Nuclear Medicine Communications最新文献

Objective: This study explored the predictive value of 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) radiomics for assessing programmed death-ligand 1 (PD-L1) expression in non-small cell lung cancer (NSCLC), aiming to noninvasively evaluate PD-L1 status and assist in selecting patients for immunotherapy.

Methods: We retrospectively analyzed 163 NSCLC patients with pretreatment 18F-FDG PET/CT scans, randomly assigning them into training (n = 130) and validation (n = 33) cohorts. Optimal radiomics features were selected via least absolute shrinkage and selection operator and combined with clinical factors to construct five predictive models: CT, PET, radiomics, clinical, and a combined model. Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), calibration curves, and decision curve analysis (DCA).

Results: All models showed predictive ability for PD-L1 expression. The combined model demonstrated superior performance, with AUCs of 0.839 [95% confidence interval (CI): 0.771-0.908] in training and 0.782 (95% CI: 0.610-0.954) in validation. Calibration curves indicated good agreement between predicted and observed probabilities (Brier scores: 0.163 and 0.191, respectively). DCA confirmed the highest net clinical benefit for the combined model.

Conclusion: The multimodal combined model, integrating PET/CT radiomics with clinical factors, shows significant potential for noninvasively predicting PD-L1 expression in NSCLC, offering a novel strategy for precise patient selection for anti-PD-L1 immunotherapy.

Purpose: To evaluate the utility of 99m Tc-pentavalent dimercaptosuccinic acid (DMSA-V) brain single-photon emission computed tomography/computed tomography (SPECT/CT) in treated adult glioma with respect to isocitrate dehydrogenase (IDH) mutation status.

Methods: This prospective study included pathologically proven glioma patients. Early and delayed SPECT/CT images were obtained following intravenous administration of 797.90 ± 61.77 MBq 99m Tc DMSA-V. Both qualitative and quantitative analyses were carried out. The reference standard was established by follow-up MRI, histopathology, and clinical evaluation to verify SPECT/CT findings. The predictive value of IDH mutation status was assessed.

Results: Our study recruited 39 patients (24 males and 15 females; mean age: 40.41 ± 14.48 years). Residual/recurrent disease was confirmed in 23 cases, whereas 16 cases were disease free. 99m Tc DMSA-V SPECT/CT revealed a specificity of 100% and a sensitivity of 73.9% in identifying residual/recurrent gliomas. IDH was mutant in 22 (56.4%) and wild in 17 (43.6%) patients. Early, delayed lesion/non-lesion ratios, and retention index were significant predictors of the true disease status in the patients with mutated IDH; the area under the curves were 0.793 [95% confidence interval (CI): 0.566-1], 0.826 (95% CI: 0.648-1), and 0.826 (95% CI: 0.648-1), respectively. Eleven patients died after a mean follow-up of 10.82 months; eight patients with positive scan and wild-type IDH vs. three with negative scan and mutant IDH ( P  = 0.033). The median survival was 14 months for the first group and was not reached for the second.

Conclusion: 99m Tc DMSA-V brain SPECT/CT is a reliable, noninvasive, and specific modality for posttherapy evaluation of glioma. It has significant diagnostic and prognostic values in the mutant IDH glioma.

Objectives: Diagnostic reference levels (DRLs) are essential indicators for optimising medical radiation exposure, although implementation varies by country. In Japan, the Association of Radiological Technologists in National University Hospitals (ARTNU) investigated baseline DRLs for nuclear medicine based on a nationwide survey in 2020. These include the 50 th and 75 th percentile values, providing practical benchmarks for administered activity management. However, comparative insights with Japan DRLs 2025 and international standards remain limited.

Methods: This nationwide survey, conducted in 2025 across 42 Japanese national university hospitals, examined radiopharmaceutical and computed tomography (CT) administered activity indices in single-photon emission computed tomography/CT (SPECT/CT) and PET/CT (PET/CT) examinations and compared the results with Japan DRLs 2020; Japan DRLs 2025; and international benchmarks from the UK, Europe, USA, Korea, Australia, and Thailand. Japan DRLs 2025 introduced procedural refinements and anatomy-based CT classifications, particularly for PET/CT, aligning with evolving clinical protocols.

Results: Data on radiopharmaceutical administered activities and CT parameters (CT dose index volume, dose length product) were collected. 18 F-fluorodeoxyglucose-PET protocols predominantly applied 4.0 MBq/kg weight-based dosing, whereas SPECT/CT uses fixed radiopharmaceutical administered activities. CT exposure was adapted according to imaging purpose and anatomical region, frequently achieving low-administered activity operation. Although ARTNU DRLs 2020 remained clinically useful, they exhibited broader administered activity distributions and lack anatomical specificity.

Conclusion: ARTNU DRLs 2020 should be revised with a follow-up survey to better reflect current practices and align with the increased granularity of Japan DRLs 2025. Japanese institutions have demonstrated concordance with global standards and ongoing administered activity optimisation through technological advancements.

Purpose: To evaluate the usefulness of [18F] fluoro-d-glucose PET combined with computed tomography ([18F]FDG PET/CT) in staging T1 lung tumors with pure solid morphology on CT, focusing on the different histology subtypes, accuracy, detection rate of metastases, and its impact on changes in TNM staging.

Patients and methods: Retrospectively, 238 patients with lung cancer and T1 nodules with pure solid morphology on CT scan, staged with [18F]FDG PET/CT and chest contrast-enhanced CT (ceCT) were included. Primary tumor (T) sizes were assessed on chest ceCT and PET/CT. Maximum standardized uptake values (SUVmax) of the primary lung tumor were obtained from PET. Prevalence of lymph node and distant metastases was assessed for the three substages of T1 lung cancer (T1a, T1b, and T1c).

Results: Sixty-two (26%) patients with solid T1 lung cancer had lymph node metastases (T1a: 22%, T1b: 16%, T1c: 38%), and 29 (12%) showed distant metastases (T1a: 11%, T1b: 11%, T1c: 14%) in PET/CT imaging. [18F]FDG PET/CT detected distant metastases in 12 patients with negative chest ceCT. [18F]FDG PET/CT upstaged 26 patients (11%) and downstaged 13 patients (6%) compared with ceCT. Primary tumor histological subtypes and SUVmax values significantly correlated with the risk of lymph node and distant metastases (P < 0.001). However, the sensitivity for mediastinal nodal detection (N+) was poor with both CT (35%) and [18F]FDG PET/CT (47.5%).

Conclusion: [18F]FDG PET/CT is useful for staging of pure solid T1 lung cancer with a detection rate of 26% for lymph node metastases and 12% for distant metastases. [18F]FDG PET/CT is more accurate and has a higher positive predictive value than chest ceCT and leads to a change in the TNM stage in 17% of patients. Due to the limited sensitivity of FDG PET/CT in detecting lymph node metastases, lymphadenectomy cannot be omitted even in small pure solid T1 lung cancer.

Purpose: The 4-point visual 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) PET/computed tomography (CT) 'Herder' score, in combination with clinical factors, is used to assess malignancy risk of solitary pulmonary nodules (SPNs) and guide management. We aim to assess the impact of four digital reconstructions on Herder visual score, Herder model probability, and subsequent management of SPNs.

Methods: [18F]FDG PET/CT examinations for SPN assessment, performed on a Siemens Biograph Vision PET/CT, were retrospectively included (398 reconstructions; Gauss 6.0, Gauss 4.5, Gauss 4.5 with data-driven gating, and All Pass). Eight expert readers assessed anonymised reconstructions randomly (four pairs, 25 cases/100 reconstructions per pair). The Herder visual score was documented, and the Herder model probability score for each reconstruction was calculated using clinical parameters. A single observer performed semiquantitative analysis (SUVmax and target-to-background ratios).

Results: 73/100 cases showed Herder visual score concordance across all four reconstructions. Although the visual score changed for at least one reconstruction in 27 cases, the risk stratification based on the Herder model probability remained identical in 15/27. In 12 cases, changes in Herder visual score altered risk stratification. However, this did not change the subsequent management plan for any patient. Semiquantitative outputs were significantly different between Gauss 6.0 and All Pass (P < 0.001) and Gauss 4.5 and All Pass (P = 0.03-0.05) with no significant difference between the other reconstructions.

Conclusion: There is excellent concordance in Herder based SPN risk stratification across all four digital PET reconstructions. Although different reconstructions can alter risk stratification, this did not impact management in our cohort.

Purpose: This preliminary study evaluates the feasibility and clinical value of sparse-view acquisition in 99m Tc-prostate specific membrane antigen (PSMA) single photon emission computed tomography (SPECT) prostate imaging. This study also compares the performance of traditional Gaussian filtering vs. an edge-preserving nonlocal means (NLM) filter in the sparse-view SPECT approach.

Methods: Ten patients with biopsy-proven prostate cancer (Gleason 4-10) underwent full-angle acquisitions (60 views), which were decimated to 30, 15, and 10 views. Images were reconstructed with ordered-subsets expectation maximization (9 iterations, 5 subsets) and postfiltered with a Gaussian kernel or NLM. Quantitative performance metrics included mean absolute percentage error (MAPE), normalized root mean square error (NRMSE), peak signal-to-noise ratio (PSNR), and normalized bias (NB). Two nuclear medicine physicians (10-12 years' experience) provided blinded visual assessments.

Results: Halving the views to 30 preserved diagnostic accuracy (MAPE_ROI1 ≤ 7%). Reducing to 15 views introduced sampling artifacts consistent with violation of the angular Nyquist limit, and 10 views produced unacceptable artifacts (MAPE_ROI1 > 50%). For 30-view reconstructions, NLM outperformed Gaussian, improving NRMSE by up to 39.3%, PSNR by 4.5%, and NB by 18.55%. Expert readers confirmed these trends, with high interobserver agreement (intraclass correlation coefficient = 0.83) for 30 views.

Conclusion: Sparse-view 99m Tc-PSMA SPECT with 30 views appears feasible for routine and emergency prostate imaging in this setting. Reconstructions from 15 views showed aliasing from angular undersampling and are not recommended without anti-aliasing strategies and further validation. This work characterizes the added value of NLM postreconstruction filtering in PSMA-SPECT and motivates larger studies.

Objective: This study aimed to assess the detection rate of gallium 68 (Ga-68) fibroblast activation protein inhibitor (FAPI) PET/computed tomography (CT) for primary and metastatic gastric adenocarcinomas and to correlate quantitative tracer uptake with different histopathological subtypes.

Methods: A single-center retrospective observational study was conducted on 90 adult patients with histopathologically proven gastric adenocarcinoma. All patients underwent Ga-68 FAPI PET/CT for initial staging before therapy. The detection rate of primary tumors and the incidence of metastases were evaluated. Semiquantitative parameters, including maximum standardized uptake value (SUV max ) and tumor-to-background ratio (TBR), were correlated with histopathology using the Kruskal-Wallis test.

Results: Ga-68 FAPI PET/CT demonstrated a 100% detection rate for primary gastric tumors, with a median SUV max of 11.81. The uptake was not significantly influenced by histopathological subtype ( P  = 0.437). Distant metastases and peritoneal carcinomatosis were detected in 52.2 and 46.7% of patients, respectively. High tracer uptake was observed even in subcentimetric peritoneal lesions. Notably, distant parenchymal metastases without peritoneal or regional involvement were detected in five (5.5%) patients. No adverse events were reported.

Conclusion: Ga-68 FAPI PET/CT shows high tracer uptake and excellent tumor-to-background delineation, with its uptake being independent of histological subtype. The modality is highly effective for detecting peritoneal and distant metastases, including otherwise occult sites of disease, which could potentially impact management decisions. These findings suggest that Ga-68 FAPI PET/CT may become a valuable tool for the staging of gastric cancer; however, the retrospective design and lack of comparison with FDG PET/CT are limitations requiring further validation in prospective multicenter studies.

Purpose: To quantify concordance between single-time-point (STP) and multiple-time-point (MTP) dosimetry for organs-at-risk (OARs) and lesions in 177 Lu-PSMA-I&T.

Methods: Thirteen men with metastatic castration-resistant prostate cancer underwent quantitative SPECT/CT at ~20, ~48, and ~120 h posttherapy. Lesions <3.0 cc were excluded. Time-activity curves (TACs) were fit with automatic model-order selection (parameters ≤ data points); accepted fits required R2 > 0.90. STP activity-time integrals were estimated with the Hänscheid formalism. Agreement metrics included paired median differences, Lin's concordance, and Bland-Altman bias/limits of agreement.

Results: For OARs, STP at ~48 h matched MTP with minimal bias (parotids Δ = 0.00 Gy/GBq, P  = 0.475; kidneys Δ = 0.02, P  = 0.157). Lesion concordance improved with later imaging (STP2-STP3), whereas ~20 h STP underestimated lesion dose coefficients (all lesions Δ = +0.36 Gy/GBq; +57.4%). TAC modeling favored mono-exponential kinetics in most lesions (83%) and kidneys, with mixed behavior in parotids.

Conclusion: A single quantitative scan at ~48 h provides OAR dosimetry concordant with MTP, while lesion estimates are best captured at ~48-120 h. Early STP imaging (~20 h) should not be used alone for lesions. Findings support a pragmatic, concordance-oriented dosimetry workflow for routine 177 Lu-PSMA-I&T care.

Objective: Skeletal metastasis is not only associated with pain but also constitutes a prevalent cause of mortality in patients with prostate cancer (PC). Accurate evaluation of skeletal disease status is essential in the management of PC. This study examines the concordance between 99m Tc-prostate-specific membrane antigen (PSMA) and 99m Tc-Methylene Diphosphonate (MDP) scans for detecting skeletal metastases in PC patients.

Methods: This prospective study evaluated 18 participants with histopathologically confirmed PC from July 2022 to July 2024. All patients underwent 99m Tc-PSMA and 99m Tc-MDP single-photon emission computed tomography/computed tomography (SPECT/CT) within an average interval of 9.5 days. Lesions were categorized on an ordinal scale. The Wilcoxon signed-rank test was employed for statistical comparison.

Results: The median prostate-specific antigen (PSA) at the time of the study was 85.9ng/ml. The disease was predominantly advanced, with 14 patients (74%) exhibiting stage 4b. The Gleason scores were 8-10 ( n  = 16) and 7 ( n  = 2). Total 244 skeletal lesions were detected. 99m Tc-MDP identified 233 lesions (95.5%), whereas 99m Tc-PSMA identified 176 lesions (72.1%). The disparity in lesion count across scans was not statistically significant ( Z  = 1.6, P  = 0.11). Area under the curve for receiver operating characteristic analysis of 99m Tc-PSMA for skeletal lesion detection was 0.878, signifying high diagnostic precision.

Conclusion: The 99m Tc-PSMA scan exhibited comparable efficacy to 99m Tc-MDP bone scintigraphy in identifying skeletal metastases in PC. The capability to identify both skeletal and supplementary soft tissue metastases, together with its potential theragnostic applications, establishes 99m Tc-PSMA scan as a viable comprehensive imaging solution, especially in resource-constrained settings with limited PSMA PET/CT access and poor patient affordability.

Objectives: Differentiated thyroid carcinoma (DTC) frequently metastasizes to lymph nodes, significantly influencing patient prognosis. Posttherapy I-131 whole-body scan with SPECT/computed tomography (CT) (Rx-WBS) is crucial in detecting residual metastatic lymph nodes (reLNs). This study aimed to construct spatial heatmaps of reLNs based on the Rx-WBS to visualize anatomical distribution and to provide references for optimizing lymph node dissection (LND) strategies.

Methods: This retrospective study included 110 intermediate- to high-risk DTC patients who underwent thyroidectomy and LND, followed by I-131 therapy within 3 months postoperatively. reLNs were manually identified and segmented on Rx-WBS using ITK-SNAP. All reLNs were registered onto a reference patient's CT image based on anatomical landmarks. Representative axial and sagittal heatmaps were generated to illustrate the reLNs' spatial patterns. Univariate analysis and multivariable negative binomial regression were used to identify the factors associated with reLNs.

Results: A total of 276 reLNs from 110 patients were mapped to the reference CT. Heatmaps demonstrated that reLNs were most concentrated in level Ⅵ (39.5%), followed by levels Ⅳ (19.2%) and Ⅲ (17.0%), clustering around the internal carotid artery and jugular vein. Levels I, Ⅴ, and the retropharyngeal space showed lower involvement. Univariate analysis revealed that age and the extent of LND were potential influencing factors.

Conclusion: This study constructed anatomical heatmaps of reLNs, revealing spatial 'hotspots' of residual metastases. These visualizations illustrate the anatomical distribution of reLNs and may assist in refining LND strategies.