Nuclear Medicine Communications最新文献

Background: Hepatocellular carcinoma (HCC) is a highly prevalent malignant tumor worldwide, with Chinese patients accounting for more than 50%. Microvascular invasion (MVI) is a significant risk factor for postoperative recurrence of HCC. 18 F-fluorodeoxyglucose PET/computed tomography ( 18 F-FDG PET/CT), as a hybrid imaging modality integrating metabolic information from PET with anatomical details from CT. This combined approach enables simultaneous assessment of glucose metabolism and structural features. It can also evaluate tumor biological behavior through metabolic parameters and heterogeneity characteristics.

Objective: To explore the predictive value of 18 F-FDG PET/CT metabolic parameters and heterogeneity index for MVI in HCC patients before liver transplantation and to construct a nomogram prediction model.

Methods: A retrospective study involving 177 HCC patients who underwent liver transplantation (100 MVI-positive cases and 77 MVI-negative cases) was conducted to analyze the correlation between clinical characteristics, PET/CT metabolic parameters (SUVmax, SUVmean, TLG, and TLR), and heterogeneity parameters (COV and HI) with MVI. Independent predictors were identified using univariate and multivariate logistic regression, and a nomogram model was constructed. The model's performance was evaluated using calibration curves and ROC curves.

Results: Univariate analysis showed significant differences in PIVKA-II, SUVmax, TLG, TLR, COV, and HI between the two groups (all P  < 0.05). Multivariate analysis indicated that PIVKA-II (OR = 1.000, P = 0.042), TLG (OR = 0.999, P = 0.024), HI (OR = 1.022, P < 0.001), and TLR (OR = 1.618, P = 0.031) were independent predictors of MVI. The area under the ROC curve (AUC) of the combined model reached 0.815 (95% confidence interval: 0.754-0.876), significantly better than any single parameter. The nomogram calibration curve showed a high consistency between predicted probabilities and actual observed probabilities (mean absolute error = 0.025).

Conclusion: The integration of PET/CT-derived parameters-specifically TLG (metabolic burden), HI (heterogeneity), and TLR (tumor-to-liver contrast)-with serum PIVKA-II provides a robust tool for preoperative MVI prediction in HCC patients undergoing liver transplantation. The validated nomogram model (AUC = 0.815) outperforms individual parameters, offering a reliable basis for clinical decision-making.

Purpose: This study aimed to evaluate correlation between various parameters from integrated 82-rubidium PET/coronary computed tomography angiography (RbPET/CCTA), like coronary artery calcium (CAC) score, coronary artery disease-reporting and data system (CAD-RADS), myocardial ischemia scores, and myocardial blood flow parameters [stress myocardial blood flow (sMBF) and myocardial flow reserve (MFR)].

Methods: In this retrospective study, 184 consecutive patients [107 women, 77 men, median age: 67 years [(interquartile range: 61-74 years)] with suspicion of CAD were imaged with RbPET/CCTA in the 'one-stop imaging' approach. The association between CAC score, CAD-RADS, relative perfusion, and myocardial blood flow was assessed.

Results: There was a weak but statistically significant inverse correlation between the global CAD-RADS score and global sMBF ( ρ = -0.239, P = 0.001) and global MFR ( ρ = -0.248, P = 0.0001). There was a significant difference in CAD-RADS 3-5 vs. CAD-RADS 0-2 for global as well as per-vessel sMBF and MFR values ( P < 0.05). There was a very weak inverse correlation between global CAC and global sMBF ( ρ = -0.165, P = 0.026) and a nonsignificant, very weak inverse correlation between global CAC and global MFR ( ρ = -0.120, P = 0.106).

Conclusion: Combined CCTA and RbPET 'one-stop imaging' provides comprehensive anatomical and physiological information in patients with suspected CAD. The PET and computed totmography parameters seem to lack linear and robust correlation. In the given circumstances, CAD-RADS scores appear to have a relatively better, though weak, correlation with sMBF, MFR, and relative ischemia scores compared with CAC scores.

Objective: Relative to planar imaging, macro-aggregated albumin-single photon emission tomography/computed tomography (MAA-SPECT/CT) offers more reliable lung shunt fraction (LSF) and lung mean dose (LMD) estimates in 90 Y radioembolization. But lung truncation in SPECT/CT can limit its utility, yielding uncertain LSF and LMD estimates. Here, the effects of lung mass on LSF and LMD corrections for lung truncation in SPECT/CT were analyzed.

Methods: 106 cases with planar LSF > 8% were analyzed. Lung truncation was simulated in 30 cases with full lung coverage, while 50 cases with clinical truncation were also assessed. Five LMD estimates were computed: (1) planar-imaging, 1-kg lung-mass (Planar 1-kg ), (2) planar-imaging, patient-specific lung-mass (Planar), (3) uncorrected-truncated SPECT and lung-mass (SPECT Trunc ), (4) truncation-corrected SPECT, 1-kg lung-mass (SPECT 1-kg ), (5) truncation-corrected SPECT, patient-specific lung-mass (SPECT Fit ). Bland-Altman analysis (mean difference ± 95% prediction interval; PI = 1.96σ) was used to compare the LMD estimates.

Results: Planar 1-kg and Planar LMD were comparable on average, but variability was high (mean ± 95% PI: 0.1 ± 7.8 Gy). The mean ± 95% PI in LMD for Planar 1-kg relative to nontruncated-SPECT (SPECT True ) was 10.4 ± 11.4 Gy. LMD differences relative to SPECT True were 0.3 ± 1.0 Gy for SPECT Trunc , 0.1 ± 1.0 Gy for SPECT 1-kg , and 0.1 ± 1.1 Gy for SPECT Fit . In clinically truncated cases, differences between Planar 1-kg and SPECT Trunc were again high (11.2 ± 10.3 Gy), with differences between SPECT Trunc , SPECT 1-kg , and SPECT Fit much smaller (mean <0.2 Gy, 95% PI < 2.0 Gy).

Conclusion: The most impactful difference in estimating LMD is using SPECT/CT data in place of planar imaging. Even when lung mass is unknown or a reference value (1-kg) is used, truncated MAA-SPECT/CT offers more robust LMD estimates than planar imaging.

Introduction: Accurate lymph node staging is essential for treatment planning and prognosis in non-small cell lung cancer (NSCLC). [ 18 F]Fluorodeoxyglucose Positron emission tomography/computed tomography ([ 18 F]FDG PET/CT) is a widely used non-invasive imaging modality. Lymph node size and maximum standardized uptake value (SUVmax) are the most utilized parameters but with known limitations. We hypothesized the lymph node-to-primary tumor SUVmax ratio (N/T SUV ratio) could mitigate the limitations and provide a more reliable diagnostic measure.

Objective: This study aims to evaluate the diagnostic accuracy of the N/T SUV ratio in comparison to other PET/CT parameters.

Materials and methods: This retrospective study evaluated consecutive patients with [ 18 F]FDG PET/CT done in Tuen Mun Hospital, Hong Kong between January 2023 and December 2023. PET/CT parameters, including SUVmax, N/T SUV ratio, visual score, and lymph node size, were analyzed. Receiver operating characteristic curves were used to determine optimal diagnostic cutoffs. Subgroup analyses were conducted based on lymph node and primary tumor characteristics.

Results: A total of 62 patients with 98 histologically confirmed lymph nodes were included. N/T SUV ratio (cutoff: 0.5) demonstrated the highest diagnostic accuracy (area under curves: 0.924), with a sensitivity of 82.69% and specificity of 95.65%. It remained consistent across patient subgroups and outperformed SUVmax, visual score, and lymph node size in distinguishing metastatic from benign nodes.

Conclusion: N/T SUV ratio (cutoff: 0.5) demonstrates the best consistency and robustness across patient subgroups, mitigating SUVmax variability. Its simplicity and reproducibility make it a valuable parameter for NSCLC nodal staging. Further studies with larger, multicenter prospective cohorts are warranted to validate its application.

During optimisation of L-mode parathyroid imaging, an artefact was identified in retrospective patient single photon emission computed tomography (SPECT) which could affect SPECT quantification. This work assessed: (1) H-mode SPECTs for the artefact; (2) differences in the artefact for [ 99m Tc] and [ 123 I], and with and without non-specific background; and (3) the impact on clinically relevant areas. Parathyroid/thyroid phantom studies were performed for L-mode and H-mode using a Perspex torso with saline bags to mimic non-specific background. SPECT/CTs were acquired with clinical parathyroid protocols and using Hermia software, volumes-of-interest were drawn in thyroid and areas of artefact in all reconstructed SPECTs. Standard uptake values (SUVs) for [ 99m Tc] and [ 123 I] were measured. Two clinicians reviewed the images and determined the artefact was more prominent within L-mode SPECTs, correlating to a greater spread of SUVs compared to H-mode. No differences were observed for [ 99m Tc] thyroid SUVs between all acquisitions ( P > 0.5). There were differences in SUVs between L-mode and H-mode for [ 123 I] ( P = 0.04) and with and without non-specific background ( P = 0.03). At the area of artefact, SUVs should be zero, however, there were measurable SUVs for L-mode and [ 123 I]. Based on these findings, H-mode proved more robust to artefacts and was preferred for clinical practice.

Objective: In this study, it is aimed to reveal the prognostic value of conventional parameters and texture features obtained from pretreatment F-18 fluorodeoxyglucose (FDG) PET/computed tomography (CT) images in newly diagnosed colon cancer patients by evaluating their relationship with overall survival and disease-free survival and to investigate the contribution of LC3b immunohistochemical (IHC) staining in colectomy materials to predict survival.

Materials and methods: Fifty-four patients who were diagnosed with colon cancer and underwent F-18 FDG PET/CT imaging in our hospital between November 2019 and January 2023 for pretreatment staging, who did not receive chemoradiotherapy, and who were operated in our hospital afterward were included in the study. In the pet imaging of the patients, the tumoral lesion was manually segmented, and SUV-based conventional parameters were obtained with the texture features of the lesion. The average 31-month survival information of the patients was obtained from the hospital information system. LC3b IHC staining could not be performed in patients whose colectomy preparations could not be accessed from the pathology archive or whose tissue was not suitable for staining. LC3b staining scores of 33 patients who could be evaluated were determined by the pathologist.

Findings: The mean sphericity value was significantly higher in the disease-free group compared with the progression group (0.67 vs. 0.56; P  = 0.021). The mean value of asphericity (0.81 vs 0.52; P  = 0.026) and the mean value of compacity (26.42 vs 20.38; P  = 0.028) were significantly higher in the progression group compared with the disease-free group. A statistically significant association was found between LC3B staining positivity and moderate-to-poor tumor differentiation.

Conclusion: PET/CT-based shape features may serve as potential noninvasive prognostic markers in colon cancer. Although a significant relationship was observed between LC3B expression and tumor differentiation levels, its potential prognostic value for survival warrants further investigation due to our limited sample size.

For patients with pulmonary hypertension, reduced administered activity of Tc-99m-macroaggregated albumin (MAA) is recommended for ventilation/perfusion scintigraphy. Although it is stated that MAA particles embolise in pulmonary capillaries, of which there are ~300 billion, they embolise in pulmonary arterioles, of which there are far fewer. This aim of this study, therefore, is to address the recommendation's validity. Using morphometric data of Horsfield, we estimated pulmonary vascular resistance (PVR) increments resulting from the administration of 100, 200, and 400 k MAA particles. We assumed two particle size distributions: one skewed left toward small particles and the other skewed right. MAA-induced PVR increments were also estimated for pulmonary vascular beds depleted by disease. Administration of 100, 200, and 400 k particles with left-skewed size distribution increases PVR by 2.7, 5.7, and 12.2%, respectively. Corresponding right-skewed values are 6.2, 13.5, and 32.4%. Following 25, 50, and 75% pulmonary vascular ablation, 200 k left-skewed particles increase PVR by 7.8, 12.2, and 29%, respectively, and right-skewed by 19, 32, and 109%, on top of PVR already increased from disease. Particle size distribution is important. Less than 200 k MAA particles should be administered to patients with pulmonary hypertension.

Objectives: Tumor volume in prostate-specific membrane antigen (PSMA-TV)-PET/computed tomography (CT) has shown an emerging impact for prognosis and response evaluation in patients with prostate cancer. We evaluated the robustness of different PSMA-TV delineation methods.

Materials and methods: A total of 40 18 F-JK-7-PSMA-PET/CT performed on the same scanner were analyzed. PSMA-TV measurements were performed using a standardized uptake value of 4.0 as a fixed threshold (T1), 41% of the single hottest voxel as an adaptive threshold (T2), and a liver-specific threshold (T3) for delineation in two reconstruction methods [four iterations and 12 subsets (R1) and three iterations and 21 subsets while applying a point spread function and a time-of-flight algorithm (R2)]. Differences between the segmentation thresholds in R1 and R2 were gathered and tested for statistical significance.

Results: PSMA-TV differed significantly between R1Tx and R2Tx for individual segmentation thresholds, with PSMA-TV in R2 being significantly smaller than in R1 using the same segmentation method. Comparing the differences in PSMA-TV between R1 and R2 reconstruction between the three separate segmentation thresholds showed significantly larger absolute volume differences for T2 compared with T3 and significantly larger relative volume differences for T2 compared with T1 and T3.

Conclusion: Reconstruction settings greatly influence the measurement of PSMA-TV, regardless of the segmentation threshold chosen; however, our results indicate that the fixed thresholds (T1 and T3) are less susceptible to reconstruction-induced volumetry effects than a relative threshold.

Objective: This study aimed to investigate the role of volumetric and dissemination parameters obtained from pretreatment 18-fluorodeoxyglucose PET/computed tomography (18F-FDG PET/CT) in predicting progression/relapse in patients with diffuse large B-cell lymphoma (DLBCL) with machine learning algorithms.

Methods: Patients diagnosed with DLBCL histopathologically, treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, and followed for at least 1 year were reviewed retrospectively. Quantitative parameters such as tumor volume [total metabolic tumor volume (tMTV)], tumor burden [total lesion glycolysis (tTLG)], and the longest distance between two tumor foci ( Dmax ) were obtained from PET images with a standard uptake value threshold of 4.0. The MTV obtained from the volume of interest with the highest volume was noted as metabolic bulk volume (MBV). By analyzing the patients' PET parameters and clinical information with machine learning algorithms, models that attempt to predict progression/recurrence over 1 year were obtained.

Results: Of the 90 patients included, 16 had progression within 1 year. Significant differences were found in tMTV, tTLG, MBV, and Dmax values between patients with and without progression. The area under curve (AUC) of the model obtained with clinical data was 0.701. While a model with an AUC of 0.871 was obtained with a random forest algorithm using PET parameters, the model obtained with the Naive Bayes algorithm including clinical data in PET parameters had an AUC of 0.838.

Conclusion: Using quantitative parameters derived from staging PET with machine learning algorithms may enable us to detect early progression in patients with DLBCL and improve early risk stratification and guide treatment decisions in these patients.