Journal of nuclear medicine technology最新文献

Left ventricular ejection fraction (LVEF) is a critical parameter in the evaluation of cardiac function, and its measurement can guide treatment decisions in patients with breast cancer undergoing chemotherapy. We obtained LVEF measurements with gated PET-based methods to determine if they produced comparable results to those obtained with cardiac MRI. Methods: Patients with breast cancer who visited the National Cyclotron and PET Centre, Chulabhorn Hospital, in Bangkok, Thailand, between July 1, 2022, and February 28, 2023, for LVEF assessment were included in this prospective study. All patients underwent PET/CT using 3 different reconstruction techniques: dual-gated with electrocardiography and respiratory gating, dual-gated with artificial intelligence-assisted list-mode respiratory-compensated PET/CT (dual-gated list-mode PET/CT), and single-gated (electrocardiography-gated) PET/CT. Additionally, single-gated PET/MRI and cardiac MRI were performed to collect data on end-diastolic volume (EDV), end-systolic volume (ESV), and LVEF. Results: There were no statistically significant differences in LVEF measurements between any modality. Dual-gated PET/CT showed the lowest average percentage difference when compared with cardiac MRI (6.45%). Differences in EDV and ESV were not statistically significant among the PET-based methods but were significant between the cardiac MRI and all PET-based methods, with consistent percentage differences ranging from -37.64% to -39.38% for EDV and -43.68% to -45.32% for ESV. Intraclass correlation coefficients showed moderate to good reliability, and Pearson correlation coefficients indicated good to strong correlations between cardiac MRI and PET/MRI and among PET-based methods. Conclusion: PET-based methods produced comparable LVEF measurements to those obtained by cardiac MRI. The use of PET-based methods to evaluate LVEF may offer advantages in terms of convenience and accessibility in this population.

¹⁷⁷Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) is an established therapeutic option for patients with neuroendocrine tumors (NETs). Although radiomics has been increasingly applied in NET research, it was developed almost exclusively using ⁶⁸Ga-DOTATOC PET imaging, whereas PRRT-related scintigraphic acquisitions remain largely unexplored. This study evaluates the feasibility of extracting hepatic radiomic features from posttreatment whole-body planar scintigraphic (WBS) and tomographic (SPECT) scans, enabling the optimization of preprocessing strategies and a direct comparison of radiomic profiles between imaging modalities. Methods: We conducted a retrospective analysis of data for 49 patients with well-differentiated, progressive metastatic gastroenteropancreatic NETs from 2 centers. All patients underwent posttreatment imaging within 2 d after each ¹⁷⁷Lu-DOTATATE PRRT cycle, for a total of 183 WBS and 108 SPECT scans. Preprocessing operations included image-intensity normalization, dividing each image by the mean counts of a region of interest positioned on the spleen (S-norm) and the third lumbar vertebra (V-norm). Radiomic features were extracted with no spatial resampling, using 64-bin discretization and relative intensity rescaling. Results: Texture extraction was successfully performed on all planar and SPECT images from both centers. Correlations between intensity-based features measured using S-norm and V-norm images showed weak yet statistically significant r values. Conversely, there was a robust correlation between histogram-based and second-order features measured on S-norm and V-norm images, reflected in high r values. V-norm intensity-based features exhibited significantly higher values and lower SDs when compared with S-norm intensity-based variables. When comparing WBS and SPECT scans, a strong correlation was observed between intensity-based variables, whereas histogram-based and second-order features showed no significant correlation. Conclusion: Radiomic analysis on ¹⁷⁷Lu-DOTATATE posttreatment scans was feasible, with proportional scaling to third-lumbar-vertebra activity resulting in the most effective intensity normalization approach, given the decreased variability compared with scaling to spleen activity. Correlations between features assessed using the 2 different scaling methods were weak for intensity-based features and strong for histogram-based and second-order features. Except for intensity-based features, radiomic features derived from WBS images were not comparable with those obtained from SPECT scans.

Intramedullary spinal cord metastasis in patients with breast cancer is exceptionally rare. A 57-y-old man with newly diagnosed breast cancer and regional and distant metastases presented with lower limb weakness. ¹⁸F-FDG PET/CT identified a tracer-avid intramedullary lesion in the thoracic spinal cord. Metastatic cells were confirmed by cerebrospinal fluid analysis. The patient's lower limb weakness resolved after radiotherapy to the spinal lesion.

We present the case of a patient with an elevated prostate-specific antigen level who underwent a prostate MRI that revealed a mass between the prostate and rectum, prompting further evaluation. Biopsy suggested low-grade B-cell lymphoma. A staging ¹⁸F-FDG PET/CT demonstrated a mildly avid pelvic mass and abdominal splenosis. Heat-damaged red blood cell scintigraphy showed uptake consistent with splenosis in the pelvis. A review of outside pathology confirmed no evidence of lymphoma, establishing splenosis as the diagnosis.

Consistent inclusion of the cerebellum is essential for accurate interpretation of brain perfusion SPECT. However, the anatomic validity of external head landmarks for patient positioning has not been quantitatively evaluated. This study assessed spatial relationships between external landmarks and the cerebellar inferior margin using CT images. Methods: We retrospectively analyzed 100 preoperative brain tumor CT studies and measured z-coordinates of the eyeball center, inferior margin of the earlobe, nasal base, external auditory meatus, and inferior margin of the cerebellum. Differences between z-coordinates of landmarks and a tilt index were calculated. Results: The inferior margin of the earlobe was consistently located caudal to the cerebellum with low variability and showed the weakest association with neck posture. Conclusion: The inferior margin of the earlobe is a stable landmark for reproducible craniocaudal head positioning and may support consistent cerebellar coverage in brain perfusion scintigraphy.

Recently, it was proposed that follow-up imaging for patients treated with ¹⁷⁷Lu-labeled radiopharmaceuticals should be focused on posttherapy SPECT/CT, given the intrinsic γ-photon emitted by ¹⁷⁷Lu, suggesting that real-time imaging of radiopharmaceutical infusions using γ-camera technology may be feasible. In this pilot feasibility study, we used a portable γ-camera situated within our theranostics suite to visualize the infusion of ¹⁷⁷Lu-labeled radiopharmaceuticals in real time. Methods: Patients were consecutively enrolled between June 5, 2025, and July 17, 2025, with any patient receiving a ¹⁷⁷Lu-based radiopharmaceutical infusion at our theranostics center being eligible for inclusion. ¹⁷⁷Lu-based radiopharmaceuticals were administered via syringe method. A portable γ-camera was used for dynamic image acquisition. An open-energy window was used to obtain 120 frames at 30 s per frame for a total of 5 or 30 min (to include the entirety of either a ¹⁷⁷Lu-PSMA-617 or a ¹⁷⁷Lu-DOTATATE infusion, respectively) using a 128 × 128 matrix and a low-energy, high-resolution collimator. Results: Six patients were imaged, and the ¹⁷⁷Lu-labeled radiopharmaceutical was visibly confined to the venous system, with measurable time-activity curves, in all patients. No evidence of immediate complication was seen during the imaging of any of the infusions, and no findings suggest an event such as extravasation occurred. Conclusion: Dynamic, real-time imaging of infusions of ¹⁷⁷Lu-labeled radiopharmaceuticals with a γ-camera is feasible. Although further study is needed, this method may be useful for the early identification of complications from infusions, potentially allowing for the alleviation of toxicities and preservation of expensive radiopharmaceutical doses.

Long-axial-field-of-view (LAFOV) PET/CT scanners (>1 m axial field of view) provide an order-of-magnitude improvement in system sensitivity compared with conventional PET/CT systems, allowing clinicians to optimize scan protocols in terms of acquisition time, injected activity, and image quality. However, implementing these optimizations requires workflow changes, which may affect the patient experience and the quality of care provided. This study aims to contextualize the workflow changes for patients while comparing their experiences after a transition from conventional to LAFOV PET/CT at a metropolitan hospital. Methods: Patient movement through a conventional PET/CT facility was observed for 1 working week. This was repeated 1 mo after transitioning to the LAFOV PET/CT system. The median times that patients spent in the uptake room, camera room, hallway, and toilet were compared. Additionally, a separate cohort of patients was invited to participate in a short survey regarding their experience during their PET/CT procedure. The same survey was provided to both cohorts. The questions used a 5-point Likert scale to assess patient concerns, physical discomforts, and perceptions of staff care. In total, 108 and 105 responses were collected for the conventional and LAFOV PET/CT cohorts, respectively. Results: Patients who were scanned using the LAFOV PET/CT system spent significantly less time in the camera room and the uptake room (after injection and when including time waiting before injection). There was a significant reduction in the number of participants who felt that the scan was too long, were concerned about the radiation involved, were anxious, or reported feeling uncomfortable after transitioning to a LAFOV PET/CT system. No significant differences were observed between the 2 cohorts regarding their perceptions of the level of staff preparation and care provided or physical discomforts experienced, including claustrophobia. Conclusion: Transitioning from a conventional to LAFOV PET/CT system reduced the time patients were required to remain stationary during the scan and resulted in decreased patient concerns. There was no evidence of a difference in the levels of physical discomfort, such as claustrophobia, experienced by the 2 cohorts despite the increased length of the gantry bore.

Alzheimer disease (AD) is the most common cause of dementia and one of the leading causes of death in adults age 65 y or older in the United States. AD presents with symptoms of cognitive impairment that worsen with disease progression, ultimately affecting an individual's functional abilities, independence, and overall health. Historically, treatment has relied on the mitigation of the adverse effects of the disease; however, the recent development of antiamyloid monoclonal antibodies allows for the targeting of pathologic factors that drive the progression of disease. Nuclear medicine has established itself as a useful tool in the evaluation of AD through the use of PET tracers, which target pathologic biomarkers such as amyloid-β and tau proteins, as well as metabolic processes reflective of neurodegenerative damage. Amyloid-β PET imaging and quantification have recently gained interest for their ability to more effectively diagnose AD and identify patients eligible for treatment with new antiamyloid therapies.

Alzheimer disease (AD) is increasingly diagnosed using molecular imaging biomarkers. PET imaging provides the opportunity to visualize amyloid and tau aggregates and in vivo neurodegenerative changes. These techniques provide exciting new avenues toward diagnosis, disease staging, and therapeutic monitoring of AD. Methods: This review details recent advances in amyloid PET, tau PET, and ¹⁸F-FDG PET as they relate to the diagnosis, staging, and treatment of AD. The increasing roles of PET in the biologically based diagnosis of AD and antiamyloid immunotherapy response monitoring are addressed. Results: Amyloid PET enables improved detection of amyloid-β plaques within the brain. Amyloid PET is increasingly vital for confirming AD diagnoses given the emergence of antiamyloid immunotherapies, which require biomarker-verified amyloid positivity to initiate treatment. Tau PET provides a direct measure of neurofibrillary tangle pathology and is useful for disease staging, the interpretation of atypical clinical presentations, and treatment decision-making. ¹⁸F-FDG PET plays a vital role in distinguishing AD from other dementia subtypes. Expanded reimbursement policies for amyloid and tau PET have increased accessibility to these modalities. Finally, quantitative methods facilitate interscan reproducibility and permit therapeutic monitoring. Conclusion: Molecular neuroimaging is poised to play a central role in the biologic definition, diagnosis, staging, and management of AD. Integrating amyloid, tau, and FDG PET with clinical assessments and fluid biomarkers provides earlier and more accurate diagnoses, opening the door to personalized treatment.