tests. Nonmetastatic extra-parenchymal lung PET-CT findings were evaluated through qualitative (visual), quantitative (measurements on CT), and semiquantitative (maximum standardized uptake value: SUVmax on PET) interpretation. Clinical data, blood tests, and PET-CT results were compared between patients with and without COVID-19 pneumonia., Results: A total of 23 18 F-FDG PET-CT scans with pulmonary infiltrates suggestive of COVID-19 and available laboratory data were included: 14 positive (cases) and 9 negative (controls) for COVID-19 infection, representing a low prevalence of COVID-19 pneumonia (1.3%). Serum lactate dehydrogenase and D-dimers tended to be increased in COVID-19 cases. Extra-parenchymal lung findings were found in 42.9% of patients with COVID-19, most frequently as mediastinal and hilar nodes with 18 F-FDG uptake (35.7%), followed by incidental pulmonary embolism in two patients (14.3%). In the control group, extra-pulmonary findings were observed in a single patient (11.1%) with 18 F-FDG uptake located to mediastinal, hilar, and cervical nodes. Nasopharyngeal and hepatic SUVmax were similar in both groups., Conclusion: In cancer patients with asymptomatic COVID-19 pneumonia, 18 F-FDG PET-CT findings are more frequently limited to thoracic structures, suggesting that an early and silent distant involvement is very rare. Pulmonary embolism is a frequent and potentially severe finding raising special concern. PET-CT can provide new pathogenic insights about this novel disease.

The inclusion of 18 F-FDG PET as a biomarker in the diagnostic criteria of neurodegenerative diseases and its indication in the presurgical assessment for drug-resistant epilepsies allow to improve specificity of these diagnosis. The traditional interpretation of neurological PET studies has been performed qualitatively, although in the last decade, several quantitative evaluation methods have emerged. This technical development has become relevant in clinical practice, improving specificity, reproducibility and reducing the interrater reliability derived from visual analysis. In this article we update/review the main imaging processing techniques currently used. This may allow the Nuclear Medicine physician to know their advantages and disadvantages when including these procedures in daily clinical practice., (Copyright © 2020 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Hypometabolism of the posterior cingulate cortex (PCC) is an important diagnostic feature of late-onset, amnestic Alzheimer's disease (AD) measured with 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). However, it is unclear whether PCC hypometabolism has diagnostic value in young-onset, non-amnestic variants of AD, which exhibit less pathology in the hippocampus and default mode network., Objective: Evaluate the prevalence and diagnostic value of PCC hypometabolism in non-amnestic variants of AD., Methods: We retrospectively identified 60 patients with young-onset, atypical dementia who have undergone a detailed clinical evaluation, FDG-PET, and an amyloid biomarker (amyloid-PET or cerebrospinal fluid analysis). We quantitatively analyzed regional hypometabolism in 70 regions of interest (ROI) using the MIMneuro® software., Results: Based on a cut-off of z-score < -1.5 for significant PCC hypometabolism, the prevalence of PCC hypometabolism in non-amnestic variants of AD was 65% compared to 28% in clinical variants of frontotemporal dementia (FTD). The ROI with the maximal hypometabolism was the dominant middle temporal gyrus in the language variant of AD (mean z score -2.28), middle occipital gyrus in PCA (-3.24), middle temporal gyrus in frontal AD (-2.70), and angular gyrus in corticobasal syndrome due to AD (-2.31). The PCC was not among the 10 most discriminant regions between non-amnestic variants of AD versus clinical variants of FTD., Conclusion: We conclude that PCC hypometabolism is not a discriminant feature to distinguish non-amnestic variants of AD from clinical variants of FTD-and should be interpreted with caution in patients with young-onset, non-amnestic dementia.

Introduction: The role of positron emission tomography (PET) in Creutzfeldt-Jakob disease is less defined than in other neurodegenerative diseases. We studied the correlation between the uptake of 18 F-florbetaben and 18 F-fluorodeoxyglucose with pathological prion protein deposition in histopathology in a case., Methods: A patient with 80 y old with a rapid neurological deterioration with a confirmed diagnosis of CJD was studied. PET and MRI studies were performed between 13-20 d before the death. A region of interest analysis was performed using Statistical Parametric Mapping., Results: MRI showed atrophy with no other alterations. FDG-PET showed extensive areas of hypometabolism including left frontoparietal lobes as well as bilateral thalamus. Correlation between uptake of 18 F-florbetaben and pathological prion protein deposition was r = 0.786 (p < 0.05). Otherwise, correlation between uptake of 18 F-FDG and pathological prion protein was r = 0.357 (p = 0.385). Immunohistochemistry with β-amyloid did not show amyloid deposition or neuritic plaques., Conclusions: Our study supports the use of FDG-PET in the assessment of CJD. FDG-PET may be especially useful in cases of suspected CJD and negative MRI. Furthermore, this case report provides more evidence about the behavioral of amyloid tracers, and the possibility of a low-affinity binding to other non-amyloid proteins, such as the pathological prion protein, is discussed.

Primary progressive aphasia is a clinical syndrome caused by a neurodegeneration of areas and neural networks involved in language, usually in the left hemisphere. The term "crossed aphasia" denotes an acquired language dysfunction caused by a lesion in the hemisphere ipsilateral to the dominant hand. A case is presented on a 75-year-old right-handed woman with a logopenic variant of primary progressive aphasia with word-finding difficulties of 2 years onset. The 18 F-FDG PET/CT showed right temporoparietal hypometabolism. A functional MRI scan was performed during a verb naming task in order to characterise language lateralisation patterns. A similar activation pattern was observed in both hemispheres, with less activation than expected in bilateral inferior frontal gyrus. These findings support that logopenic variant of primary progressive aphasia should not be considered as a neurodegeneration starting in the left brain hemisphere, but as a syndrome characterised by asymmetric neurodegeneration of brain regions and neural networks involved in language., (Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.)

Background and Purpose: Although primitive reflexes (PRs) are inhibited during the first years of childhood, they may reappear with brain injury. PRs have been linked to frontal lobe dysfunction, but their precise topography has not yet been defined. The purpose of this study was to map which regions of the brain display a reduced glucose metabolism in patients with cognitive impairment and PRs., Methods: A prospective study was conducted to evaluate PRs in a group of patients assessed due to suspected cognitive decline. Neurological and neuropsychological examinations and (18) F-fluorodeoxyglucose positron emission tomography fused with computerized tomography were performed. Voxel-based brain mapping analysis by means of statistical parametric mapping was used to compare patients with and without PRs., Results: The study included 99 patients (33 diagnosed with Alzheimer's disease, 33 on the frontotemporal dementia spectrum and 33 with other diagnoses). Mean age was 71 ± 9.7 years; time since symptom onset was 3.6 ± 2.9 years. At least one PR was observed in 43 cases (43.4% of the whole sample; 48.5% in the Alzheimer disease group, 63.6% in frontotemporal dementia and 18.2% in the group with other diagnoses). The group of patients with PRs exhibited a decreased cerebral metabolism in the bilateral superior frontal gyri (Brodmann area 6), bilateral putamina and thalami., Conclusions: The presence of PRs was associated with hypometabolism at the superior frontal gyrus and putamen. This suggests that dysfunction in the corticostriatal motor circuit (supplementary motor area-putamen-thalamus) may constitute the anatomical basis of the recurrence of PRs., (© 2015 EAN.)

The logopenic variant of primary progressive aphasia (lvPPA) has been associated with Alzheimer disease, although this relationship is still subject to debate. The purpose of this study is to determine the frequency of amyloid biomarkers in patients with lvPPA, and record any potential clinical or topographic differences between patients with and without amyloid deposits. We conducted cognitive examination and positron-emission tomography studies with fluorodeoxyglucose ((18)F) and florbetapir ((18)F) in a cohort of 16 patients diagnosed with lvPPA. We evaluated the prevalence of amyloid deposits as well as any clinical and metabolic differences between the groups with and without significant presence of amyloid deposits. Eleven patients (69 %) were considered amyloid-positive. The amyloid-positive group displayed less metabolic activity in the left temporoparietal region than the control group, while the amyloid-negative group showed lower metabolism in the left temporoparietal region extending to the anterior temporal and basal frontal regions. The percentage of change in patients with clinical and FDG-PET follow-up did not differ between the amyloid-positive and amyloid-negative subgroups. The frequency of amyloid-positive cases confirms that lvPPA is frequently associated with Alzheimer disease. Amyloid-negative patients show a different cerebral metabolic pattern. These findings show the relevance of using amyloid PET to study lvPPA, and also suggest that the logopenic variant may not be specific to Alzheimer disease in certain cases.

Purpose: Diagnosing progressive primary aphasia (PPA) and its variants is of great clinical importance, and fluorodeoxyglucose (FDG) positron emission tomography (PET) may be a useful diagnostic technique. The purpose of this study was to evaluate interobserver variability in the interpretation of FDG PET images in PPA as well as the diagnostic sensitivity and specificity of the technique. We also aimed to compare visual and statistical analyses of these images., Methods: There were 10 raters who analysed 44 FDG PET scans from 33 PPA patients and 11 controls. Five raters analysed the images visually, while the other five used maps created using Statistical Parametric Mapping software. Two spatial normalization procedures were performed: global mean normalization and cerebellar normalization. Clinical diagnosis was considered the gold standard., Results: Inter-rater concordance was moderate for visual analysis (Fleiss' kappa 0.568) and substantial for statistical analysis (kappa 0.756-0.881). Agreement was good for all three variants of PPA except for the nonfluent/agrammatic variant studied with visual analysis. The sensitivity and specificity of each rater's diagnosis of PPA was high, averaging 87.8 and 89.9% for visual analysis and 96.9 and 90.9% for statistical analysis using global mean normalization, respectively. In cerebellar normalization, sensitivity was 88.9% and specificity 100%., Conclusion: FDG PET demonstrated high diagnostic accuracy for the diagnosis of PPA and its variants. Inter-rater concordance was higher for statistical analysis, especially for the nonfluent/agrammatic variant. These data support the use of FDG PET to evaluate patients with PPA and show that statistical analysis methods are particularly useful for identifying the nonfluent/agrammatic variant of PPA.

Primary progressive aphasia (PPA) may be the onset of several neurodegenerative diseases. This study evaluates a cohort of patients with PPA to assess their progression to different clinical syndromes, associated factors that modulate this progression, and patterns of cerebral metabolism linked to different clinical evolutionary forms. Thirty-five patients meeting PPA criteria underwent a clinical and neuroimaging (18)F-Fluorodeoxyglucose PET evaluation. Survival analysis was performed using time from clinical onset to the development of a non-language symptom or deficit (PPA-plus). Cerebral metabolism was analyzed using Statistical Parametric Mapping. Patients classified into three PPA variants evolved to atypical parkinsonism, behavioral disorder and motor neuron disease in the agrammatic variant; to behavioral disorder in the semantic; and to memory impairment in the logopenic. Median time from the onset of symptoms to PPA-plus was 36 months (31-40, 95 % confidence interval). Right laterality, and years of education were associated to a lower risk of progression, while logopenic variant to a higher risk. Different regions of hypometabolism were identified in agrammatic PPA with parkinsonism, motor neuron disease and logopenic PPA-plus. Clinical course of PPA differs according to each variant. Left anterior temporal and frontal medial hypometabolism in agrammatic variant is linked to motor neuron disease and atypical parkinsonism, respectively. PPA variant, laterality and education may be associated to the risk of progression. These results suggest the possibility that clinical and imaging data could help to predict the clinical course of PPA.

Aims: To assess the significance and the impact of focal FDG uptake in the colon in oncology patients without known colorectal carcinoma., Materials and Methods: A retrospective study was undertaken on 2,220 (18)F-FDG PET/CT studies carried out consecutively in the Nuclear Medicine Department in our hospital from 2 December 2008 to 31 May 2010. Inclusion criteria were patients with abnormal (18)F-FDG uptake in colorectal area that could not be explained (or not previously known) by their clinical histories. Patients previously diagnosed with colorectal carcinoma were excluded. A total of 86 patients (57 male, average age 63.4, range 46-85) were finally included. Colonoscopy with biopsy was established as a reference test. The impact of these findings on the diagnostic-therapeutic management in these patients was evaluated., Results: A colonoscopy was performed in 54 of the 86 patients, this examination not having been done up-to-date in the remaining 32 patients. Biopsy was obtained in 43 lesions of the 54 patient in whom a colonoscopy was performed. Colon disease was detected in 49 of these 54 patients, obtaining 54 FDG incidental foci which corresponded to 10 previously unsuspected primary colorectal carcinoma, 3 metastases, 27 adenomatous polyps with different degrees of dysplasia and 14 inflammatory processes. In the remaining 5 patients, the colonoscopy was normal. PET/CT modified the diagnostic and treatment management in most of the patients (49/54, that is 91%)., Conclusions: These results confirm the need to determine the cause of abnormal (18)F-FDG colorectal uptakes in the PET/CT studies by using colonoscopy and biopsy. This approach allows for the detection and early treatment of malignant and premalignant lesions., (Copyright © 2011 Elsevier España, S.L. y SEMNIM. All rights reserved.)

La sarcoidosis is a granulomatous disease of unknown etiology. It may mimic malignancy and may affect multiple organs, with a variable clinical course. Pancreatic involvement is very rare. We present the case of a 78-year-old woman with systemic sarcoidosis whose (18)F-FDG PET/CT scan showed a pancreatic lesion and multiple lymphatic (thoracic and non-thoracic) and visceral lesions. The abnormal (18)F-FDG uptake in the pancreas was limited to the tail. A second (18)F-FDG PET/CT study performed 4 months and 3 weeks after the first PET/CT, following corticosteroid therapy during three and a half months, evidenced partial regression of the disease, with persistent (18)F-FDG pathological uptake in the pancreatic lesion., (Copyright © 2010 Elsevier España, S.L. and SEMNIM. All rights reserved.)

Objectives: A meta-analysis of the literature was performed in this article in order to evaluate the diagnostic accuracy of 18F-FDG PET in suspected recurrent head and neck cancer., Material and Methods: A systematic review of the literature was performed using 1987 to 2007 MEDLINE and CANCERLIT databases, applying selection criteria to the studies found. Sensitivity, specificity, positive and negative likelihood ratios, and odds ratio were calculated. The diagnostic accuracy was evaluated with ROC (receive-operating-characteristics) curves., Results: Nineteen articles were included in the meta-analysis. Sensitivity of 18F-FDG PET was 94 %, specificity 80 %, and the summary ROC curve showed a good trade-off between sensitivity and specificity., Conclusions: 18F-FDG PET was useful in patients with suspected recurrence of head and neck cancer, showing a high sensitivity and intermediate-high specificity.

We present the case of a male patient with gastrointestinal stromal tumor (GIST) in whom we conducted two (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) studies, the first one prior to beginning the treatment with Glivec and the second after one month of treatment. The first (18)F-FDG PET scan detected multiple FDG avid foci in distal esophagus, liver and in an interaortocava lymph node. The second (18)F-FDG PET showed very good response to therapy, with an almost complete disease remission. After 23 months of follow-up, the early response to treatment detected by (18)F-FDG PET was confirmed. The utility of (18)F-FDG PET in the evaluation of response to treatment in GIST is discussed and compared with CT.

Introduction: 18F-FDG PET has demonstrated its usefulness in detecting recurrences of differentiated thyroid cancer (DTC) with high thyroglobulin (Tg) levels and negative 131I whole-body scan (WBS); however, the number of patients analyzed is low and different studies report disparate results., Objective: To estimate the diagnostic accuracy of 18F-FDG PET in this subgroup of patients., Materials and Methods: Fifty eight patients (64 18F-FDG PET studies) with histologically proven DTC treated with total thyroidectomy followed by at least one session of 131I therapy for the ablation of thyroid remnants were retrospectively analyzed. Results were verified by pathology, clinical follow-up, response to treatment, or by comparison with conventional diagnostic methods. Sensitivity (Se), specificity (Sp), likelihood ratios (LR), diagnostic accuracy (DA), positive and negative predictive values (PPV, NPV), and Tg levels were calculated for patients with positive and negative 18F-FDG PET results., Results: Twenty seven studies were true positives, 1 false positive, 25 true negatives, and 11 false negatives. Se was 71 %, Sp 96 %, PPV 96.4 %; NPV 69.4 %, DA 81.3 %, positive LR 17.75, and negative LR 0.3. The mean Tg level was 202.34 ng/ml in patients with positive 18F-FDG PET and 40.94 ng/ml in those with negative 18F-FDG PET; the difference between the two groups (161.4 ng/ml) was significant at p <0.05., Conclusions: 18F-FDG PET is a useful for detecting residual or recurrent DTC in patients with elevated Tg and negative 131I WBS.

Objective: This study aims to evaluate the impact of Positron Emission Tomography on therapeutic decisions in patients with suspicion of recurrence of head and neck cancers., Material and Methods: The diagnostic and therapeutic impact of FDG-PET was evaluated in 59 of 60 studies performed in a sample of 54 patients. The impact was graded on five levels (high, moderate, low, no impact and negative impact) following the Hicks et al. classification modified by us., Results: The FDG-PET impact was high in 28 studies (47.46 %), moderate in 7 (11.86 %), low in 20 (33.90 %), no impact in 3 (5.09 %) and finally negative impact in 1 study (1.69 %)., Conclusions: FDG-PET is useful in the management of patients in 59.32 % of the studies with indeterminate physical examination and conventional imaging tests. This paper supplies new data since we did not find any studies showing statistical results on therapeutic impact of FDG-PET in head and neck cancers in a systematic review of the literature made by our group.