Two experiments investigated proactive facilitation (PF) or proactive interference (PI) in the recall of recently learned targets, under conditions of assessing the detection and recollection of target changes across two learning phases (with A-B/A-D word pairs). Some changes established meaningful connections across the phases; others did not. Task instructions on the subsequent cued-recall test (Experiment 1) or during Phase 2 study (Experiment 2) guided participants (university students) to monitor and report the changes.
View Article and Find Full Text PDFPET radiomics applied to oncology allow the measurement of intratumoral heterogeneity. This quantification can be affected by image protocols; hence, there is an increased interest in understanding how radiomic expression on PET images is affected by different imaging conditions. To address that interest, this study explored how radiomic features are affected by changes in F-FDG uptake time, image reconstruction, lesion delineation, and radiomic binning settings.
View Article and Find Full Text PDFObjective: This meta-analysis sought to identify the mortality and ambulatory state 30 days and one year post-operatively in octogenarians treated for ruptured abdominal aortic aneurysm (rAAA) by endovascular aneurysm repair (EVAR) or open repair (OR). rAAA is a life threatening emergency occurring increasingly in octogenarians. Surgical treatment, open or endovascular, offers the only chance of survival albeit with significant mortality and morbidity rates and a high burden to society.
View Article and Find Full Text PDFObjectives: Whole body [F]-fluorodihydrotestosterone positron emission tomography ([F]FDHT PET) imaging directly targets the androgen receptor and is a promising prognostic and predictive biomarker in metastatic castration-resistant cancer (mCRPC). To optimize [F]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 [F]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.
Radiolabeled prostate-specific membrane antigen (PSMA) PET has demonstrated promising results for prostate cancer (PCa) imaging. Quantification of PSMA radiotracer uptake is desired as it enables reliable interpretation of PET images, use of PSMA uptake as an imaging biomarker for tumor characterization, and evaluation of treatment effects. The aim of this study was to perform a full pharmacokinetic analysis of 2-(3-(1-carboxy-5-[(6-F-fluoro-pyridine-3-carbonyl)-amino]-pentyl)-ureido)-pentanedioic acid (F-DCFPyL), a second-generation F-labeled PSMA ligand.
View Article and Find Full Text PDFF-fluorodihydrotestosterone (F-FDHT) PET/CT potentially provides a noninvasive method for assessment of androgen receptor expression in patients with metastatic castration-resistant prostate cancer (mCRPC). The objective of this study was to assess simplified methods for quantifying F-FDHT uptake in mCRPC patients and to assess effects of tumor perfusion on these F-FDHT uptake metrics. Seventeen mCRPC patients were included in this prospective observational multicenter study.
View Article and Find Full Text PDFBackground: 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.
View Article and Find Full Text PDFBackground: Partial-volume effects generally result in an underestimation of tumor tracer uptake on PET-CT for small lesions, necessitating partial-volume correction (PVC) for accurate quantification. However, investigation of PVC in dynamic oncological PET studies to date is scarce. The aim of this study was to investigate PVC's impact on tumor kinetic parameter estimation from dynamic PET-CT acquisitions and subsequent validation of simplified semi-quantitative metrics.
View Article and Find Full Text PDFPET is increasingly used for prostate cancer (PCa) diagnostics. Important PCa radiotracers include Ga-prostate-specific membrane antigen HBED-CC (Ga-PSMA), F-DCFPyL, F-fluoromethylcholine (F-FCH), and F-dihydrotestosterone (F-FDHT). Knowledge on the variability of tracer uptake in healthy tissues is important for accurate PET interpretation, because malignancy is suspected only if the uptake of a lesion contrasts with its background.
View Article and Find Full Text PDFThere is increased interest in various new quantitative uptake metrics beyond SUV in oncologic PET/CT studies. The purpose of this study was to investigate the variability and test-retest ratio (TRT) of metabolically active tumor volume (MATV) measurements and several other new quantitative metrics in non-small cell lung cancer using F-FDG PET/CT with different segmentation methods, user interactions, uptake intervals, and reconstruction protocols. Ten patients with advanced non-small cell lung cancer received 2 series of 2 whole-body F-FDG PET/CT scans at 60 min after injection and at 90 min after injection.
View Article and Find Full Text PDFDespite the wealth of genetic information available, mechanisms underlying pathological effects of disease-associated mutations in components of G protein-coupled receptor (GPCR) signaling cascades remain elusive. In this study, we developed a scalable approach for the functional analysis of clinical variants in GPCR pathways along with a complete analytical framework. We applied the strategy to evaluate an extensive set of dystonia-causing mutations in G protein Gαolf.
View Article and Find Full Text PDFPurpose: Severity of abdominal obesity and possibly levels of metabolic activity of abdominal visceral adipose tissue (VAT) are associated with an increased risk for cardiovascular disease (CVD). In this context, the purpose of the current study was to evaluate the reproducibility and repeatability of a semi-automated method for assessment of the metabolic activity of VAT using 2-deoxy-2-[F]fluoro-D-glucose ([F]FDG) positron emission tomography (PET)/x-ray computed tomography (CT).
Procedures: Ten patients with lung cancer who underwent two baseline whole-body [F]FDG PET/low-dose (LD) CT scans within 1 week were included.
F-fluorodihydrotestosterone (F-FDHT) is a radiolabeled analog of the androgen receptor's primary ligand that is currently being credentialed as a biomarker for prognosis, response, and pharmacodynamic effects of new therapeutics. As part of the biomarker qualification process, we prospectively assessed its reproducibility and repeatability in men with metastatic castration-resistant prostate cancer. We conducted a prospective multiinstitutional study of metastatic castration-resistant prostate cancer patients undergoing 2 (test/retest) F-FDHT PET/CT scans on 2 consecutive days.
View Article and Find Full Text PDFBackground: 3'-Deoxy-3'-[F]fluorothymidine ([F]FLT) was proposed as an imaging biomarker for the assessment of in vivo cellular proliferation with positron emission tomography (PET). The current study aimed to validate [F]FLT as a perfusion-independent PET tracer, by gaining insight in the intra-tumoural relationship between [F]FLT uptake and perfusion in non-small cell lung cancer (NSCLC) patients undergoing treatment with a tyrosine kinase inhibitor (TKI). Six patients with metastatic NSCLC, having an activating epidermal growth factor receptor (EGFR) mutation, were included in this study.
View Article and Find Full Text PDFIntroduction: 3'-deoxy-3'-[F]fluorothymidine (F-FLT) positron emission tomography (PET) provides a non-invasive method to assess cellular proliferation and response to antitumor therapy. Quantitative F-FLT uptake metrics are being used for evaluation of proliferative response in investigational setting, however multi-center repeatability needs to be established. The aim of this study was to determine the repeatability of F-FLT tumor uptake metrics by re-analyzing individual patient data from previously published reports using the same tumor segmentation method and repeatability metrics across cohorts.
View Article and Find Full Text PDFPurpose: Positron-emission tomography can be useful in oncology for diagnosis, (re)staging, determining prognosis, and response assessment. However, partial-volume effects hamper accurate quantification of lesions <2-3× the PET system's spatial resolution, and the clinical impact of this is not evident. This systematic review provides an up-to-date overview of studies investigating the impact of partial-volume correction (PVC) in oncological PET studies.
View Article and Find Full Text PDFThe objective of this study was to validate several parametric methods for quantification of 3'-deoxy-3'-F-fluorothymidine (F-FLT) PET in advanced-stage non-small cell lung carcinoma (NSCLC) patients with an activating epidermal growth factor receptor mutation who were treated with gefitinib or erlotinib. Furthermore, we evaluated the impact of noise on accuracy and precision of the parametric analyses of dynamic F-FLT PET/CT to assess the robustness of these methods. Ten NSCLC patients underwent dynamic F-FLT PET/CT at baseline and 7 and 28 d after the start of treatment.
View Article and Find Full Text PDFPurpose: [F]-fluorothymidine ([F]-FLT) is a PET-tracer enabling in-vivo visualization and quantification of tumor cell proliferation. For qualitative and quantitative analysis, adequate knowledge of normal tissue uptake is indispensable. This study aimed to quantitatively investigate baseline tracer uptake of blood pool, lung, liver and bone marrow and their precision, and to assess the longitudinal effect of systemic treatment on biodistribution.
View Article and Find Full Text PDFThe positron emission tomography (PET) tracer 3'-deoxy-3'-[F]fluorothymidine ([F]FLT) has been proposed to measure cell proliferation non-invasively . Hence, it should provide valuable information for response assessment to tumor therapies. To date, [F]FLT uptake has found limited use as a response biomarker in clinical trials in part because a better understanding is needed of the determinants of [F]FLT uptake and therapy-induced changes of its retention in the tumor.
View Article and Find Full Text PDFUnlabelled: Accurate quantification of tracer uptake in small tumors using PET is hampered by the partial-volume effect as well as by the method of volume-of-interest (VOI) delineation. This study aimed to investigate the effect of partial-volume correction (PVC) combined with several VOI methods on the accuracy and precision of quantitative PET.
Methods: Four image-based PVC methods and resolution modeling (applied as PVC) were used in combination with several common VOI methods.
Unlabelled: Change in (18)F-FDG uptake may predict response to anticancer treatment. The PERCIST suggest a threshold of 30% change in SUV to define partial response and progressive disease. Evidence underlying these thresholds consists of mixed stand-alone PET and PET/CT data with variable uptake intervals and no consensus on the number of lesions to be assessed.
View Article and Find Full Text PDF