Annals of Nuclear Medicine最新文献

Objective: To investigate whether metabolic and volumetric 18F-FDG PET parameters are associated with histopathological response, metastatic disease at diagnosis, overall survival (OS), and progression-free survival (PFS) in pediatric osteosarcoma (OST) patients. Additionally, to compare absolute and relative threshold methods for metabolic tumor volume (MTV) calculation.

Methods: This single-center retrospective study included 26 pediatric OST patients who underwent 18F-FDG PET/CT at diagnosis and, when available, after neoadjuvant chemotherapy. SUVmax, SUVpeak, MTV, total lesion glycolysis (TLG) and anatomic tumor volume of the primary tumor, along with whole-body MTV (wb-MTV) and whole-body TLG encompassing all FDG-avid metastatic lesions, were measured and their percentage changes (∆) between PET scans were calculated. MTV and TLG were calculated using absolute (SUV 2.0) and relative (40% of tumor SUVmax) threshold methods.

Results: Baseline 18F-FDG PET parameters did not predict histopathological response. But, we found that ΔSUVmax, ΔMTV (2.0), ΔTLG (2.0), and ΔTLG (40%) were associated with histopathological response (p = 0.029). Although not statistically significant, patients with metastases had higher baseline SUVmax, SUVpeak, MTV (2.0), and TLG (2.0) values. Anatomic tumor volume did not differ between the metastatic and localized groups. Patients with wb-MTV (40%) > 137.5 had a significantly higher mortality risk (HR = 4.27, p = 0.017). Kaplan-Meier analysis revealed that patients with primary tumors exhibiting SUVmax > 5.56 and SUVpeak > 4.57 had significantly lower estimated 5-year OS rates (p = 0.036 and 0.029), even after excluding patients with metastasis at diagnosis.

Conclusions: ΔSUVmax, ΔMTV (2.0), ΔTLG (2.0), and ΔTLG (40%) were found to be associated with histopathologic response, suggesting that these changes may serve as predictors of histopathologic outcome. MTV (2.0) may be a more reliable indicator of tumor aggressiveness than anatomic tumor volume, as it tended to be higher in the metastatic group. Our finding suggests that using absolute threshold may better reflect tumor burden in primary lesions with high metabolic activity, whereas relative threshold may be more suitable for evaluating total tumor burden, including low 18F-FDG uptake metastases. Inferior survival outcome is associated with elevated baseline SUVmax and SUVpeak values persisted even when patients with metastatic disease were excluded, suggesting their potential prognostic value.

Objective: Colonoscopy is the gold standard for colorectal cancer (CRC) screening; however, its invasiveness, cost, and associated risks limit its use in population-wide programs. Therefore, effective noninvasive tools for identifying individuals at high risk for colorectal adenomas-the precursors to CRC-are needed. 2-deoxy-2-[¹⁸F] fluoro-D-glucose positron emission tomography/computed tomography (FDG PET/CT) captures systemic metabolic and inflammatory activity and may offer imaging biomarkers for adenoma risk stratification.

Methods: We retrospectively analyzed 754 asymptomatic individuals who underwent both colonoscopy and FDG PET/CT within 30 days as part of health screening. PET/CT-derived variables included standardized uptake values (SUVs) from visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), skeletal muscle, liver, spleen, bone marrow, and colorectal wall. Clinical data included age, sex, and body mass index (BMI). A least absolute shrinkage and selection operator (LASSO) logistic regression model was trained on 452 individuals and tested in a separate validation cohort of 302.

Results: The final LASSO model selected eight variables, including VAT area (positive association) and multiple tissue-specific SUV features (negative associations). In the test set, the model achieved an area under the curve (AUC) of 0.693 (95% confidence interval: 0.631-0.754), significantly outperforming individual predictors such as VAT area (AUC = 0.630, P = 0.011), VAT HU (AUC = 0.585, P = 0.001), and SAT SUVmax (AUC = 0.616, P = 0.046). Decision curve analysis demonstrated superior net clinical benefit compared to univariable models.

Conclusion: A multivariable model integrating FDG PET/CT-derived metabolic features with clinical parameters enables noninvasive prediction of colorectal adenomas. This imaging-based approach may help identify individuals most likely to benefit from colonoscopy, potentially improving the efficiency of CRC screening strategies in opportunistic or high-risk settings.

Objective: This study aimed to employ RadioTherapy extension of the Particle and Heavy Ion Transport code System (RT-PHITS) Monte Carlo (MC) simulation for estimating absorbed doses in target organs and tumors in patients administered with ¹⁷⁷Lu-DOTATATE, using single-photon emission computed tomography/computed tomography (SPECT/CT) imaging.

Methods: Quantitative SPECT/CT images were obtained from 17 patients across the abdominal region at four time points: approximately 4, 24, 72, and 120 h following the administration of ¹⁷⁷Lu-DOTATATE. The liver, spleen, left and right kidneys, and total kidneys were automatically segmented on the CT images using the TotalSegmentator tool. Tumors were manually delineated based on SPECT/CT images. Image registration was performed using an Elastix-based method, with the first SPECT/CT time point serving as the reference. Voxel-level time-integrated activity (TIA) maps were created by fitting mono-exponential functions. These TIA maps, together with the reference CT images, were input into RT-PHITS to calculate dose distributions. The absorbed doses calculated by RT-PHITS were compared with those from IDAC-Dose 2.1 through two approaches: first, by using independently derived time-integrated activity coefficients (TIACs) from each method to assess the combined effects of kinetic modeling and dose calculation technique; second, by applying the same TIACs-obtained from time-integrated activity data-to both methods to isolate the influence of the dose calculation approach.

Results: RT-PHITS yielded higher mean absorbed doses per unit of administered activity compared to IDAC-Dose. The relative differences ranged between 0.63% and 15.35%, with the right kidney showing the largest discrepancy. When the same time-integrated data were used for both RT-PHITS and IDAC-Dose, relative differences remained below 10.40%.

Conclusion: RT-PHITS is a capable tool for calculating absorbed doses in ¹⁷⁷Lu-DOTATATE therapy. It consistently produced higher dose estimates than the organ-based method, emphasizing the benefits of patient-specific dosimetry, especially in organs that contain or are near tumors.

Background: Lutetium-177 (¹⁷⁷Lu)-PSMA-617, a targeted radioligand therapy, has demonstrated significant survival benefits in patients with metastatic castration-resistant prostate cancer (mCRPC). Its application in patients with a superscan pattern, indicative of extensive skeletal metastases, is less studied due to concerns about hematologic toxicity from bone marrow involvement.

Methods: This study analyzed 133 mCRPC patients treated with ¹⁷⁷Lu-PSMA-617, divided into Superscan and Non-superscan groups. PSA response (≥ 50% decline), PSA progression free survival (PFS), overall survival (OS), and treatment safety were assessed.

Results: Among 133 patients, 17 (12.8%) exhibited a superscan pattern. The overall PSA response rate was 45.8%, (47.0% in the superscan group versus 45.6% in the non-superscan group; p = 0.485). Median PSA PFS was 8 months overall (95% CI: 5.5-10.4), with 4 months (95% CI: <1-10.5) in the superscan group and 8 months (95% CI: 5.6-10.3) in the non-superscan group (p = 0.311). Median OS was 13 months overall (95% CI: 8.6-17.3), with 6 months (95% CI: <1-18.7) in the superscan group and 14 months (95% CI: 9.3-18.6) in the non-superscan group (p = 0.052). Significant but manageable decreases were seen in platelet (PLT) and Alkaline phosphatase (ALP), and no significant changes in Hemoglobin (Hb), white blood cells (WBC), Lactate dehydrogenase (LDH), or creatinine, with no differences between superscan and non-superscan groups. Baseline hemoglobin was a significant predictor of OS (HR = 0.6, p = 0.001), while superscan pattern did not show statistical differences (HR = 1.0, p = 0.949).

Conclusion: This retrospective study suggests that ¹⁷⁷Lu-PSMA-617 is a feasible and safe radioligand therapy for mCRPC patients with a superscan pattern, showing comparable PSA response rates to non-superscan patients.

Background: ¹²³I-MIBG has been shown to visualize impaired cardiac neuronal function, but data of this imaging modality in patients with acute myocarditis are scarce. Nonetheless, an association with reduced cardiac function has been observed previously. The aim of this study was to establish and evaluate semi-quantitative and quantitative parameters in ¹²³I-MIBG scintigraphy and SPECT/CT in patients with acute myocarditis and identify associations with left ventricular ejection fraction (LVEF) and biomarkers.

Methods: Eight patients with acute myocarditis and a gender and age-matched control group who underwent ¹²³I-MIBG scintigraphy and SPECT/CT were retrospectively analysed. Semi-quantitative Heart-to-Mediastinum (H/M) ratio and washout rate were calculated, additionally SPECT/CT system calibration and a whole-heart-segmentation were used for absolute quantification of tracer uptake. ROC analysis for the prediction of acute myocarditis and correlation of imaging parameters with LVEF and serological biomarkers was performed.

Results: Seven patients (87.5%) showed visually decreased tracer uptake. Planar imaging parameters showed significant differences compared to the control group (e.g. H/M ratio 1.6 ± 0.3 vs. 2.3 ± 0.8, p < 0.05), as well as multiple quantitative parameters e.g. SUVmean (1.7 ± 0.5 vs. 3.0 ± 1.0; p < 0.01). Additionally, correlation between imaging parameters and LVEF (e.g. SUVmax r = 0.85, p < 0.01) and NT-proBNP (e.g. H/M r = - 0.88, p < 0.05) was observed.

Conclusion: ¹²³I-MIBG visualizes impairment of cardiac neuronal function in patients with acute myocarditis and is associated with reduced ejection fraction and elevated NT-proBNP. We could establish an absolute quantification approach that could offer novel diagnostic opportunities for disease assessment and risk stratification, which will be focused on further studies.

Purpose: Implementing a relative value unit (RVU)-based system able to quantify activity and resource utilization in a nuclear medicine department (NMD).

Methods: A retrospective study was conducted in the NMD of a tertiary hospital, analyzing costs and procedures performed during the first half of 2024. A list of diagnostic and therapeutic procedures was drawn up, and the cost per procedure was calculated. Thyroid scintigraphy was considered as the unitary reference of the RVU. For the cost RVU (cRVU), the total expense of a procedure was divided by the unitary cost of the RVU. Complexity RVU (xRVU) was obtained, excluding the radiopharmaceutical cost.

Results: In the first semester of 2024, 5245 procedures (diagnostics and ambulatory therapies) were performed. The catalog comprised 44 diagnostic procedures and 7 therapeutic procedures. The RVU had a cost of 99.885 euros. For diagnostic procedures, the mean ± SD of cRVU and xRVU was 4.057 ± 4.020 and 1.631 ± 0.494, respectively. For therapeutic procedures, the mean ± SD of cRVU and xRVU was 45.164 ± 66.000 and 14.072 ± 10.546, respectively.

Conclusion: The cRVU per procedure varied significantly between diagnostic and therapeutic procedures. The expense of the radiopharmaceutical overstates the actual complexity of the procedure. The novel definition of xRVU, excluding radiotracer cost, offers a more realistic measure of the staff and departmental performance.