Switching of RNA splicing regulators in immature neuroblasts during adult neurogenesis.

The lateral wall of the mouse subventricular zone harbors neural stem cells (NSC, B cells) which generate proliferating transient-amplifying progenitors (TAP, C cells) that ultimately give rise to neuroblasts (NB, A cells). Molecular profiling at the single-cell level struggles to distinguish these different cell types. Here, we combined transcriptome analyses of FACS-sorted cells and single-cell RNAseq to demonstrate the existence of an abundant, clonogenic and multipotent population of immature neuroblasts (iNB cells) at the transition between TAP and migrating NB (mNB).

Distribution and predictors of F-18-FDG uptake values of non-malignant cervical lymph nodes in pediatric patients.

Background: F-18-flurodeoxyglucose (FDG) PET/CT is routinely used for staging, evaluation of response to treatment and follow-up of most pediatric malignancies. Cervical lymph nodes can be involved in some pediatric malignancies, but increased uptake in non-malignant cervical lymph nodes is not exceptional in this population. The aim of the present study is to identify predictors of the maximum uptake in non-malignant cervical lymph nodes in the pediatric population.

Prostate Cancer Radioligand Therapy: Beta-labeled Radiopharmaceuticals.

Prostate cancer is the most common malignancy in men worldwide, with an estimated 174,650 new cases per year in the United States, and the second cancer-related cause of death, after lung cancer, with 31,620 deaths per year. While the 5 year survival rate for prostate cancer in patients without metastatic spread is nearly 100%, those with distant metastases have 5 year survival rates of approximately 30%. Initial diagnosis and assessment are based on PSA levels, Gleason score (derived from prostate biopsy), and advanced imaging modalities, including prostate MR imaging and PSMA-PET/computed tomography in patients with high-risk features.

Impact of Single-Time-Point Estimates of Lu-PRRT Absorbed Doses on Patient Management: Validation of a Trained Multiple-Linear-Regression Model in 159 Patients and 477 Therapy Cycles.

Dosimetry after Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) enables estimation of radiation doses absorbed by normal organs and target lesions. This process is time-consuming and requires multiple posttreatment studies on several subsequent days. In a previous study, we described a newly developed multiple-linear-regression model to predict absorbed doses (ADs) from a single-time-point (STP) posttreatment study acquired 168 h after the first infusion and 24 h after the following ones, with similar results to the standard multiple-time-point (MTP) protocol.

Towards accurate Lu SPECT activity quantification and standardization using lesion-to-background voxel ratio.

Background: Conventional calibration of the gamma camera consists of the calculation of calibration factors (CFs) (ratio of counts/cc and true concentration activity) as the function of the volume of interest (VOI). However, such method shows inconsistent results when the background activity varies. The aim of the present study was to propose a new calibration method by considering the sphere-to-background counts/voxel ratio (SBVR) in addition to the VOI for CFs calculation.

False Positive Findings of [F]PSMA-1007 PET/CT in Patients After Radical Prostatectomy with Undetectable Serum PSA Levels.

Background: PET-CT using prostate-specific membrane antigen (PSMA)-targeting radiopharmaceuticals labeled with Ga or F has emerged as the most sensitive staging tool in prostate cancer (PC). Nonetheless, the occurrence of false positive (FP) findings presents a major concern of this approach. In this prospective study, we investigated the frequency and pattern of false-positive findings of [F]PSMA-1007 PET/CT in patients after radical prostatectomy with undetectable serum PSA levels.

Quantitative SPECT/CT for Dosimetry of Peptide Receptor Radionuclide Therapy.

Neuroendocrine tumors (NETs) are uncommon malignancies of increasing incidence and prevalence. As these slow growing tumors usually overexpress somatostatin receptors (SSTRs), the use of Ga-DOTA-peptides (gallium-68 chelated with dodecane tetra-acetic acid to somatostatin), which bind to the SSTRs, allows for PET based imaging and selection of patients for peptide receptor radionuclide therapy (PRRT). PRRT with radiolabeled somatostatin analogues such as Lu-DOTATATE (lutetium-177-[DOTA,Tyr]-octreotate), is mainly used for the treatment of metastatic or inoperable NETs.

Quantitative SPECT/CT parameters of myocardial Technetium-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) uptake in suspected cardiac transthyretin amyloidosis.

Background: Tc-labelled bisphosphonates are used for imaging assessment of patients with transthyretin cardiac amyloidosis (ATTR). Present study evaluates whether quantitative SPECT/CT measurement of absolute myocardial Tc-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid (Tc-DPD) uptake can diagnose patients with suspected ATTR.

Methods: Twenty-eight patients (25 male, age 80.

Simple model for estimation of absorbed dose by organs and tumors after PRRT from a single SPECT/CT study.

Background: Following each cycle of peptide receptor radionuclide therapy (PRRT), absorbed doses by tumors and normal organs are typically calculated from three quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT) studies acquired at t = 24 h, t = 96 h, t = 168 h after the first cycle of treatment and from a single study at t after the subsequent cycles. In the present study, we have assessed the feasibility of a single SPECT/CT study after each PRRT cycle using a trained multiple linear regression (MLR) model for absorbed dose calculation and have evaluated its impact on patient management. Quantitative [Lu]-DOTA-TATE SPECT/CT data after PRRT of seventy-two consecutive metastatic neuroendocrine tumors patients were retrospectively evaluated.

Lessons Learned from Post-COVID-19 Vaccination PET/CT Studies.

Vaccination against coronavirus 2019 (COVID-19) has created new challenges. Lymphadenopathy with increased uptake in patients undergoing PET/CT may mislead to unnecessary further evaluation. We have analyzed routinely performed PET/CT studies after Pfizer-BioNTech vaccination to familiarize ourselves with the PET/CT appearance of various PET tracers and to prevent the consequences of misinterpretation.

[RADIONUCLIDE THERAPY OF NEUROENDOCRINE TUMORS - IMPROVEMENTS IN THE PROTOCOL FOR MEASUREMENT OF PATIENT RADIATION EXPOSURE].

Aims: The aim of this study was to evaluate the predictive power of the absorbed dose to kidneys after the first course of treatment with [177Lu]-DOTA-TATE on the cumulative kidney absorbed dose after 3 or 4 cycles of treatment.

Background: Peptide receptor radionuclide therapy (PRRT) with [177Lu]-DOTA-TATE is an effective treatment for somatostatin receptor positive neuroendocrine tumors (NETs). Post-treatment scans (PTS) are required after each cycle of treatment for personalized radiation dosimetry in order to calculate the dose to organs and tumors and to ensure a cumulative absorbed dose to kidneys under a safety threshold of 25 Gy.

[F]-FDHT PET/CT as a tool for imaging androgen receptor expression in high-grade glioma.

Background: G lioblastoma (GBM) is associated with poor overall survival. Recently, we showed that androgen receptor (AR) protein is overexpressed in 56% of GBM specimens and AR antagonists induced dose-dependent death in several GBM cell lines and significantly reduced tumor growth and prolonged the lifespan of mice implanted with human GBM. 16β-18F-fluoro-5α-dihydrotestosterone ([F]-FDHT) is a positron emission tomography (PET) tracer used to detect AR expression in prostate and breast cancers.

Perceptual omission errors in positron emission tomography and computed tomography reporting.

Background: Omission errors in medical imaging can lead to missed diagnosis and harm to patients. The subject has been studied in conventional imaging, but no data is available for functional imaging in general and for PET/CT in particular. In this work, we evaluated the frequency and characteristics of perceptual omission errors in the PET component of oncologic PET/CT imaging, and we analyzed the hazardous scenarios prone to such modality-specific errors.

Can a penalized-likelihood estimation algorithm be used to reduce the injected dose or the acquisition time in Ga-DOTATATE PET/CT studies?

Background: Image quality and quantitative accuracy of positron emission tomography (PET) depend on several factors such as uptake time, scanner characteristics and image reconstruction methods. Ordered subset expectation maximization (OSEM) is considered the gold standard for image reconstruction. Penalized-likelihood estimation (PL) algorithms have been recently developed for PET reconstruction to improve quantitation accuracy while maintaining or even improving image quality.

Dosimetry after peptide receptor radionuclide therapy: impact of reduced number of post-treatment studies on absorbed dose calculation and on patient management.

Background: After each cycle of [Lu]-DOTA-TATE peptide receptor radionuclide therapy (PRRT) dosimetry is performed to enable precise calculation of the radiation-absorbed dose to tumors and normal organs. Absorbed doses are routinely calculated from three quantitative single-photon emission computed tomography (SPECT) studies corrected by computed tomography (CT) acquired at t = 24 h, t = 96 h, and t = 168 h after the first cycle of treatment. After following cycles, a single SPECT/CT study is performed.

Comparison of NEMA characterizations for Discovery MI and Discovery MI-DR TOF PET/CT systems at different sites and with other commercial PET/CT systems.

Background: This article compares the physical performance of the 4-ring digital Discovery MI (DMI) and PMT-based Discovery MI-DR (DMI-DR) PET/CT systems. Physical performance was assessed according to the NEMA NU 2-2012 standards. Performance measures included spatial resolution, image quality, scatter fraction and count rate performance, and sensitivity.

Predictive power of the post-treatment scans after the initial or first two courses of [Lu]-DOTA-TATE.

Background: The aim of this study was to evaluate the predictive power of the absorbed dose to kidneys after the first course of treatment with [Lu]-DOTA-TATE for neuroendocrine tumors (NETs) on the cumulative kidney absorbed dose after 3 or 4 cycles of treatment. Post-treatment scans (PTS) are acquired after each cycle of peptide receptor radionuclide therapy (PRRT) with [Lu]-DOTA-TATE for personalized radiation dosimetry in order to ensure a cumulative absorbed dose to kidneys under a safety threshold of 25 Gy. One hundred eighty-seven patients who completed treatment with [Lu]-DOTA-TATE and underwent PTS for dosimetry calculation were included in this retrospective study.

Distinct Molecular Signatures of Quiescent and Activated Adult Neural Stem Cells Reveal Specific Interactions with Their Microenvironment.

Deciphering the mechanisms that regulate the quiescence of adult neural stem cells (NSCs) is crucial for the development of therapeutic strategies based on the stimulation of their endogenous regenerative potential in the damaged brain. We show that LeX cells sorted from the adult mouse subventricular zone exhibit all the characteristic features of quiescent NSCs. Indeed, they constitute a subpopulation of slowly dividing cells that is able to enter the cell cycle to regenerate the irradiated niche.

Reducing the number of CTs performed to monitor personalized dosimetry during peptide receptor radionuclide therapy (PRRT).

Background: Peptide receptor radionuclide therapy (PRRT) with [Lu]-DOTA-TATE is an effective treatment of neuroendocrine tumors (NETs). After each cycle of treatment, patient dosimetry evaluates the radiation dose to the risk organs, kidneys, and bone marrow, the most radiosensitive tissues. Absorbed doses are calculated from the radioactivity in the blood and from single photon emission computed tomography (SPECT) images corrected by computed tomography (CT) acquired after each course of treatment.

Isolation of Neural Stem and Progenitor Cells from the Adult Brain and Live Imaging of Their Cell Cycle with the FUCCI System.

Neural stem cells (NSCs) enter quiescence in early embryonic stages to create a reservoir of dormant NSCs able to enter proliferation and produce neuronal precursors in the adult mammalian brain. Various approaches of fluorescent-activated cell sorting (FACS) have emerged to allow the distinction between quiescent NSCs (qNSCs), their activated counterpart (aNSCs), and the resulting progeny. In this article, we review two FACS techniques that can be used alternatively.

Age-related neurogenesis decline in the subventricular zone is associated with specific cell cycle regulation changes in activated neural stem cells.

Although neural stem cells (NSCs) sustain continuous neurogenesis throughout the adult lifespan of mammals, they progressively exhibit proliferation defects that contribute to a sharp reduction in subventricular neurogenesis during aging. However, little is known regarding the early age-related events in neurogenic niches. Using a fluorescence-activated cell sorting technique that allows for the prospective purification of the main neurogenic populations from the subventricular zone (SVZ), we demonstrated an early decline in adult neurogenesis with a dramatic loss of progenitor cells in 4 month-old young adult mice.

First principles transport coefficients and reaction rates of Ar2(+) ions in argon for cold plasma jet modeling.

Momentum-transfer collision cross-sections and integral collision cross-sections for the collision-induced dissociation are calculated for collisions of ionized argon dimers with argon atoms using a nonadiabatic semiclassical method with the electronic Hamiltonian calculated on the fly via a diatomics-in-molecules semiempirical model as well as inverse-method modeling based on simple isotropic rigid-core potential. The collision cross-sections are then used in an optimized Monte Carlo code for evaluations of the Ar 2 (+) mobility in argon gas, longitudinal diffusion coefficient, and collision-induced dissociation rates. A thorough comparison of various theoretical calculations as well as with available experimental data on the Ar 2 (+) mobility and collision cross-sections is performed.

TGFβ lengthens the G1 phase of stem cells in aged mouse brain.

Neurogenesis decreases during aging causing a progressive cognitive decline but it is still controversial whether proliferation defects in neurogenic niches result from a loss of neural stem cells or from an impairment of their progression through the cell cycle. Using an accurate fluorescence-activated cell sorting technique, we show that the pool of neural stem cells is maintained in the subventricular zone of middle-aged mice while they have a reduced proliferative potential eventually leading to the subsequent decrease of their progeny. In addition, we demonstrate that the G1 phase is lengthened during aging specifically in activated stem cells, but not in transit-amplifying cells, and directly impacts on neurogenesis.

Ab initio transport coefficients of Ar⁺ ions in Ar for cold plasma jet modeling.

Collision cross sections and transport coefficients are calculated for Ar{+} ions, in the ground state {2}P_{3/2} and in the metastable state {2}P_{1/2}, colliding with their parent gas. Differential and integral collision cross sections are obtained using a numerical integration of the nuclear Schrödinger equation for several published interaction potentials. The Cohen-Schneider semi-empirical model is used for the inclusion of the spin-orbit interaction.

Ion collision cross sections and transport coefficients extended to intermediate energies and reduced electric fields for He(2)(+) ions colliding with He.

This work is devoted to the calculation of transport coefficients for He(2)(+) ions in gaseous He at intermediate reduced electric fields. These swarm data are of great interest for a better understanding of the mechanisms of formation and propagation of the fast plasma bullets or ionization waves observed in dielectric barrier plasma jet devices. For transport data, the collision cross sections required are determined from several theoretical methods based on quantum, semiclassical, and hybrid approaches and a diatomics-in-molecules model for the potential energy surfaces of He(2)(+).