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Immune checkpoint inhibitors (ICI) represent the backbone treatment for advanced non-small cell lung cancer (NSCLC). Emerging data suggest that increased gut microbiome diversity is associated with favorable response to ICI and that antibiotic-induced dysbiosis is associated with deleterious outcomes. 18F-FDG physiologic colonic uptake on PET/CT increases following treatment with antibiotics (ATB) and could act as a surrogate marker for microbiome composition and predict prognosis. The aim of this study was to determine if 18F-FDG physiologic colonic uptake prior to ICI initiation correlates with gut microbiome profiling and clinical outcomes in patients with advanced NSCLC. Seventy-one patients with advanced NSCLC who underwent a PET/CT prior to ICI were identified. Blinded colonic contouring was performed for each colon segment and patients were stratified according to the median of the average colon SUVmax as well as for each segment in low vs. high SUVmax groups. Response rate, progression-free survival (PFS), and overall survival (OS) were compared in the low vs. high SUVmax groups. Gut microbiome composition was analyzed for 23 patients using metagenomics sequencing. The high colon SUVmax group had a higher proportion of non-responders (p = 0.033) and significantly shorter PFS (4.1 vs. 11.3 months, HR 1.94, 95% CI 1.11–3.41, p = 0.005). High caecum SUVmax correlated with numerically shorter OS (10.8 vs. 27.6 months, HR 1.85, 95% CI 0.97–3.53, p = 0.058). Metagenomics sequencing revealed distinctive microbiome populations in each group. Patients with low caecum SUVmax had higher microbiome diversity (p = 0.046) and were enriched with Bifidobacteriaceae, Lachnospiraceae, and Bacteroidaceae. Lower colon physiologic 18F-FDG uptake on PET/CT prior to ICI initiation was associated with better clinical outcomes and higher gut microbiome diversity in patients with advanced NSCLC. Here, we propose that 18F-FDG physiologic colonic uptake on PET/CT could serve as a potential novel marker of gut microbiome composition and may predict clinical outcomes in this population.

We consider the Stokes-transport system, a model for the evolution of an incompressible viscous fluid with inhomogeneous density. This equation was already known to be globally well-posed for any L 1 ∩ L ∞ initial density with finite first moment in R 3 . We show that similar results hold on different domain types. We prove that the system is globally well-posed for L ∞ initial data in bounded domains of R 2 and R 3 as well as in the infinite strip R × ( 0 , 1 ) . These results contrast with the ill-posedness of a similar problem, the incompressible porous medium equation, for which uniqueness is known to fail for such a density regularity.

Objectives The change in tumor fluorodeoxyglucose (FDG) uptake by positron emission tomography (PET) scan after one cycle of platinum-based chemotherapy has been shown to predict progression-free and overall survival (PFS and OS) among advanced non-small cell lung cancer (NSCLC) patients. Using early FDG-PET response to determine subsequent chemotherapy, we aim to evaluate the role that adaptive chemotherapy regimens have on later CT response, PFS, and OS in patients with advanced NSCLC. Materials and Methods Chemotherapy-naive patients with metastatic NSCLC received carboplatin and paclitaxel (CP) on day one and repeated FDG-PET on day 18. PET-responding patients continued CP chemotherapy for a total of four cycles. PET non-responders were switched to alternate docetaxel and gemcitabine (DG) for three additional cycles. The primary outcome was the CT Response Evaluation Criteria in Solid Tumors (RECIST 1.0) response. Secondary endpoints included PFS and OS. Results Forty-six patients initiated treatment with chemotherapy on trial and were evaluable by PET/CT. Of these, 19 (41%) met the FDG-PET criteria for the response after a single cycle of CP. Only one non-responding patient had a CT response. Despite the lack of CT response in the DG arm, no trend for worse PFS or OS was seen between the two arms. Conclusions This work demonstrates that changing chemotherapy in the event of non-response by PET did not lead to improved CT RECIST response. However, non-responding patients who switched chemotherapy had similar PFS and OS to those who responded by PET and continued the same regimen.

Immune checkpoint inhibitors (ICI) represent the backbone treatment for advanced non-small cell lung cancer (NSCLC). Emerging data suggest that increased gut microbiome diversity is associated with favorable response to ICI and that antibiotic-induced dysbiosis is associated with deleterious outcomes.Seventy-one patients with advanced NSCLC who underwent a PET/CT prior to ICI were identified. Blinded colonic contouring was performed for each colon segment and patients were stratified according to the median of the average colon SUVThe high colon SUVLower colon physiologic

The peritoneum is the largest and most complex serous membrane in the human body. The peritoneal membrane is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum is one continuous sheet, forming two layers and a potential space between them - the peritoneal cavity- which is subdivided into multiple communicating spaces containing small amount of serous fluid that facilitates frictionless movement of mobile intraabdominal viscera. Peritoneum also contributes to fluid exchange mechanism and plays a role in immune response. The peritoneum is subject to many neoplastic and non-neoplastic processes including infections, trauma, developmental and inflammatory processes. Different Nuclear Medicine imaging techniques can be used to diagnose peritoneal diseases, most of these techniques can be customized depending on the clinical scenario and expected findings. Peritoneal scintigraphy can detect abnormal peritoneal communication or compartmentalization. Several nuclear medicine techniques can help characterize intraperitoneal fluid collections and differentiate sterile from infected fluid. PET imaging plays an important role in imaging of different neoplastic and non-neoplastic peritoneal pathologies. Nuclear radiologists need to be familiar with peritoneal anatomy and pathology to interpret peritoneal findings in dedicated peritoneal nuclear medicine imaging studies, as part of more general nuclear medicine scans, or on CT or MRI component of hybrid imaging studies. The purpose of this article is to review the normal peritoneal anatomy, various pathologic processes involving the peritoneum, and different nuclear medicine and hybrid imaging techniques that can help detect, characterize, and follow up peritoneal pathology.

[18 F]DCFPyL is a clinical-stage PET radiotracer used to image prostate cancer. This report details the efficient production of [18 F]DCFPyL using single-step direct radiofluorination, without the use of carboxylic acid-protecting groups. Radiolabeling reaction optimization studies revealed an inverse correlation between the amount of precursor used and the radiochemical yield. This simplified approach enabled automated preparation of [18 F]DCFPyL within 28 minutes using HPLC purification (26% ± 6%, at EOS, n = 4), which was then scaled up for large-batch production to generate 1.46 ± 0.23 Ci of [18 F]DCFPyL at EOS (n = 7) in high molar activity (37 933 ± 4158 mCi/μmol, 1403 ± 153 GBq/μmol, at EOS, n = 7). Further, this work enabled the development of [18 F]DCFPyL production in 21 minutes using an easy cartridge-based purification (25% ± 9% radiochemical yield, at EOS, n = 3).

Planar perfusion scintigraphy with 99mTc-labeled macroaggregated albumin is often used for pretherapy quantification of regional lung perfusion in lung cancer patients, particularly those with poor respiratory function. However, subdividing lung parenchyma into rectangular regions of interest, as done on planar images, is a poor reflection of true lobar anatomy. New tridimensional methods using SPECT and SPECT/CT have been introduced, including semiautomatic lung segmentation software. The present study evaluated inter- and intraobserver agreement on quantification using SPECT/CT software and compared the results for regional lung contribution obtained with SPECT/CT and planar scintigraphy. Methods: Thirty lung cancer patients underwent ventilation-perfusion scintigraphy with 99mTc-macroaggregated albumin and 99mTc-Technegas. The regional lung contribution to perfusion and ventilation was measured on both planar scintigraphy and SPECT/CT using semiautomatic lung segmentation software by 2 observers. Interobserver and intraobserver agreement for the SPECT/CT software was assessed using the intraclass correlation coefficient, Bland-Altman plots, and absolute differences in measurements. Measurements from planar and tridimensional methods were compared using the paired-sample t test and mean absolute differences. Results: Intraclass correlation coefficients were in the excellent range (above 0.9) for both interobserver and intraobserver agreement using the SPECT/CT software. Bland-Altman analyses showed very narrow limits of agreement. Absolute differences were below 2.0% in 96% of both interobserver and intraobserver measurements. There was a statistically significant difference between planar and SPECT/CT methods (P < 0.001) for quantification of perfusion and ventilation for all right lung lobes, with a maximal mean absolute difference of 20.7% for the right middle lobe. There was no statistically significant difference in quantification of perfusion and ventilation for the left lung lobes using either method; however, absolute differences reached 12.0%. The total right and left lung contributions were similar for the two methods, with a mean difference of 1.2% for perfusion and 2.0% for ventilation. Conclusion: Quantification of regional lung perfusion and ventilation using SPECT/CT-based lung segmentation software is highly reproducible. This tridimensional method yields statistically significant differences in measurements for right lung lobes when compared with planar scintigraphy. We recommend that SPECT/CT-based quantification be used for all lung cancer patients undergoing pretherapy evaluation of regional lung function.

9600 Background: Immune checkpoint inhibitors (ICI) represent the backbone treatment of advanced non-small cell lung cancer (aNSCLC) patients. Emerging evidence suggests increased gut microbiome (GM) diversity is associated with favorable response. Conversely, antibiotic-induced dysbiosis may be associated with deleterious outcomes in patients receiving ICI in multiple retrospective studies and one prospective study. 18F-FDG physiologic colonic uptake on PET/CT increases following treatment with antibiotics and could be a surrogate marker for GM diversity and therefore clinical response. The aim of this study was to determine if 18F-FDG physiologic colonic uptake prior to ICI initiation correlates with outcomes and GM metagenomics in patients with advanced NSCLC. Methods: 71 patients with aNSCLC who underwent PET/CT prior to ICI were identified. For each patient, the colon was manually contoured, SUVmax was measured in each segment of the colon by a nuclear medicine specialist and average SUVmax was calculated for the whole colon. Patients were stratified in two groups according to median colon SUVmax (low vs high uptake). 18F-FDG physiologic colonic uptake was then compared to overall survival (OS), objective response (ORR), and progression-free survival (PFS). For patients with available stool samples (n = 10), GM composition was defined using metagenomics sequencing. Results: 71 patients (54% men, median age: 68 years) with aNSCLC were included in the study and ICI was the first line of therapy in 38% of those patients. The mean colon SUV for the low and high uptake groups were 1.41 (CI 95% 1.35-1.47) and 2.18 (CI 95% 1.90-2.46) respectively. The high uptake group had a higher proportion of non-responders (p = 0.033) and significant shorter PFS (4.1 months vs 11.3 months, p = 0.005). In the caecum, high uptake also correlated with numerically shorter OS (10.82 vs 27.56 months, p = 0.058) compared to low uptake group. Despite the low number of samples, metagenomics sequencing revealed that PLS-DA (Partial Least Squares Discriminant Analysis) for diversity was lower in the high SUV group (p = 0.008). Conclusions: Higher colon SUVmax on pre-ICI FDG PET/CT is associated with worse clinical outcomes and lower baseline GM diversity in patients with advanced NSCLC. Here, we propose that 18F-FDG physiologic colonic uptake on PET/CT could serve as a surrogate marker of GM diversity and predicts clinical outcomes.

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FDG PET/CT has been used to help characterize indeterminate pulmonary nodules, and to stage Non-Small Cell Lung Cancer (NSCLC) since January of 1998. The ever-expanding utilization of this modality in oncologic imaging cancer patients presented unique challenges for imagers who may not have received specialized training in the interpretation of PET/CT images. Interpretation of FDG PET/CT is particularly challenging in the thorax where inflammatory processes are common and often coexist with malignancy, rendering accurate tumor staging difficult. This article presents a systematic approach to FDG PET/CT interpretation in lung cancer staging, addressing common confounding situations often encountered. Although this illustrative discussion focuses on lung cancer staging, most of these tips could be applied to other types of cancer as well.

Even with recent hardware improvements, superpixel segmentation of large 3D medical images at interactive speed ( Tasks will be scheduled in blocks (work units) using a wavefront propagation strategy, therefore allowing sparse scheduling. Because work units has been designed as spatially cohesive, the fast Thread Group Shared Memory can be used and reused through a Gauss-Seidel like acceleration. The work unit partitioning scheme will however vary on odd- and even-numbered iterations to reduce convergence barriers. Synchronization will be ensured by an 8-step 3D variant of the traditional Red Black Ordering scheme. An attack model and early termination will also be described and implemented as additional acceleration techniques. Using our hybrid framework and typical operating parameters, we were able to compute the superpixels of a high-resolution 512x512x512 aortic angioCT scan in 283 ms using a AMD R9 290X GPU. We achieved a 22.3X speed-up factor compared to the published reference GPU implementation.

The evaluation of pulmonary nodules constitutes a large part of PET-CT studies. In this study, we aimed to evaluate the different interpretation criteria in F-fluorodeoxyglucose PET attenuation-corrected and non-attenuation-corrected studies as individual predictors of malignancy in order to propose a useful combination of criteria that can be used in daily practice to classify nodules appropriately.We performed a historical prospective survey of all consecutive patients referred to our service for the initial assessment of pulmonary nodules and sought the final characterization of these nodules either from tissue sampling or from radiological and clinical follow-up.A total of 104 nodules from 82 patients were included, with a prevalence of malignancy of 53%. Absence of uptake on non-attenuation-corrected studies was found to be the best predictive criterion for benignancy, with a negative predictive value of 97%, and the highest relative risk for malignancy, with a value of 20.9. Uptake higher than that of the mediastinum on attenuation-corrected images was found to be the best criterion for predicting malignancy, with a positive predictive value of 89% and a sensitivity of 73%, which is slightly better than the use of a maximal standardized uptake value cutoff of 3.0. By combining our best negative and positive criteria, we were able to classify 71% (74/104) of the lung nodules with a high level of confidence. More specifically, these two criteria allowed the correct classification of 72% (40/55) of malignant nodules and 57% (28/49) of benign nodules. The 30 remaining nodules were equally distributed in terms of malignancy and had similar characteristics on both PET and CT images.A probabilistic approach to pulmonary nodule characterization may help the reading physician to appropriately classify lung nodules into useful categories for the treating physician, moving away from nonstandardized reporting terms.

We report the first, to our knowledge, findings describing the relationships between both static and dynamic analysis parameters of 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) PET and the expression of the proliferation marker Ki-67, and the protein expression and enzymatic activity of thymidine kinase-1 (TK1) in surgically resected lung lesions.Static and dynamic analyses (4 rate constants and 2 compartments) of (18)F-FLT PET images were performed in a cohort of 25 prospectively accrued, clinically suspected lung cancer patients before surgical resection (1 lesion was found to be benign after surgery). The maximal and overall averaged expression of Ki-67 and TK1 were determined by semiquantitative analysis of immunohistochemical staining. TK1 enzymatic activity was determined by in vitro assay of extracts prepared from flash-frozen samples of the same tumors.Static (18)F-FLT uptake (partial-volume-corrected maximum-pixel standardized uptake value from 60- to 90-min summed dynamic data) was significantly correlated with the overall (ρ = 0.57, P = 0.006) and maximal (ρ = 0.69, P0.001) immunohistochemical expressions of Ki-67 and TK1 (overall expression: ρ = 0.65, P = 0.001; maximal expression: ρ = 0.68, P0.001) but not with TK1 enzymatic activity (ρ = 0.34, P = 0.146). TK1 activity was significantly correlated with TK1 protein expression only when immunohistochemistry was scored for maximal expression (ρ = 0.52, P = 0.029). Dynamic analysis of (18)F-FLT PET revealed correlations between the flux constant (K(FLT)) and both overall (ρ = 0.53, P = 0.014) and maximal (ρ = 0.50, P = 0.020) TK1 protein expression. K(FLT) was also associated with both overall (ρ = 0.59, P = 0.005) and maximal (ρ = 0.63, P = 0.002) Ki-67 expression. We observed no significant correlations between TK1 enzyme activity and K(FLT). In addition, no significant relationships were found between TK1 expression, TK1 activity, or Ki-67 expression and any of the compartmental rate constants.The absence of observable correlations of the imaging parameters with TK1 activity suggests that (18)F-FLT uptake and retention within cells may be complicated by a variety of still undetermined factors in addition to TK1 enzymatic activity.