the Quarterly Journal of Nuclear Medicine and Molecular Imaging最新文献

The long-term management of patients after pulmonary embolism (PE) remains a major challenge, owing to the risk of persistent symptoms, complications, and recurrence. Residual pulmonary vascular obstruction (RPVO) is common, affecting up to 50% of patients after six months of anticoagulation. Ventilation-perfusion (V/Q) scintigraphy is the imaging modality of choice for detecting RPVO, which typically presents as mismatched perfusion defects, as it offers a sensitivity superior to that of computed tomography pulmonary angiography (CTPA), together with lower radiation exposure and the absence of iodinated contrast agents. V/Q scintigraphy plays a pivotal role in the screening of chronic thromboembolic pulmonary hypertension (CTEPH) and chronic thromboembolic pulmonary disease (CTEPD). Furthermore, follow-up V/Q scintigraphy may aid in the diagnosis of recurrent PE and in predicting recurrence risk.

Pulmonary embolism (PE) remains a major diagnostic challenge due to its potentially life-threatening nature and the clinical burden associated with anticoagulation therapy. While computed tomography pulmonary angiography (CTPA) has become the dominant imaging modality for suspected PE, limitations including radiation exposure - particularly to breast tissue-iodinated contrast administration, and concerns about overdiagnosis have prompted renewed interest in alternative strategies. Ventilation-perfusion (V/Q) scintigraphy, grounded in physiological assessment of pulmonary ventilation and perfusion, offers a non-invasive approach with substantially lower radiation and an excellent safety profile. However, planar V/Q imaging is limited by a high proportion of nondiagnostic studies. Recent advances in single-photon emission computed tomography (SPECT) and hybrid SPECT/CT have significantly improved diagnostic accuracy, reduced inconclusive results, and enhanced the ability to distinguish embolic from non-embolic causes of perfusion defects. Despite widespread adoption, formal outcome validation of SPECT-based diagnostic algorithms has been lacking until the recent completion of the international SPECTACULAR randomized controlled trial, designed to compare planar V/Q, CTPA, and SPECT V/Q strategies using three-month thromboembolic recurrence as the reference for clinical safety. Results will be available shortly following presentation at SNMMI annual meeting 2025. Lung scintigraphy plays an essential role in specific populations, including pregnancy or contrast use is restricted. Moreover, ongoing developments in V/Q PET imaging and artificial intelligence-driven post-processing promise improved spatial resolution, quantification, and workflow efficiency, while advanced molecular tracers may enable characterization of thrombus biology. In summary, V/Q scintigraphy - particularly SPECT and SPECT/CT - remains a robust and clinically valuable modality for diagnosing acute PE, offering a radiation-sparing alternative to CTPA. Technological innovation and high-quality outcome evidence are likely to support its broader integration into future diagnostic pathways.

Lung scintigraphy is a common nuclear medicine procedure for evaluating pulmonary perfusion and ventilation, particularly in the diagnosis of pulmonary embolism (PE) and preoperative lung function assessment. With the advent of artificial intelligence (AI), this modality is undergo-ing a transformative evolution. This review explores the multifaceted integration of AI across the lung scintigraphy workflow - from patient positioning and image acquisition to reconstruction, interpretation, and reporting. We review clinically available, published, and possible future applications of AI. We begin with AI for PE detection, segmentation, and classification, and highlight emerging opportunities in diagnosing chronic obstructive pulmonary disease (COPD), chronic thromboembolic pulmonary hypertension (CTEPH), and pneumonia. The paper also discusses AI-driven image enhancement, cross-modality image synthesis, and automated lung lobe segmentation. Throughout, we emphasize the importance of representative datasets and internal validation. We touch on clinical integration of AI and the potential for AI to revitalize lung scintigraphy amidst competing imaging modalities. Through this overview, we aim to inform clinicians and researchers of the current landscape and future directions of AI in lung scintigraphy, to caution against common pitfalls, and remind of the continued responsibility of clinicians to prevent medical errors.

Pulmonary ventilation scintigraphy is a key examination for assessing regional lung function, with important implications for the management of numerous pulmonary diseases. Several radiopharmaceuticals are available for ventilation imaging, such as gases tracers (133Xe and 81mKr) or aerosol-based radiopharmaceuticals ([99mTc]Tc-DTPA; Technegas, Cyclopharm Limited, Kingsgrove, Australia), each with specific physical and technical characteristics that influence image quality, practical implementation, and clinical interpretation. The choice of tracer therefore has direct consequences for diagnostic accuracy and workflow in routine practice. This review summarizes the main agents currently used for ventilation scintigraphy and outlines their respective properties, advantages, and limitations.

Lung scintigraphy has withstood the test of time having been in use for over 60 years. It has evolved today to a tomographic modality with optimal radiopharmaceuticals for both ventilation (V) and perfusion (Q) imaging using technetium-99m radiolabeled agents. In addition to the SPECT imaging of V and Q, today's multimodality imaging devices can add low-dose CT to provide anatomical correlation further improving the sensitivity and, in particular, specificity of lung scanning for pulmonary embolism (PE). Lung scanning has moved beyond just imaging for PE now to assessing regional lung function and the matching between ventilation and perfusion for optimal gas exchange. This helps guide decisions regarding surgical and similar interventions. The enhanced capability afforded by SPECT/CT imaging of regional ventilation and perfusion also brings some attendant challenges such as apparent artefacts due to ventilation patterns that exceed normal perfusion at the borders of the lungs. However, with appropriate experience, the lung scan can now produce an answer on the diagnosis of PE in better than 95% of cases with few indeterminate reports.

Background: The effect of breathing on the [¹⁸F]fluorocholine parathyroid uptake profile has not been yet evaluated. The main objective of our study is to assess the technical feasibility of respiratory-gated [¹⁸F]fluorocholine PET/CT in patients with hyperparathyroidism. Specifically, we aimed to investigate whether respiratory motion correction has a measurable impact on quantitative PET parameters compared to free-breathing PET in a cohort of patients with clearly identifiable hypermetabolic parathyroid lesions.

Methods: Respiratory-gated [¹⁸F]fluorocholine PET/CT was performed using a pressure-sensitive belt placed around the thorax. An elliptic volume of interest was drawn on each hyperfunctioning parathyroid on both respiratory-gated and free-breathing PET scans, and SUVmax and SUVpeak were measured. An image profile was drawn across hypermetabolic targets on the coronal view, and full-width-at-half-maxima (FWHM) of glandular uptake profile was calculated. Wilcoxon signed-rank test and Mann-Whitney U-test were used for intragroup and intergroup comparison, respectively. A P value <0.05 was considered as significant.

Results: A total of 143 hyperfunctioning parathyroid glands (61 superior, 79 inferior, three ectopic) were identified in 110 patients. Respiratory-gated PET showed a statistically significant increase in both SUVmax and SUVpeak compared to ungated PET across all glands (P<0.001). The effect was more pronounced for inferior glands, with a mean SUVmax increment of 10.14%, compared to 7.81% for superior glands, although the difference was not statistically significant for the latter. The mean extent of respiratory parathyroid blurring in the axial direction was 13.7 mm. FWHM analysis revealed a significant reduction in respiratory blurring in respiratory-gated PET (P<0.001).

Conclusions: Respiratory gating improves image quality and visual assessment of hyperfunctioning parathyroid glands by reducing image blurring. Further research is necessary to assess the diagnostic impact of these findings in clinical practice, especially in cases with indeterminate ungated [¹⁸F]Fluorocholine PET examinations.

Positron emission tomography/computed tomography (PET/CT) with 2-[fluorine-18]fluoro-2-deoxy-D-glucose ([18F]-FDG) is a well-established imaging tool in adult oncology and is increasingly utilized also in pediatric oncology due to its ability to combine functional and anatomic information, thereby enhancing diagnostic accuracy and improving patient management. However, [18F]-FDG uptake in children differs physiologically from adults, and this radiotracer is not tumor-specific, with uptake occurring in various benign conditions such as inflammation, infection, and trauma. Accurate interpretation of pediatric [18F]-FDG PET/CT requires comprehensive knowledge of the normal distribution of FDG in children, recognition of physiological variants, and awareness of common benign lesions and PET/CT-related artifacts. Misinterpretation can lead to unnecessary follow-up studies, suboptimal treatment decisions, and/or increased radiation exposure. This review discusses the typical patterns of physiologic [18F]-FDG uptake in children, common benign mimics of malignancy, and potential artifacts and pitfalls encountered in pediatric [18F]-FDG PET/CT imaging, focus especially on head and neck (lymph nodes), brown adipose tissue, bone marrow and thymus. By increasing familiarity with these patterns, this review aims to improve diagnostic confidence, reduce interpretive errors, and promote safer and more effective imaging practices in pediatric oncology.