Nuclear Medicine Communications最新文献

Revascularization of obstructed coronary arteries by coronary artery stenting through percutaneous intervention was a breakthrough in interventional cardiology, pioneered and perfected over the past four decades. Though it is associated with complications, the most dreaded is coronary stent infection (CSI), which may be complicated by the formation of in-stent restenosis, aneurysm/pseudoaneurysm formation, abscess, perforation of the coronaries, or pericardial effusion. The lack of standardized guidelines and the unpredictable course in multimorbid patients complicates management. While the role of [ 18 F]fluorodeoxyglucose PET/computed tomography ([ 18 F]FDG PET/CT) is well-established in prosthetic valve endocarditis and cardiac device infection, its application in CSI warrants systematic evaluation. This case series assessed the utility of [ 18 F]FDG PET/CT in suspected CSI by correlating metabolic findings with clinical, biochemical, and anatomical modalities to characterize its diagnostic and response-assessment value.

Background: Graves' disease (GD), a leading cause of hyperthyroidism, exhibits heterogeneous responses to iodine-131 therapy, underscoring the need for accurate predictive tools. While pertechnetate ( 99m TcO 4- ) thyroid scintigraphy provides essential functional insights, its clinical utility is restricted by limited resolution and the subjective interpretation of results. Deep learning emerges as a promising approach for extracting prognostic features from imaging data.

Objective: This research seeks to construct a radiomic model employing deep learning methodologies, utilizing thyroid scintigraphy, to predict the efficacy of initial iodine-131 therapy in patients diagnosed with GD.

Methods: This retrospective study involved 121 patients diagnosed with GD who underwent pretreatment thyroid scintigraphy. A ResNet50 convolutional neural network was implemented, trained end-to-end on standardized thyroid scintigraphy data to classify treatment outcomes as either cured or not cured. Gradient-weighted class activation mapping (Grad-CAM) was employed to identify region-specific predictive features. Radiomic features extracted from deep learning were further analyzed using least absolute shrinkage and selection operator regression, with a random forest (RF) model serving as the final predictive tool. Performance metrics, including the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity, were evaluated on independent training and validation datasets, using an 8 : 2 split.

Results: The ResNet50 model yielded AUC values of 0.828 [95% confidence interval (CI): 0.740-0.915] and 0.806 (95% CI: 0.656-0.956) for the training and validation datasets, respectively. A set of 16 critical radiomic features, extracted from the global pooling layer of ResNet50, enabled the construction of an RF classifier that exhibited enhanced generalization performance, as evidenced by a test AUC of 0.924. Decision curve analysis substantiated the model's clinical utility across a broad spectrum of threshold probabilities (10-90%). Grad-CAM visualizations revealed that the model predominantly concentrated on regions of thyroid parenchyma associated with treatment-responsive tissue.

Conclusion: This study introduces a pioneering deep learning framework that employs thyroid scintigraphy radiomics to predict iodine-131 therapeutic outcomes in GD. By combining ResNet50 for feature extraction with interpretable Grad-CAM localization, this approach advances personalized nuclear medicine strategies and mitigates the 'black box' limitation typically associated with artificial intelligence models. These findings require validation across multicenter cohorts to refine and optimize precision treatment protocols.

Background and objective: The optimal hydration strategy to enhance radioactive iodine (I-131) clearance without compromising therapeutic efficacy remains undefined. This study aimed to evaluate whether a structured high-hydration regimen accelerates I-131 clearance, reduces radiation exposure to nontarget organs, and shortens isolation time.

Methods: In this prospective cohort study, 456 women with papillary thyroid carcinoma receiving I-131 therapy were assigned to a high-hydration group ( ∼ 2500 ml/day) or a low-hydration group ( ∼ 1900 ml/day). Key measures included I-131 effective half-life (T_eff), time to hospital discharge, bladder cumulative dose, residual tumor uptake, and short-term reproductive outcomes.

Results: The high-hydration group demonstrated a significantly shorter T_eff (22.4 ± 6.2 vs. 28.0 ± 7.3 h; P  < 0.001), earlier discharge (median 2.0 vs. 3.0 days; P  < 0.001), and a lower bladder cumulative dose (18.5 ± 5.7 vs. 22.1 ± 6.9 mGy; P  < 0.001). Tumor uptake remained comparable between groups ( P  = 0.552). No significant differences were observed in 12-month reproductive outcomes. The benefits were more pronounced in obese patients ( P -interaction = 0.02-0.04).

Conclusion: A structured high-hydration regimen significantly accelerates I-131 clearance, reduces bladder radiation exposure, and facilitates earlier discharge without impairing therapeutic efficacy or short-term reproductive safety. These findings support the implementation of tailored hydration protocols, particularly for obese patients, to minimize radiation exposure and optimize posttherapy management.

Objectives: In primary hyperparathyroidism, preoperative localisation of a parathyroid adenoma enables focussed excision rather than full neck exploration, with reduced complication rates, recovery time and cost. In this study, we sought to improve parathyroid adenoma localisation on 99m Tc-sestamibi so more patients can benefit from focussed excision.

Methods: We performed a baseline audit of our 99m Tc-sestamibi service, followed by three sequential changes: cycle 1: acquisition of new single-photon emission computed tomography/computed tomography (SPECT/CT) scanners, cycle 2: optimisation of image acquisition and reconstruction, cycle 3: addition of arterial phase iodinated contrast to SPECT/CT. We classified reporter confidence using a 5-point Likert scale. We correlated adenoma location on imaging with 'gold standard' location based on surgical and pathology results. We calculated the sensitivity, specificity, and receiver operator characteristics following each change cycle.

Results: Results comparing each cycle to the baseline audit: Baseline: 44% confidently located, 31% failed to identify an adenoma. Sensitivity: 69.8%, specificity: 95.7%, area under the curve (AUC): 0.92. Cycle 1: 54% confidently located, 24% failed to identify an adenoma. Sensitivity: 77.6%, specificity: 93.3%, AUC: 0.95. Cycle 2: 48% confidently located, 18% failed to identify an adenoma. Sensitivity: 84.3%, specificity: 95.9%, AUC: 0.98. Cycle 3: 67% confidently located, 6% failed to identify an adenoma. Sensitivity: 94.7%, specificity: 90%, AUC: 0.99 ( P  < 0.001).

Conclusion: Our study demonstrated that sequential improvements in 99m Tc-sestamibi SPECT/CT significantly improved test performance by reducing the number of localisation failures, increasing test sensitivity, and reducing the number of false negatives. As a result, more patients can benefit from focussed excision parathyroidectomy.

Purpose: This study aimed to evaluate the influence of silicon photomultiplier PET (SiPM-PET) and the Bayesian penalized-likelihood (BPL) reconstruction algorithm on the measurement of metabolic tumor volume (MTV), in comparison with conventional photomultiplier tube PET (PMT-PET).

Materials and methods: Six phantoms of varying shapes and volumes (1.2 to 20 ml) were prepared using an agar-based fluorodeoxyglucose F-18 mixture with a background-to-lesion activity ratio of 1 : 4 and placed in a 5-L water tank. Each phantom was scanned using PMT-PET and SiPM-PET systems. PMT-PET images were reconstructed with conventional ordered-subset expectation maximization (OSEM), whereas SiPM-PET data were reconstructed using both OSEM and BPL. MTV was calculated using relative threshold-based segmentation [30, 40, 42, and 50% of maximum standardized uptake value (SUV max )] and a gradient-based method with weight coefficients of 0.3, 0.4, 0.5, and 0.6. Measured MTVs were compared with true phantom volumes to assess accuracy.

Results: SiPM-PET provided a more accurate geometric representation of phantom contours than PMT-PET. Across all conditions, a 40% SUV max threshold and a weight coefficient of 0.4 yielded MTVs closest to the true volumes. When SiPM-PET was combined with BPL, gradient-based segmentation produced MTVs with the smallest deviation from the known volumes, particularly for irregularly shaped phantoms.

Conclusion: SiPM-PET using BPL facilitated clearer delineation of phantom boundaries compared with PMT-PET and SiPM-PET with OSEM. Under the present experimental conditions, MTVs obtained from SiPM-PET with BPL, especially when using the gradient-based method, showed improved agreement with true phantom volumes, suggesting potential advantages for volumetric assessment in oncologic PET imaging.

Background: Lutetium-177 (Lu-177) prostate-specific membrane antigen (PSMA) therapy is an emerging treatment for metastatic castration-resistant prostate cancer (mCRPC), but there is limited evidence on whether imaging can predict treatment-related toxicity. This study investigated whether pretreatment PSMA PET imaging parameters could forecast toxicity and outcomes in Asian patients undergoing Lu-177 PSMA therapy.

Patients and methods: In this retrospective analysis, men with mCRPC treated with Lu-177 PSMA-617 at Koo Foundation Sun Yat-Sen Cancer Center, Taipei, were reviewed. Baseline Ga-68 PSMA-11 PET imaging metrics - including standardized uptake values (SUV), total lesion PSMA (TLP), and total tumor volume (TTV) - were assessed. Treatment response was measured by prostate-specific antigen (PSA) decline, and adverse effects and survival were evaluated from clinical records.

Results: Eighteen men (median age: 75, range: 55-91) received a median of 2 (range: 1-6) cycles of Lu-177 PSMA therapy, with a mean administered radioactivity of 7.0 GBq (range: 3.0-7.4 GBq) per cycle. Grade 3/4 hematologic toxicities occurred in six (33.3%) patients, with thrombocytopenia (27.8%) and anemia (22.2%) most common. Higher TLP and TTV were linked to increased toxicity and poorer survival, while higher SUV mean was associated with better PSA response.

Conclusion: Pretreatment PSMA PET imaging may help predict adverse effects in Asian mCRPC patients undergoing Lu-177 PSMA therapy. Larger, prospective studies are needed for confirmation.

Tumor thrombus (TT) represents the intravascular extension of the tumor, most commonly seen in renal cell carcinoma (RCC) and hepatocellular carcinoma (HCC). It is clinically significant with direct implications on staging, prognosis, and therapeutic decision-making. TT is most commonly noted in RCC and HCC, but can also occur in several other malignancies, such as adrenal cortical carcinoma, colorectal carcinoma, pancreatic neuroendocrine tumors, thyroid carcinoma, and testicular carcinoma. Differentiating TT and bland thrombus is crucial. Surgical resection offers survival benefit in select cases, whereas systemic therapies, including immunotherapy and targeted agents, are transforming the management of RCC and HCC with vascular invasion. TT is a marker of aggressive tumor biology that significantly worsens the prognosis. This review highlights current knowledge about the pathogenesis, imaging features, prognostic impact, and therapeutic approaches to TT, with emphasis on the evolving role of nuclear medicine, and provides a narrative review of peer-reviewed literature and available guidelines.

Background: [ 18 F]fluoro-2-deoxy-D-glucose ([ 18 F]FDG)-PET/MRI is a 'one-stop-shop' combination that enriches lesion characterization, locoregional and distant staging in breast cancer patients. The combination consists of a breast (bpPET/MRI) and whole-body (wbPET/MRI) within a single protocol. Despite acceptable test-retest reproducibility of standardized uptake value (SUV) in PET examinations being 10%, limited knowledge concerning agreement between metabolic parameters from each protocol (bpPET/MRI and wbPET/MRI) is available.

Objective: Feasibility study to verify whether differences of metabolic parameters in breast tumor, on prone bpPET/MRI acquired between 30 and 55 min postinjection, and compared to wbPET/MRI at 60 min, remained within the 10% margin acceptable in clinical practice.

Methods: Breast cancer patients underwent [ 18 F]FDG-PET/MRI: bpPET/MRI and wbPET/MRI. Maximum SUV (SUVmax) and mean SUV (SUVmean) measurements of the index tumor, contralateral breast, liver, and blood pool were obtained from bpPET/MRI images acquired every 5 min between 30 and 55 min. These values were compared with wbPET/MRI SUVs at 60 min (reference).

Results: Twenty patients were included. The majority of PET/MRI exams remained within the 10% margin at all timepoints. At 45 and 50 min the mean percentage difference of SUVmax and SUVmean compared to 60 min was less than 1.3-3.6%. Other SUV measurements remained within 10% margin in majority of cases, while bloodpool SUVs did differ.

Conclusion: Metabolic parameters for local staging in the index tumor on bpPET/MRI may be considered comparable to the metabolic parameters retrieved from wbPET/MRI in breast cancer patients. These findings reinforce the potential of a breast-dedicated protocol integrated in the whole-body [ 18 F]FDG PET/MRI in breast cancer patients.

Rationale and objectives: Best practices for quantifying longitudinal changes in 99m Tc-sestamibi uptake with molecular breast imaging (MBI) have not been established. The objective of this work is to quantify the variability of tumor-to-normal tissue 99m Tc-sestamibi uptake measurements in patient data and the resulting impact on categorizing uptake changes throughout neoadjuvant systemic therapy (NST).

Materials and methods: In 60 patients with locoregional breast cancer undergoing NST, tumor-to-normal-tissue ratios of average contour counts ( ) and activity concentrations ( ) were calculated from physician contours on craniocaudal and mediolateral-oblique MBI images acquired at pre-NST, mid-NST, and post-NST with a commercial dual-headed system. Measurement variability was quantified in pre-NST images by using different contours and detector views. This analysis was then used to define patient-specific thresholds above which calculated and values at mid-NST and post-NST imaging had 'changed' from pre-NST values.

Results: Pre-NST values ranged from 1-5 to 1-100 and in general decreased by 10-30% at mid-NST and by 50-70% at post-NST. uncertainty was significantly higher than uncertainty (53% vs. 35% median value; paired t -test; P  < 0.007), driven primarily by normal-tissue contour placement within the heterogeneous signal in normal breast parenchyma. In paired comparisons, a significantly higher number of cases 'changed' when the metric was derived from a single image instead of averaged across images (McNemar's test, P  < 0.0125).

Conclusion: By ensuring consistent acquisition conditions and standardizing contour definitions, robust metrics of tumor and normal-tissue uptake can be extracted from heterogenous clinical MBI data for longitudinal quantitative evaluations.