Syphilis Mimicking Malignant Pulmonary Tumor With Nodal and Bone Metastasis on 18 F-FDG PET/CT.

ABSTRACT: A 52-year-old man suffering left pleuritic pain underwent a chest CT showing a subpleural pulmonary nodule in the left upper lobe. Because of the possibility of a lung tumor, he was referred for 18 F-FDG PET/CT. The scan revealed FDG uptake in the pulmonary nodule, in an upper right paratracheal lymph node, and at 4 destructive bone lesions. Pathologic examination after pulmonary biopsy manifested only the presence of inflammatory cells. Further clinical history research proved risky sexual behavior with a positive syphilis serology test. A follow-up PET/CT 7 months after penicillin therapy showed a complete metabolic response of all the lesions.

Lung cancer screening using low-dose CT and FDG-PET in liver transplant recipients.

To address the feasibility of implementing a lung cancer screening program in liver transplant recipients (LTR) targeted to detect early-stage lung cancer one hundred twenty-four LTR (89% male, 59.8+/-8.8 y old), who entered the lung cancer screening program at our hospital were reviewed. The results of the diagnostic algorithm using low-dose CT and F-18-fluorodeoxyglycose positron emission tomography (FDG-PET) were analyzed. Lung cancer was detected in 12 LTR (9.7%), most of which corresponded to the non-small cell subtype. Two of the 12 lung cancers were detected in the baseline study (prevalence of 1.6%), whereas 10 patients were diagnosed with lung cancer in the follow-up (incidence of 8.1%). Considering all cancers, 10 of 12 (83.3%) were diagnosed at stage I, one cancer was diagnosed at stage IIIA, and another one at stage IV. The sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values of F-18-fluorodeoxyglycose positron emission tomography to detect malignancy in our cohort were 81.8%,100%, 99.3%, 100%, and 99.3%, respectively. A carefully followed multidisciplinary lung cancer screening algorithm in LTR that includes F-18-fluorodeoxyglycose positron emission tomography and low-dose CT allows lung cancer to be diagnosed at an early stage while reducing unnecessary invasive procedures.

FDG-PET/CT and new radiopharmaceuticals in patients with multiple myeloma.

Multiple myeloma is a monoclonal gammopathy, a clonal proliferative disorder of plasma cells that produces a protein called M or myeloma protein in the bone marrow, usually IgG or IgA. It accounts for 1% in the general cancer statistics and represents 10% of all hematologic tumours, with a cumulative incidence in Spain of about 5/100,000/year. The incidence increases with age, so that 50% of cases are diagnosed in patients over 75 years of age, being infrequent in the population under 40 years of age. This publication details the indications of FDG PET/CT for the staging and response assessment in patients with MM, accepted by the international working group on myeloma, as well as new molecular imaging radiopharmaceuticals with potential value for personalised medicine.

Early Imaging and Molecular Changes with Neoadjuvant Bevacizumab in Stage II/III Breast Cancer.

This prospective, phase II study evaluated novel biomarkers as predictors of response to bevacizumab in patients with breast cancer (BC), using serial imaging methods and gene expression analysis. Patients with primary stage II/III BC received bevacizumab 15 mg/kg (cycle 1; C1), then four cycles of neoadjuvant docetaxel doxorubicin, and bevacizumab every 3 weeks (C2-C5). Tumour proliferation and hypoxic status were evaluated using 18F-fluoro-3'-deoxy-3'-L-fluorothymidine (FLT)- and 18F-fluoromisonidazole (FMISO)-positron emission tomography (PET) at baseline, and during C1 and C5. Pre- and post-bevacizumab vascular changes were evaluated using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Molecular biomarkers were assessed using microarray analysis. A total of 70 patients were assessed for treatment efficacy. Significant decreases from baseline in tumour proliferation (FLT-PET), vascularity, and perfusion (DCE-MRI) were observed during C1 (p ≤ 0.001), independent of tumour subtype. Bevacizumab treatment did not affect hypoxic tumour status (FMISO-PET). Significant changes in the expression of 28 genes were observed after C1. Changes in vascular endothelial growth factor receptor (VEGFR)-2p levels were observed in 65 patients, with a > 20% decrease in VEGFR-2p observed in 13/65. Serial imaging techniques and molecular gene profiling identified several potentially predictive biomarkers that may predict response to neoadjuvant bevacizumab therapy in BC patients.

Ultra-low dose whole-body CT for attenuation correction in a dual tracer PET/CT protocol for multiple myeloma.

PURPOSE: To investigate within phantoms the minimum CT dose allowed for accurate attenuation correction of PET data and to quantify the effective dose reduction when a CT for this purpose is incorporated in the clinical setting. METHODS: The NEMA image quality phantom was scanned within a large parallelepiped container. Twenty-one different CT images were acquired to correct attenuation of PET raw data. Radiation dose and image quality were evaluated. Thirty-one patients with proven multiple myeloma who underwent a dual tracer PET/CT scan were retrospectively reviewed. 18F-fluorodeoxyglucose PET/CT included a diagnostic whole-body low dose CT (WBLDCT: 120 kV-80mAs) and 11C-Methionine PET/CT included a whole-body ultra-low dose CT (WBULDCT) for attenuation correction (100 kV-40mAs). Effective dose and image quality were analysed. RESULTS: Only the two lowest radiation dose conditions (80 kV-20mAs and 80 kV-10mAs) produced artifacts in CT images that degraded corrected PET images. For all the other conditions (CTDIvol ≥ 0.43 mGy), PET contrast recovery coefficients varied less than ± 1.2%. Patients received a median dose of 6.4 mSv from diagnostic CT and 2.1 mSv from the attenuation correction CT. Despite the worse image quality of this CT, 94.8% of bone lesions were identifiable. CONCLUSION: Phantom experiments showed that an ultra-low dose CT can be implemented in PET/CT procedures without any noticeable degradation in the attenuation corrected PET scan. The replacement of the standard CT for this ultra-low dose CT in clinical PET/CT scans involves a significant radiation dose reduction.

Pulmonary Artery Sarcoma With Low 18F-FDG Uptake.

ABSTRACT: A 75-year-old man presented with dyspnea for more than 2 months, with blood test showing low platelet count and cardiac ultrasound showing severe pulmonary hypertension (>54 mm Hg). A CT pulmonary angiogram showed a filling defect in the pulmonary trunk, right and left pulmonary arteries, raising the possibilities of pulmonary embolism or artery sarcoma. FDG PET/CT was performed for further evaluation and showed low uptake in the pulmonary wall, which supported the diagnosis of pulmonary embolism. Patient was treated with anticoagulants with no changes on repeated CT pulmonary angiogram. Patient underwent surgery, and histopatological examination revealed a pulmonary artery sarcoma.

The utility of ADC value in diffusion-weighted whole-body MRI in the follow-up of patients with multiple myeloma. Correlation study with 18F-FDG PET-CT.

OBJECTIVES: To analyze the feasibility of DWI-MRI and ADC to evaluate treatment response in patients with multiple myeloma (MM). To correlate the variations of ADC and SUVmax in 18F-FDG PET-CT. METHODS: 27 patients with MM that had a whole-body MRI and 18F-FDG PET-CT performed at baseline and after treatment were retrospectively recruited between February 2018 and May 2020. Three target bone lesions were selected for each patient and their ADC, SUVmax and Deauville score were measured in every study. Correlation between ADC and SUVmax of the lesions was evaluated, as well as changes in mean ADC, SUVmax, and Deauville score between studies. Patients were classified as responder or non-responder according to the IMWG, MRI (MY-RADS) and PET-CT (IMPeTUs) response criteria. Agreement between the MRI and PET-CT criteria with the IMWG criteria was evaluated. RESULTS: The correlation between the ADC and SUVmax of all the target lesions was strong, negative and significant (r=-0.603; p < 0.001). After treatment, mean ADC in lesions from responders was significantly higher than in non-responders (1585.51 × 10-6 mm2/s vs 698.17 × 10-6 mm2/s; p < 0.001). SUVmax of the same lesions was significantly lower in responders than in non-responders (2.05 vs 5.33; p < 0.001). There was a very strong or strong agreement of the IMWG response criteria with both MRI (κ = 0.852; p < 0.001) and PET (κ = 0.767; p < 0.001) criteria. CONCLUSION: DWI-MRI and ADC may be used to assess treatment response in MM patients, showing a good correlation with 18F-FDG PET-CT and the IMWG response criteria.

Elevated circulating metalloproteinase 7 predicts recurrent cardiovascular events in patients with carotid stenosis: a prospective cohort study.

BACKGROUND: Major adverse cardiovascular events are the main cause of morbidity and mortality over the long term in patients undergoing carotid endarterectomy. There are few reports assessing the prognostic value of markers of inflammation in relation to the risk of cardiovascular disease after carotid endarterectomy. Here, we aimed to determine whether matrix metalloproteinases (MMP-1, MMP-2, MMP-7, MMP-9 and MMP-10), tissue inhibitor of MMPs (TIMP-1) and in vivo inflammation studied by 18F-FDG-PET/CT predict recurrent cardiovascular events in patients with carotid stenosis who underwent endarterectomy. METHODS: This prospective cohort study was carried out on 31 consecutive patients with symptomatic (23/31) or asymptomatic (8/31) severe (> 70%) carotid stenosis who were scheduled for carotid endarterectomy between July 2013 and March 2016. In addition, 26 healthy controls were included in the study. Plasma and serum samples were collected 2 days prior to surgery and tested for MMP-1, MMP-2, MMP-7, MMP-9, MMP-10, TIMP-1, high-density lipoprotein, low-density lipoprotein, high-sensitivity C-reactive protein and erythrocyte sedimentation rate. 18F-FDG-PET/CT focusing on several territories' vascular wall metabolism was performed on 29 of the patients because of no presurgical availability in 2 symptomatic patients. Histological and immunohistochemical studies were performed with antibodies targeting MMP-10, MMP-9, TIMP-1 and CD68. RESULTS: The patients with carotid stenosis had significantly more circulating MMP-1, MMP-7 and MMP-10 than the healthy controls. Intraplaque TIMP-1 was correlated with its plasma level (r = 0.42 P = .02) and with 18F-FDG uptake (r = 0.38 P = .05). We did not find any correlation between circulating MMPs and in vivo carotid plaque metabolism assessed by 18F-FDG-PET. After a median follow-up of 1077 days, 4 cerebrovascular, 7 cardiovascular and 11 peripheral vascular events requiring hospitalization were registered. Circulating MMP-7 was capable of predicting events over and above the traditional risk factors (HR = 1.15 P = .006). When the model was associated with the variables of interest, the risk predicted by 18F-FDG-PET was not significant. CONCLUSIONS: Circulating MMP-7 may represent a novel marker for recurrent cardiovascular events in patients with moderate to severe carotid stenosis. MMP-7 may reflect the atherosclerotic burden but not plaque inflammation in this specific vascular territory.

Assessment of metabolic patterns and new antitumoral treatment in osteosarcoma xenograft models by [18F]FDG and sodium [18F]fluoride PET.

BACKGROUND: Osteosarcoma is the most common malignant bone tumor in children and young adults that produces aberrant osteoid. The aim of this study was to assess the utility of 2-deoxy-2-[18F-] fluoro-D-glucose ([18F] FDG) and sodium [18F] Fluoride (Na [18F] F) PET scans in orthotopic murine models of osteosarcoma to describe the metabolic pattern of the tumors, to detect and diagnose tumors and to evaluate the efficacy of a new treatment based in oncolytic adenoviruses. METHODS: Orthotopic osteosarcoma murine models were created by the injection of 143B and 531MII cell lines. [18F]FDG and Na [18F] F PET scans were performed 30 days (143B) and 90 days (531MII) post-injection. The antitumor effect of two doses (107 and 108 pfu) of the oncolytic adenovirus VCN-01 was evaluated in 531 MII model by [18F] FDG PET studies. [18F] FDG uptake was quantified by SUVmax and Total Lesion Glycolysis (TLG) indexes. For Na [18F] F, the ratio tumor SUVmax/hip SUVmax was calculated. PET findings were confirmed by histopathological techniques. RESULTS: The metabolic pattern of tumors was different between both orthotopic models. All tumors showed [18F] FDG uptake, with a sensitivity and specificity of 100%. The [18F] FDG uptake was significantly higher for the 143B model (p < 0.001). Sensitivity for Na [18F] F was around 70% in both models, with a specificity of 100%. 531MII tumors showed a heterogeneous Na [18F] F uptake, significantly higher than 143B tumors (p < 0.01). Importantly, [18F] FDG and Na [18F] F uptake corresponded to highly cellular or osteoid-rich tumors in the histopathological analysis, respectively. [18F] FDG data confirmed that the oncolytic treatment of 531MII tumors produced a significant reduction in growth even with the 107 pfu dose. CONCLUSIONS: PET studies demonstrated that the different osteosarcoma xenograft models developed tumors with diverse metabolic patterns that can be described by multitracer PET studies. Since not all tumors produced abundant osteoid, [18F] FDG demonstrated a better sensitivity for tumor detection and was able to quantitatively monitor in vivo response to the oncolytic adenovirus VCN-01.

Significant dose reduction is feasible in FDG PET/CT protocols without compromising diagnostic quality.

PURPOSE: To reduce the radiation dose to patients by optimizing oncological FDG PET/CT protocols. METHODS: The baseline PET/CT protocol in our institution for oncological PET/CT examinations consisted of the administration of 5.18 MBq/kg of FDG and a CT acquisition with a reference current-time product of 120 mAs. In 2016, FDG activity was reduced to 4.44 and 3.70 MBq/kg and reference CT current-time-product was reduced to 100 and 80 mAs. 322 patients scanned with different protocols were retrospectively evaluated. For each patient, effective dose was calculated. The overall image quality was subjectively rated by the referring physician on a 4-point scale (IQ score: 1 excellent, 2 good, 3 poor but interpretable, 4 poor not interpretable). Image quality was quantitatively evaluated measuring noise in the liver. RESULTS: CT Results: Effective dose was progressively reduced from 9.5 ±â€¯2.8 to 8.0 ±â€¯2.3 and 6.2 ±â€¯1.5 mSv (p < 0.001). A mean dose reduction of 34.9% was achieved. There was a significant degradation of IQ score (p < 0.05) and noise (p < 0.001). Nevertheless, the number of poor quality studies (IQ score >2) did not increase. PET Results: Effective dose was gradually reduced from 6.5 ±â€¯1.4 to 5.7 ±â€¯1.3 and 5.0 ±â€¯1.0 mSv (p < 0.001). Average dose reduction was 23.4%. IQ score (p < 0.05) and noise (p < 0.001) significantly degraded for lower activity protocols. However, all images with reduced activity were scored as interpretable (IQ score ≤ 3). CONCLUSIONS: A significant radiation dose reduction of 28.7% was reached. Despite a slight reduction in image quality, the new regime was successfully implemented with readers reporting unchanged clinical confidence.

18F-FDG PET/CT in breast cancer: Evidence-based recommendations in initial staging.

Current guidelines do not systematically recommend 18F-FDG PET/CT for breast cancer staging; and the recommendations and level of evidence supporting its use in different groups of patients vary among guidelines. This review summarizes the evidence about the role of 18F-FDG PET/CT in breast cancer staging and the therapeutic and prognostic impact accumulated in the last decade. Other related aspects, such as the association of metabolic information with biology and prognosis are considered and evidence-based recommendations for the use of 18F-FDG PET/CT in breast cancer staging are offered. We systematically searched MEDLINE for articles reporting studies with at least 30 patients related to clinical questions following the Problem/Population, Intervention, Comparison, and Outcome framework. We critically reviewed the selected articles and elaborated evidence tables structuring the summarized information into methodology, results, and limitations. The level of evidence and the grades of recommendation for the use of 18F-FDG PET/CT in different contexts are summarized. Level III evidence supports the use of 18F-FDG PET/CT for initial staging in patients with recently diagnosed breast cancer; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a weak recommendation in this population. In patients with locally advanced breast cancer, level II evidence supports the use of 18F-FDG PET/CT for initial staging; the diagnostic and therapeutic impact of the 18F-FDG PET/CT findings is sufficient for a strong recommendation in this population. In patients with recently diagnosed breast cancer, the metabolic information from baseline 18F-FDG PET/CT is associated with tumor biology and has prognostic implications, supported by level II evidence. In conclusion, 18F-FDG PET/CT is not recommended for staging all patients with early breast cancer, although evidence of improved regional and systemic staging supports its use in locally advanced breast cancer. Baseline tumor glycolytic activity is associated with tumor biology and prognosis.

18F-fluorodeoxyglucose positron emission tomography in the diagnosis of malignancy in patients with paraneoplastic neurological syndrome: a systematic review and meta-analysis.

PURPOSE: The detection of occult cancer in patients suspected of having a paraneoplastic neurological syndrome (PNS) poses a diagnostic challenge. The aim of our study was to perform a systematic review and meta-analysis to assess the diagnostic performance of FDG PET for the detection of occult malignant disease responsible for PNS. METHODS: A systematic review of the literature (MEDLINE, EMBASE, Cochrane, and DARE) was undertaken to identify studies published in any language. The search strategy was structured after addressing clinical questions regarding the validity or usefulness of the test, following the PICO framework. Inclusion criteria were studies involving patients with PNS in whom FDG PET was performed to detect malignancy, and which reported sufficient primary data to allow calculation of diagnostic accuracy parameters. When possible, a meta-analysis was performed to calculate the joint sensitivity, specificity, and detection rate for malignancy (with 95% confidence intervals [CIs]), as well as a subgroup analysis based on patient characteristics (antibodies, syndrome). RESULTS: The comprehensive literature search revealed 700 references. Sixteen studies met the inclusion criteria and were ultimately selected. Most of the studies were retrospective (12/16). For the quality assessment, the QUADAS-2 tool was applied to assess the risk of bias. Across 16 studies (793 patients), the joint sensitivity, specificity, and detection rate for malignancy with FDG PET were 0.87 (95% CI: 0.80-0.93), 0.86 (95% CI: 0.83-0.89), and 14.9% (95% CI: 11.5-18.7), respectively. The area under the curve (AUC) of the summary ROC curve was 0.917. Homogeneity of results was observed for sensitivity but not for specificity. Some of the individual studies showed large 95% CIs as a result of small sample size. CONCLUSIONS: The results of our meta-analysis reveal high diagnostic performance of FDG PET in the detection of malignancy responsible for PNS, not affected by the presence of onconeural antibodies or clinical characteristics.

Non-invasive in vivo imaging of cardiac stem/progenitor cell biodistribution and retention after intracoronary and intramyocardial delivery in a swine model of chronic ischemia reperfusion injury.

BACKGROUND: The safety and efficacy of cardiac stem/progenitor cells (CSC) have been demonstrated in previous preclinical and clinical assays for heart failure. However, their optimal delivery route to the ischemic heart has not yet been assessed. This study was designed to determine by a non-invasive imaging technique (PET/CT) the biodistribution and acute retention of allogeneic pig CSC implanted by two different delivery routes, intracoronary (IC) and intramyocardial (IM), in a swine preclinical model of chronic ischemia-reperfusion. METHODS: Ischemia-reperfusion was induced in six Goettingen hybrid minipigs by 90 min coronary artery occlusion followed by reperfusion. Thirty days later, animals were allocated to receive IC (n = 3) or NOGA®-guided IM injection (n = 3) of 50 million of 18F-FDG/GFP-labeled allogeneic pig CSC. Acute retention was quantified by PET/CT 4 h after injection and cell engraftment assessed by immunohistochemical quantification of GFP+ cells three days post-injection. RESULTS: Biodistribution of 18F-FDG-labeled CSC was clearly visualized by PET/CT imaging and quantified. No statistical differences in acute cell retention (percentage of injected dose, %ID) were found in the heart when cells were administered by NOGA®-guided IM (13.4 ± 3.4%ID) or IC injections (17.4 ± 4.1%ID). Interestingly, engrafted CSC were histologically detected only after IM injection. CONCLUSION: PET/CT imaging of 18F-FDG-labeled CSC allows quantifying biodistribution and acute retention of implanted cells in a clinically relevant pig model of chronic myocardial infarction. Similar levels of acute retention are achieved when cells are IM or IC administered. However, acute cell retention does not correlate with cell engraftment, which is improved by IM injection.

Role of [¹8F]FDG PET in prediction of KRAS and EGFR mutation status in patients with advanced non-small-cell lung cancer.

PURPOSE: The tumour molecular profile predicts the activity of epidermal growth factor receptor (EGFR) inhibitors in non-small-cell lung cancer (NSCLC). However, tissue availability and tumour heterogeneity limit its assessment. We evaluated whether [(18)F]FDG PET might help predict KRAS and EFGR mutation status in NSCLC. METHODS: Between January 2005 and October 2011, 340 NSCLC patients were tested for KRAS and EGFR mutation status. We identified patients with stage III and IV disease who had undergone [(18)F]FDG PET/CT scanning for initial staging. SUVpeak, SUVmax and SUVmean of the single hottest tumour lesions were calculated, and their association with KRAS and EGFR mutation status was assessed. A receiver operator characteristic (ROC) curve analysis and a multivariate analysis (including SUVmean, gender, age and AJCC stage) were performed to identify the potential value of [(18)F]FDG PET/CT for predicting KRAS mutation. RESULTS: From 102 patients staged using [(18)F]FDG PET/CT, 28 (27%) had KRAS mutation (KRAS+), 22 (22%) had EGFR mutation (EGFR+) and 52 (51%) had wild-type KRAS and EGFR profiles (WT). KRAS+ patients showed significantly higher [(18)F]FDG uptake than EGFR+ and WT patients (SUVmean 9.5, 5.7 and 6.6, respectively; p < 0.001). No significant differences were observed in [(18)F]FDG uptake between EGFR+ patients and WT patients. ROC curve analysis for KRAS mutation status discrimination yielded an area under the curve of 0.740 for SUVmean (p < 0.001). The multivariate analysis showed a sensitivity and specificity of 78.6% and 62.2%, respectively, and the AUC was 0.773. CONCLUSION: NSCLC patients with tumours harbouring KRAS mutations showed significantly higher [(18)F]FDG uptake than WT patients, as assessed in terms of SUVpeak, SUVmax and SUVmean. A multivariate model based on age, gender, AJCC stage and SUVmean might be used as a predictive marker of KRAS mutation status in patients with stage III or IV NSCLC.

Impact of time-of-flight and point-spread-function in SUV quantification for oncological PET.

BACKGROUND: Accuracy in the quantification of the SUV is a critical point in PET because proper quantification of tumor uptake is essential for therapy monitoring and prognosis evaluation. Recent advances such as time-of-flight (TOF) and point-spread-function (PSF) reconstructions have dramatically improved detectability. However, first experiences with these techniques have shown a consistent tendency to measure markedly high SUV values, bewildering nuclear medicine physicians and referring clinicians. PURPOSE: We investigated different reconstruction and quantification procedures to determine the optimum protocol for an accurate SUV quantification in last generation PET scanners. METHODS: Both phantom and patient images were evaluated. A complete set of experiments was performed using a body phantom containing 6 spheres with different background levels and contrasts. Whole-body FDG PET/CT of 20 patients with breast and lung cancer was evaluated. One hundred five foci were identified by 2 experienced nuclear medicine physicians.Each acquisition was reconstructed both with classical and advanced (TOF, PSF) reconstruction techniques. Each sphere and each in vivo lesion was quantified with different parameters as follows: SUV(max), SUV(mean), and SUV(50) (mean within a 50% isocontour). RESULTS: This study has confirmed that quantification with SUV(max) produces important overestimation of metabolism in new generation PET scanners. This is a relevant result because, currently, SUV(max) is the standard parameter for quantification. SUV(50) has been shown as the best alternative, especially when applied to images reconstructed with PSF + TOF. CONCLUSIONS: SUV(50) provides accurate quantification and should replace SUV(max) in PET tomographs incorporating advanced reconstruction techniques. PSF + TOF reconstruction is the optimum for both detection and accurate quantification.

Functional imaging in radiation therapy planning for head and neck cancer.

Functional imaging and its application to radiotherapy (RT) is a rapidly expanding field with new modalities and techniques constantly developing and evolving. As technologies improve, it will be important to pay attention to their implementation. This review describes the main achievements in the field of head and neck cancer (HNC) with particular remarks on the unsolved problems.

FDG Uptake and the Diagnostic Yield of Transbronchial Needle Aspiration.

OBJECTIVE: The objective of our study was to investigate whether fluorodeoxyglucose (FDG) positron emission tomography scanning uptake impacts the yield of transbronchial needle aspiration (TBNA). METHODS: We carried out a retrospective analysis of data from 140 consecutive patients (178 lymph nodes) undergoing positron emission tomography-computed tomography scanning and subsequent TBNA with rapid onsite cytologic evaluation of the specimen. Patient and lymph node characteristics, including nodal station, size, FDG uptake, number of passes with the needle, sample adequacy, and the final diagnosis were recorded. RESULTS: The diagnostic yield of TBNA was 75%. Themean short axis lymph node diameter was 18.7±9 mm and mean maximum standardized uptake value (SUVmax) was 7.7±4. The diagnostic yield depended on the lymph node size [odds ratio (OR)=1.07 (1.00-1.14); P=0.04], clinical suspicion of malignancy [OR=5.13 (1.95-13.52); P=0.001], malignant diagnosis [OR=4.91 (1.71-14.09); P=0.003], and FDG uptake [for SUVmax cutoff of 3.0: OR=33.8 (9.2-124); P<0.001]. Only clinical suspicion of cancer [OR=6.2 (2.2-17.2); P=0.001] and FDG uptake [for SUVmax cutoff of 3.0: OR=33.8 (9.2-123.8); P<0.001] remained significant on multivariate analysis. Receiver operating characteristic curves combining 3 key variables (lymph node size, clinical suspicion of malignancy, and SUVmax) showed an area of 0.83 under the curve for a 2.5 SUVmax cutoff and 0.84 for a 3.0 cutoff. CONCLUSIONS: FDG uptake is the single most important variable impacting the TBNA yield. TBNA of lymph nodes with an SUVmax less than 3.0 is rarely diagnostic.

BAT: a new target for human obesity?

Two types of adipose tissue can be distinguished histologically and functionally: white (WAT) and brown adipose tissue (BAT). Whereas BAT is specialized in the production of heat, WAT stores excess energy as triacylglycerols. BAT is present throughout life in rodents, whereas in humans it was thought to involute rapidly postnatally, having essentially disappeared within the first years after birth. However, positron emission tomography has provided evidence that adults retain metabolically active BAT depots that can be induced in response to cold and sympathetic nervous system activation. These findings together with the recent identification of specific molecular determinants (PRDM16 and BMP7) activating brown adipogenesis highlights BAT as a potential relevant target for pharmacological and gene expression manipulation to combat human obesity.