Search

Background and purpose: Total hip arthroplasty (THA) is usually performed using 1 of 3 surgical approaches: direct lateral (DLA), posterior (PA), or anterior (AA). AA is different from DLA and PA owing to limited intraoperative visibility of the femoral canal. This could affect stem positioning and therefore migration. We aimed to perform an exploratory radiostereometric analysis (RSA) study with 3 groups for surgical approach assessing stem migration up to 5 years postoperatively. Patients and methods: 61 patients with unilateral osteoarthritis of the hip were included. 21 patients were allocated to the DLA, 20 to the PA, and 20 to the AA group. All patients received an uncemented, collarless, double-tapered, fully hydroxyapatite-coated Profemur Gladiator stem. Migration was measured with model-based RSA. Baseline RSA was on day 1 postoperatively. The follow-ups were at day 8, at 5 weeks, and at 3, 6, 12, 24, and 60 months after surgery. Generalized linear mixed models were used to analyze maximum total point motion (MTPM) migrations. Results: Group mean differences in MTPM were 0.4 mm (95% confidence interval [CI] –1.5 to 2.4) for DLA vs. PA, 1.1 mm (CI –1.0 to 3.3) for AA vs. DLA, and 1.6 mm (CI –0.8 to 3.9) for AA vs. PA, when adjusted for sex and age as covariates. 2 stems in the AA group had excessive early migration. For all stems the migrations occurred mainly within 5-week follow-up and then stabilized. Conclusion: At 5-year follow-up, there were no statistically significant differences in stem migration associated with the 3 surgical approaches used in this study.

Background and purpose: Studies evaluating pain and patient-reported outcome measures (PROMs) related to type of revision total hip arthroplasty (rTHA) are sparse. Our aim was to compare pain, physical function, quality of life, and patient satisfaction among different types of aseptic rTHA at 1-year follow-up. Patients and methods: We performed a retrospective study from an institutional registry with 426 primary THAs scheduled for rTHA in a fast-track setting between 2012 and 2021. Revisions were grouped by 4 types of surgery: head and/or liner exchange, cup revision, stem revision, and cup and stem revision. Pain during mobilization and at rest (NRS 0–10), physical function (HOOS-PS and HHS) and health-related quality of life (EQ-5D) were registered preoperatively, at 3 months, and 1 year postoperatively. Patient satisfaction was surveyed at the 1-year follow-up by 2 questions related to hip function and willingness to undergo the same surgery. Results: With a response rate of 85%, all outcomes improved in the 4 groups but there were neither statistical nor clinical differences between types of rTHA at 1-year follow-up. NRS pain during mobilization improved overall by 2.7 (95% confidence interval 2.3–3.1) until 1-year follow-up, both being statistically significant and clinically relevant. The improvements were mainly seen at the 3-month follow-up, with minor progress observed at 1 year. About 80% reported improved hip function and willingness to undergo the surgery again at the 1-year follow-up. Conclusion: Significant improvements in NRS pain and PROMS were found in all groups after rTHA, with no group differences at 1 year. This is relevant preoperative information for both clinicians and patients eligible for rTHA.

Abstract Background Machine learning studies require a large number of images often obtained on different PET scanners. When merging these images, the use of harmonized images following EARL-standards is essential. However, when including retrospective images, EARL accreditation might not have been in place. The aim of this study was to develop a convolutional neural network (CNN) that can identify retrospectively if an image is EARL compliant and if it is meeting older or newer EARL-standards. Materials and methods 96 PET images acquired on three PET/CT systems were included in the study. All images were reconstructed with the locally clinically preferred, EARL1, and EARL2 compliant reconstruction protocols. After image pre-processing, one CNN was trained to separate clinical and EARL compliant reconstructions. A second CNN was optimized to identify EARL1 and EARL2 compliant images. The accuracy of both CNNs was assessed using fivefold cross-validation. The CNNs were validated on 24 images acquired on a PET scanner not included in the training data. To assess the impact of image noise on the CNN decision, the 24 images were reconstructed with different scan durations. Results In the cross-validation, the first CNN classified all images correctly. When identifying EARL1 and EARL2 compliant images, the second CNN identified 100% EARL1 compliant and 85% EARL2 compliant images correctly. The accuracy in the independent dataset was comparable to the cross-validation accuracy. The scan duration had almost no impact on the results. Conclusion The two CNNs trained in this study can be used to retrospectively include images in a multi-center setting by, e.g., adding additional smoothing. This method is especially important for machine learning studies where the harmonization of images from different PET systems is essential.

Abstract Background FDG-PET/CT has a high negative predictive value to detect residual nodal disease in patients with locally advanced squamous cell head and neck cancer after completing concurrent chemoradiotherapy (CCRT). However, the positive predictive value remains suboptimal due to inflammation after radiotherapy, generating unnecessary further investigations and possibly even surgery. We report the results of a preplanned secondary end point of the ECLYPS study regarding the potential advantages of dual time point FDG-PET/CT imaging (DTPI) in this setting. Standardized dedicated head and neck FDG-PET/CT images were obtained 12 weeks after CCRT at 60 and 120 min after tracer administration. We performed a semiquantitative assessment of lymph nodes, and the retention index (RI) was explored to optimize diagnostic performance. The reference standard was histology, negative FDG-PET/CT at 1 year, or > 2 years of clinical follow-up. The time-dependent area under the receiver operator characteristics (AUROC) curves was calculated. Results In total, 102 subjects were eligible for analysis. SUV values increased in malignant nodes (median SUV1 = 2.6 vs. SUV2 = 2.7; P = 0.04) but not in benign nodes (median SUV1 = 1.8 vs. SUV2 = 1.7; P = 0.28). In benign nodes, RI was negative although highly variable (median RI = − 2.6; IQR 21.2), while in malignant nodes RI was positive (median RI = 12.3; IQR 37.2) and significantly higher (P = 0.018) compared to benign nodes. A combined threshold (SUV1 ≥ 2.2 + RI ≥ 3%) significantly reduced the amount of false-positive cases by 53% (P = 0.02) resulting in an increased specificity (90.8% vs. 80.5%) and PPV (52.9% vs. 37.0%), while sensitivity (60.0% vs. 66.7%) and NPV remained comparably high (92.9% vs. 93.3%). However, AUROC, as overall measure of benefit in diagnostic accuracy, did not significantly improve (P = 0.62). In HPV-related disease (n = 32), there was no significant difference between SUV1, SUV2, and RI in malignant and benign nodes, yet this subgroup was small. Conclusions DTPI did not improve the overall diagnostic accuracy of FDG-PET/CT to detect residual disease 12 weeks after chemoradiation. Due to differences in tracer kinetics between malignant and benign nodes, DTPI improved the specificity, but at the expense of a loss in sensitivity, albeit minimal. Since false negatives at the 12 weeks PET/CT are mainly due to minimal residual disease, DTPI is not able to significantly improve sensitivity, but repeat scanning at a later time (e.g. after 12 months) could possibly solve this problem. Further study is required in HPV-associated disease.

This study investigates the impact of perioperative tourniquet on skeletal muscle cells during total knee arthroplasty (TKA) and its effects on the gene expression of apoptotic, inflammatory, and angiogenic pathways. The randomized controlled trial included 44 patients undergoing TKA. The patients were randomized to undergo surgery with (n = 23) or without (n = 21) tourniquet. The tourniquet was inflated before skin incision and deflated before wound closure in the tourniquet group. Biopsies from the lateral vastus muscle were obtained from both groups before wound closure and 8 weeks after surgery. The messenger ribonucleic acid (mRNA) expression and protein levels of angiopoietin‐like 4 (ANGPTL4), Hypoxia‐inducible Factor 1α, and Vascular Endothelial Growth Factor Alpha (VEGF‐A) in the biopsies were examined by reverse transcription‐quantitative polymerase chain reaction and tissue microarray, respectively. Differences in mean values (ΔCt for mRNA expression and staining positivity for protein expression) were compared with t‐tests. The apoptotic marker BID and the angiogenic marker VEGF‐A were significantly lower in the tourniquet group compared to the control group (p = 0.03, p = 0.047). However, there was a significant upregulation of VEGF‐A 8 weeks after surgery in the tourniquet group compared to perioperative biopsies (p = 0.002), indicating persistent changes. A significant upregulation in protein expression of the angiogenic marker ANGPTL4 was found perioperatively in the tourniquet group (p = 0.02). Our results demonstrate that the angiogenic gene expression is significantly altered by the tourniquet, the effects of which might contribute to postoperative interstitial edema, increased pain, and decreased muscle strength. These effects could lead to delayed rehabilitation and ultimately reduced patient satisfaction after TKA. [ABSTRACT FROM AUTHOR]

Background and purpose: Outcomes following revision total knee arthroplasty (TKA) may depend on the indication for revision surgery. We compared pain, patient-reported outcome measures (PROMs), and patient satisfaction among different indications for an aseptic TKA revision. Patients and methods: This was a retrospective study of prospective data from an institutional registry of 178 primary TKAs revised between 2012 and 2020. Patients were grouped by the main reason for their revision: loosening, malposition, instability, or stiffness. Pain during mobilization and at rest (NRS 0–10), physical function (KOOS-PS and KSS), and quality of life (EQ-5D) were surveyed preoperatively and at 2 months and 1 year postoperatively. Patient satisfaction was evaluated through questions related to knee function and their willingness to undergo the same surgery again at 1-year follow-up. Results: Pain and PROMs improved in all groups and did not differ statistically significantly between the 4 groups at 1-year follow-up, but equivalence for pain was not confirmed between groups. Overall, pain during mobilization improved by 2.4 (95% CI 1.9–3.0) at 1-year follow-up, which was both clinically and statistically significant. Improvements were seen within 2 months of surgery, with no further improvements seen 1 year postoperatively. Approximately 2/3 of patients reported that their knee function had improved and would undergo the same surgery again, at 1-year follow-up. Conclusion: Statistically significant and clinically relevant improvements in pain and PROMs were seen in all 4 revision groups 1 year after revision TKA. These results may assist clinicians and patients during preoperative counselling.

Abstract Background 89Zirconium-immuno-positron emission tomography (89Zr-immuno-PET) is used for assessment of target status to guide antibody-based therapy. We aim to determine the relation between antibody tumor uptake and target concentration to improve future study design and interpretation. Methods The relation between tumor uptake and target concentration was predicted by mathematical modeling of 89Zr-labeled antibody disposition in the tumor. Literature values for trastuzumab kinetics were used to provide an example. Results 89Zr-trastuzumab uptake initially increases with increasing target concentration, until it levels off to a constant value. This is determined by the total administered mass dose of trastuzumab. For a commonly used imaging dose of 50 mg 89Zr-trastuzumab, uptake can discriminate between immunohistochemistry score (IHC) 0 versus 1–2–3. Conclusion The example for 89Zr-trastuzumab illustrates the potential to assess target expression. The pitfall of false-positive findings depends on the cut-off to define clinical target positivity (i.e., IHC 3) and the administered mass dose.

Leptospirosis is caused by bacteria that are members of the Leptospira genus. This illness can occur in a variety of environments, although it is more prevalent in tropical regions where humidity and wetness greatly aid in its spread. Geographically broad, leptospirosis primarily affects tropical, temperate, and subtropical regions. Bacteria can enter the body through the vaginal system, mucosa, conjunctiva, and tiny abrasions. Hazardous germs are released into the urine when the bacteria settle in the complex kidney pathways. Leptospirosis symptoms are similar to those of other diseases, making diagnosis challenging. The majority of leptospirosis patients are resolved without problems. Laboratory techniques are used to research leptospirosis in humans and animals. Humans are classified as accidental hosts because they have had direct or indirect interaction with leptospirosis-infected animals. Leptospirosis infection can occur in at-risk groups who work in contaminated environments or animal shelters, such as abattoir and sewer workers, coal mines, plumbers, salver workers, agricultural workers, veterinarians, military personnel, abattoir employees, animals, meat handlers, and fishing industry workers. Antimicrobial therapy is one way to treat leptospirosis. Among the antibiotics are doxycycline, amoxicillin, ceftriaxone, ampicillin, penicillin, and erythromycin. Reducing the incidence of leptospirosis in domestic and wild animals can help manage the disease in people. Leptospirosis in wild animals is difficult to control, but in domesticated animals, vaccinations using inactivated whole cells or outer membrane preparations can effectively manage the disease. [ABSTRACT FROM AUTHOR]

Abstract Background Positron emission tomography (PET) is routinely used for cancer staging and treatment follow-up. Metabolic active tumor volume (MATV) as well as total MATV (TMATV—including primary tumor, lymph nodes and metastasis) and/or total lesion glycolysis derived from PET images have been identified as prognostic factor or for the evaluation of treatment efficacy in cancer patients. To this end, a segmentation approach with high precision and repeatability is important. However, the implementation of a repeatable and accurate segmentation algorithm remains an ongoing challenge. Methods In this study, we compare two semi-automatic artificial intelligence (AI)-based segmentation methods with conventional semi-automatic segmentation approaches in terms of repeatability. One segmentation approach is based on a textural feature (TF) segmentation approach designed for accurate and repeatable segmentation of primary tumors and metastasis. Moreover, a convolutional neural network (CNN) is trained. The algorithms are trained, validated and tested using a lung cancer PET dataset. The segmentation accuracy of both segmentation approaches is compared using the Jaccard coefficient (JC). Additionally, the approaches are externally tested on a fully independent test–retest dataset. The repeatability of the methods is compared with those of two majority vote (MV2, MV3) approaches, 41%SUVMAX, and a SUV > 4 segmentation (SUV4). Repeatability is assessed with test–retest coefficients (TRT%) and intraclass correlation coefficient (ICC). An ICC > 0.9 was regarded as representing excellent repeatability. Results The accuracy of the segmentations with the reference segmentation was good (JC median TF: 0.7, CNN: 0.73). Both segmentation approaches outperformed most other conventional segmentation methods in terms of test–retest coefficient (TRT% mean: TF: 13.0%, CNN: 13.9%, MV2: 14.1%, MV3: 28.1%, 41%SUVMAX: 28.1%, SUV4: 18.1%) and ICC (TF: 0.98, MV2: 0.97, CNN: 0.99, MV3: 0.73, SUV4: 0.81, and 41%SUVMAX: 0.68). Conclusion The semi-automatic AI-based segmentation approaches used in this study provided better repeatability than conventional segmentation approaches. Moreover, both algorithms lead to accurate segmentations for both primary tumors as well as metastasis and are therefore good candidates for PET tumor segmentation.

Abstract Background Radiomics is aimed at image-based tumor phenotyping, enabling application within clinical-decision-support-systems to improve diagnostic accuracy and allow for personalized treatment. The purpose was to identify predictive 18-fluor-fluoro-2-deoxyglucose (18F-FDG) positron-emission tomography (PET) radiomic features to predict recurrence, distant metastasis, and overall survival in patients with head and neck squamous cell carcinoma treated with chemoradiotherapy. Methods Between 2012 and 2018, 103 retrospectively (training cohort) and 71 consecutively included patients (validation cohort) underwent 18F-FDG-PET/CT imaging. The 434 extracted radiomic features were subjected, after redundancy filtering, to a projection resulting in outcome-independent meta-features (factors). Correlations between clinical, first-order 18F-FDG-PET parameters (e.g., SUVmean), and factors were assessed. Factors were combined with 18F-FDG-PET and clinical parameters in a multivariable survival regression and validated. A clinically applicable risk-stratification was constructed for patients’ outcome. Results Based on 124 retained radiomic features from 103 patients, 8 factors were constructed. Recurrence prediction was significantly most accurate by combining HPV-status, SUVmean, SUVpeak, factor 3 (histogram gradient and long-run-low-grey-level-emphasis), factor 4 (volume-difference, coarseness, and grey-level-non-uniformity), and factor 6 (histogram variation coefficient) (CI = 0.645). Distant metastasis prediction was most accurate assessing metabolic-active tumor volume (MATV)(CI = 0.627). Overall survival prediction was most accurate using HPV-status, SUVmean, SUVmax, factor 1 (least-axis-length, non-uniformity, high-dependence-of-high grey-levels), and factor 5 (aspherity, major-axis-length, inversed-compactness and, inversed-flatness) (CI = 0.764). Conclusions Combining HPV-status, first-order 18F-FDG-PET parameters, and complementary radiomic factors was most accurate for time-to-event prediction. Predictive phenotype-specific tumor characteristics and interactions might be captured and retained using radiomic factors, which allows for personalized risk stratification and optimizing personalized cancer care. Trial registration Trial NL3946 (NTR4111), local ethics commission reference: Prediction 2013.191 and 2016.498. Registered 7 August 2013, https://www.trialregister.nl/trial/3946

Abstract Purpose Correct identification of tumour receptor status is important for treatment decisions in breast cancer. [18F]FES PET and [18F]FDHT PET allow non-invasive assessment of the oestrogen (ER) and androgen receptor (AR) status of individual lesions within a patient. Despite standardised analysis techniques, interobserver variability can significantly affect the interpretation of PET results and thus clinical applicability. The purpose of this study was to determine visual and quantitative interobserver variability of [18F]FES PET and [18F]FDHT PET interpretation in patients with metastatic breast cancer. Methods In this prospective, two-centre study, patients with ER-positive metastatic breast cancer underwent both [18F]FES and [18F]FDHT PET/CT. In total, 120 lesions were identified in 10 patients with either conventional imaging (bone scan or lesions > 1 cm on high-resolution CT, n = 69) or only with [18F]FES and [18F]FDHT PET (n = 51). All lesions were scored visually and quantitatively by two independent observers. A visually PET-positive lesion was defined as uptake above background. For quantification, we used standardised uptake values (SUV): SUVmax, SUVpeak and SUVmean. Results Visual analysis showed an absolute positive and negative interobserver agreement for [18F]FES PET of 84% and 83%, respectively (kappa = 0.67, 95% CI 0.48–0.87), and 49% and 74% for [18F]FDHT PET, respectively (kappa = 0.23, 95% CI − 0.04–0.49). Intraclass correlation coefficients (ICC) for quantification of SUVmax, SUVpeak and SUVmean were 0.98 (95% CI 0.96–0.98), 0.97 (95% CI 0.96–0.98) and 0.89 (95% CI 0.83–0.92) for [18F]FES, and 0.78 (95% CI 0.66–0.85), 0.76 (95% CI 0.63–0.84) and 0.75 (95% CI 0.62–0.84) for [18F]FDHT, respectively. Conclusion Visual and quantitative evaluation of [18F]FES PET showed high interobserver agreement. These results support the use of [18F]FES PET in clinical practice. In contrast, visual agreement for [18F]FDHT PET was relatively low due to low tumour-background ratios, but quantitative agreement was good. This underscores the relevance of quantitative analysis of [18F]FDHT PET in breast cancer. Trial registration ClinicalTrials.gov , NCT01988324. Registered 20 November 2013, https://clinicaltrials.gov/ct2/show/NCT01988324?term=FDHT+PET&draw=1&rank=2 .

Background and purpose — Patient-reported outcomes (PROMs) after primary total hip arthroplasty (THA) and revision THA are important information in the preoperative shared decision-making process. We present 1-year results on pain, function, and quality of life following primary and revision THA. Patients and methods — From 2010 to 2018, 3,559 primary THA and 406 revision THAs were included in our institutional quality registry. PROMs were registered preoperatively, 3 months, and 1 year after surgery, numeric rating scale (0–10) for pain during mobilization and at rest, healthrelated quality of life (EQ-5D), and a hip-specific physical function score (HOOS-PS). 2 anchor questions were asked 1 year after surgery concerning joint function and willingness to go through surgery again. Results — There were statistically significant improvements in all PROMs at the 3-month follow-up in both groups. All PROMs improved more in the primary group relative to the revision group. 1 year after surgery, pain during mobilization was reduced with a mean change of 5.1 (SD 2.6) for primary THA and 2.9 (SD 3.0) for revision THA. 93% of primary THA patients reported both better function 1 year after surgery and that they would have gone through surgery again, compared with 78% and 79% in the revision THA group. Interpretation — Primary THA patients reported better function and more pain relief than the revision THA group 1 year after surgery. Pain during mobilization shows the most marked improvement in both groups, which is important preoperative information for patients.

Abstract Purpose Recently, updated EARL specifications (EARL2) have been developed and announced. This study aims at investigating the impact of the EARL2 specifications on the quantitative reads of clinical PET–CT studies and testing a method to enable the use of the EARL2 standards whilst still generating quantitative reads compliant with current EARL standards (EARL1). Methods Thirteen non-small cell lung cancer (NSCLC) and seventeen lymphoma PET–CT studies were used to derive four image datasets—the first dataset complying with EARL1 specifications and the second reconstructed using parameters as described in EARL2. For the third (EARL2F6) and fourth (EARL2F7) dataset in EARL2, respectively, 6 mm and 7 mm Gaussian post-filtering was applied. We compared the results of quantitative metrics (MATV, SUVmax, SUVpeak, SUVmean, TLG, and tumor-to-liver and tumor-to-blood pool ratios) obtained with these 4 datasets in 55 suspected malignant lesions using three commonly used segmentation/volume of interest (VOI) methods (MAX41, A50P, SUV4). Results We found that with EARL2 MAX41 VOI method, MATV decreases by 22%, TLG remains unchanged and SUV values increase by 23–30% depending on the specific metric used. The EARL2F7 dataset produced quantitative metrics best aligning with EARL1, with no significant differences between most of the datasets (p>0.05). Different VOI methods performed similarly with regard to SUV metrics but differences in MATV as well as TLG were observed. No significant difference between NSCLC and lymphoma cancer types was observed. Conclusions Application of EARL2 standards can result in higher SUVs, reduced MATV and slightly changed TLG values relative to EARL1. Applying a Gaussian filter to PET images reconstructed using EARL2 parameters successfully yielded EARL1 compliant data.

The North Sea (NS) is changing rapidly. Temporal variations in fishing intensity and eutrophic conditions, along with the ongoing impact of climate change, act in synergy resulting in modifications in marine communities. Although zooplankton has been extensively investigated, studies often ignore the large-sized meso- and macro-zooplankton (>500 µm), including holoplankton and meroplankton taxa. Here, we examined changes in abundances and community structure of these organisms between 1975 and 2018, using univariate and multivariate analysis, at different taxonomic levels. Abrupt changes in the abundances of (sub)communities occurred during different time periods and resulted in a significant restructuration of the entire community in 2006. These changes were consistent with the regime shifts reported in the NS and were a consequence of the environmental pressures on the whole community or on specific subcommunities. In the long term, the community shifted from higher abundances of hydrozoans and holoplankton taxa to an increasing abundance of decapods. Furthermore, we reveal the environmental variables that most explain the variability in the community dynamics, highlighting the importance of temperature and top-down processes. Our study underlines the relevance of investigations at different taxonomic levels, which elucidates how distinct responses to environmental changes ultimately shape the entire community structure. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is a serious global health threat and broad-spectrum beta-lactamase-producing Enterobactericeae (ESBL) are major contributors. This research focuses on the presence of Escherichia coli as a producer of ESBL in the fresh feces of deer. This study aimed to gain deeper insight into ESBL sourced from deer. 129 fresh stool samples were collected. A total of 89 samples came from the East Java region and 40 samples came from the East Nusa Tenggara region. Identification was carried out which was then followed by PCR. We found 9 positive samples of ESBL-producing E. coli containing the blaTEM gene as the ESBL encoding gene. 33 samples (25.28%) were positive for E. coli. 8 isolates (24.24%) were multidrug-resistant, East Java (6 isolates) and East Nusa Tenggara (2 isolates). All isolates of multidrug-resistant E. coli 7 isolates were ESBL positive (87.5%) and contained the blaTEM gene. The presence of MDR and ESBL-producing E. coli isolates have been confirmed in deer. Deer should be considered as a source of MDR and ESBL transmission for public health. [ABSTRACT FROM AUTHOR]

Abstract Objectives Whole body [18F]-fluorodihydrotestosterone positron emission tomography ([18F]FDHT PET) imaging directly targets the androgen receptor and is a promising prognostic and predictive biomarker in metastatic castration-resistant cancer (mCRPC). To optimize [18F]FDHT PET-CT for diagnostic and response assessment purposes, we assessed how count statistics and reconstruction protocol affect its accuracy, repeatability, and lesion detectability. Methods Whole body [18F]FDHT PET-CT scans were acquired on an analogue PET-CT on two consecutive days in 14 mCRPC patients harbouring a total of 336 FDHT-avid lesions. Images were acquired at 45 min post-injection of 200 MBq [18F]FDHT at 3 min per bed position. List-mode PET data were split on a count-wise basis, yielding two statistically independent scans with each 50% of counts. Images were reconstructed according to current EANM Research Ltd. (EARL1, 4 mm voxel) and novel EARL2 guidelines (4 mm voxel + PSF). Per lesion, we measured SUVpeak, SUVmax, SUVmean, and contrast-to-noise ratio (CNR). SUV was normalized to dose per bodyweight as well as to the parent plasma input curve integral. Variability was assessed with repeatability coefficients (RCs). Results Count reduction increased liver coefficient of variation from 9.0 to 12.5% and from 10.8 to 13.2% for EARL1 and EARL2, respectively. SUVs of EARL2 images were 12.0–21.7% higher than EARL1. SUVs of 100% and 50% count data were highly correlated (R 2 > 0.98; slope = 0.97–1.01; ICC = 0.99–1.00). Intrascan variability was volume-dependent, and count reduction resulted in higher intrascan variability for EARL2 than EARL1 images. Intrascan RCs were lowest for SUVmean (8.5–10.6%), intermediate for SUVpeak (12.0–16.0%), and highest for SUVmax (17.8–22.2%). Count reduction increased test-retest variance non-significantly (p > 0.05) for all SUV types and normalizations. For SUVpeak at 50% of counts, RCs remained

Abstract Background Positron emission tomography (PET) is increasingly used to guide local treatment in glioma. The purpose of this study was a direct comparison of two potential tracers for detecting glioma infiltration, O-(2-[18F]-fluoroethyl)-l-tyrosine ([18F] FET) and [11C] choline. Methods Eight consecutive patients with newly diagnosed diffuse glioma underwent dynamic [11C] choline and [18F] FET PET scans. Preceding craniotomy, multiple stereotactic biopsies were obtained from regions inside and outside PET abnormalities. Biopsies were assessed independently for tumour presence by two neuropathologists. Imaging measurements were derived at the biopsy locations from 10 to 40 min [11C] choline and 20–40, 40–60 and 60–90 min [18F] FET intervals, as standardized uptake value (SUV) and tumour-to-brain ratio (TBR). Diagnostic accuracies of both tracers were compared using receiver operating characteristic analysis and generalized linear mixed modelling with consensus histopathological assessment as reference. Results Of the 74 biopsies, 54 (73%) contained tumour. [11C] choline SUV and [18F] FET SUV and TBR at all intervals were higher in tumour than in normal samples. For [18F] FET, the diagnostic accuracy of TBR was higher than that of SUV for intervals 40–60 min (area under the curve: 0.88 versus 0.81, p = 0.026) and 60–90 min (0.90 versus 0.81, p = 0.047). The diagnostic accuracy of [18F] FET TBR 60–90 min was higher than that of [11C] choline SUV 20–40 min (0.87 versus 0.67, p = 0.005). Conclusions [18F] FET was more accurate than [11C] choline for detecting glioma infiltration. Highest accuracy was found for [18F] FET TBR for the interval 60–90 min post-injection.

Abstract Background Total metabolic active tumour volume (TMATV) and total tumour burden (TTB) are increasingly studied as prognostic and predictive factors in non-small cell lung cancer (NSCLC) patients. In this study, we investigated the repeatability of TMATV and TTB as function of uptake interval, positron emission tomography/computed tomography (PET/CT) image reconstruction settings, and lesion delineation method. We used six lesion delineation methods, four direct PET image-derived delineations and two based on a majority vote approach, i.e. intersection between two or more delineations (MV2) and between three or more delineations (MV3). To evaluate the accuracy of those methods, they were compared with a reference delineation obtained from the consensus of the segmentations performed by three experienced observers. Ten NSCLC patients underwent two baseline whole-body [18F]2-Fluoro-2-deoxy-2-D-glucose ([18F]FDG) PET/CT studies on separate days, within 3 days. Two scans were obtained on each day at 60 and 90 min post-injection to assess the influence of tracer uptake interval. PET/CT images were reconstructed following the European Association of Nuclear Medicine Research Ltd. (EARL) compliant settings and with point-spread-function (PSF) modelling. Repeatability between the measurements of each day was determined and the influence of uptake interval, reconstruction settings, and lesion delineation method was assessed using the generalized estimating equations model. Results Based on the Jaccard index with the reference delineation, the MV2 lesion delineation method was the most successful method for automated lesion segmentation. The best overall repeatability (lowest repeatability coefficient, RC) was found for TTB from 90 min of tracer uptake scans reconstructed with EARL compliant settings and delineated with 41% of lesion’s maximum SUV method (RC = 11%). In most cases, TMATV and TTB repeatability were not significantly affected by changes in tracer uptake time or reconstruction settings. However, some lesion delineation methods had significantly different repeatability when applied to the same images. Conclusions This study suggests that under some circumstances TMATV and TTB repeatability are significantly affected by the lesion delineation method used. Performing the delineation with a majority vote approach improves reliability and does not hamper repeatability, regardless of acquisition and reconstruction settings. It is therefore concluded that by using a majority vote based tumour segmentation approach, TMATV and TTB in NSCLC patients can be measured with high reliability and precision.

PurposeRadiolabeled Prostate-Specific Membrane Antigen (PSMA) PET/CT is the current standard-of-care for lesion detection in patients with biochemically recurrent (BCR) prostate cancer (PCa). However, rigorous verification of detected lesions is not always performed in routine clinical practice. To aid future 18F-radiolabeled PSMA PET/CT interpretation, we aimed to identify clinical/imaging characteristics that increase the likelihood that a PSMA-avid lesion is malignant.Materials and methods262 patients with BCR, who underwent 18F-DCFPyL PSMA PET/CT, were retrospectively analyzed. The malignant nature of 18F-DCFPyL PET-detected lesions was verified through any of the following metrics: (1) positive histopathological examination; (2) additional positive imaging; (3) a ≥50% decrease in Prostate-Specific Antigen (PSA) following irradiation of the lesion(s).ResultsIn 226/262 PET scans (86.3%) at least one lesion suspicious for recurrent PCa was detected ('positive scan'). In 84/226 positive scans (37.2%), at least one independent verification metric was available. PSMA PET-detected lesions were most often confirmed to be malignant (PCa) in the presence of a CT-substrate (96.5% vs. 55.6% without CT-substrate), with SUVpeak ≥3.5 (91.4% vs. 60.0% with SUVpeak2 PET-positive lesions (94.1% vs. 64.2% in patients with 1-2 PET-positive lesions; pConclusionsIn this study, the clinical verification of 18F-DCFPyL PET-positive lesions in patients with BCR was performed. Diagnostic certainty of PET-detected lesions increases in the presence of characteristic abnormalities on CT, when SUVpeak is ≥3.5, when PSA-levels exceed 2.0 ng/mL or in patients with more than two PET-positive lesions.

BackgroundPET-based tumor delineation is an error prone and labor intensive part of image analysis. Especially for patients with advanced disease showing bulky tumor FDG load, segmentations are challenging. Reducing the amount of user-interaction in the segmentation might help to facilitate segmentation tasks especially when labeling bulky and complex tumors. Therefore, this study reports on segmentation workflows/strategies that may reduce the inter-observer variability for large tumors with complex shapes with different levels of user-interaction.MethodsTwenty PET images of bulky tumors were delineated independently by six observers using four strategies: (I) manual, (II) interactive threshold-based, (III) interactive threshold-based segmentation with the additional presentation of the PET-gradient image and (IV) the selection of the most reasonable result out of four established semi-automatic segmentation algorithms (Select-the-best approach). The segmentations were compared using Jaccard coefficients (JC) and percentage volume differences. To obtain a reference standard, a majority vote (MV) segmentation was calculated including all segmentations of experienced observers. Performed and MV segmentations were compared regarding positive predictive value (PPV), sensitivity (SE), and percentage volume differences.ResultsThe results show that with decreasing user-interaction the inter-observer variability decreases. JC values and percentage volume differences of Select-the-best and a workflow including gradient information were significantly better than the measurements of the other segmentation strategies (p-valueConclusionsFDG PET segmentations of bulky tumors using strategies with lower user-interaction showed less inter-observer variability. None of the methods led to good results in all cases, but use of either the gradient or the Select-the-best workflow did outperform the other strategies tested and may be a good candidate for fast and reliable labeling of bulky and heterogeneous tumors.

Acquisition time and injected activity of 18F-fluorodeoxyglucose (18F-FDG) PET should ideally be reduced. However, this decreases the signal-to-noise ratio (SNR), which impairs the diagnostic value of these PET scans. In addition, 89Zr-antibody PET is known to have a low SNR. To improve the diagnostic value of these scans, a Convolutional Neural Network (CNN) denoising method is proposed. The aim of this study was therefore to develop CNNs to increase SNR for low-count 18F-FDG and 89Zr-antibody PET. Super-low-count, low-count and full-count 18F-FDG PET scans from 60 primary lung cancer patients and full-count 89Zr-rituximab PET scans from five patients with non-Hodgkin lymphoma were acquired. CNNs were built to capture the features and to denoise the PET scans. Additionally, Gaussian smoothing (GS) and Bilateral filtering (BF) were evaluated. The performance of the denoising approaches was assessed based on the tumour recovery coefficient (TRC), coefficient of variance (COV; level of noise), and a qualitative assessment by two nuclear medicine physicians. The CNNs had a higher TRC and comparable or lower COV to GS and BF and was also the preferred method of the two observers for both 18F-FDG and 89Zr-rituximab PET. The CNNs improved the SNR of low-count 18F-FDG and 89Zr-rituximab PET, with almost similar or better clinical performance than the full-count PET, respectively. Additionally, the CNNs showed better performance than GS and BF.