18F-FDG Positron Emission Tomography Scans Research Articles

Exceptionally Rare Isolated Thyroidal Metastasis of Pulmonary Carcinosarcoma: A Tale of 18F-FDG-positive Thyroid Nodule.

Pulmonary carcinosarcomas (PCS) are uncommon and aggressive malignant tumors with epithelial and mesenchymal components and have a worse prognosis than other non-small-cell lung cancers. Metastases of non-thyroidal malignancies to the thyroid are rare. We reported a unique case of isolated thyroidal metastasis of PCS and discussed 18F-fluorodeoxyglucose (18F-FDG) positivity in incidentally found thyroid nodules on 18F-FDG positron emission tomography scan.

PET4 Response As an Independent Predictor of Long-Term Outcomes in ECHELON2 (A+CHP Vs. CHOP) in CD30+PTCL

Background: Peripheral T-cell lymphomas (PTCLs) are uncommon, heterogeneous, and often aggressive subtypes of lymphoma characterized by a high risk of progression even after combination chemotherapy. The phase III, ECHELON-2 trial showed that the combination of brentuximab vedotin with chemotherapy (A+CHP) in patients (pts) with CD30-positive PTCLs improved progression-free survival (PFS) and overall survival (OS) compared to CHOP. In PTCL, positron emission tomography (PET) is a valuable way to assess disease burden and stage at the time of diagnosis and evaluate treatment response. Prior retrospective studies have shown that interim and end of treatment PET may predict outcomes; however, there are no prospective studies confirming their predictive value. In the ECHELON-2 study, PET4 outcomes were prospectively collected, and the objective of this exploratory analysis is to investigate the potential for interim PET scans to predict treatment response and long-term outcomes. Objective: To evaluate the role of interim 18F-FDG PET imaging (PET4) in predicting end of treatment (EOT) response, progression free survival (PFS), and overall survival (OS) in pts (pts) with CD30+PTCL treated with A+CHP or CHOP in the ECHELON-2 trial. Methods: The ECHELON-2 trial included prospective 18F-FDG PET scans and assessment of treatment response including long-term PFS per investigator and OS. PET4 status was based on Deauville score by Independent Review Facility (IRF) assessment using scans at the cycle 4 response assessment. Deauville scores 1-3 are considered negative (PET4neg) and 4-5 positive (PET4pos). EOT response is the best response after completion of study treatment and prior to long term follow up per Cheson 2007 by IRF assessment. Kaplan-Meier methods were used to estimate PFS and OS; p-values are based on stratified log-rank tests. All analyses are exploratory, and p-values are descriptive. Results: In this study, 452 pts were included, with 226 randomized to the A+CHP treatment arm and 226 to the CHOP treatment arm; median follow up was 66.8 months (range 0-90). Of randomized pts, 32 pts in the A+CHP arm and 41 pts in the CHOP arm were not evaluable for PET4. The overall results showed that the PET4neg evaluable subgroup had a higher proportion of pts achieving complete responses (CR) than PET4pos (80% vs. 9%) at EOT (Table 1). In pts assessed for PET4, pts who were PET4neg had improved PFS and OS in both the A+CHP and CHOP treatment arms (Figure 1). For A+CHP pts, those who achieved PET4neg had an improved PFS [HR 0.36, CI-95 (0.19-0.66), p=0.0006] and OS [HR 0.38, CI-95 (0.18-0.78), p=0.0060] compared to those who were PET4pos. Similarly, pts in the CHOP arm who achieved PET4neg had an improved PFS [HR 0.26, CI-95 (0.17-0.41), p<0.0001] and OS [HR 0.24, CI-95 (0.14-0.41), p< 0.0001] compared to those who were PET4pos. Among pts with anaplastic large cell lymphoma (sALCL) (n=316), 19 pts in the A+CHP arm and 32 in the CHOP arm were not evaluable for PET4. The results in this subgroup show that 128/143 (90%) A+CHP pts who had PET4 assessments achieved PET4neg. These pts experienced improved PFS [HR 0.28, CI-95 (0.14-0.60), p=0.0004] and OS [HR 0.38, CI-95 (0.16-0.94), p 0.0292] compared to PET4pos pts. For CHOP pts who had PET4 assessments 98/122 (80%), achieved PET4neg; these pts experienced improved PFS [HR 0.31, CI-95 (0.12-0.55), p<0.0001] and improved OS [HR 0.25, CI-95 (0.12-0.25), p= 0.0002] compared to PET4pos pts. Conclusion: In an exploratory analysis of interim PET imaging as part of the ECHELON-2 study, PET4neg by Deauville was associated with improved PFS and OS in both the A+CHP and CHOP arms. Our findings support the use of PET4 response in PTCL as a predictor of outcomes in both the A+CHP and CHOP pts. These findings emphasize the potential of PET scans to enhance risk stratification, individualize therapy decisions, and improve pt outcomes in the management of PTCLs. Further analysis will be presented at the meeting.

Internal dose assessment of lymphoma 18F-FDG Positron Emission Tomography (PET) scan

This study aimed to assess the internal radiation exposure of patients who have undergone a Positron Emission Tomography (PET) scan using 18F-FDG radiopharmaceutical. A total of 24 patients (8 men, 16 women, with an average age of 43.88 ± 18.57 years and weight of 57.54 ± 13.04 kg) who had been diagnosed with lymphoma were administered with 300.80 ± 23.09 MBq of 18F-FDG for a PET scan of the whole body. The IDAC-Dose 2.1 program, developed by the International Commission on Radiological Protection (ICRP), was used to measure absorbed and effective doses. The organs selected for absorbed dose analysis were the breast, kidneys, adrenals, liver, and brain, with the brain receiving the highest absorbed dose and the breast receiving the lowest absorbed dose. The effective dose for all patients was 4.85 ± 0.37 mSv, and the ratio of the effective dose to the administered activity was 1.611 × 10−2 mSv/MBq. The safety of the current practice using 18F-FDG PET scan was ascertained, given that the ratio of effective dose to administered activity was lower than 1.9 x 10−2 mSv/MBq.

Glucose uptake and distribution across the human skeleton using state-of-the-art total-body PET/CT

A growing number of studies have demonstrated that the skeleton is an endocrine organ that is involved in glucose metabolism and plays a significant role in human glucose homeostasis. However, there is still a limited understanding of the in vivo glucose uptake and distribution across the human skeleton. To address this issue, we aimed to elucidate the detailed profile of glucose uptake across the skeleton using a total-body positron emission tomography (PET) scanner. A total of 41 healthy participants were recruited. Two of them received a 1-hour dynamic total-body 18F-fluorodeoxyglucose (18F-FDG) PET scan, and all of them received a 10-minute static total-body 18F-FDG PET scan. The net influx rate (Ki) and standardized uptake value normalized by lean body mass (SUL) were calculated as indicators of glucose uptake from the dynamic and static PET data, respectively. The results showed that the vertebrae, hip bone and skull had relatively high Ki and SUL values compared with metabolic organs such as the liver. Both the Ki and SUL were higher in the epiphyseal, metaphyseal and cortical regions of long bones. Moreover, trends associated with age and overweight with glucose uptake (SULmax and SULmean) in bones were uncovered. Overall, these results indicate that the skeleton is a site with significant glucose uptake, and skeletal glucose uptake can be affected by age and dysregulated metabolism.

Improving the Classification of PCNSL and Brain Metastases by Developing a Machine Learning Model Based on 18F-FDG PET.

Background: The characteristic magnetic resonance imaging (MRI) and the positron emission tomography (PET) findings of PCNSL often overlap with other intracranial tumors, making definitive diagnosis challenging. PCNSL typically shows iso-hypointense to grey matter on T2-weighted imaging. However, a particular part of PCNSL can demonstrate T2-weighted hyperintensity as other intracranial tumors. Moreover, normal high uptake of FDG in the basal ganglia, thalamus, and grey matter can mask underlying PCNSL in 18F-FDG PET. In order to promote the efficiency of diagnosis, the MRI-based or PET/CT-based radiomics models combining histograms with texture features in diagnosing glioma and brain metastases have been widely established. However, the diagnosing model for PCNSL has not been widely reported. The study was designed to investigate a machine-learning (ML) model based on multiple parameters of 2-deoxy-2-[18F]-floor-D-glucose (18F-FDG) PET for differential diagnosis of PCNSL and metastases in the brain. Methods: Patients who underwent an 18F-FDG PET scan with untreated PCNSL or metastases in the brain were included between May 2016 and May 2022. A total of 126 lesions from 51 patients (43 patients with untreated brain metastases and eight patients with untreated PCNSL), including 14 lesions of PCNSL, and 112 metastatic lesions in the brain, met the inclusion criteria. PCNSL or brain metastasis was confirmed after pathology or clinical history. Principal component analysis (PCA) was used to decompose the datasets. Logistic regression (LR), support vector machine (SVM), and random forest classification (RFC) models were trained by two different groups of datasets, the group of multi-class features and the group of density features, respectively. The model with the highest mean precision score was selected. The testing sets and original data were used to examine the efficacy of models separately by using the weighted average F1 score and area under the curve (AUC) of the receiver operating characteristic curve (ROC). Results: The multi-class features-based RFC and SVM models reached identical weighted-average F1 scores in the testing set, and the score was 0.98. The AUCs of RFC and SVM models calculated from the testing set were 1.00 equally. Evaluated by the original dataset, the RFC model based on multi-class features performs better than the SVM model, whose weighted-average F1 scores of the RFC model calculated from the original data were 0.85 with an AUC of 0.93. Conclusions: The ML based on multi-class features of 18F-FDG PET exhibited the potential to distinguish PCNSL from brain metastases. The RFC models based on multi-class features provided comparatively high efficiency in our study.

Focal 18 F-FDG uptake predicts progression of pre-invasive squamous bronchial lesions to invasive cancers.

Pre-invasive squamous lesions of the central airways can progress into invasive lung cancers. Identifying these high-risk patients could enable detection of invasive lung cancers at an early stage. In this study, we investigated the value of 18 F-fluorodeoxyglucose (18 F-FDG) positron emission tomography (PET) scans in predicting progression in patients with pre-invasive squamous endobronchial lesions. In this retrospective study, patients with pre-invasive endobronchial lesions, who underwent an 18 F-FDG PET scan at the VU University Medical Center Amsterdam, between January 2000 and December 2016, were included. Autofluorescence bronchoscopy (AFB) was used for tissue sampling and was repeated every 3 months. The minimum and median follow-up was 3 and 46.5months. Study endpoints were the occurrence of biopsy proven invasive carcinoma, time-to-progression and overall survival (OS). A total number of 40 of 225 patients met the inclusion criteria of which 17 (42.5%) patients had a positive baseline 18 F-FDG PET scan. A total of 13 of 17 (76.5%) developed invasive lung carcinoma during follow-up, with a median time to progression of 5.0months (range, 3.0-25.0). In 23 (57.5%) patients with a negative 18 F-FDG PET scan at baseline, 6 (26%) developed lung cancer, with a median time to progression of 34.0months (range, 14.0-42.0months, p < 0.002). With a median OS of 56.0months (range, 9.0-60.0 months) versus 49.0months (range, 6.0-60.0months) (p=0.876) for the18 F-FDG PET positive and negative groups, respectively. Patients with pre-invasive endobronchial squamous lesions and a positive baseline 18 F-FDG PET scan were at high-risk for developing lung carcinoma, highlighting that this patient group requires early radical treatment.

Dynamic Brain Imaging Response to Spinal Cord Stimulation Differential Frequencies DiFY SCS-PET Clinical Trial

ObjectivesThis study with sequential 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)–computed tomography (CT) scanning was designed to investigate any objective measurable effect of differential frequency stimulation (40 Hz, 4000 Hz, and 10,000 Hz) on specific pain matrix areas in patients who underwent spinal cord stimulation (SCS) for intractable lumbar neuropathic pain. Materials and MethodsIn this single-center, randomized, blinded study, four brain 18F-FDG PET scans were performed for each patient—at baseline before SCS implant and after 40-Hz, 4000-Hz, and 10,000-Hz stimulation. After 40-Hz stimulation for four weeks, patients were randomized 1:1 (4000 Hz/10,000 Hz), crossing over at another four weeks. 18F-FDG PET-CT brain scans acquired on the GE-Discovery 710 PET system (GE Healthcare, Chicago, IL) with 128-slice CT (250-MBq dose) were analyzed using the PMOD software (PMOD Technologies Ltd, Zurich, Switzerland). A total of 18 pain regions, the right and left prefrontal cortex (PFC), insula, anterior cingulate cortex (ACC), hippocampus, amygdala, primary somatosensory cortices, secondary somatosensory cortices (SSCII), thalami, parabrachial, and periaqueductal gray (PAG), were analyzed. ResultsA total of 14 patients received 40 Hz for four weeks before crossing over to 10,000 Hz/4000 Hz. A total of 57 PET-CT scans (15 for baseline and 14 each for 40 Hz, 4000 Hz, and 10,000 Hz) were analyzed for maximum standardized uptake value (SUVmax), with a statistically significant difference in SUVmax between 40 Hz and baseline (p = 0.002) and 4000 Hz and baseline (p = 0.001) when pooled across 18 pain matrices. There was no statistical difference in SUVmax between 10,000 Hz and baseline. The pooled analysis showed a proportionately higher thalamic region reduction (59.5%) in metabolic activity than other pain matrices, PFC (52%), insula (50%), ACC (52%), SSCII (49%), and PAG (52%). ConclusionThis large cohort of brain PET scans (n = 57) shows statistically significant differences in brain metabolic activity at 40 Hz and 4000 Hz from baseline, with effect on both nociceptive and affect-cognitive pathways (proportionately higher reduction in the thalamus), highlighting the possible mechanism of SCS. Clinical Trial RegistrationThe Clinicaltrials.gov registration number for the study is NCT03716557.

Comparison between a dual-time-window protocol and other simplified protocols for dynamic total-body 18F-FDG PET imaging

PurposeEfforts have been made both to avoid invasive blood sampling and to shorten the scan duration for dynamic positron emission tomography (PET) imaging. A total-body scanner, such as the uEXPLORER PET/CT, can relieve these challenges through the following features: First, the whole-body coverage allows for noninvasive input function from the aortic arteries; second, with a dramatic increase in sensitivity, image quality can still be maintained at a high level even with a shorter scan duration than usual. We implemented a dual-time-window (DTW) protocol for a dynamic total-body 18F-FDG PET scan to obtain multiple kinetic parameters. The DTW protocol was then compared to several other simplified quantification methods for total-body FDG imaging that were proposed for conventional setup.MethodsThe research included 28 patient scans performed on an uEXPLORER PET/CT. By discarding the corresponding data in the middle of the existing full 60-min dynamic scan, the DTW protocol was simulated. Nonlinear fitting was used to estimate the missing data in the interval. The full input function was obtained from 15 subjects using a hybrid approach with a population-based image-derived input function. Quantification was carried out in three areas: the cerebral cortex, muscle, and tumor lesion. Micro- and macro-kinetic parameters for different scan durations were estimated by assuming an irreversible two-tissue compartment model. The visual performance of parametric images and region of interest-based quantification in several parameters were evaluated. Furthermore, simplified quantification methods (DTW, Patlak, fractional uptake ratio [FUR], and standardized uptake value [SUV]) were compared for similarity to the reference net influx rate Ki.ResultsKi and K1 derived from the DTW protocol showed overall good consistency (P < 0.01) with the reference from the 60-min dynamic scan with 10-min early scan and 5-min late scan (Ki correlation: 0.971, 0.990, and 0.990; K1 correlation: 0.820, 0.940, and 0.975 in the cerebral cortex, muscle, and tumor lesion, respectively). Similar correlationss were found for other micro-parameters. The DTW protocol had the lowest bias relative to standard Ki than any of the quantification methods, followed by FUR and Patlak. SUV had the weakest correlation with Ki. The whole-body Ki and K1 images generated by the DTW protocol were consistent with the reference parametric images.ConclusionsUsing the DTW protocol, the dynamic total-body FDG scan time can be reduced to 15 min while obtaining accurate Ki and K1 quantification and acceptable visual performance in parametric images. However, the trade-off between quantification accuracy and protocol implementation feasibility must be considered in practice. We recommend that the DTW protocol be used when the clinical task requires reliable visual assessment or quantifying multiple micro-parameters; FUR with a hybrid input function may be a more feasible approach to quantifying regional metabolic rate with a known lesion position or organs of interest.

Amyloid pathology induces dysfunction of systemic neurotransmission in aged APPswe/PS2 mice.

This study aimed to investigate how amyloid pathology affects the functional aspects of neurotransmitter systems in Alzheimer’s disease. APPswe/PS2 mice (21 months of age) and wild-type (WT) mice underwent positron emission tomography (PET) and magnetic resonance spectroscopy (MRS). First, we obtained 18F-FDG and 18F-florbetaben PET scans to evaluate neuronal integrity and amyloid pathology. Second, 18F-FPEB and 18F-FMZ PET data were acquired to assess the excitatory-inhibitory neurotransmission. Third, to monitor the dopamine system, 18F-fallypride PET was performed. Amyloid PET imaging revealed that radioactivity was higher in the AD group than that in the WT group, which was validated by immunohistochemistry. In the cortical and limbic areas, the AD group showed a 25–27% decrease and 14–35% increase in the glutamatergic and GABAergic systems, respectively. The dopaminergic system in the AD group exhibited a 29% decrease in brain uptake compared with that in the WT group. A reduction in glutamate, N-acetylaspartate, and taurine levels was observed in the AD group using MRS. Our results suggest that dysfunction of the neurotransmitter system is associated with AD pathology. Among the systems, the GABAergic system was prominent, implying that the inhibitory neurotransmission system may be the most vulnerable to AD pathology.

Prognostic impact of an integrative analysis of [18F]FDG PET parameters and infiltrating immune cell scores in lung adenocarcinoma

BackgroundHigh levels of 18F-fluorodeoxyglucose (18F-FDG) tumor uptake are associated with worse prognosis in patients with non-small cell lung cancer (NSCLC). Meanwhile, high levels of immune cell infiltration in primary tumor have been linked to better prognosis in NSCLC. We conducted this study for precisely stratified prognosis of the lung adenocarcinoma patients using the integration of 18F-FDG positron emission tomography (PET) parameters and infiltrating immune cell scores as assessed by a genomic analysis.ResultsUsing an RNA sequencing dataset, the patients were divided into three subtype groups. Additionally, 24 different immune cell scores and cytolytic scores (CYT) were obtained. In 18F-FDG PET scans, PET parameters of the primary tumors were obtained. An ANOVA test, a Chi-square test and a correlation analysis were also conducted. A Kaplan–Meier survival analysis with the log-rank test and multivariable Cox regression test was performed to evaluate prognostic values of the parameters. The terminal respiratory unit (TRU) group demonstrated lower 18F-FDG PET parameters, more females, and lower stages than the other groups. Meanwhile, the proximal inflammatory (PI) group showed a significantly higher CYT score compared to the other groups (P = .001). Also, CYT showed a positive correlation with tumor-to-liver maximum standardized uptake value ratio (TLR) in the PI group (P = .027). A high TLR (P = .01) score of 18F-FDG PET parameters and a high T follicular helper cell (TFH) score (P = .005) of immune cell scores were associated with prognosis with opposite tendencies. Furthermore, TLR and TFH were predictive of overall survival even after adjusting for clinicopathologic features and others (P = .024 and .047).ConclusionsA high TLR score was found to be associated with worse prognosis, while high CD8 T cell and TFH scores predicted better prognosis in lung adenocarcinoma. Furthermore, TLR and TFH can be used to predict prognosis independently in patients with lung adenocarcinoma.

Diffuse Thyroid Uptake in FDG PET/ CT Scan cCan Predict Subclinical Thyroid Disorders

     Background: 18F-FDG positron emission tomography (PET) has established itself in the field of oncology and it is useful in the initial staging and follow-up of a variety of malignancies. Significant thyroid uptake is often identified as an accidental finding on whole-body positron emission tomography for non-thyroid disease. Aim of this study: to investigate the effect of 18F-FDG on thyroid gland function after performing PET scan compared to thyroid function prior to scan. Materials and Methods:  43 subjects who had an 18F-FDG PET scan as part of a cancer screening program participated in this study. All cancers  are diagnosed using 18F-FDG, except for prostate cancer, brain cancer and neuro-endocrine tumors, which  are diagnosed using Ga-68. Thyroid stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3) were measured. Results: Clinical information and results of thyroid function tests were available for 43 patients. Twenty- three out of 43 patients (53.48%) had abnormally high TSH levels with incident hypothyroidism, while 20 out of 43 patients (46.51%) had abnormally low TSH levels with incident hyperthyroidism, and the association was significant (p &lt;0.05). Conclusion: Thyroid hormone abnormality is strongly associated with the degree of diffuse thyroid uptake on 18F-FDG PET. As a result, an autoimmune process could be the most likely pathological cause of diffuse thyroid uptake.

Comparative study between 18F-FDG PET scan and conventional CT in assessment of non-small cell lung cancer patients after treatment

Background: Lung cancer is one of the most common malignancies worldwide. Hence, timely diagnosis and accurate staging of the carcinoma as well as strict follow up is critical for better prognosis. Imaging studies play a key role in post-treatment follow up of patients with lung cancer. Positron emission tomography (PET) scanning has developed as an important tool in the multi-disciplinary management of lung cancer. The combination of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) has a great impact on the diagnosis, staging, and hence on the follow up of lung cancer patients compared to conventional CT study only. Methods: A retrospective comparative study conducted on 15 patients histopathologically proven to have NSCLC. Conclusion: 18F-FDG PET scan had a superior role in monitoring tumor turn over in case of no appreciable time interval changes in its size according to the CT.

Unified Deep Learning-Based Mouse Brain MR Segmentation: Template-Based Individual Brain Positron Emission Tomography Volumes-of-Interest Generation Without Spatial Normalization in Mouse Alzheimer Model.

Although skull-stripping and brain region segmentation are essential for precise quantitative analysis of positron emission tomography (PET) of mouse brains, deep learning (DL)-based unified solutions, particularly for spatial normalization (SN), have posed a challenging problem in DL-based image processing. In this study, we propose an approach based on DL to resolve these issues. We generated both skull-stripping masks and individual brain-specific volumes-of-interest (VOIs—cortex, hippocampus, striatum, thalamus, and cerebellum) based on inverse spatial normalization (iSN) and deep convolutional neural network (deep CNN) models. We applied the proposed methods to mutated amyloid precursor protein and presenilin-1 mouse model of Alzheimer’s disease. Eighteen mice underwent T2-weighted MRI and 18F FDG PET scans two times, before and after the administration of human immunoglobulin or antibody-based treatments. For training the CNN, manually traced brain masks and iSN-based target VOIs were used as the label. We compared our CNN-based VOIs with conventional (template-based) VOIs in terms of the correlation of standardized uptake value ratio (SUVR) by both methods and two-sample t-tests of SUVR % changes in target VOIs before and after treatment. Our deep CNN-based method successfully generated brain parenchyma mask and target VOIs, which shows no significant difference from conventional VOI methods in SUVR correlation analysis, thus establishing methods of template-based VOI without SN.

18F-FDG positron emission tomography scanning in systemic sclerosis-associated interstitial lung disease: a pilot study

BackgroundInterstitial lung disease is a common complication of systemic sclerosis (SSc-ILD), and it remains difficult to accurately predict its course. Progressing ILD could be more metabolically active, suggesting that the 18F-FDG tracer could be a tool in the managing of SSc-ILD.MethodsIn our center, SSc patients and controls (non-Hodgkin lymphoma cured after first-line regimen) who had received a PET/CT were screened retrospectively. The FDG uptake (visual intensity, pattern, SUVmax) was systematically recorded in > 30 regions of interest (ROIs) linked to SSc in a blind reviewing by 2 independent nuclear medicine physicians using a standardized form.ResultsAmong the 545 SSc patients followed up in our center, 36, including 22 SSc-ILDs, had a PET/CT, whose indication was cancer screening in most cases. The mean ± SD age was 57.9 ± 13.0 years with 20/36 females. Fourteen patients had a disease duration of less than 2 years. A third had anti-centromere antibodies and 27.8% had anti-topoisomerase antibodies. Pulmonary FDG uptakes were higher in SSc patients than in controls (n = 89), especially in those with ILD compared with those without ILD. Pulmonary FDG uptakes were positively correlated with the ILD severity (fibrosis extent, %FVC, and %DLCO). No significant difference was found in the FDG uptakes from extrathoracic ROIs. Progressing SSc-ILDs within the 2 years after PET/CT (n = 9) had significant higher pulmonary FDG uptakes at baseline than stable SSc-ILDs (n = 13).ConclusionPET/CT could be a useful tool in the assessment of the severity and the prediction of pulmonary function outcome of SSc-ILD.

Liver tumor F-18 FDG-PET before and immediately after microwave ablation enables imaging and quantification of tumor tissue contraction.

Poor liver tumor visibility after microwave ablation (MWA) limits direct tumor ablation margin assessments using contrast-enhanced CT or ultrasound (US). Positron emission tomography (PET) or PET/CT may offer improved intraprocedural assessment of liver tumor ablation margins versus current imaging techniques, as 18F-fluorodeoxyglucose (18F-FDG)-avid tumors remain visible on PET immediately following ablation. The purpose of this study was to assess intraprocedural 18F-FDG PET scans before and immediately after PET/CT-guided MWA for visualization and quantification of metabolic liver tumor tissue contraction resulting from MWA. This retrospective study, conducted at a large academic medical center after Institutional Review Board approval, included 36 patients (20 men; mean age 63 [range 37-85]) who underwent PET/CT-guided MWA of 42 18F-FDG-avid liver tumors from May 2013 to March 2018. Tumor metabolic diameters (short/long axes) were measured for each tumor on pre- and post-ablation PET images. Tumor metabolic volumes were calculated using tumor diameter measurements and compared with automated volumes using an SUV threshold algorithm. A two-tailed paired t test was used for the analyses. Comparing intraprocedural pre- and post-ablation PET images, mean metabolic tumor short- and long-axis diameters decreased from 21.4 to 14.9 mm [- 29%, p < 0.001, standard deviation (SD) 18%] and from 24.0 to 18.0 mm (- 24%, p < 0.001, SD 16%), respectively. The mean calculated tumor metabolic volume decreased from 10.5 to 4.6 mm3 (- 55%, p < 0.001, SD 26%). The mean automated tumor metabolic volume decreased from 10.6 to 5.8 mm3 (- 45%, p < 0.001, SD 30%). Intraprocedural PET images of 18F-FDG-avid liver tumors allow visualization and quantification of MWA-induced metabolic tumor tissue contraction during 18F-FDG PET/CT-guided procedures. The ability to visualize contracted tumor immediately post-MWA may facilitate emerging intraprocedural PET and PET/CT imaging techniques that address a clinical gap in directly assessing the ablation margin.

Metabolic network as an objective biomarker in monitoring deep brain stimulation for Parkinson\u2019s disease: a longitudinal study

BackgroundWith the advance of subthalamic nucleus (STN) deep brain stimulation (DBS) in the treatment of Parkinson’s disease (PD), it is desired to identify objective criteria for the monitoring of the therapy outcome.This paper explores the feasibility of metabolic network derived from positron emission tomography (PET) with 18F-fluorodeoxyglucose in monitoring the STN DBS treatment for PD.MethodsAge-matched 33 PD patients, 33 healthy controls (HCs), 9 PD patients with bilateral DBS surgery and 9 controls underwent 18F-FDG PET scans. The DBS patients were followed longitudinally to investigate the alternations of the PD-related metabolic covariance pattern (PDRP) expressions.ResultsThe PDRP expression was abnormally elevated in PD patients compared with HCs (P < 0.001). For DBS patients, a significant decrease in the Unified Parkinson’s Disease Rating Scale (UPDRS, P = 0.001) and PDRP expression (P = 0.004) was observed 3 months after STN DBS treatment, while a rollback was observed in both UPDRS and PDRP expressions (both P < 0.01) 12 months after treatment. The changes in PDRP expression mediated by STN DBS were generally in line with UPDRS improvement. The graphical network analysis shows increased connections at 3 months and a return at 12 months confirmed by small-worldness coefficient.ConclusionsThe preliminary results demonstrate the potential of metabolic network expression as complimentary objective biomarker for the assessment and monitoring of STN DBS treatment in PD patients.Clinical Trial Registration ChiCTR-DOC-16008645. http://www.chictr.org.cn/showproj.aspx?proj=13865.

Semi-quantitative analysis of 18F fluorodeoxyglucose uptake in the assessment of disease activity and therapeutic response in rheumatoid arthritis: An institutional experience.

18F fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) can be used to image synovial inflammation in patients with rheumatoid arthritis (RA). Recently, clinical application of novel therapies for RA, such as tumor necrosis factor-α (TNF-α) inhibitor and anti-interleukin-6 receptor antibody, has been introduced. The radiological assessment of disease activity changes of patients who underwent these therapies will help the clinicians to obtain more information about the patients and to decide drug withdrawal or change of medication. It is considered that 18F-FDG PET scan is generally very expensive; however, the information from 18F-FDG PET about patients during biological treatments helps discontinuation of these treatments with incomplete response despite its high costs and with possible side effects such as malignant lymphoma. In this study, we evaluated if the 18F-FDG uptake of the affected joints represented by standardized uptake value (SUV) correlated with the clinical assessment of patients with RA. In addition, we would like to evaluate if there was a correlation between the difference of SUV and improvement of clinical findings in RA patients undergoing anti TNF therapies. RA patients who underwent anti-TNFα therapies in a tertiary care hospital were assessed using whole-body 18F-FDG PET/computed tomography (CT). PET assessments were performed on hip joints, knees, shoulders, wrists, ankles, MCP, and PIP for a total of 28 joints in each patient. The 18F–FDG uptake was then quantified using the maximum SUV (SUVmax) prior to, and 6 months after the initiation of treatment with anti-TNF-α drugs. Disease activity score (DAS28 and DAS28-C-reactive protein [CRP]) were recorded and white blood cell, matrix metalloproteinases (MMP-3) and rheumatoid factor (RF) were examined in all patients. The average of SUVmax among measured joints, or the sum of these joints (total SUVmax), correlated with DAS28 (r = 0.671, P < 0.001), DAS28-CRP (r = 0.623, P < 0.001), ESR (r = 0.542, P < 0.001), CRP (r = 0.411, P = 0.002), MMP-3 (r = 0.399, P = 0.006), and RF (r = 0.447, P = 0.002). There were correlations between ΔSUV and ΔDAS28 (r = 0.651, P < 0.001), ΔSUV and ΔDAS28-CRP (r = 0.682, P < 0.001), ΔSUV and ΔESR (r = 0.449, P = 0.023), and ΔSUV and ΔMMP-3 (r = 0.457, P = 0.027), respectively. The number of PET-positive joints and the cumulative SUV significantly correlated with the DAS28, which is a composite disease activity score (DAS) that combines the swollen and tender joint counts, the erythrocyte sedimentation rate (DAS28-ESR) or CRP serum levels (DAS28 − CRP) or RF (DAS28 − RF) or metalloproteinases-3 (DAS28-MMP-3). At baseline and at 6 months' post-treatment with anti-TNFα drugs, there was a significant correlation between the PET results, either visual, the cumulative SUVs or the composite SUV index, and the comprehensive clinical assessment (DAS28), the CRP levels and the number of joints positive for RA, and cumulative synovial thickness. By reflecting inflammatory activity, 18F-FDG PET may enhance the diagnostic performance and expectation of disease prognosis in RA, especially with early synovial inflammation. The intensity of uptake varied from mild to intense (SUVmax values from 3.10 to 6.0). Overall, these values correlated well with the clinical evaluation of involved joints. 18F–FDG PET imaging data provided a distribution of joint involvement with varying degrees of severity and phase of disease activity (moderate, low, and remission) in the same patient. PET/CT imaging with 18F-FDG shows better image quality, provides more confirmative diagnostic information, and will be promising imaging modality in diagnosis and management of RA.

Delayed effects of a single-dose whole-brain radiation therapy on glucose metabolism and myelin density: a longitudinal PET study

Purpose Radiotherapy is an important treatment option for brain tumors, but the unavoidable irradiation of normal brain tissue can lead to delayed cognitive impairment. The mechanisms involved are still not well explained and, therefore, new tools to investigate the processes leading to the delayed symptoms of brain irradiation are warranted. In this study, positron emission tomography (PET) is used to explore delayed functional changes induced by brain irradiation. Materials and methods Male Wistar rats were subjected to a single 25-Gy dose of whole brain X-ray irradiation, or sham-irradiation. To investigate delayed effects of radiation on cerebral glucose metabolism and myelin density, 18F-fluorodeoxyglucose (18F-FDG) PET scans were performed at baseline and on day 64 and 94, whereas N-11C-methyl-4,4′-diaminostilbene (11C-MeDAS) PET scans were performed at baseline and on day 60 and 90 post-irradiation. In addition, the open field test (OFT) and novel spatial recognition (NSR) test were performed at baseline and on days 59 and 89 to investigate whether whole brain irradiation induces behavioral changes. Results Whole-brain irradiation caused loss of bodyweight and delayed cerebral hypometabolism, with 18F-FDG uptake in all brain regions being significantly decreased in irradiated rat on day 64 while it remained unchanged in control animals. Only amygdala and cortical brain regions of irradiated rats still showed reduced 18F-FDG uptake on day 94. 11C-MeDAS uptake in control animals was significantly lower on days 60 and 90 than at the baseline, suggesting a reduction in myelin density in young adults. In irradiated animals, 11C-MeDAS uptake was similarly reduced on day 60, but on day 90 tracer uptake was somewhat increased and not significantly different from baseline anymore. Behavioral tests showed a similar pattern in control and irradiated animals. In both groups, the OFT showed significantly reduced mobility on days 59 and 89, whereas the NSR did not reveal any significant changes in spatial memory over time. Interestingly, a positive correlation between the NSR and 11C-MeDAS uptake was observed in irradiated rats. Conclusions Whole-brain irradiation causes delayed brain hypometabolism, which is not accompanied by white matter loss. Irradiated animals showed similar behavioral changes over time as control animals and, therefore, cerebral hypometabolism could not be linked to behavioral abnormalities. However, spatial memory seems to be associated with myelin density in irradiated rats.

Neuroinflammation in frontotemporal lobar degeneration revealed by 11 C-PBR28 PET.

This study used 11C‐PBR28 positron emission tomography (PET) imaging to determine whether levels of 18‐kDa translocator protein (TSPO), an inflammation‐specific biomarker, are increased in frontotemporal lobar degeneration (FTLD) patients. 11C‐PBR28, 18F‐FDG, and 11C‐PIB brain PET scans, as well as magnetic resonance imaging (MRI), were conducted in four FTLD patients and 22 healthy controls. 11C‐PBR28 scans revealed that all FTLD patients showed increased TSPO binding versus controls. Significantly greater increases in TSPO were observed in the frontal, lateral temporal, parietal, and occipital cortices, topographically consistent with individual clinical phenotypes and with brain MRI and 18F‐FDG PET. Amyloid burden was not increased.

Impact of different image reconstructions on PET quantification in non-small cell lung cancer: a comparison of adenocarcinoma and squamous cell carcinoma

Positron emission tomography (PET) using 18F-fludeoxyglucose (18F-FDG) is an established imaging modality for tumor staging in patients with non-small cell lung cancer (NSCLC). There is a growing interest in using 18F-FDG PET for therapy response assessment in NSCLC which relies on quantitative PET parameters such as standardized uptake values (SUV). Different reconstruction algorithms in PET may affect SUV. We sought to determine the variation of SUV in patients with NSCLC when using ordered subset expectation maximization (OSEM) and block sequential regularized expectation maximization (BSREM) in latest-generation digital PET/CT, including a subanalysis for adenocarcinoma and squamous cell carcinoma. A total of 58 patients (34 = adenocarcinoma, 24 = squamous cell carcinoma) who underwent a clinically indicated 18F-FDG PET/CT for staging were reviewed. PET images were reconstructed with OSEM and BSREM reconstruction with noise penalty strength β-levels of 350, 450, 600, 800 and 1200. Lung tumors maximum standardized uptake value (SUVmax) were compared. Lung tumors SUVmax were significantly lower in adenocarcinomas compared to squamous cell carcinomas in all reconstructions evaluated (all p < 0.01). Comparing BSREM to OSEM, absolute SUVmax differences were highest in lower β-levels of BSREM with + 2.9 ± 1.6 in adenocarcinoma and + 4.0 ± 2.9 in squamous cell carcinoma (difference between histology; p-values > 0.05). There was a statistically significant difference of the relative increase of SUVmax in adenocarcinoma (mean + 34.8%) and squamous cell carcinoma (mean 23.4%), when using BSREM350 instead of OSEMTOF (p < 0.05). In NSCLC the relative change of SUV when using BSREM instead of OSEM is significantly higher in adenocarcinoma as compared to squamous cell carcinoma. The impact of BSREM on SUV may vary in different histological subtypes of NSCLC. This highlights the importance for careful standardization of β-value used for serial 18F-FDG PET scans when following-up NSCLC patients.