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The role of torso computed tomography (CT) in evaluating body composition has been unexplored. This study assessed the potential of low-dose torso CT from positron emission tomography (PET)/CT for analyzing body composition and its relation to muscle strength. We retrospectively recruited 384 healthy Korean adults (231 men, 153 women) who underwent torso 18F-FDG PET/CT, bioelectrical impedance analysis (BIA), and muscle strength tests (handgrip strength [HGS] and knee extension strength [KES]). CT images were segmented into three compartments: torso volumetric, abdominal volumetric, and abdominal areal. Muscle amounts from each compartment were indexed to height (m2). BIA and HGS served as reference standards, with correlation coefficients (r) calculated. Torso muscle volumetric index (TorsoMVI) had the strongest correlations with BIA-derived values (r = 0.80 for men; r = 0.73 for women), surpassing those from the abdominal compartments. TorsoMVI was also correlated significantly with HGS (r = 0.39, p < 0.01) and differentiated between normal and possible sarcopenia in men (n = 225, 5960 ± 785 cm3/m2 vs. n = 6, 5210 ± 487 cm3/m2, p = 0.02). In women, KES correlated more strongly with muscle parameters than HGS. Despite gender-specific variations, torso CT-derived parameters show promise for evaluating body composition and sarcopenia. [ABSTRACT FROM AUTHOR]

18F-FP-CIT is a high-resolution imaging marker of nigrostriatal neuronal integrity, differentiating Parkinsonism with loss of dopaminergic terminals (presynaptic Parkinsonian syndrome [PS]) from Parkinsonism without nigrostriatal degeneration (non-PS). We assessed the diagnostic accuracy of 18F-FP-CIT PET in patients with clinically uncertain PS (CUPS) at the first visit. Among the 272 patients who underwent 18F-FP-CIT PET imaging at the first visit between September 2008 and July 2012, 111 had CUPS (age, 62.6 ± 10.5 y; male:female, 45:66; symptom duration, 13.1 ± 8.8 months). Uncertainty criteria included only one of the three cardinal signs of Parkinsonism, two signs without bradykinesia, or atypical signs. The baseline clinical and 18F-FP-CIT PET imaging diagnostic accuracy was compared with the accuracy of clinical diagnosis after > 2-year follow-up. Nuclear medicine physicians assessed the 18F-FP-CIT PET images visually. Focal dopamine transporter binding deficit in the posterior putamen was considered PS. Bilateral symmetric striatum without focal deficit, suggesting normal 18F-FP-CIT PET, and focal deficits elsewhere in the striatum suggesting vascular Parkinsonism were considered non-PS. Seventy-nine patients had PS, and 32 did not. Baseline clinical diagnosis included PS in 45 patients, non-PS in 24, and inconclusive in 42. Among patients in whom initial clinical diagnosis (PS or non-PS) was possible, the sensitivity, specificity, and accuracy of the baseline clinical and 18F-FP-CIT PET imaging diagnoses were 54.4, 50.0, and 53.2%, and 98.7, 100, and 99.1%, respectively. The respective positive and negative predictive values were 95.6 and 66.7%, and 100 and 97.0%. Among those with initially inconclusive diagnosis, 64.2% were eventually diagnosed with PS while 35.7% were diagnosed with non-PS. The final clinical diagnosis of these patients all matched those made by 18F-FP-CIT PET imaging, except in one patient with scan without evidence of dopaminergic deficit (SWEDD). 18F-FP-CIT PET diagnosis was more accurate than clinical diagnosis, reducing the false-negative and inconclusive clinical diagnosis rates at baseline in patients with CUPS. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to develop and validate post- and preoperative models for predicting recurrence after curative-intent surgery using an FDG PET-CT metabolic parameter to improve the prognosis of patients with synchronous colorectal cancer liver metastasis (SCLM). Methods: In this retrospective multicenter study, consecutive patients with resectable SCLM underwent upfront surgery between 2006 and 2015 (development cohort) and between 2006 and 2017 (validation cohort). In the development cohort, we developed and internally validated the post- and preoperative models using multivariable Cox regression with an FDG metabolic parameter (metastasis-to-primary-tumor uptake ratio [M/P ratio]) and clinicopathological variables as predictors. In the validation cohort, the models were externally validated for discrimination, calibration, and clinical usefulness. Model performance was compared with that of Fong's clinical risk score (FCRS). Results: A total of 374 patients (59.1 ± 10.5 years, 254 men) belonged in the development cohort and 151 (60.3 ± 12.0 years, 94 men) in the validation cohort. The M/P ratio and nine clinicopathological predictors were included in the models. Both postoperative and preoperative models showed significantly higher discrimination than FCRS (p <.05) in the external validation (time-dependent AUC = 0.76 [95% CI 0.68–0.84] and 0.76 [0.68–0.84] vs. 0.65 [0.57–0.74], respectively). Calibration plots and decision curve analysis demonstrated that both models were well calibrated and clinically useful. The developed models are presented as a web-based calculator (https://cpmodel.shinyapps.io/SCLM/) and nomograms. Conclusions: FDG metabolic parameter-based prognostic models are well-calibrated recurrence prediction models with good discriminative power. They can be used for accurate risk stratification in patients with SCLM. Key Points: • In this multicenter study, we developed and validated prediction models for recurrence in patients with resectable synchronous colorectal cancer liver metastasis using a metabolic parameter from FDG PET-CT. • The developed models showed good predictive performance on external validation, significantly exceeding that of a pre-existing model. • The models may be utilized for accurate patient risk stratification, thereby aiding in therapeutic decision-making. [ABSTRACT FROM AUTHOR]

We compared the effects of ezetimibe/rosuvastatin 10/5 mg versus rosuvastatin 20 mg on carotid atherosclerotic plaque inflammation measured by 18FDG PET/CT. Fifty patients with acute coronary syndrome (ACS) were randomly assigned to the ezetimibe/rosuvastatin 10/5 mg and rosuvastatin 20 mg groups. The primary outcome was the percent change in the target-to-background ratio (TBR) of the index vessel in the most diseased segment (MDS), as assessed by 18FDG PET/CT at baseline and at 6 months. Forty-eight patients completed follow-up PET/CT. MDS TBR was − 6.2 ± 13.9% for patients in the ezetimibe/rosuvastatin group and − 10.8 ± 17.7% for those in the rosuvastatin group (difference, 4.6 percentage points; upper limitation of one-sided confidence interval = 13.8; p = 0.60 for noninferiority). In conclusion, combination therapy with ezetimibe 10 mg and rosuvastatin 5 mg compared with rosuvastatin 20 mg did not meet the criterion for non-inferiority for primary outcome, and the present study was not conclusive on whether the former was non-inferior to the latter. [ABSTRACT FROM AUTHOR]

Purpose: Tau accumulation is a core pathologic change in various neurodegenerative diseases including Alzheimer's disease and frontotemporal lobar degeneration-tau. Recently, tau positron emission tomography tracers such as [F] AV-1451 and [F] THK5351 have been developed to detect tau deposition in vivo. In the present study, we performed a head to head comparison of these two tracers in Alzheimer's disease and frontotemporal dementia cases and aimed to investigate which tracers are better suited to image tau in these disorders. Methods: A cross-sectional study was conducted using a hospital-based sample at a tertiary referral center. We recruited eight participants (two Alzheimer's disease, four frontotemporal dementia and two normal controls) who underwent magnetic resonance image, amyloid positron emission tomography with [F]-Florbetaben and tau positron emission tomography with both THK5351 and AV-1451. To measure regional AV1451 and THK5351 uptakes, we used the standardized uptake value ratios by dividing mean activity in target volume of interest by mean activity in the cerebellar hemispheric gray matter. Results: Although THK5351 and AV-1451 uptakes were highly correlated, cortical uptake of AV-1451 was more striking in Alzheimer's disease, while cortical uptake of THK5351 was more prominent in frontotemporal dementia. THK5351 showed higher off-target binding than AV-1451 in the white matter, midbrain, thalamus, and basal ganglia. Conclusions: AV-1451 is more sensitive and specific to Alzheimer's disease type tau and shows lower off-target binding, while THK5351 may mirror non-specific neurodegeneration. [ABSTRACT FROM AUTHOR]

Drug-induced parkinsonism (DIP) is the common cause of parkinsonism. It is difficult to make a differentiation between DIP and Parkinson's disease (PD) because there are no notable differences in the clinical characteristics between the two entities. In this study, we examined the relationship between the characteristics of [F] fluorinated- N-3-fluoropropyl-2-β-carboxymethoxy-3-β-(4-iodophenyl)nortropane (FP-CIT) positron emission tomography (PET) images and clinical features in DIP patients. We retrospectively studied 76 patients with DIP who underwent [F] FP-CIT PET. We also enrolled 16 healthy controls who underwent it. We compared the clinical characteristics between the DIP patients with normal [F] FP-CIT PET scans and those with abnormal ones. Symmetric parkinsonism was more frequent in the patients with normal [F] FP-CIT PET scans as compared with those with abnormal ones. Interval from drug intake to onset of parkinsonism was longer in the patients with abnormal [F] FP-CIT PET scans as compared with those with normal ones. A semi-quantitative analysis showed that specific to non-specific binding ratios in the putamen was lower in the patients with abnormal [F] FP-CIT PET scans as compared with those with normal ones and the age-matched control group. Our results suggest that symmetric parkinsonism was more prevalent, and the duration of drug exposure before the onset of parkinsonism was shorter in the patients with normal [F] FP-CIT PET scans as compared with those with abnormal ones. [ABSTRACT FROM AUTHOR]

Purpose: Dopamine transporter (DAT) imaging can demonstrate presynaptic dopaminergic neuronal loss in Parkinson's disease (PD). However, differentiating atypical parkinsonism (APD) from PD is often difficult. We investigated the usefulness of dual-phase F-18 FP-CIT positron emission tomography (PET) imaging in the differential diagnosis of parkinsonism. Methods: Ninety-eight subjects [five normal, seven drug-induced parkinsonism (DIP), five essential tremor (ET), 24 PD, 20 multiple system atrophy-parkinson type (MSA-P), 13 multiple system atrophy-cerebellar type (MSA-C), 13 progressive supranuclear palsy (PSP), and 11 dementia with Lewy bodies (DLB)] underwent F-18 FP-CIT PET. PET images were acquired at 5 min (early phase) and 3 h (late phase) after F-18 FP-CIT administration (185 MBq). Regional uptake pattern of cerebral and cerebellar hemispheres was assessed on early phase images and striatal DAT binding pattern was assessed on late phase images, using visual, quantitative, and statistical parametric mapping (SPM) analyses. Results: Striatal DAT binding was normal in normal, ET, DIP, and MSA-C groups, but abnormal in PD, MSA-P, PSP, and DLB groups. No difference was found in regional uptake on early phase images among normal DAT binding groups, except in the MSA-C group. Abnormal DAT binding groups showed different regional uptake pattern on early phase images compared with PD in SPM analysis (FDR < 0.05). When discriminating APD from PD, visual interpretation of the early phase image showed high diagnostic sensitivity and specificity (75.4 % and 100 %, respectively). Regarding the ability to distinguish specific APD, sensitivities were 81 % for MSA-P, 77 % for MSA-C, 23 % for PSP, and 54.5 % for DLB. Conclusions: Dual-phase F-18 FP-CIT PET imaging is useful in demonstrating striatal DAT loss in neurodegenerative parkinsonism, and also in differentiating APD, particularly MSA, from PD. [ABSTRACT FROM AUTHOR]