Cristae formation is a mechanical buckling event controlled by the inner mitochondrial membrane lipidome.

Cristae are high-curvature structures in the inner mitochondrial membrane (IMM) that are crucial for ATP production. While cristae-shaping proteins have been defined, analogous lipid-based mechanisms have yet to be elucidated. Here, we combine experimental lipidome dissection with multi-scale modeling to investigate how lipid interactions dictate IMM morphology and ATP generation. When modulating phospholipid (PL) saturation in engineered yeast strains, we observed a surprisingly abrupt breakpoint in IMM topology driven by a continuous loss of ATP synthase organization at cristae ridges. We found that cardiolipin (CL) specifically buffers the inner mitochondrial membrane against curvature loss, an effect that is independent of ATP synthase dimerization. To explain this interaction, we developed a continuum model for cristae tubule formation that integrates both lipid and protein-mediated curvatures. This model highlighted a snapthrough instability, which drives IMM collapse upon small changes in membrane properties. We also showed that cardiolipin is essential in low-oxygen conditions that promote PL saturation. These results demonstrate that the mechanical function of cardiolipin is dependent on the surrounding lipid and protein components of the IMM.

New rabies viral resources for multi-scale neural circuit mapping.

Comparisons and linkage between multiple imaging scales are essential for neural circuit connectomics. Here, we report 20 new recombinant rabies virus (RV) vectors that we have developed for multi-scale and multi-modal neural circuit mapping tools. Our new RV tools for mesoscale imaging express a range of improved fluorescent proteins. Further refinements target specific neuronal subcellular locations of interest. We demonstrate the discovery power of these new tools including the detection of detailed microstructural changes of rabies-labeled neurons in aging and Alzheimer's disease mouse models, live imaging of neuronal activities using calcium indicators, and automated measurement of infected neurons. RVs that encode GFP and ferritin as electron microscopy (EM) and fluorescence microscopy reporters are used for dual EM and mesoscale imaging. These new viral variants significantly expand the scale and power of rabies virus-mediated neural labeling and circuit mapping across multiple imaging scales in health and disease.

Poor sleep quality is associated with decreased regional brain glucose metabolism in healthy middle-aged adults.

Sleep disturbance is associated with the development of neurodegenerative disease. We aimed to address the effects of sleep quality on brain glucose metabolism measured by 18F-Fl uorodeoxyglucose (18F-FDG) positron emission tomography (PET) in healthy middle-aged adults. A total of 378 healthy men (mean age: 42.8±3.6 years) were included in this study. Participants underwent brain 18F-FDG PET and completed the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K). Additionally, anthropometric measurements were obtained. PETs were spatially normalized to MNI space using PET templates from SPM5 with PMOD. The Automated Anatomical Labeling 2 atlas was used to define regions of interest (ROIs). The mean uptake of each ROI was scaled to the mean of the global cortical uptake of each individual and defined as the standardized uptake value ratio (SUVR). After the logarithmic transformation of the regional SUVR, the effects of the PSQI-K on the regional SUVR were investigated using Bayesian hierarchical modeling. Brain glucose metabolism of the posterior cingulate, precuneus, and thalamus showed a negative association with total PSQI-K scores in the Bayesian model ROI-based analysis. Voxel-based analysis using statistical parametric mapping revealed a negative association between the total PSQI-K scores and brain glucose metabolism of the precuneus, postcentral gyrus, posterior cingulate, and thalamus. Poor sleep quality is negatively associated with brain glucose metabolism in the precuneus, posterior cingulate, and thalamus. Therefore, the importance of sleep should not be overlooked, even in healthy middle-aged adults.

AIBP controls TLR4 inflammarafts and mitochondrial dysfunction in a mouse model of Alzheimer's disease.

Microglia-driven neuroinflammation plays an important role in the development of Alzheimer's disease. Microglia activation is accompanied by the formation and chronic expression of TLR4 inflammarafts, defined as enlarged and cholesterol-rich lipid rafts serving as an assembly platform for TLR4 dimers and complexes of other inflammatory receptors. The secreted apoA-I binding protein (APOA1BP or AIBP) binds TLR4 and selectively targets cholesterol depletion machinery to TLR4 inflammaraft-expressing inflammatory, but not homeostatic microglia. Here we demonstrated that amyloid-beta (Aß) induced formation of TLR4 inflammarafts in microglia in vitro and in the brain of APP/PS1 mice. Mitochondria in Apoa1bp-/- APP/PS1 microglia were hyperbranched and cupped, which was accompanied by increased reactive oxygen species and the dilated endoplasmic reticulum. The size and number of Aß plaques and neuronal cell death were significantly increased, and the animal survival was decreased in Apoa1bp-/-APP/PS1 compared to APP/PS1 female mice. These results suggest that AIBP exerts control of TLR4 inflammarafts and mitochondrial dynamics in microglia and plays a protective role in Alzheimer's disease associated oxidative stress and neurodegeneration.

Enhanced mitochondrial buffering prevents Ca2+ overload in naked mole-rat brain.

Deleterious Ca2+ accumulation is central to hypoxic cell death in the brain of most mammals. Conversely, hypoxia-mediated increases in cytosolic Ca2+ are retarded in hypoxia-tolerant naked mole-rat brain. We hypothesized that naked mole-rat brain mitochondria have an enhanced capacity to buffer exogenous Ca2+ and examined Ca2+ handling in naked mole-rat cortical tissue. We report that naked mole-rat brain mitochondria buffer >2-fold more exogenous Ca2+ than mouse brain mitochondria, and that the half-maximal inhibitory concentration (IC50 ) at which Ca2+ inhibits aerobic oxidative phosphorylation is >2-fold higher in naked mole-rat brain. The primary driving force of Ca2+ uptake is the mitochondrial membrane potential (Δψm ), and the IC50 at which Ca2+ decreases Δψm is ∼4-fold higher in naked mole-rat than mouse brain. The ability of naked mole-rat brain mitochondria to safely retain large volumes of Ca2+ may be due to ultrastructural differences that support the uptake and physical storage of Ca2+ in mitochondria. Specifically, and relative to mouse brain, naked mole-rat brain mitochondria are larger and have higher crista density and increased physical interactions between adjacent mitochondrial membranes, all of which are associated with improved energetic homeostasis and Ca2+ management. We propose that excessive Ca2+ influx into naked mole-rat brain is buffered by physical storage in large mitochondria, which would reduce deleterious Ca2+ overload and may thus contribute to the hypoxia and ischaemia-tolerance of naked mole-rat brain. KEY POINTS: Unregulated Ca2+ influx is a hallmark of hypoxic brain death; however, hypoxia-mediated Ca2+ influx into naked mole-rat brain is markedly reduced relative to mice. This is important because naked mole-rat brain is robustly tolerant against in vitro hypoxia, and because Ca2+ is a key driver of hypoxic cell death in brain. We show that in hypoxic naked mole-rat brain, oxidative capacity and mitochondrial membrane integrity are better preserved following exogenous Ca2+ stress. This is due to mitochondrial buffering of exogenous Ca2+ and is driven by a mitochondrial membrane potential-dependant mechanism. The unique ultrastructure of naked mole-rat brain mitochondria, as a large physical storage space, may support increased Ca2+ buffering and thus hypoxia-tolerance.

Dopamine receptor and dopamine transporter in obesity: A meta-analysis.

The brain plays a major role in controlling the desire to eat. This meta-analysis aimed to assess the association between dopamine receptor (DR) availability and dopamine transporter (DAT) availability, measured using positron emission tomography, and obesity. We performed a systematic search of MEDLINE (from inception to November 2020) and EMBASE (from inception to November 2020) for articles published in English using the keywords "dopamine receptor," "dopamine transporter," "obesity," and "neuroimaging." Body mass index (BMI) and the corresponding binding potential (BPND ) were extracted from figures in each study using Engauge Digitizer, version 12.1, and plotted for radiopharmaceuticals and regions of interest (ROIs). Five studies involving 119 subjects with DR and five studies including 421 subjects with DAT were eligible for inclusion in this study. In overweight or obese subjects with BMI of 25 kg/m2 or higher, DR availability from 11 C-Racloprie was negatively associated with BMI. However, DR availability from 11 C-PHNO was positively associated with BMI. DAT ratio was calculated after dividing DAT availabilities of overweight/obese BMI with mean DAT availabilities of normal BMI. The association between DAT ratio and BMI was not significant regardless of radiopharmaceuticals. In conclusion, dopamine plays a main role in the reward system with regard to obesity. Overweight and obese subjects had negative association between DR availability from 11 C-Raclopride and BMI. However, the association of DR availability with BMI was dependent on radiopharmaceuticals. DAT availability did not show the significant relationship with BMI regardless of radiopharmaceuticals.

Therapeutic Effect of Dupilumab on Systemic and Vascular Inflammation in Adults with Severe Atopic Dermatitis: Feasibility Study Using 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography.

Atopic dermatitis (AD) is an inflammatory skin disease associated with increased systemic and vascular inflammation. Although dupilumab has been proven to be effective against severe AD, imaging studies analysing its inflammation-reducing effect have rarely been reported. The aim of this study was to evaluate the effect of dupilumab on systemic and vascular inflammation in adult patients with severe AD, using 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT). A total of 33 adult patients with severe AD and 25 healthy controls underwent 18F-FDG PET/CT at baseline. Patients on dupilumab treatment underwent 18F-FDG PET/CT again after achieving a 75% reduction from baseline on the Eczema Area and Severity Index (EASI-75). Patients with AD exhibited increased 18F-FDG uptake values in the liver, spleen, pancreas, and carotid artery compared with healthy controls. However, compared with baseline, there was no statistically significant difference in 18F-FDG uptake in major organs and arteries after achieving EASI-75 with dupilumab treatment. In conclusion, while dupilumab treatment resulted in a significant clinical improvement and reduced serum inflammatory markers in adult patients with severe AD, no changes in systemic and vascular inflammation were observed on 18F-FDG PET/CT imaging.

Multi-omics analysis revealed TEK and AXIN2 are potential biomarkers in multifocal papillary thyroid cancer.

BACKGROUND: Papillary thyroid carcinoma (PTC), the most common endocrine cancer, accounts for 80-85% of all malignant thyroid tumors. This study focused on identifying targets that affect the multifocality of PTC. In a previous study, we determined 158 mRNAs related to multifocality in BRAF-mutated PTC using The Cancer Genome Atlas. METHODS: We used multi-omics data (miRNAs and mRNAs) to identify the regulatory mechanisms of the investigated mRNAs. miRNA inhibitors were used to determine the relationship between mRNAs and miRNAs. We analyzed the target protein levels in patient sera using ELISA and immunohistochemical staining of patients' tissues. RESULTS: We identified 44 miRNAs that showed a negative correlation with mRNA expression. Using in vitro experiments, we identified four miRNAs that inhibit TEK and/or AXIN2 among the target mRNAs. We also showed that the downregulation of TEK and AXIN2 decreased the proliferation and migration of BRAF ( +) PTC cells. To evaluate the diagnostic ability of multifocal PTC, we examined serum TEK or AXIN2 in unifocal and multifocal PTC patients using ELISA, and showed that the serum TEK in multifocal PTC patients was higher than that in the unifocal PTC patients. The immunohistochemical study showed higher TEK and AXIN2 expression in multifocal PTC than unifocal PTC. CONCLUSIONS: Both TEK and AXIN2 play a potential role in the multifocality of PTC, and serum TEK may be a diagnostic marker for multifocal PTC.

SLC6A3 gene polymorphisms are associated with striatal dopamine transporter changes after glucose loading.

We investigated the association between SLC6A3 gene polymorphisms and changes in dopamine transporter (DAT) availability after glucose loading in humans. An intravenous injection of 18 F-FP-CIT was administered after infusion of glucose or placebo, and the emission data were acquired over 90 min in 38 healthy male participants. DAT availability expressed in terms of binding potential (BPND ) was recorded. The 40-bp variable number of tandem repeats (VNTR) in the 3' untranslated region and two single nucleotide polymorphisms (SNPs), rs2652511 and rs2937639, in the SLC6A3 gene were genotyped. Among the 38 participants, those with a VNTR other than 10R/10R (n = 7) were excluded. The alleles of the two SNPs (rs2652511 and rs2937639) appeared to be inherited together in two fixed combinations (C-G or T-A) in 29 of 31 individuals. The BPND in the ventral striatum (VST), caudate nucleus, and putamen was not significantly different after glucose or placebo loading according to genotype. However, BPND s from the caudate nucleus and putamen of all participants with rs2652511 CT/rs2937639 AG (n = 6) were higher after glucose loading. In conclusion, the SLC6A3 gene polymorphism is associated with the changes in DAT availability after glucose loading. DAT availability after glucose or placebo loading in the VST, caudate nucleus, and putamen did not differ according to the SLC6A3 genotype.

Limited power of dopamine transporter mRNA mapping for predicting dopamine transporter availability.

Dopamine transporters (DAT) are transmembrane proteins that translocate dopamine from the extracellular space into presynaptic neurons. We aimed to investigate the predictive power of DAT mRNA for DAT protein expression, measured using positron emission tomography (PET). We performed 18 F-FP-CIT PET scans in 35 healthy individuals. Binding potentials (BPND ) from the ventral striatum, caudate nucleus, putamen, and middle frontal, orbitofrontal, cingulate, parietal, and temporal cortices were measured. DAT gene expression data were obtained from the freely available Allen Human Brain Atlas derived from six healthy donors. The auto-correlation of PET-derived BPND s for DAT was intermediate (mean ρ2  = .66) with ρ2 ranging from .0811 to 1. However, the auto-correlation of mRNA expression was weak across the probes with a mean ρ2 of .09-.23. Cross-correlations between PET-derived BPND s and mRNA expression were weak with a mean ρ2 ranging from 0 to .22 across the probes. In conclusion, we observed weak associations between DAT mRNA expression and DAT availability in human brains. Therefore, DAT mRNA mapping may have only limited predictive power for DAT availability in humans. However, the difference in distribution of DAT mRNA and DAT protein may influence this limitation.

Hedonic Rating of Sucrose Is Sub-Regionally Associated with Striatal Dopamine Transporter in Humans.

BACKGROUND: Eating behavior is determined by both homeostatic and hedonic values. OBJECTIVE: We investigated the association of hedonic value with striatal dopamine transporter (DAT) availability sub-regionally. METHOD: An intravenous bolus injection of 18F-FP-CIT was administered after the infusion of glucose or placebo, and the emission data were acquired over 90 min. DAT availability and binding potential (BPND) were measured via the simplified reference tissue method. Subjects were assessed with sensory taste test of sucrose solutions. The "most liked" sucrose concentration (%) was determined as the hedonic rating for sucrose. RESULTS: Twenty healthy males participated in this study. After glucose loading, BPNDs of putamen significantly increased, and those of caudate nucleus showed the increasing trend, while those of ventral striatum were not significantly different. After glucose loading, the "most liked" sucrose concentration (%) was negatively associated with BPNDs of caudate nucleus and showed the trend of positive association with those from ventral striatum. Slopes of regression lines were significantly different according to the sub-regions of striatum. CONCLUSION: We have highlighted that striatal DAT increased after glucose loading in dorsal striatum, not in ventral striatum. These changes of striatal DAT were sub-regionally associated with the hedonic rating of sucrose from each subject.

Photoreceptor disc membranes are formed through an Arp2/3-dependent lamellipodium-like mechanism.

The light-sensitive outer segment of the vertebrate photoreceptor is a highly modified primary cilium filled with disc-shaped membranes that provide a vast surface for efficient photon capture. The formation of each disc is initiated by a ciliary membrane evagination driven by an unknown molecular mechanism reportedly requiring actin polymerization. Since a distinct F-actin network resides precisely at the site of disc morphogenesis, we employed a unique proteomic approach to identify components of this network potentially driving disc morphogenesis. The only identified actin nucleator was the Arp2/3 complex, which induces the polymerization of branched actin networks. To investigate the potential involvement of Arp2/3 in the formation of new discs, we generated a conditional knockout mouse lacking its essential ArpC3 subunit in rod photoreceptors. This knockout resulted in the complete loss of the F-actin network specifically at the site of disc morphogenesis, with the time course of ArpC3 depletion correlating with the time course of F-actin loss. Without the actin network at this site, the initiation of new disc formation is completely halted, forcing all newly synthesized membrane material to be delivered to the several nascent discs whose morphogenesis had already been in progress. As a result, these discs undergo uncontrolled expansion instead of normal enclosure, which leads to formation of unusual, large membrane whorls. These data suggest a model of photoreceptor disc morphogenesis in which Arp2/3 initiates disc formation in a "lamellipodium-like" mechanism.

PRCD is essential for high-fidelity photoreceptor disc formation.

Progressive rod-cone degeneration (PRCD) is a small protein residing in the light-sensitive disc membranes of the photoreceptor outer segment. Until now, the function of PRCD has remained enigmatic despite multiple demonstrations that its mutations cause blindness in humans and dogs. Here, we generated a PRCD knockout mouse and observed a striking defect in disc morphogenesis, whereby newly forming discs do not properly flatten. This leads to the budding of disc-derived vesicles, specifically at the site of disc morphogenesis, which accumulate in the interphotoreceptor matrix. The defect in nascent disc flattening only minimally alters the photoreceptor outer segment architecture beyond the site of new disc formation and does not affect the abundance of outer segment proteins and the photoreceptor's ability to generate responses to light. Interestingly, the retinal pigment epithelium, responsible for normal phagocytosis of shed outer segment material, lacks the capacity to clear the disc-derived vesicles. This deficiency is partially compensated by a unique pattern of microglial migration to the site of disc formation where they actively phagocytize vesicles. However, the microglial response is insufficient to prevent vesicular accumulation and photoreceptors of PRCD knockout mice undergo slow, progressive degeneration. Taken together, these data show that the function of PRCD is to keep evaginating membranes of new discs tightly apposed to each other, which is essential for the high fidelity of photoreceptor disc morphogenesis and photoreceptor survival.

Hepatic Fat Quantification with the Multi-Material Decomposition Algorithm by Using Low-Dose Non-Contrast Material-Enhanced Dual-Energy Computed Tomography in a Prospectively Enrolled Cohort.

The early diagnosis of hepatic steatosis is important. No study has assessed hepatic fat quantification by using low-dose dual-energy computed tomography (CT). We assessed the accuracy of hepatic fat quantification using the multi-material decomposition (MMD) algorithm with low-dose non-contrast material-enhanced dual-energy CT. We retrospectively reviewed 33 prospectively enrolled patients who had undergone low-dose non-contrast material-enhanced dual-energy CT and magnetic resonance image (MRI) proton density fat fraction (PDFF) on the same day. Percentage fat volume fraction (FVF) images were generated using the MMD algorithm on the low-dose dual-energy CT data. We assessed the correlation between FVFs and MRI-PDFFs by using Spearman's rank correlation. With a 5% cutoff value of MRI-PDFF for fatty liver, a receiver operating characteristic (ROC) curve analysis was performed to identify the optimal criteria of FVF for diagnosing fatty liver. CTDIvol of CT was 2.94 mGy. FVF showed a strong correlation with MRI-PDFF (r = 0.756). The ROC curve analysis demonstrated that FVF ≥ 4.61% was the optimal cutoff for fatty liver. With this cutoff value for diagnosing the fatty liver on low-dose dual-energy CT, the sensitivity, specificity, and area under the curve were 90%, 100%, and 0.987, respectively. The MMD algorithm using low-dose non-contrast material-enhanced dual-energy CT is feasible for quantifying hepatic fat.

Spatially resolved correlative microscopy and microbial identification reveal dynamic depth- and mineral-dependent anabolic activity in salt marsh sediment.

Coastal salt marshes are key sites of biogeochemical cycling and ideal systems in which to investigate the community structure of complex microbial communities. Here, we clarify structural-functional relationships among microorganisms and their mineralogical environment, revealing previously undescribed metabolic activity patterns and precise spatial arrangements within salt marsh sediment. Following 3.7-day in situ incubations with a non-canonical amino acid that was incorporated into new biomass, samples were resin-embedded and analysed by correlative fluorescence and electron microscopy to map the microscale arrangements of anabolically active and inactive organisms alongside mineral grains. Parallel sediment samples were examined by fluorescence-activated cell sorting and 16S rRNA gene sequencing to link anabolic activity to taxonomic identity. Both approaches demonstrated a rapid decline in the proportion of anabolically active cells with depth into salt marsh sediment, from ~60% in the top centimetre to 9.4%-22.4% between 2 and 10 cm. From the top to the bottom, the most prominent active community members shifted from sulfur cycling phototrophic consortia, to putative sulfate-reducing bacteria likely oxidizing organic compounds, to fermentative lineages. Correlative microscopy revealed more abundant (and more anabolically active) organisms around non-quartz minerals including rutile, orthoclase and plagioclase. Microbe-mineral relationships appear to be dynamic and context-dependent arbiters of biogeochemical cycling.

Prognostic value of metabolic activity of the psoas muscle evaluated by preoperative 18F-FDG PET-CT in breast cancer: a retrospective cross-sectional study.

BACKGROUND: This study aimed to evaluate the potential of metabolic activity of the psoas muscle measured by 18F-fluorodeoxyglucose positron emission tomography-computed tomography to predict treatment outcomes in patients with resectable breast cancer. METHODS: The medical records of 288 patients who had undergone surgical resection for stages I-III invasive ductal carcinoma of the breast between January 2014 and December 2014 in Pusan National University Hospital were reviewed. The standardized uptake values (SUVs) of the bilateral psoas muscle were normalized using the mean SUV of the liver. SUVRmax was calculated as the ratio of the maximum SUV of the average bilateral psoas muscle to the mean SUV of the liver. SUVRmean was calculated as the ratio of the mean SUV of the bilateral psoas muscle to the mean SUV of the liver. RESULTS: Univariate analyses identified a higher T stage, higher N stage, estrogen receptor negativity, progesterone receptor negativity, human epidermal growth factor receptor 2 positivity, triple-negative breast cancer, mastectomy (rather than breast-conserving surgery), SUVRmean > 0.464, and SUVRmax > 0.565 as significant adverse factors for disease-free survival (DFS). Multivariate Cox regression analysis revealed that N3 stage (hazard ratio [HR] = 5.347, P = 0.031) was an independent factor for recurrence. An SUVRmax > 0.565 (HR = 4.987, P = 0.050) seemed to have a correlation with shorter DFS. CONCLUSIONS: A higher SUVRmax of the psoas muscle, which could be a surrogate marker of insulin resistance, showed strong potential as an independent prognostic factor for recurrence in patients with resectable breast cancer.

Spine-Hip Discordance and FRAX assessment Fracture Risk in Postmenopausal Women with Osteopenia from Concordant Diagnosis Between Lumbar Spine and Femoral Neck.

The diagnostic criteria proposed by the World Health Organization did not consider the discrepancy in diagnosis between lumbar spine (LS) and femoral neck (FN) and the clinical implications is unclear. Therefore, this retrospective study evaluated the probability of fracture risk in postmenopausal women with lumbar spine (LS)-femoral neck (FN) bone mineral density (BMD) discordance or not Patients included 1066 healthy postmenopausal women (median age 55.5 years) who visited our hospital for a health check-up between May 2013 and April 2017. Discordance was defined as a difference of one or two degrees between LS BMD and FN BMD. TBS was calculated from dual energy absorptiometry (DXA) images. Fracture risk was assessed using the Fracture Risk Assessment Tool (FRAX), including TBS-adjusted FRAX Seven hundred and two patients (65.9%) showed concordant LS and FN results, whereas 364 patients (34.1%) exhibited discordance. Normal BMD was found in 519 concordant patients (73.9%). Concordant patients showed significantly higher FRAX scores, including TBS-adjusted FRAX results, than discordant patients with low LS or FN. Furthermore, FRAX results in concordant osteopenia patients were similar to that of osteoporosis patients with osteopenia or a normal result at one site. FRAX and TBS-adjusted FRAX results in concordant osteopenia patients were comparable to that of discordant osteoporosis patients We concluded that patients with colncordant osteopenia in both the FN and LS should be managed in a similar way to patients with discordant osteoporosis.

Diagnostic role of PET or PET/CT for prosthetic joint infection: A systematic review and Meta-analysis.

OBJECTIVE: We aimed to explore the role of the diagnostic accuracy of positron emission tomography/computed tomography (PET/CT) or PET for the detection of periprosthetic infection (PPI) of lower limb arthroplasty through a systematic review and meta-analysis. METHODS: The MEDLINE and EMBASE from the earliest available date of indexing through October 31, 2020, were searched for studies evaluating the diagnostic performance of PET or PET/CT for the detection of PPI of lower limb arthroplasty. We determined the sensitivities and specificities across studies, calculated positive and negative likelihood ratios (LR+ and LR-), and constructed summary receiver operating characteristic curves. RESULTS: Across 25 results of 19 studies (826 patients), the pooled sensitivity for PET or PET/CT was 0.88 (95% CI; 0.80-0.93) with heterogeneity (χ2=119, P=0.00) and a pooled specificity of 0.89 (95% CI; 0.83-0.93) with heterogeneity (χ22=170, P=0.00). Likelihood ratio syntheses gave an overall positive LR+ of 7.9 (95% CI; 5.1-12.2) and negative LR- of 0.14 (95% CI; 0.08-0.23). The pooled DOR was 57 (95% CI; 31-106). CONCLUSION: The PET or PET/CT demonstrated good sensitivity and specificity for the detection of PPI of lower limb arthroplasty. At present, the literature regarding the use of PET or PET/CT for the detection of PPI of lower limb arthroplasty remains still limited; thus, further large multicenter studies would be necessary to substantiate the diagnostic accuracy of PET or PET/CT for the detection of PPI of lower limb arthroplasty.

18F-FDG PET/CT for assessing of disease activity of idiopathic inflammatory myopathies. A systematic review and meta-analysis.

OBJECTIVE: The purpose of current investigation was to evaluate the diagnostic accuracy of fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for the determination of disease activity of idiopathic inflammatory myopathies (IM) using diagnostic accuracy test. SUBJECTS AND METHODS: The PubMed and EMBASE database, from the earliest available date of indexing through August 31, 2020, were searched for results investigating the diagnostic accuracy of 18F-FDG PET/CT for the determination of disease activity of IM. We calculated the pooled sensitivities and specificities of included studies, calculated positive and negative likelihood ratios (LR+ and LR-), and obtained summary receiver operating characteristic (SROC) curves. RESULTS: Across 4 studies with 5 results (90 patients), the pooled sensitivity was 0.94 (95% CI; 0.87-0.97) without heterogeneity (I2=0.0, P=0.8) and a pooled specificity was 0.90 (95% CI; 0.72-0.97) with heterogeneity (I2=65.1, P=0.02). Likelihood ratio (LR) syntheses showed an overall positive likelihood ratio (LR+) of 9.2 (95% CI; 3.1-28.0) and negative likelihood ratio (LR-) of 0.07 (95% CI; 0.03-0.16). The pooled DOR was 131 (95% CI; 26-664). The hierarchical SROC curve shows the areas under the curve of 0.96 (95% CI; 0.94-0.98). CONCLUSION: Fluorine-18-FDG PET/CT has a good performance for the detection of active disease status in patients with IM. Although there are no guidelines for adopting imaging techniques, more objective and updated criteria for the assessment of disease activity incorporated with 18F-FDG PET/CT should be introduced and validated. Further studies are necessary to determine if 18F-FDG PET/CT-based treatment of IM can improve outcomes.

Association of leukotrienes and prostaglandins with splenic 18F-FDG uptake in hepatobiliary cancer patients.

OBJECTIVE: In this study, we aimed to evaluate the relationship between lipid metabolites and diffuse splenic 18F-FDG uptake with the means of leukotriene (LT) and prostaglandin (PG). SUBJECTS AND METHODS: We enrolled 36 patients with hepatobiliary malignancies who underwent fluorine-18-fluorodeoxyuglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for staging workup. Patients were divided into two groups according to spleen to liver ratio (S/L ratio) of 18F-FDG uptake. Blood sample of each patient was collected on the day of conducting PET/CT scanning. Several types of LT and PG, including LTB4, LTC4, LTE4, PGD2, PGE2, and PGF2α were measured from blood plasma samples from 36 patients using enzyme immunoassay (EIA kit, Cayman Chemical Co.). RESULTS: White blood cell counts (P=0.0176) and C-reactive protein (P=0.0036) were higher in patients with splenic 18F-FDG uptake exceeding hepatic 18F-FDG uptake. Among the several types of PG and LT, PGD2 (P=0.0033) was higher in patients with hepatic 18F-FDG uptake exceeding splenic 18F-FDG uptake, however, LTC4 (P=0.0237) and LTE4 (P=0.0429) were higher in patients with splenic 18F-FDG uptake over hepatic uptake. Higher levels of LTC4 and lower levels of PGD2 are shown in patients with splenic 18F-FDG uptake. CONCLUSION: If the clinician incidentally finds splenic 18F-FDG uptake exceeding hepatic uptake, concurrent inflammation should be considered.