Nuclear Medicine Communications最新文献

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.

Background: To analyze the uptake patterns of dual-nuclide PET using 2-[ 18 F]-fluoro-2-deoxy- D -glucose (FDG) and O-(2-[ 18 F]-fluoroethyl)- L -tyrosine (FET) in intracranial lesions.

Methods: This study was conducted from July 2023 to September 2024. Patients with intracranial lesions underwent FDG PET and FET-PET scans on separate days before surgery. Four uptake patterns were observed: type A, positive uptake of both FET and FDG; type B, positive uptake of FET with negative uptake of FDG; type C, negative uptake of FET with positive uptake of FDG; and type D, negative uptake of both FET and FDG. Correlations between standardized uptake values (SUVs) of FET/FDG and tumor proliferation marker Ki-67/tumor protein p53 (P53) were analyzed using Pearson correlation analysis.

Results: Among 28 patients, type A was observed in 17, type B in nine, and type D in two patients. Dual-nuclide PET-based diagnoses were completely consistent with the pathology in nine, partially consistent in 17, and inconsistent in only two patients. Except for mature teratomas, all intracranial tumors demonstrated positive FET uptake. Correlations were observed between FDG and Ki-67: SUV max ( P  = 0.011) and SUV mean ( P  = 0.012). In addition, correlations were observed between the FDG/FET ratio and Ki-67: SUV max ( P  = 0.029) and SUV mean ( P  = 0.021).

Conclusion: Dual-nuclide PET is valuable in diagnosing intracranial lesions. Type A is the most common uptake pattern. The SUV of FDG is positively correlated with the Ki-67 level. Compared with single-modality PET, dual-nuclide PET uptake patterns provide diagnostic insights into intracranial lesions.

Background: Treatment and outcome of soft tissue sarcomas (STS) are presently guided by stage and clinicopathological factors. Radiomics, the quantitative analysis of images applied to [ 18 F]fluoro-2-deoxy- d -glucose (FDG) PET could improve prognostication and thereby treatment outcomes, especially due to its ability to quantify intratumoural metabolic heterogeneity. However, the data for its utility in STS is limited.

Objectives: This study aimed to assess the prognostic value of pretreatment FDG PET-derived radiomic features for patients with STS. A retrospective analysis was performed of patients with STS who underwent FDG PET and were treated with curative intent in a sarcoma centre ( n = 44). Tumour segmentation was performed using a 40% maximum standardised uptake value threshold, and 107 radiomic features were extracted. Univariable and multivariate Cox regression evaluated radiomic features against local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS), disease-free survival (DFS), and overall survival. Survival difference was then assessed using Kaplan-Meier survival curves constructed from receiver operating characteristic (ROC) derived thresholds.

Results: Our study demonstrated measures of tumour heterogeneity predicted outcome, the strongest predictor being, GLSZMSZNUN, which was a significant predictor on multivariate analysis of DRFS [heart rate (HR) = 0.00031, 95% confidence interval (CI) = 2.1 × 10-7-0.45, P = 0.03] and DFS (HR = 0.00047, 95% CI = 1.3 × 10-6-0.16, P = 0.01). Stratification using ROC-derived thresholds showed survival difference for LRFS ( P = 0.045), DRFS ( χ2 = 4.7, P < 0.001), and DFS ( χ2 = 8.1, P = 0.005).

Conclusion: Multiple PET radiomic features demonstrated significant prognostic utility independent of standard clinical features and predicted survival outcomes in STS. Larger prospective multicentre cohorts are required to verify our findings and enable integration into clinical decision aids and precision medicine in STS.

Objective: This study analysed the safety and effectiveness of a 20% dose reduction of 177 Lutetium-labelled prostate-specific membrane antigen (PSMA) radioligand therapy in patients with metastatic castration-resistant prostate carcinoma (mCRPC) and preexisting impaired renal function.

Methods: In this retrospective study, 16 mCRPC patients with impaired renal function - estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m 2 who received 177 Lu-PSMA-I&T were identified. Median number of cycles was 4 (range 1-8 cycles), and median interval between cycles was 6 weeks. Renal function was monitored throughout the treatment. Therapy response was assessed via prostate-specific antigen (PSA) measurements. Patients received a 20% dose reduction from the standard dose of 7.4 GBq. Mean follow-up time was 8.5 months (range 2-37 months). Kaplan-Meier analysis was performed to obtain progression-free survival (PFS) and overall survival (OS).

Results: Mean baseline eGFR was 48 ml/min/1.73 m 2 (range 21-59 ml/min/1.73 m 2 ). Mean end-of-treatment eGFR was 51 ml/min/1.73 m 2 (range 19-83 ml/min/1.73 m 2 ). At the end of follow-up, the mean eGFR was 48 ml/min/1.73 m 2 (range 20-83 ml/min/1.73 m 2 ). There was no evidence that eGFR was affected by the 177 Lu-PSMA-I&T treatment either after the last cycle or at the end of follow-up ( P  > 0.05). No patients suffered grade 4 renal toxicity. After 1 cycle, 50% of patients had a partial PSA response, which increased to 73% after two cycles. Median PFS was 12 months [95% confidence interval (CI): 4-14 months], and OS was 17 months (95% CI: 13-40 months).

Conclusion: Findings support the feasibility of 177 Lu-PSMA-I&T treatment in mCRPC patients with preexisting renal impairment (eGFR 21-59 ml/min/1.73 m 2 ) when a 20% dose reduction is applied.

Objectives: Technetium-99 m ( 99m Tc)-sestamibi, a lipophilic cationic molecule that accumulates in cells rich in mitochondria, can help to characterize the solid renal masses. This study evaluated the accuracy of 99m Tc-sestamibi single photon emission computed tomography/computed tomography (SPECT/CT) in the characterization of solid renal lesions, and we explored whether dynamic imaging could provide added diagnostic value over delayed SPECT/CT in the differentiation of renal lesions into benign and malignant.

Methods: In this prospective study, all referred patients with a solid renal mass who have not undergone any intervention underwent 99m Tc-sestamibi SPECT/CT imaging and, based on lesion (TLsC) to renal background uptake ratio (TRBKG) with a cutoff 0.5, the renal masses were classified as either positive or negative for 99m Tc-sestamibi uptake, and the results compared with final histopathological reports.

Results: Thirty-six patients (28 men and 8 women) were included, of which five patients' renal lesions were 99m Tc-sestamibi positive and 31 were negative. Of the five 99m Tc-sestamibi-positive lesions, four were benign in nature, whereas 30 of 31 99m Tc-sestamibi-negative lesions were malignant. Thus, the sensitivity, specificity, and accuracy of 99m Tc-sestamibi for differentiation of benign and malignant renal lesions were 80% [95% confidence interval (CI), 37.56-96.38], 96.8% (95% CI, 83.81-99.43), and 94.4% (95% CI, 81.86-98.46), respectively. The area under the receiver operating characteristic curve was 0.935 (95% CI 0.84-1.00). Dynamic imaging showed no significant incremental value over delayed 99m Tc-sestamibi SPECT/CT for lesion classification (McNemar's exact P  = 1.00; Fisher's exact P  = 0.163).

Conclusion: The study showed high diagnostic accuracy of 99m Tc-sestamibi SPECT/CT in differentiating benign from malignant solid renal lesions. Its high specificity and negative predictive value make it a potential and valuable noninvasive diagnostic tool for characterizing solid renal lesions, thus guiding further management. Dynamic imaging, however, did not demonstrate incremental diagnostic value over delayed SPECT/CT for characterization of renal lesions.

Background: This study evaluates the diagnostic value of PET/computed tomography imaging features using dual tracers, 18 F-fluorodeoxyglucose ( 18 F-FDG) and 18 F-fluorothymidine ( 18 F-FLT), combined with metabolic parameters and clinical characteristics, to differentiate benign and malignant pulmonary occupying lesions (POLs).

Methods: This retrospective study included 81 patients with pathologically confirmed POLs (median age = 59, interquartile range 49-69), with tissue obtained by bronchoscopic biopsy, percutaneous transthoracic needle biopsy, or surgical resection. We analyzed 18 F-FDG and 18 F-FLT PET imaging features (geometry, intensity, and texture) alongside clinical data and metabolic parameters to construct a combined prediction model.

Results: The predictive model integrating dual-tracer ( 18 F-FDG and 18 F-FLT) PET radiomics, metabolic parameters, and clinical characteristics demonstrated strong diagnostic performance. Malignant lesions were associated with significantly higher age, 18 F-FLT maximum standardized uptake value (SUVmax), and FLT/FDG SUVmax ratio compared to benign cases (all P  < 0.05). In the test cohort (25 cases: 13 benign, 12 malignant), the radiomics model outperformed the metabolic-clinical model, with area under the receiver operating characteristic curve (AUC) values of 0.962 [95% confidence interval (CI): 0.883-1.000] vs. 0.718 (95% CI: 0.496-0.940). The nomogram combining multimodal features achieved optimal performance (AUC: 0.981; 95% CI: 0.942-1.000), though the upper CI limit (1.000) may reflect high predictive accuracy tempered by small-sample variability. Decision curve analysis confirmed the nomogram's superior clinical net benefit over radiologists' judgment and single-modality models. Calibration curves showed excellent agreement between predicted probabilities and observed outcomes.

Conclusion: The dual-tracer radiomics model significantly enhances the differential diagnosis of benign and malignant pulmonary lesions, with the nomogram offering high clinical application potential.