Nuclear Medicine Communications最新文献

Objective: The objective of this study is to evaluate the combined prognostic values of 18F-fluorodeoxyglucose (18F-FDG) PET and computed tomography (CT)-derived entropy-based heterogeneity features from hybrid PET/CT scanner using machine learning in patients with lung adenocarcinoma undergoing curative surgery.

Methods: Presurgical 18F-FDG PET/CT from 131 patients with lung adenocarcinoma were divided into training (n = 92) and temporal validation (n = 39) cohorts. In the training cohort, we integrated entropy-based heterogeneity features from 18F-FDG PET/CT for disease-free survival (DFS) prediction using machine learning approach. The predictive value of clinical variables and 18F-FDG PET/CT-based machine learning for DFS was examined using Cox regression analyses, and independent prognosticators were used to develop the survival prediction model. The model was then tested in the temporal validation cohort.

Results: In the training cohort, 18F-FDG PET/CT-based machine learning, female sex, and pN status independently predicted DFS. The model, incorporating these predictors significantly predicted DFS in the training (hazard ratio = 1.483, P < 0.001) and validation cohorts (hazard ratio = 1.753, P < 0.001). This model outperformed traditional staging system in both cohorts (c-indices = 0.717 vs. 0.621 in training; and 0.728 vs. 0.644 in validation). The model also predicted overall survival in both cohorts (hazard ratio = 1.370, P < 0.001 in training; hazard ratio = 1.574, P = 0.017 in validation).

Conclusion: Our preliminary results suggest that integrating prognostic values from 18F-FDG PET and CT-based heterogeneity features with clinical prognosticators is feasible and may support personalized treatment strategies for patients with resectable lung adenocarcinoma.

Objectives: The objective of this study is to evaluate the efficacy of multi-parametric MRI (mpMRI) and prostate-specific membrane antigen (PSMA) PET-computed tomography (CT) in preoperative loco-regional assessment of prostate carcinoma, correlating findings with histopathology.

Materials and methods: This prospective observational study enrolled 44 men (mean age 67.5 years) with suspected localized prostate cancer. All participants underwent mpMRI and PSMA PET-CT scans prior to histopathological confirmation via transrectal ultrasound-guided biopsies or radical prostatectomy. Imaging results were analyzed for sensitivity, specificity, and agreement with histopathology using Cohen's Kappa statistic. Key parameters, such as Prostate Imaging Reporting and Data System (PI-RADS) scores (mpMRI) and maximum standardized uptake (SUVmax) values (PSMA PET-CT), were correlated with Gleason scores.

Results: MpMRI exhibited a sensitivity of 95% and specificity of 50%, while PSMA PET-CT achieved 96.3% sensitivity and 57.1% specificity. MpMRI showed strong agreement with histopathology for tumor site localization (Kappa = 0.760), surpassing PSMA PET-CT (Kappa = 0.651). PSMA PET-CT identified metastases in 27.2% of cases, while mpMRI detected extra-prostatic extension in 50%. Higher PI-RADS scores and SUVmax values were associated with increased Gleason scores, indicating aggressive disease.

Conclusion: Both mpMRI and PSMA PET-CT offer high sensitivity for prostate cancer detection. MpMRI is superior for local staging, while PSMA PET-CT excels in identifying distant metastases. Their combined application enhances diagnostic accuracy and supports improved preoperative risk stratification in prostate carcinoma management.

Background: The clinical utility of 18 F-fluorodeoxyglucose (FDG) PET/computed tomography (PET/CT) imaging in bladder cancer is often compromised by high urinary FDG accumulation, which can interfere with the accurate detection of primary tumors and metastatic sites. This study aimed to evaluate the added benefit of delayed PET/CT imaging after diuretic administration in patients with bladder cancer, focusing on its ability to overcome the limitations posed by high FDG excretion into the bladder.

Methods: This prospective study was conducted at the Sohag Oncology Center, Egypt, and included patients with pathologically confirmed bladder cancer between March 2022 and March 2024. All patients underwent dual-phase PET/CT imaging, with early-phase imaging performed 45-90 min after the 18 F-FDG injection, followed by delayed imaging 1 h later after administering intravenous furosemide (20 mg) and enhanced hydration. The PET/CT images were analyzed qualitatively and quantitatively, with a maximum standardized uptake value (SUV max ) used to assess tumor activity in both early and delayed phases. Results were validated through biopsy, a combination of MRI and clinical follow-up for at least 6 months, or both.

Results: A total of 39 patients were included in the study (33 males, 6 females, aged 42-80 years). Residual bladder lesions were observed in 12.8% of the early images and 58.9% of the delayed images, with a significant increase in SUV max ( P  = 0.018). Lymph node involvement was detected in 12 patients, showing a similar rise in SUVmax ( P  = 0.012). Also, delayed PET/CT imaging improved sensitivity for both bladder lesions and metastatic lymph nodes (92.6 and 93%, respectively), while maintaining specificity (100% for bladder lesions, 74% for lymph nodes).

Conclusion: Delayed PET/CT postdiuretic administration improves image quality in bladder cancer via reducing urinary radiotracer activity, thus minimizing bladder interference and improving lesion detectability and characterization.

Objectives: Using personalized treatment with Lu-177-labeled radiopharmaceuticals, rather than using a fixed activity of 7.4 GBq, the administered radioactivity is adjusted in each patient. Achieving precise control of the administered activity would be possible during Lu-177 infusion if real-time monitoring techniques were possible. However, these techniques are not currently available. In this study, we used Monte Carlo simulations to simulate imaging of the administration site in an arm phantom with a pinhole gamma camera to explore the feasibility of achieving real-time monitoring and control of the administered activity during infusion.

Methods: We used the Geant4 toolkit to simulate a compact gamma camera. We simulated the basic performance of the camera within an energy window of 208 keV ± 10% and the imaging of an arm phantom to evaluate the feasibility of visualizing and quantifying the inflow of Lu-177-labeled radiopharmaceutical activity.

Results: The spatial resolution with the 1.0-mm pinhole collimator for Lu-177 was 1.8 mm full width at half maximum (FWHM) at 50 mm, whereas it was 1.2 mm FWHM for the 0.5-mm pinhole collimator. Our gamma camera captured the activity of Lu-177 in a 3.0-mm diameter vessel within the arm phantom, achieving measurements in only 1 min. The maximum values among the mean estimation errors of the administered activity were 0.73% and -3.53% for the 1.0 and 0.5-mm pinhole collimators, respectively, both occurring within the initial 1 min.

Conclusion: Monte Carlo simulations demonstrated the feasibility of real-time monitoring of administered activity during Lu-177 infusion by imaging the administration site with our pinhole gamma camera.

Objectives: To evaluate the treatment patterns and outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with radium-223 dichloride in the UK.

Methods: Patients initiating treatment with radium-223 from 1 September 2017 to 1 September 2019 in 15 UK oncology centres were included. Demographics, treatment, clinical, biochemical, and outcome data were collected prospectively. Quality of life data were obtained using analgesic scores and components of the Functional Assessment Cancer Therapy - Prostate (FACT-P) questionnaire.

Results: A total of 550 consecutive, evaluable patients were included. The most common prior therapy for mCRPC was enzalutamide. At final analysis, after a median follow-up of 13.3 months, 55% of patients had completed six cycles of treatment. Median overall survival was 13.7 months (95% confidence interval, 12.6-14.8 months). Poor performance status, prior use of docetaxel in the metastatic hormone sensitive prostate cancer (mHSPC) setting, number of lines of prior treatment, and abnormal platelet count were independent variables associated with poor prognosis. Adverse events led to treatment discontinuation in 5.5% of patients. WHO analgesic scores and FACT-P questionnaire scores did not significantly change after treatment administration.

Conclusion: The National Radium-223 Dichloride Audit was the first and largest multicentre prospective analysis of treatment patterns, outcomes, and quality of life data in patients treated with radium-223 in the UK. Radium-223 can be administered safely to patients previously treated with other life-prolonging therapies. Efficacy and safety data compare favourably with clinical trial and other real-world data. Our results suggest that its use earlier in the treatment pathway is associated with longer survival.

Purpose: COVID-19 vaccine-induced reactive axillary lymph nodes (RAL) on fluorodeoxyglucose (FDG) PET/computed tomography (CT) imaging can mimic malignant lymphadenopathy, leading to diagnostic errors. Reported RAL prevalence varies widely in the literature, and factors contributing to its development remain poorly understood. This meta-analysis aims to evaluate vaccine-induced RAL observed on FDG PET/CT imaging and consolidate evidence from multiple studies to assess its prevalence, duration, and associations with vaccine-related factors and demographic characteristics.

Method: Using multiple databases, a systematic review and meta-analysis was conducted on studies reporting RAL on FDG PET/CT following COVID-19 vaccination. The primary outcome was RAL prevalence, while the secondary outcomes were maximum standardized uptake value (SUV max ), vaccine-to-scan interval, and associations with vaccine type and demographics.

Results: A total of 25 studies comprising of 5010 subjects were included. Mean SUV max of reactive nodes was 2.8 ± 1.2. Overall, RAL prevalence was 38.6% ± 17.6, higher in females (58.1% versus 41.9%, P  = 0.02) and younger individuals (mean age 63.3 versus 70.7 years, P  = 0.03). The RAL rate was not statistically different between mRNA (39.9% ± 16.9) and non-mRNA vaccines (26.3% ± 30.9). However, subanalysis showed about 40% RAL with Pfizer and Moderna mRNA vaccines and AstraZeneca non-mRNA vaccine, versus much lower, below 20%, RAL with Sinovac and Johnson & Johnson non-mRNA vaccines. Stricter PET/CT interpretation criteria using blood pool threshold reduced RAL prevalence to <20%. RAL rate declined with time but was still present after 1 month.

Conclusion: Low activity RAL is common on FDG PET/CT after COVID-19 vaccination, while higher activity RAL (above blood pool) that can lead to clinical errors is less frequent. The frequency of RAL is affected by expected factors, such as age, gender, vaccine type, and time after vaccination, which indirectly suggest the link between RAL and COVID-19 postvaccinal immunity.

Objective: The primary treatments for Graves' disease include antithyroid drugs (ATD), thyroidectomy, and iodine-131 (I-131) therapy. This study aimed to identify factors predicting treatment outcomes and the treatment period required to achieve euthyroidism after I-131 administration.

Methods: This study included 109 patients with Graves' disease who underwent I-131 therapy. Patients achieving euthyroidism or hypothyroidism within 1 year were classified as the success group, whereas those with remaining hyperthyroidism were classified as the failure group. Thyroid volume, computed tomography (CT) values, 24-h radioiodine uptake, effective half-life, the levels of free triiodothyronine, free thyroxine, thyroid-stimulating hormone, and thyrotropin receptor antibody, history of I-131 therapy, history of ATD use, history of potassium iodide use, and thyroid absorbed dose were analysed.

Results: Larger thyroid volume [odds ratio = 0.982, 95% confidence interval (CI): 0.967-0.998, P  < 0.05] was identified as a predictive factor for treatment failure, as determined by multivariable logistic regression. In contrast, a shorter treatment period was associated with lower thyroid volume (hazard ratio = 0.990, 95% CI: 0.982-0.999, P  < 0.05), higher thyroid absorbed dose (hazard ratio = 1.007, 95% CI: 1.002-1.011, P  < 0.01), and lower thyroid CT values (hazard ratio = 0.963, 95% CI: 0.939-0.987, P  < 0.01), as identified by multivariable Cox regression.

Conclusion: Larger thyroid volume was associated with treatment failure. Smaller thyroid volume, higher thyroid absorbed dose, and lower thyroid CT values were significant predictors of the treatment period required to achieve euthyroidism after I-131 administration.

As a promising approach, in vivo pretargeting can leverage the unique tumor-targeting properties of antibodies for nuclear imaging and therapy while bypassing their pharmacokinetic limitations. The core premise of pretargeting is that targeted vectors and radioisotopes are administered separately, leading to a higher target background ratio than traditional imaging methods using long-lived radionuclides. This strategy directly relies on chemical reactions, namely bioorthogonal reactions. The inverse electron-demand Diels-Alder (IEDDA) cycloaddition between 1, 2, 4, 5-tetrazine and strained alkene dienophile is an emerging catalyst-free 'click' chemistry. The IEDDA reaction has been used in various chemical environments because of its selectivity, efficiency, cleanliness, biocompatibility, and bioorthogonality. In the present review, we briefly focused on the IEDDA reaction in pretargeted nuclear imaging and radioimmunotherapy and discussed the common bioorthogonal click reactions in vivo systems.

Background: In thallium-201 (Tl-201) stress myocardial perfusion imaging (MPI), elevated lung-to-heart ratio (LHR) can help to predict adverse cardiac events and identify coronary artery disease. However, few studies have evaluated the LHR values on Tl-201 MPI in patients with chronic obstructive pulmonary disease (COPD).

Objective: To examine whether LHR in COPD may be altered, considering the combined effects of hypoxia, inflammation, and capillary loss.

Methods: We retrospectively evaluated patients with normal Tl-201 pharmacologic stress MPI, no adverse cardiac events in the subsequent 2 years, and pulmonary function tests, coronary angiography, and echocardiography results obtained within 6 months. Patients with COPD (study group) were matched 1:1 by sex and age to controls with normal pulmonary function (control group). Subgroups within the study group were established based on COPD severity determined by spirometry. MPI images were interpreted using a 17-segment american heart association (AHA) model and a 0-4-point scale. LHR and right ventricle/left ventricle (RV/LV) ratios were also documented.

Results: Patients with severe COPD exhibited lower poststress LHR values than those with mild-to-moderate COPD. Compared with the control group, the moderate COPD group displayed higher stress LHR, stress RV/LV ratio, and tricuspid regurgitation maximum pressure gradient (TRmaxPG) values. Moreover, poststress LHR showed a positive correlation with the stress RV/LV ratio and TRmaxPG value. These findings were statistically significant ( P  < 0.05).

Conclusion: In Tl-201 pharmacologic stress MPI, our study suggests a nuanced relationship between COPD severity and LHR, emphasizing the need to reconsider normal LHR thresholds in COPD. Larger studies are warranted to validate and expand upon these findings.

Background: Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure when left ventricular mechanical dyssynchrony (LVdys) is present, yet approximately 30-40% of patients do not respond to therapy. The purpose of this study is to use unsupervised learning to identify phenotypes of patients with a better response rate.

Methods: Unsupervised learning integrating gated single-photon emission computed tomography (SPECT) was used to identify clinical phenotypes among patients undergoing CRT. We utilized hierarchical clustering analysis to group 217 patients based on 49 pretreatment variables, including demographic, clinical, and phase analysis of gated SPECT data. Fibrosis was measured by the percentage of pixels with less than 50% of maximum relative counts. LVdys was evaluated by phase SD >43° and phase bandwidth >135°.

Results: We identified three phenotypes of patients: two with similar response rates (86.2 and 87.0%) but with different characteristics, one presenting borderline LVdys, low fibrosis and nondilated heart and the other high LVdys, moderate fibrosis and a dilated heart; the third phenotype represents patients with moderate LVdys, substantial amounts of cardiac fibrosis and a dilated heart that do not have a good response to CRT (55.9%).

Conclusion: Our results suggest that evaluating cardiac dyssynchrony, fibrosis, and remodeling through phase analysis of gated SPECT is relevant in characterizing the phenotype of good responders. Patients with substantial amounts of cardiac fibrosis have less benefit from CRT. This work suggests that CRT recommendations based on customized selection criteria associated with gated SPECT can lead to higher response rates.