Asia Oceania Journal of Nuclear Medicine and Biology最新文献

The role of neoadjuvant therapy in neuroendocrine tumors (NET) remains an area requiring further advanced clinical exploration. ¹⁷⁷Lu-DOTATATE has demonstrated significant therapeutic efficacy in managing metastatic NET, with reports of notable tumor size reduction in specific cases. This report highlights the case of a young patient diagnosed with an initially inoperable hepatic hilum NET. The patient received two cycles of ¹⁷⁷Lu-DOTATATE, resulting in remarkable tumor shrinkage on follow-up imaging, which facilitated surgical intervention. The patient underwent a complex left trisectionectomy resection, including anastomosis of the right portal vein, resection and interposition graft of the right hepatic artery, Roux-en-Y hepaticojejunostomy, and jejunojejunostomy. Due to residual involvement of the common hepatic duct and right portal vein margins, two additional cycles of adjuvant ¹⁷⁷Lu-DOTATATE were administered post-surgery. Long-term follow-up imaging over a 20-month period has demonstrated stable disease, emphasizing the potential benefits of incorporating neoadjuvant and adjuvant ¹⁷⁷Lu-DOTATATE in selected NET cases.

Objectives: To evaluate whether radiomic features extracted from ¹⁸F-NaF PET/CT scans, analyzed using machine learning (ML) methods, can improve the differentiation between true metastatic bone lesions (TP) and false-positive benign uptake (FP), thereby enhancing the diagnostic utility of ¹⁸F-NaF PET/CT.

Methods: This retrospective study included 62 patients with known primary malignancies who underwent ¹⁸F-NaF PET/CT. Lesions were classified as TP or FP based on consensus interpretation including follow-up. Patients were randomly split into training (n=41) and validation (n=21) groups. Radiomic features were extracted from PET images using LIFEx software. Feature selection (ANOVA, RFE) and ML model training (SVM, Random Forest, XGBoost) were performed. Model performance was evaluated using accuracy, specificity, sensitivity, and AUC, initially with a train/validation split and subsequently with 5-fold cross-validation incorporating feature engineering and hyperparameter tuning. Feature importance was assessed using SHAP.

Results: Significant differences in SUV_max (p=0.006) and SUV_mean (p=0.034) were observed between TP and FP lesions. Initial validation showed XGBoost performed best (AUC=0.78). After optimization and 5-fold cross-validation on the combined dataset (n=62), the tuned XGBoost model achieved the highest performance (Mean Accuracy: 85.7% ±2.9%, Mean AUC: 0.86), outperforming Random Forest (AUC: 0.79) and SVM (AUC: 0.74). SHAP analysis identified SUV_max, SUV_mean, Voxel Volume Num, GLRLM RLNU, and Skew.

Conclusion: Radiomics-based machine learning classifiers, particularly XGBoost, demonstrated strong performance in distinguishing true metastatic from false-positive benign lesions on ¹⁸F-NaF PET/CT. Integrating radiomics and ML can potentially improve the diagnostic accuracy and robustness of ¹⁸F-NaF PET/CT for assessing bone metastases. Further validation in larger cohorts is warranted.

Tumor necrosis factor-alpha (TNF-α) inhibitors, such as adalimumab, are integral in the managing refractory ankylosing spondylitis (AS). However, their immunosuppressive effects elevate the risk of reactivation of latent tuberculosis (TB), especially extrapulmonary TB (EPTB), which can present with non-specific symptoms and mimic malignancy. We report the case of a 40-year-old man with ankylosing spondylitis who had been on long-term adalimumab therapy. He presented with a low-grade fever and weight loss. An ¹⁸F-FDG PET/CT scan revealed intense FDG uptake in the peritoneum, omentum, and mesentery. There was no ascites or visceral involvement; however, a few FDG-avid retroperitoneal, mediastinal, and right cervical lymph nodes were noted, along with a right pleural effusion and no lesions in the lung parenchyma. Despite a negative microbiological workup, empirical anti-tubercular therapy (ATT) was initiated due to strong clinical and imaging suspicion of tuberculosis. The patient showed significant clinical improvement, and a follow-up PET/CT scan six months later indicated complete metabolic resolution of the lesions. This case underscores the diagnostic challenge of peritoneal TB in immunosuppressed individuals. It highlights the supportive role of FDG PET/CT in guiding empirical therapy and monitoring treatment response without microbiological confirmation.

Objectives: This study evaluates the utility of interim ¹⁸F-FDG PET/CT (iPET)-guided therapy in a Southeast Asian population, addressing gaps in region-specific data. Key outcomes included treatment response rates and progression-free survival (PFS) stratified by iPET results (Deauville score (DS) 1-3 vs. 4-5) across all clinical risk groups (including early-stage favorable/unfavorable and advanced-stage based on the International Prognostic Score (IPS)). Findings will inform optimal risk-adapted strategies in resource-aware settings.

Methods: A prospective study was conducted of 100 patients with Hodgkin Lymphoma (HL) at the Vietnam National Cancer Hospital from March 2020 to March 2024. All patients underwent baseline clinical assessment and imaging (CT and/or PET/CT), followed by two cycles of ABVD chemotherapy. IPET was performed for early response assessment using Deauville scores (DS), with subsequent treatment adjusted according to NCCN guidelines.

Results: A total of 100 patients with classical Hodgkin lymphoma (mean age: 32±13.8 years; range 9-73) were analyzed. Bulky disease and extranodal involvement were observed in 10.0% and 15.0% of cases, respectively. Early-stage disease (stage I-II) was present in 72.0%, and advanced-stage (stage III-IV) in 28.0%. After two cycles of ABVD, 78.0% of patients had a negative iPET result (DS 1-3), of whom 88.5% were DS 1, while 22.0% had a positive iPET result (DS 4-5), predominantly DS 4 (72.7%). In early-stage disease, the 3-year progression-free survival (PFS) was significantly higher in the favorable group than in the unfavorable group (95.7% vs. 81.2%, p=0.03). In advanced-stage disease, low-risk (IPS 0-3) patients achieved a 3-year PFS of 88.2%, whereas high-risk (IPS 4-7) patients had a markedly lower PFS of 42.9% (p<0.001). Overall, patients with negative iPET had substantially better 3-year PFS than those with positive iPET (93.6% vs. 40.9%, p<0.0001). The predictive performance of iPET for treatment outcomes showed a sensitivity of 72.3%, specificity 89.0%, PPV 59.0%, NPV 93.6%, and overall accuracy 86.0% (95% CI 0.78-0.91). Diagnostic accuracy remained high across subgroups, ranging from 84.0% in early-stage disease to 89.5% in advanced-stage, and was highest in favorable early-stage (90.8%) and low-risk advanced-stage (93.7%) patients. In multivariate analysis, iPET was identified as an independent predictor of PFS (p<0.05).

Conclusion: In a real-world Vietnamese cohort with Hodgkin lymphoma, interim PET/CT guided by Deauville scoring after two cycles of ABVD chemotherapy showed strong predictive value for treatment response. The results advocate for broader integration of NCCN-consistent risk-adapted strategies in Southeast Asia.

Neuroendocrine tumors (NETs) represent a heterogeneous group of neoplasms originating from neuroendocrine cells. Overexpression of somatostatin receptors is typically correlated with tumor differentiation. Localization and characterization of the primary tumor are essential, as radical surgery remains the treatment of choice for resectable disease. Additionally, identifying metastatic disease and assessing its extent are crucial for disease staging and monitoring response aimed at reducing total tumor volume. Radioguided surgery based on the ability to detect somatostatin receptor overexpression, is a valuable tool that aids in the identification of microscopic and occult endocrine tumors. In this context, we present three patients who achieved improved outcomes due to enhanced detection and identification of previously indeterminate or undetected lesions on prior imaging or even the detection of tumors that were not easily visualized without radioguided assistance. Complete tumor removal is a key prognostic factor in patients with NETs, improving quality of life and reducing the risk of tumor recurrence or locorregional metastasis. Achieving R0 or R1 resections has been associated with better survival outcomes. The successful implementation of radioguided surgery for NETs requires a multidisciplinary approach, both surgeons and nuclear medicine specialists playing a relevant role, and who must be aware of its prognostic significance.

Primary Sjögren syndrome (SS) is an autoimmune disease affecting exocrine glands, with predisposition to development of lymphoma (lymphomagenesis). We report a case of Sjogren's syndrome and discuss the role of FDG PET/CT in the primary diagnosis of lymphoma transformation in SS. Furthermore, we reviewed the literature regarding the utility of FDG PET/CT to assess systemic disease activity and also its role in the SS associated lymphoma with light into the new PET tracers that can be explored for these indications in the future. Published data suggest promising role of FDG PET/CT in SS associated lymphomas, and demands larger studies for its establishment.

Objectives: To determine the detection rate of bone metastasis on bone scan of prostate cancer patients with rising serum prostate-specific antigen (PSA) following radical prostatectomy (RP) and to identify the predictive factors associated with bone metastasis.

Methods: A study was conducted in 120 patients with rising serum PSA after RP. The data collected were pre and post-RP clinical parameters, including a trigger PSA (tPSA) level that prompted the treating physician to request a bone scan and PSA doubling time (PSADT). Bone scans were classified as positive or negative in conjunction with follow-up imaging and clinical information.

Results: Of 120 bone scans, 6 (5%) were positive and 114 (95%) were negative for bone metastasis. In the median tPSA ranges of <0.5, 0.5-1.0, and >1.0 ng/mL, scan positivity was 2.1%, 6.3%, and 30%, respectively. Patients with positive scans showed higher tPSA (1.228 vs 0.256 ng/mL; p=0.003) and shorter PSADT (3.5 vs 12.2 months; p=0.005) than those with negative scans. The most significant predictors of a positive bone scan were tPSA (>1 vs ≤1 ng/mL; OR 15.286, 95% CI 2.594-90.064, p=0.003) and PSADT (<6 vs ≥6 months; OR 17.333, 95% CI 1.618-185.646, p=0.018).

Conclusion: The detection rate of bone metastasis on bone scans in post-RP recurrent prostate cancer patients is only 5%, but the probability is much higher with tPSA >1 ng/mL and PSADT <6 months. Given its wide accessibility in Thailand, a bone scan should remain the preferred screening test for bone metastasis, with expected positive results in patients with high or rapidly rising PSA levels.

Objectives: to investigate the capability of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]-FDG PET/CT) derived volumetric parameters to predict human epidermal growth factor receptor 2 (HER2) status in breast cancer patients.

Methods: retrospective study enrolled 47 female patients with breast cancer. All patients had pretreatment [¹⁸F]-FDG PET/CT. Clinical data, pathology report and HER2 status were retrieved from medical records. In an attempt to assess the predictive value of the PET-derived metabolic parameters, Receiver operating characteristic (ROC) curve was constructed with area under curve analysis performed to detect best cutoff value of significant parameters for detection of HER2 positive.

Results: No statistically significant difference was noted among both groups (HER2 positive and negative) in respect to age, menopausal status, histology, grade, T-stage, N-stage, or antigen Kiel 67 (Ki-67) index. ROC curve successfully marked cutoff point ≥42.35 for total lesion glycolysis (TLG) and  12.75 for metabolic tumor value (MTV) that are capable to discriminate positive versus negative HER2 expression in breast cancer patients with area under curve (AUC) 0.728 and 0.723 and P-values 0.002 and 0.004 respectively. Such cutoff point was not deduced for standard uptake value (SUV) max. Primary tumor TLG cutoff correlated well with age where 77.8% of patients with TLG  42.35 were older than 45 years old compared to 22.2% of them who were younger than 45 years, P-value0.047. Also 70.3% of patients with TLG exceeds  42.35 had T3 and 4 primary tumors while 65% of those with TLG <42.35 their primary tumors were T1 and 2, P-value0.03. As regards Primary tumor MTV cutoff point, significant correlations were noted in respect to T-stage where 78.2% of the patients with primary tumor MTV  12.75 were T3 and 4, compared to 66.6% of those with primary tumor MTV <12.75 were T1 and 2, P-value0.011.

Conclusion: PET-derived volumetrics may serve as non-invasive predictors of biological processes represented here as HER2 expression in breast cancer patients.

Objectives: Gastroparesis is a complication following lung transplantation. This study aimed to assess the prevalence of gastroparesis in patients with lung transplants undergoing solid phase gastric emptying scintigraphy (GES). Specifically, we investigated which type of lung transplant is more susceptible to gastroparesis and whether timing of GES post-transplantation impacts diagnosis of severe gastroparesis.

Methods: This retrospective analysis included lung-transplant recipients between January 2008 and February 2024, who underwent GES. Patients received a standardized egg sandwich labeled with 500 uCi Technetium-99m sulfur colloid. GES results were compared to normal values for percentages retained at 2- and 4-hours post-meal.

Results: Among 485 lung-transplant recipients, 111 (50% male; mean age 63 years) underwent posttransplant GES. Gastroparesis was diagnosed in 23% of lung transplant recipients during the study period. Of those who underwent GES, 67% exhibited delayed gastric emptying, with 38 patients (34%) demonstrating severe retention (>30% at 4 hours). Delayed gastric emptying rates were highest in bilateral lung transplant recipients (73%), followed by left (66%) and right (56%) lung transplant recipients. Timing of GES beyond 6 months or one-year post-transplant did not significantly increase the incidence of delayed gastric emptying (p>0.05). There was no significant difference in proportion of patients with delayed gastric emptying when patients were stratified by gender and age.

Conclusions: Our findings suggest that laterality of lung transplant does not influence risk of delayed gastric emptying. Moreover, early evaluation of gastrointestinal symptoms with GES did not impact the severity or rate of gastroparesis. We recommend routine screening with GES for symptomatic lung transplant recipients, irrespective of transplant timing, to facilitate timely management and reduce post-operative complications associated with gastroparesis.

Objectives: This study evaluated the necessity of a ventilation scan in patients suspected of PE with a history of COVID-19 infection.

Methods: This was a cross-sectional study of patients with PCR-confirmed COVID-19 and suspected PE at a tertiary care hospital in 2020. They underwent ventilation/perfusion (V/Q) scintigraphy using single-photon emission computed tomography/computed tomography (SPECT/CT) and CT scans with or without contrast. Two blinded nuclear medicine physicians interpreted the images for PE and COVID-19. Clinical and laboratory data were extracted and analyzed.

Results: 96 patients with suspected PE and COVID-19 infection. The study excluded eight patients who could not undergo ventilation scans and confirmed PE in five patients with multiple mismatched V/Q defects on SPECT/CT. The study ruled out PE in 83 patients who had either regular perfusion scans, perfusion defects with COVID-19 features, or matched V/Q defects. The study found that the prevalence of PE was 5.68%, and the necessity of ventilation scans was 28.40% in this population.

Conclusion: It was found that PE was present in 5.68% of the patients, and ventilation scans were needed for 28.40% of the patients to confirm or exclude it.