Phantom imaging demonstration of positronium lifetime with a long axial field-of-view PET/CT and I.

Purpose: Measuring the ortho-positronium (oPs) lifetime in human tissue bears the potential of adding clinically relevant information about the tissue microenvironment to conventional positron emission tomography (PET). Through phantom measurements, we investigate the voxel-wise measurement of oPs lifetime using a commercial long-axial field-of-view (LAFOV) PET scanner.

Methods: We prepared four samples with mixtures of Amberlite XAD4, a porous polymeric adsorbent, and water and added between 1.

Lymphoma Therapy Response Assessment with Low-Dose [F]FDG Total-Body PET/CT.

The improved sensitivity of total-body (TB) PET/CT offers the possibility of reducing injected activities. The aim of our study was to define a lower limit of reduced injected activities in [F]FDG TB PET/CT for interim and end-of-treatment assessment of patients with lymphoma at 2 acquisition times. Twenty-four consecutive patients with lymphoma who were undergoing interim and end-of-treatment TB PET/CT were prospectively enrolled in this study.

Kinetics of the amino acid uptake tracer O-(2-[F]fluoroethyl)-L-tyrosine (FET) in human brain.

Background: The large neutral amino acid [F]fluoroethoxy-L-tyrosine ([F]FET) is a popular tracer for detection and staging of intracranial tumors by positron emission tomography (PET). While its high tumoral uptake reflects over-expression of the L-type amino acid transporter (LAT1), there is little knowledge about the kinetics of [F]FET uptake in healthy brain tissue, owing to the limited PET data in healthy volunteers, and to the requirement of an arterial input function for compartmental analysis. To address this, we used long axial field-of-view (LAFOV) dynamic 40-min recordings of 28 post-operative patients with intracranial tumors to undertake parametric brain mapping relative to an image-derived arterial input function (IDIF) obtained from the aorta.

Model selection for dynamic PET compartmental modelling of F-FDG uptake using a long axial field-of-view PET scanner with delay and motion correction.

Background: In dynamic PET with tracer kinetic modeling, model complexity is an important but often under-recognised challenge affecting robust parameter estimation, particularly for noisy data. Traditional methods often neglect tissue heterogeneity and apply a single model universally. We applied a model selection approach alongside delay and motion correction, enabling the selection of models with varying complexity to better account for tissue heterogeneity.

New Promising Targets for Imaging in Cardiovascular Diseases.

Cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide, driven by complex and dynamic molecular processes such as inflammation, fibrosis, metabolic dysregulation, thrombosis, and vascular remodeling. While conventional imaging techniques provide valuable anatomical and functional information, they fail to capture these underlying pathophysiological mechanisms at the molecular level. Molecular imaging, particularly with PET and SPECT, offers the potential to noninvasively visualize and quantify these processes, enabling earlier diagnosis, better risk stratification, and more precise treatment guidance.

New semiquantitative parameters in digital [F]FDG PET/CT improve diagnostic accuracy in suspected infective endocarditis.

Background: The purpose of this study was to identify semiquantitative parameters of [F]FDG PET/CT using a digital PET scanner, which may increase diagnostic accuracy and readers' confidence in the diagnosis of infective endocarditis (IE).

Results: Images of 82 patients undergoing [F]FDG PET/CT for suspected IE were visually and semiquantitatively analyzed. Standardized uptake values (SUV) of suspected foci, also normalized to liver, mediastinum and surrounding activity were calculated.

Head-to-head comparison of florbetapir and FDG PET for the early detection of amyloidosis in systemic amyloidosis and plasma cell dyscrasias.

Rationale And Objectives: Systemic amyloidosis is underdiagnosed in light-chain amyloidosis (AL), as is plasma cell dyscrasias (PCD). Early detection and accurate evaluation of organ involvement in systemic amyloidosis remain critical challenges. We aimed to assess the utility of [F]florbetapir (FBP) and [F]fluorodeoxyglucose (FDG) positron emission tomography (PET) for the early detection and evaluation of organ involvement in systemic amyloidosis.

Non-invasive arterial input function estimation using an MRA atlas and machine learning.

Background: Quantifying biological parameters of interest through dynamic positron emission tomography (PET) requires an arterial input function (AIF) conventionally obtained from arterial blood samples. The AIF can also be non-invasively estimated from blood pools in PET images, often identified using co-registered MRI images. Deploying methods without blood sampling or the use of MRI generally requires total body PET systems with a long axial field-of-view (LAFOV) that includes a large cardiovascular blood pool.

FAPI PET Versus FDG PET/CT in Gastrointestinal Cancers: An Overview.

Fibroblast activation protein (FAP) is a type II transmembrane serine protease that is highly expressed in cancer-associated fibroblasts (CAFs) but absent in quiescent fibroblasts. Its overexpression is associated with poor prognosis in various cancers and contributes to treatment resistance. In recent years, radiolabeled FAP inhibitors (FAPI) for PET imaging have shown promising clinical value across a range of cancers.

Optimizing theranostics chatbots with context-augmented large language models.

: Nuclear medicine theranostics is rapidly emerging, as an interdisciplinary therapy option with multi-dimensional considerations. Healthcare Professionals do not have the time to do in depth research on every therapy option. Personalized Chatbots might help to educate them.

Partial volume effect correction impairs the diagnostic utility of [F]-THK-5351 PET in nonfluent-agrammatic variant primary progressive aphasia.

Objectives: Partial volume effects in positron emission tomography occur frequently in neurodegenerative diseases due to increasing cortical atrophy during the disease course, and fronto-temporal dementia is often characterized by severe atrophy. The aim of this study was to challenge partial volume effect correction (PVEC) in patients with nonfluent-agrammatic variant primary progressive aphasia (nfv-PPA) imaged with [F]-THK-5351 PET a marker of reactive neuroinflammatory astrogliosis as well as tau-binding.

Methods: Patients with nfv-PPA (n = 20) were imaged with [F]-THK-5351 PET accompanied by structural magnetic resonance tomography imaging (MRI).

Is Long-Axial-Field-of-View PET/CT Cost-Effective? An International Health-Economic Analysis.

Our aim is to assess the cost-effectiveness of long-axial-field-of-view (LAFOV) versus short-axial FOV (SAFOV) PET/CT systems using international data. Our model compares equipment and operational costs for a PET/CT center and investigates the effect of camera choice (SAFOV vs. LAFOV) and operational models.

Radioactivity levels in the saliva of patients undergoing targeted radioligand therapy with [Lu]Lu-PSMA-I&T and [Lu]Lu-DOTA-TOC.

Objectives: The number of patients receiving radioligand therapy (RLT) has risen sharply in recent years. This raises concerns about possible risks to dental healthcare workers due to their exposure to the patients and their saliva. We therefore set about to measure the salivary radioactivity in patients undergoing Lu-RLT.

Feasibility of an Ultra-Low-Dose PET Scan Protocol with CT-Based and LSO-TX-Based Attenuation Correction Using a Long-Axial-Field-of-View PET/CT Scanner.

Long-axial-field-of-view (LAFOV) PET scanners enable substantial reduction in injected radiotracer activity while maintaining clinically feasible scan times. Whole-body CT scans performed for PET attenuation correction can significantly add to total radiation exposure. We investigated the feasibility of an ultra-low-dose PET protocol and the application of a CT-less PET attenuation correction method (lutetium oxyorthosilicate background transmission [LSO-TX]) that uses Lu background radiation from detector scintillators with low-count PET data.

Ectopic Right Kidney Imaged With Dynamic 82Rb PET/CT.

Ectopic kidney in the thoracic region are infrequent in clinical practice. A 64-year-old man underwent a Rubidium (82Rb) positron emission tomography/computed tomography (PET-CT) scan for the evaluation of myocardial ischemia due to a diagnosed 2-vessel coronary artery disease. While no myocardial perfusion abnormalities were detected, the scan showed the presence of a diaphragmatic high stand on the right side, with evidence of an ectopic kidney.

Using mpMRI, PSMA, and GRPR PET to Assess Focal Therapy Eligibility and Plan Treatment in Biopsy-proven Low-/Intermediate-risk Prostate Cancer: A Whole-mount Pathology-based Study.

Purpose: Focal therapy (FT) is an emerging strategy for selectively ablating prostate cancer (PCa). However, existing challenges comprise conventional techniques inadequately identifying appropriate candidates and insufficient characterization of multifocality and sampling-biases in the biopsy-based trials. We evaluated the value of adding prostate-specific membrane antigen (PSMA) and gastrin-releasing peptide receptors (GRPR) PET to multiparametric MRI (PET/mpMRI) in preoperative assessments for FT, with whole-mount pathology as a comprehensive reference.

Diagnostic accuracy in NSCLC lymph node staging with Total-Body and conventional PET/CT.

Introduction: Our aim was to characterize the diagnostic accuracy indices for nodal (N)-staging with [F]FDG Total-Body (TB) and short-axial field-of-view (SAFOV) PET/CT in non-small cell lung cancer (NSCLC) patients referred for staging or restaging.

Methods: In this prospective single center cross-over head-to-head comparative study 48 patients underwent [F]FDG TB and SAFOV PET/CT on the same day. In total 700 lymph node levels (1R/L, 2R/L, 3a/p, 4R/L, 5, 6, 7, 8R/L, 9R/L, 10-14R/L) of 28 patients could be correlated to a composite reference standard (histopathological correlation, imaging after localized or systemic treatment), which allowed determination of true positive (TP), false positive (FP), true negative (TN) and false negative (FN) lesions.

Characterization of Effective Half-Life for Instant Single-Time-Point Dosimetry Using Machine Learning.

Single-time-point (STP) image-based dosimetry offers a more convenient approach for clinical practice in radiopharmaceutical therapy (RPT) compared with conventional multiple-time-point image-based dosimetry. Despite numerous advancements, current STP methods are limited by the need for strict and late timing in data acquisition, posing challenges in routine clinical settings. This study introduces a new concept of instant STP (iSTP) dosimetry, achieved by predicting the effective half-life ( ) of organs using machine learning applied on pretherapy patient data (PET and clinical values).

AI in Breast Cancer Imaging: An Update and Future Trends.

Breast cancer is one of the most common types of cancer affecting women worldwide. Artificial intelligence (AI) is transforming breast cancer imaging by enhancing diagnostic capabilities across multiple imaging modalities including mammography, digital breast tomosynthesis, ultrasound, magnetic resonance imaging, and nuclear medicines techniques. AI is being applied to diverse tasks such as breast lesion detection and classification, risk stratification, molecular subtyping, gene mutation status prediction, and treatment response assessment, with emerging research demonstrating performance levels comparable to or potentially exceeding those of radiologists.

Annual percentage change of MR Parkinsonism index in progressive supranuclear palsy: a feasibility study.

Objectives: Considerable evidence suggests that midbrain-based magnetic resonance Parkinsonism index (MRPI) measurements are reliable biomarkers for the diagnosis of progressive supranuclear palsy (PSP). However, the longitudinal atrophy pattern of PSP and potential differences in change rates among PSP phenotypic spectrum remain unclear. This study aims to investigate the longitudinal changes of MRPI measurements and explore their potential role in PSP phenotype progression monitoring.

A mathematical model for the investigation of combined treatment of radiopharmaceutical therapy and PARP inhibitors.

Background: Although the combined treatment with radiopharmaceutical therapy (RPT) and poly (ADP-ribose) polymerase inhibitors (PARPi) shows promise, a critical challenge remains in the limited quantitative understanding needed to optimize treatment protocols. This study introduces a mathematical model that quantitatively represents homologous recombination deficiency (HRD) and facilitates patient-specific customization of therapeutic schedules.

Methods: The model predicts therapeutic outcomes based on the absorbed dose by DNA and the resulting radiobiological responses, with DNA double-strand breaks (DSBs) being the critical determinant of cancer cell fate.

Improved FAPI-radiopharmaceutical pharmacokinetics from the perspectives of a dose escalation study.

Purpose: This study explores the use of fibroblast activation protein inhibitors (FAPI) targeting radiopharmaceuticals as a new approach for pan-cancer treatment, focusing on key factors affecting their effectiveness. We hypothesized that adjusting the administered radiotracer dose one could enhance the tumor-to-background ratios.

Methods: In a dose-escalation study with PC3 xenografts, all radiotracers were administered at doses between 10 and 1500 pmol, followed by biodistribution and PET/CT imaging.

Automatic bone marrow segmentation for precise [Lu]Lu-PSMA-617 dosimetry.

Background: Bone marrow (BM) is the dominant dose-limiting organ in [Lu]Lu-PSMA-617 therapy for patients with metastasized castration resistant prostate cancer, where BM dosimetry is challenging due to segmentation.

Purpose: We aim to develop an automatic image-based segmentation method on peri-therapeutic sequential [Lu]Lu-PSMA-617 images for personalized BM dosimetry.

Methods: Quantitative SPECT/CT imaging at 2, 20, 40 and 60 (n = 14)/200 (n = 16) h post [Lu]Lu-PSMA-617 injection were analyzed for 10 patients with 30 treatment cycles.

The Evolution of Artificial Intelligence in Nuclear Medicine.

Nuclear medicine has continuously evolved since its beginnings, constantly improving the diagnosis and treatment of various diseases. The integration of artificial intelligence (AI) is one of the latest revolutionizing chapters, promising significant advancements in diagnosis, prognosis, segmentation, image quality enhancement, and theranostics. Early AI applications in nuclear medicine focused on improving diagnostic accuracy, leveraging machine learning algorithms for disease classification and outcome prediction.