Annals of Nuclear Medicine最新文献

Objective

In ^99mTc myocardial perfusion SPECT, extra-cardiac accumulation from organs such as the liver or gastrointestinal tract may overlap with the inferior wall, causing artifacts that interfere with image interpretation. This study aimed to quantitatively evaluate the effectiveness of a novel image reconstruction method, the masking process on unsmoothed images (MUS method; CardioMUSk®, PDRadiopharma Inc., Tokyo, Japan), in reducing the influence of extra-cardiac accumulation using both phantom and clinical images.

Methods

This retrospective study included 200 patients (400 scans) who underwent a one-day stress-rest protocol using ^99mTc-sestamibi (MIBI) with pharmacologic stress administered first. Image reconstruction was performed using filtered back projection (FBP) and ordered subset expectation maximization with resolution recovery (OS-EM-RR), both with and without the MUS method. First, visual classification of extra-cardiac accumulation patterns relative to the inferior wall was performed, and the separation capability of each reconstruction method was assessed. Next, phantom experiments were conducted to investigate the effects of extra-cardiac accumulation volume, proximity, and concentration on contrast in the inferior wall. Furthermore, quantitative comparison of relative contrast between the inferior wall and the lateral and septal walls was performed using clinical data.

Results

The MUS method reduced the proportion of visually unseparated cases from 15.5% to 3.5% compared with the conventional method. In phantom studies, larger extra-cardiac accumulation and closer proximity to the myocardium resulted in greater degradation of inferior wall contrast. When a distance of 2 cm was maintained between extra-cardiac accumulation and the myocardium, the effect was substantially reduced. In clinical images, the MUS method significantly improved relative contrast in the inferolateral/inferior wall at the mid-ventricular level (Wilcoxon p = 0.030) and in the inferoseptal/inferior wall at the basal level (Wilcoxon p < 0.001), while no significant improvement was observed in the basal inferolateral/inferior wall region (Wilcoxon p = 0.605).

Conclusion

The MUS method demonstrated enhanced separation of extra-cardiac accumulation and improved contrast in the inferior myocardial wall compared with conventional methods. It was particularly effective in cases where extra-cardiac accumulation overlapped or closely contacted the myocardium, indicating its potential clinical utility in ^99mTc myocardial perfusion SPECT.

Objective

This study evaluates the impact of prior PRRT with Lu-177 DOTATATE on the response to TARE in NET patients with liver metastases.

Methods

Twenty-one patients who underwent TARE after PRRT between 2015 and 2022 were retrospectively analyzed. Tumor-specific cumulative Lu-177 DOTATATE counts were calculated from SPECT/CT images. Treatment planning was conducted with a standard target dose of 150 Gy to the tumoral tissue. Treatment response was assessed using changes in SUVmax, SUVmean, and somatostatin receptor-expressing tumor volume (SRE-TV) values derived from Ga-68 DOTATATE PET/CT before and 2–4 months after TARE. Lesion size was evaluated using RECIST v1.1 criteria. Dosimetry calculations were performed on Tc-99 m MAA SPECT/CT and Y-90 microsphere PET/MRI using Simplicit90Y™. Statistical analyses included Spearman correlation and Kruskal–Wallis tests.

Results

The median age of patients was 56 years (range 36–78 years). PRRT involved a mean cumulative Lu-177 DOTATATE dose of 43.5 ± 13.4 GBq (1175 ± 362 mCi). Post-TARE reductions in SUVmax (38.49 ± 20.46 to 19.94 ± 10.43 g/mL), SUVmean (9.51 ± 5.60 to 5.39 ± 3.64 g/mL), and SRE-TV (217.43 ± 155.87 to 175.62 ± 147.77 cm³) were observed. No significant correlation was found between cumulative Lu-177 DOTATATE counts and changes in SUV parameters, SRE-TV values, or lesion size after TARE. Similarly, no correlation was detected between tumor-to-normal liver activity ratios, calculated using either the partition model or voxel-based dosimetry and cumulative Lu-177 DOTATATE counts.

Conclusion

Prior PRRT does not significantly affect TARE response in NET patients with liver metastases. Radioembolization planning should prioritize factors like tumor, target, or healthy liver doses over previous PRRT.

Cardiac amyloidosis, characterized by extracellular deposition of amyloid fibrils within the myocardium, is an increasingly recognized cause of heart failure. With the advent of disease-modifying therapies, imaging has become central to diagnosis, subtype differentiation, prognostication, and treatment monitoring. This review provides a comprehensive update on multimodality imaging in cardiac amyloidosis, emphasizing its clinical utility across the disease continuum. Echocardiography, technetium-labeled bone scintigraphy, amyloid-specific positron emission tomography, cardiac magnetic resonance, and cardiac computed tomography each contribute uniquely to detecting amyloid burden and assessing cardiac function. In addition to outlining a practical diagnostic approach, we highlight emerging imaging biomarkers for monitoring treatment response and predicting clinical outcomes. The integration of these modalities into clinical practice enhances diagnostic accuracy, enables individualized risk stratification, and supports optimized, evidence-based care for patients with cardiac amyloidosis.

Rationale and objective

To develop and validate the predictive value of ¹⁸F-FDG PET/CT radiomics models based on data preprocessing methods for axillary lymph-node (ALN) status after neoadjuvant chemotherapy (NAC) for breast cancer.

Materials and methods

According to the status of ALN after NAC, we divided the breast cancer patients of the three scanners into the pathological complete remission (pCR) and non-pCR groups, respectively. Totally 630 models were obtained based on various data preprocessing, feature filtering, and modeling approaches. On the one hand, different data preprocessing methods were compared to analyze the advantages of different preprocessing methods. On the other hand, the AUC of predicting ALN status was compared among all models, and the model with the best prediction was obtained. Finally, the optimal model is combined with the clinical and the corresponding Nomogram is plotted.

Results

The comparison of the data preprocessing modalities revealed that the model prediction of tumor-to-liver ratio (TLR) radiomics was better than origin radiomics (OR), and the effect of Combat and Limma was better than without batch effects. All preprocessing modalities could be used as a potential method that can further optimize the model. The optimal model had a predicted AUC of 0.798 for ALN status after NAC for breast cancer in the test set and an AUC of 0.811 when combined with clinical characteristics.

Conclusion

It is necessary to pre-process the data before conducting a study on multicenter data, and the model developed in this way can effectively predict the status of ALN after NAC in breast cancer.

The C-X-C motif chemokine receptor 4 (CXCR4) has emerged as a critical molecular imaging target in various malignancies due to its central role in tumor progression, metastasis, and resistance to therapy. Among the imaging modalities developed to exploit this target, [68Ga]Ga-Pentixafor—a positron emission tomography (PET) radiopharmaceutical—has shown potential in diagnostic imaging. However, its diagnostic utility in solid tumors remains relatively underexplored, particularly in comparison to the widely utilized [18F]fluorodeoxyglucose ([18F]FDG) PET/CT. Comprehensive literature search was performed across PubMed, Scopus, Web of Science and Embase, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies included those reporting CXCR4-targeted PET imaging in solid tumors, with data on lesion detection, semiquantitative uptake values including maximum standardized uptake value (SUVmax) and tumor-to-background ratio (TBR). Data extraction focused on study design, patient demographics, tumor types, imaging protocols, and key findings. The quality of included studies was assessed using standardized risk-of-bias tools using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. This systematic review analyzed data from 26 studies, encompassing 831 patients with various solid malignancies to assess the diagnostic utility of [68Ga]Ga-Pentixafor PET/CT. Tracer uptake varied significantly among tumor types, with higher SUVmax values observed in adrenocortical carcinoma, small cell lung cancer, and desmoplastic small round cell tumors, while lower uptake was noted in breast cancer, glioblastoma, and melanoma. Certain malignancies, such as prostate cancer, pleural mesothelioma, and colorectal carcinoma, exhibited minimal or absent CXCR4 expression on PET imaging. A correlation between in vivo PET uptake and histopathologic CXCR4 expression was evident in specific tumor types, though heterogeneity in receptor expression was reported. When compared to [18F]FDG PET/CT, [68Ga]Ga-Pentixafor PET/CT demonstrated lower lesion detectability, highlighting its potential as a theranostic tool for CXCR4-targeted therapies rather than a primary diagnostic modality. [68Ga]Ga-Pentixafor PET/CT represents a promising, yet evolving, tool in oncology. While its diagnostic performance may not rival that of [18F]FDG PET/CT across all tumor types, its theranostic potential underscores its value in the precision medicine landscape.

Objective

To evaluate the diagnostic performance of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in detecting metastatic conjunctival melanoma (CM).

Methods

This retrospective study enrolled 67 patients with histopathologically confirmed CM who underwent ¹⁸F-FDG PET/CT for follow-up or suspected recurrence. Parameters including short-axis diameter of lesions, maximum standardized uptake value (SUVmax), the target-to-nontarget (T/NT) ratios of cervical lymph nodes, and bone lesion characterization (osteolytic, osteoblastic, or unchanged) were evaluated. Metastases were confirmed via either histopathology or ≥ 6-month imaging follow-up. Diagnostic sensitivity, specificity, accuracy, and metastatic patterns were analyzed at patient level.

Results

A total of 16 patients were confirmed metastasis. The median interval from surgery to metastasis was 20.3 months (range 1–100 months), with 56.3% (9/16) occurring within the first postoperative year. PET/CT detected metastases in 13 patients, missed metastases in 3 patients (2 with small preauricular lymph nodes and 1 with tiny pulmonary metastases), and misdiagnosed 1 patient with parotid benign nodules as metastatic. PET/CT demonstrated a sensitivity of 81.3%, specificity of 98.0%, and accuracy of 94.0%. The most common metastatic sites included lymph nodes (62.5%), bone (37.5%), lung (31.3%), and liver (25.0%), with PET/CT demonstrating detection rates of 95.5%, 100%, 86.7%, and 100%, respectively. PET/CT also identified metastases in rare sites, including the thyroid, cerebellum, adrenal glands, pericardium, pancreas, and subcutaneous/soft tissue. Lymph node metastases in CM predominately occurred in ipsilateral regional nodes (90.1%), with rare bilateral involvement (9.1%). Metastatic lymph nodes in the cervical and submandibular regions showed significantly higher mean SUVmax (11.6 ± 10.5 vs. 2.9 ± 0.9; p = 0.005) and T/NT ratios (6.9 ± 8.2 vs. 3.0 ± 1.0; p = 0.011) compared to inflammatory lymph nodes. SUVmax of metastatic lymph nodes, lung metastases, and liver metastases showed positive correlations with lesion size (p < 0.05 for all). Among metastatic lymph nodes, 53.2% had a short-axis diameter < 10 mm, and 59.1% of bone metastases exhibited no abnormal CT density.

Conclusion

¹⁸F-FDG PET/CT provides high diagnostic accuracy in detecting systemic metastases of CM during follow-up assessments, particularly for small lymph nodes, early bone metastases, and uncommon sites.

Objective

Amyloid-β (Aβ) aggregates have been recognized as therapeutic targets for Alzheimer’s disease (AD). Targeted alpha therapy (TAT) using α-particles has the potential to be applied as a novel treatment approach for AD by reducing the quantity of Aβ aggregates. In this study, we developed a novel astatine-211-labeled pyridyl benzofuran (PBF) derivative, [²¹¹At]APBF-2, as a small molecule-based Aβ-TAT agent and evaluated its potential for in vivo use.

Methods

[²¹¹At]APBF-2 was synthesized in a one-step astatination process using the tributyltin precursor. In the Aβ aggregation inhibition assay, [²¹¹At]APBF-2 was added to a sample containing Aβ_1–42 monomers and thioflavin-T (ThT) and the mixture was incubated for 24 h. The quantity of Aβ aggregates was evaluated by measuring ThT fluorescence intensity. The biodistribution of [²¹¹At]APBF-2 (25 kBq/100 μL) was evaluated using ddY mice (n = 5).

Results

[²¹¹At]APBF-2 was synthesized in radiochemical yield of 57% with a radiochemical purity of over 95%. In the in vitro assay, [²¹¹At]APBF-2 showed a dose-dependent decrease in ThT fluorescence intensity, suggesting the ability of [²¹¹At]APBF-2 to inhibit Aβ aggregation. In the biodistribution study using normal mice, the initial brain uptake of [²¹¹At]APBF-2 was observed (2.95% injected dose/g at 2 min), demonstrating favorable Blood–brain barrier permeability.

Conclusions

These results suggest the feasibility of using [²¹¹At]APBF-2 as an Aβ-TAT agent for in vivo applications.

Objective

Tumor-infiltrating lymphocytes (TILs) are key immune biomarkers associated with prognosis and treatment response in early-stage breast cancer (BC), particularly in the triple-negative subtype. This study aimed to evaluate whether [18F]FDG PET/CT imaging and routine cell blood count (CBC)-derived biomarkers can serve as non-invasive surrogates for TILs, using machine-learning models.

Material and methods

We retrospectively analyzed 358 patients with biopsy-proven early-stage invasive BC who underwent pre-treatment [18F]FDG PET/CT imaging. PET-derived biomarkers were extracted from the primary tumor, lymph nodes, and lymphoid organs (spleen and bone marrow). CBC-derived biomarkers included neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR). TILs were assessed histologically and categorized as low (0–10%), intermediate (11–59%), or high (≥ 60%). Correlations were assessed using Spearman’s rank coefficient, and classification and regression models were built using several machine-learning algorithms.

Results

Tumor SUVmax and tumor SUVmean showed the highest correlation with TIL levels (ρ = 0.29 and 0.30 respectively, p < 0.001 for both), but overall associations between TILs and PET or CBC-derived biomarkers were weak. No CBC-derived biomarker showed significant correlation or discriminative performance. Machine-learning models failed to predict TIL levels with satisfactory accuracy (maximum balanced accuracy = 0.66). Lymphoid organ metrics (SLR, BLR) and CBC-derived parameters did not significantly enhance predictive value.

Discussion

In this study, neither [18F]FDG PET/CT nor routine CBC-derived biomarkers reliably predict TILs levels in early-stage BC. This observation was made in presence of potential scanner-related variability and for a restricted set of usual PET metrics. Future models should incorporate more targeted imaging approaches, such as immunoPET, to non-invasively assess immune infiltration with higher specificity and improve personalized treatment strategies.