Molecular Imaging and Biology最新文献

{"title":"Deep Learning-based Synthesis of Amyloid PET Images from Structural MRI in Alzheimer's Disease.","authors":"Zongpai Zhang, Jingpu Wu, Puyang Wang, Keyi Chai, Shanshan Jiang, Chiadi U Onyike, Gwenn S Smith, Jinyuan Zhou","doi":"10.1007/s11307-026-02145-1","DOIUrl":"https://doi.org/10.1007/s11307-026-02145-1","url":null,"abstract":"<p><strong>Rationale: </strong>Amyloid-beta (Aβ) plaques in Alzheimer's disease (AD) are commonly imaged with specific PET radiotracers. To overcome the cost and availability limitations of PET, developing a more accessible diagnostic tool is essential. This study aimed to develop a deep-learning model that can synthesize Aβ-PET images from widely available MRI scans.</p><p><strong>Methods: </strong>The study utilized 431 subjects with both structural MRI and Aβ-PET scans from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, including 213 cognitively normal (CN), 180 mild cognitive impairment (MCI), and 38 AD dementia cases. A specialized Vector Quantized Generative Adversarial Network (VQGAN) framework has been trained to generate Aβ-PET images from MRI features, utilizing datasets from patients across various stages of AD spectrum. A paired t-test was used to compare synthetic and real Aβ-PET scans, while an ANOVA was performed to evaluate standardized uptake value ratio differences among the CN, MCI, and AD dementia groups.</p><p><strong>Results: </strong>The synthesized Aβ-PET images closely resemble real Aβ-PET scans in terms of regional Aβ distribution, accurately capturing disease-stage characteristics across the AD spectrum. In three key cortical brain regions (frontal cortex, lateral temporal lobe, and posterior cingulate cortex and precuneus), the synthetic images have successfully replicated disease-related Aβ trends, showing statistically significant group differences (p < 0.05). Quantitative evaluation has confirmed the superiority of VQGAN over other models (lower MAE, higher PSNR/SSIM), demonstrating minimized errors, reduced noise, and better structural fidelity in synthesized images.</p><p><strong>Conclusion: </strong>This technology potentially offers a cost-effective, non-invasive alternative method for AD diagnosis and staging.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149112239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction: Subcutaneous Adipose Tissue FDG Uptake is Associated with Systemic Inflammatory Indices Independent of Primary-Tumor Metabolic Burden in Breast Cancer.","authors":"Mehmet Tarık Tatoğlu, İlker Nihat Ökten, Ebru İbişoğlu, Tuçe Akkurt Söylemez, Hatice Uslu, Ferda Yerdelen Tatoğlu","doi":"10.1007/s11307-026-02144-2","DOIUrl":"https://doi.org/10.1007/s11307-026-02144-2","url":null,"abstract":"","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149040073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid CNN-Transformer Framework for Molecular Imaging-based Early Alzheimer's Disease Detection.","authors":"S Murugesan, P S Manjunath, Praful R Pardhi, Anil Kumar Katta, Amiya Kumar Sahoo, Gudapati Syam Prasad","doi":"10.1007/s11307-026-02134-4","DOIUrl":"https://doi.org/10.1007/s11307-026-02134-4","url":null,"abstract":"<p><strong>Purpose: </strong>Hybrid convolutional neural network (CNN)-transformer models are increasingly proposed for molecular imaging, but scan-level leakage and targets derived from the same image-quantification pipeline can overstate performance. We tested whether an image-only hybrid model could classify florbetapir PET amyloid positivity under participant-disjoint validation.</p><p><strong>Procedures: </strong>The Dallas Lifespan Brain Study contributed 551 longitudinal PET scans from 295 participants; 152 scans (27.6%) were amyloid-positive using the released global standardized uptake value ratio (SUVR) threshold of 1.09. Raw PET volumes were rigidly registered without label access and represented by 24 axial slices. CNN-GAP, slice-transformer, and age/sex baselines were evaluated using nested five-fold stratified group cross-validation. Calibration and operating thresholds were learned only within validation partitions, and 95% confidence intervals used 2,000 participant-cluster bootstrap resamples.</p><p><strong>Results: </strong>The hybrid achieved ROC-AUC 0.496 (95% CI 0.427-0.569), PR-AUC 0.274, balanced accuracy 0.490, and Matthews correlation coefficient -0.017. It did not outperform CNN-GAP (paired AUC difference -0.006, 95% CI -0.078 to 0.065) and performed below the age/sex baseline (AUC 0.690; hybrid-minus-baseline difference -0.194, 95% CI -0.287 to -0.100). Baseline-only and stable-label sensitivity analyses yielded hybrid AUCs of 0.529 and 0.502.</p><p><strong>Conclusions: </strong>Raw registered PET slices did not provide stable participant-generalizable classification of an SUVR-derived amyloid target. Participant-level separation, validated tracer quantification, demographic baselines, and external validation remain necessary before clinical interpretation.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149030966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"In Vivo Quantification of Myelin Injury Following Ischemic Stroke.","authors":"Rongyi Wang, Jing Zheng, Jinxiang Liu, Zhuoqun Li, Chunwei Wang, Kai Zhu, Jinming Zhang, Chunying Wu, Erik F J de Vries, Pengfei Liu, Xu Wang, Yanming Wang","doi":"10.1007/s11307-026-02143-3","DOIUrl":"https://doi.org/10.1007/s11307-026-02143-3","url":null,"abstract":"<p><strong>Purpose: </strong>Ischemic stroke involves substantial myelinated white matter injury, a key cause of long-term neurological deficits. However, conventional MRI often lacks sufficient sensitivity and specificity to detect myelin pathology and resolve lesional heterogeneity, limiting accurate correlation with clinical outcomes and prognostic assessment. To address this limitation, we recently developed a myelin-targeted PET radiotracer, [¹¹C]MeDAS, which enables in vivo characterization of myelin integrity with high sensitivity and specificity. To establish its utility in ischemic stroke, we conducted a translational imaging study across species.</p><p><strong>Procedures: </strong>Dynamic [¹¹C]MeDAS-PET/CT imaging, incorporating perfusion correction, was performed sequantially in a rodent middle cerebral artery occlusion (MCAO) model, a rhesus monkey with spontaneous ischemic stroke, and a cohort of six patients with acute ischemic stroke.</p><p><strong>Results: </strong>In MCAO rats, tracer uptake was significantly reduced in the lesioned hemisphere (SUV ratio: 0.64 ± 0.08, P < 0.001), closely correlating with histological myelin loss. In the non-human primate, infarcted regions exhibited up to 60% SUV reduction in SUV, while stroke patients demonstrated 26-43% lower uptake in infarct cores. Notably, these reductions persisted after perfusion correction. Furthermore, voxel-level analyses revealed pathological heterogeneity within lesions that appeared homogeneous on MRI.</p><p><strong>Conclusions: </strong>This translational study in rodent model, non-human primates, and human patients demonstrates that [¹¹C]MeDAS-PET is a promising molecular imaging approach for assessing tissue alterations following ischemic stroke. These findings warrant further investigation of [¹¹C]MeDAS-PET as an imaging marker for ischemic stroke.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149017683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Proof-of-Concept of CAIX-Targeted α-Particle Delivery in a Patient-Derived Hypoxic Head and Neck Squamous Cell Carcinoma Model.","authors":"Sylvia T M Wenker, Gerben M Franssen, Janneke D M Molkenboer-Kuenen, Mark W Konijnenberg, Daphne Lobeek, Giulia Tamborino, Hans Peters, Sanne A M van Lith, Sandra Heskamp, Johan Bussink","doi":"10.1007/s11307-026-02142-4","DOIUrl":"https://doi.org/10.1007/s11307-026-02142-4","url":null,"abstract":"<p><strong>Purpose: </strong>Tumor hypoxia correlates with a poor prognosis in many solid tumors, including head and neck squamous cell carcinoma (HNSCC). Carbonic anhydrase IX (CAIX) is an endogenous hypoxia-related marker and can be targeted using the humanized monoclonal antibody girentuximab (hG250). A potential new therapy to treat hypoxic tumors is CAIX-targeted α therapy (CAIX-TAT) as α-particles cause complex DNA damage independent of oxygen levels. Here, we investigate the targeting potential of CAIX-TAT in patient-derived HNSCC SCCNij153 xenografts.</p><p><strong>Methods: </strong>DOTA-hG250 was labeled with indium-111 (¹¹¹In) or actinium-225 (²²⁵Ac), and in vivo biodistribution was assessed in SCCNij153 tumor-bearing mice. The spatial distribution of radiolabeled hG250 was correlated to CAIX expression using autoradiography and immunofluorescence. Absorbed doses of [²²⁵Ac]Ac-DOTA-hG250 in healthy tissue and CAIX-positive (CAIX+) tumor regions were calculated from ex vivo biodistribution data and quantitative longitudinal SPECT imaging. Finally, SCCNij153 tumor sections from mice injected with [²²⁵Ac]Ac-DOTA-hG250 were stained for the DNA damage marker γH2AX.</p><p><strong>Results: </strong>[¹¹¹In]In-DOTA-hG250 accumulates in SCCNij153 tumors 3 days after injection (25.4 ± 5.0 %IA/g). Autoradiography and CAIX immunofluorescence of ex vivo tumor tissue shows that this uptake is predominantly present in the CAIX+ tumor areas. Dosimetry calculations indicated that treatment with 15 kBq [²²⁵Ac]Ac-DOTA-hG250 would result in an absorbed dose of 92.5 ± 35.4 Gy for CAIX+ tumor areas. Tumor sections obtained 7 days after [²²⁵Ac]Ac-DOTA-hG250 showed that ²²⁵Ac colocalized with CAIX expression and a trend was observed towards more γH2AX foci compared with DOTA-hG250 injected mice.</p><p><strong>Conclusion: </strong>Radiolabeled hG250 binds to CAIX+ tumor regions in SCCNij153 tumor-bearing mice. Additional studies are required to assess the therapeutic potential and underlying mechanism-of-action of CAIX-TAT for hypoxic tumors.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148990672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction: Collagen-binding ⁶⁸Ga-CBP8 PET/MR in Deep Pelvic Endometriosis: First-in-human Application.","authors":"Antonino Andrea Blandino, Peter Caravan, Anuradha S Shenoy-Bhangle, Peter R Movilla, Elio Quiros, Mario V Russo, Michael J Misialek, Liran Domachevsky, Leo L Tsai, Onofrio Antonio Catalano","doi":"10.1007/s11307-026-02141-5","DOIUrl":"https://doi.org/10.1007/s11307-026-02141-5","url":null,"abstract":"","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148970288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Artificial Intelligence Across the Cancer Theranostics Workflow: Critical Appraisal of Current Evidence and Future Clinical Translation.","authors":"Zahra Mansouri, Yazdan Salimi, Azadeh Akhavanallaf, Habib Zaidi","doi":"10.1007/s11307-026-02136-2","DOIUrl":"https://doi.org/10.1007/s11307-026-02136-2","url":null,"abstract":"<p><p>Artificial intelligence (AI) is transforming cancer management and theranostics by improving the accuracy, efficiency, and personalization of diagnostic and therapeutic workflows. Routine and accurate clinical implementation of theranostics remains limited by complex dosimetry procedures, demanding imaging protocols, and challenges in quantitative image analysis. This review critically evaluates the role of AI throughout the cancer theranostic workflow, with a focus on its potential to address the key clinical and technical challenges that continue to limit the routine implementation of personalized radiopharmaceutical therapy. It examines the current maturity of AI applications, their readiness for clinical translation, and the future prospects. Recent advances in machine learning and deep learning have enabled automated image interpretation, enhanced quantitative imaging, accelerated acquisition protocols, single-time-point dosimetry, and supported radiomics and multi-omics analyses. Emerging concepts, such as theranostic digital twins, physics- and biology-informed neural networks, and explainable AI are also discussed as future directions for precision medicine. Despite substantial progress, challenges related to data quality, interpretability, ethics, privacy, standardization, and clinical validation continue to hinder widespread clinical adoption. Nevertheless, AI-driven technologies are expected to play a central role in advancing personalized radiopharmaceutical therapy and facilitating routine dosimetry-guided treatment in clinical practice.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148956140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Association of Atherosclerosis [⁶⁸Ga]Ga-FAPI-04 Uptake with Calcified Plaque Burden and Cardiovascular Risk Factors: Comparison with [¹⁸F]FDG PET/CT.","authors":"Meiyan Lin, Zhenying Chen, Shaoming Chen, Jieling Zheng, Qun Liu, Sujuan Ouyang, Weibing Miao","doi":"10.1007/s11307-026-02137-1","DOIUrl":"https://doi.org/10.1007/s11307-026-02137-1","url":null,"abstract":"<p><strong>Purpose: </strong>This study aimed to evaluate the association of atherosclerosis [⁶⁸Ga]Ga-FAPI-04 uptake with calcified plaque burden, cardiovascular risk factors (CVRFs), and to compare these findings with [¹⁸F]FDG PET/CT.</p><p><strong>Methods: </strong>A retrospective analysis was performed on 69 patients (referred for non-cardiovascular indications) who underwent both [⁶⁸Ga]Ga-FAPI-04 and [¹⁸F]FDG PET/CT between August 2020 and November 2023. Tracer uptake was quantified using target-to-background ratio (TBR). The wilcoxon signed-rank test was used to compare two tracers' uptake, while partial correlation and generalized linear model adjusted for age and sex were applied to assess associations with calcified plaque (CP) and CVRFs.</p><p><strong>Results: </strong>FAPI-TBR was significantly higher than that of [¹⁸F]FDG in patient-based analyses, in PET-positive arterial wall regions on both modalities, and in the subgroup with concomitant calcification (all P < 0.001). The number of FAPI-positive lesions exhibited significant positive correlations with CP burden and the number of CVRFs; mean TBR‑FAPI was also positively associated with CVRF count (r = 0.250 ~ 0.257, all P < 0.05). Subgroup analyses revealed that high-risk patients (CVRFs ≥ 4) had significantly higher TBR-FAPI than low-risk patients [median (IQR): 1.77 (0.32) vs. 1.54 (0.31); P = 0.047], whereas no such difference was observed for [¹⁸F]FDG uptake. Furthermore, TBR-FAPI was significantly elevated in overweight patients compared to normal-weight patients (P < 0.001).</p><p><strong>Conclusion: </strong>[⁶⁸Ga]Ga-FAPI-04 PET provides complementary information to [¹⁸F]FDG by reflecting fibrotic remodeling, and may aid in refining cardiovascular risk stratification; however, prospective studies are warranted to establish its clinical utility.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148930562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Macrocycle Chelator Conjugation on the C3 Hydroxyl Group of 17β-Estradiol reduces Estrogen Receptor Binding.","authors":"Pierre Cheung, Mallesh Pandrala, Abraham Moses, Madeleine Landry, Craig S Levin, Corinne Beinat","doi":"10.1007/s11307-026-02140-6","DOIUrl":"https://doi.org/10.1007/s11307-026-02140-6","url":null,"abstract":"<p><strong>Purpose: </strong>Tumor heterogeneity in breast cancer complicates accurate molecular characterization when using standard-of-care imaging modalities. In this study, gallium-68 labeled estradiol-derivatives were synthesized and evaluated as candidate tracers to be used for multiplexed PET imaging with the goal of improving the molecular characterization of breast cancer.</p><p><strong>Procedures: </strong>17β-estradiol was conjugated to DOTA and NODAGA macrocycles and radiolabeled with gallium-68. The selectivity of the resulting radiotracers, [⁶⁸ Ga]Ga-DOTA-estradiol and [⁶⁸ Ga]Ga-NODAGA-estradiol, were assessed in vitro using recombinant human estrogen receptor (ER) protein and cell lines. In vivo PET/CT imaging was performed in mice bearing ER-positive and ER-negative tumors using [⁶⁸Ga]Ga-NODAGA-estradiol.</p><p><strong>Results: </strong>Both radiotracers were obtained with high radiochemical purity. Neither [⁶⁸ Ga]Ga-DOTA-estradiol nor [⁶⁸ Ga]Ga-NODAGA-estradiol displayed selective binding to the recombinant human ER and no uptake difference could be identified between ER-positive and ER-negative cells. Competition blocking studies using non-radioactive [^NatGa]Ga-DOTA-estradiol and [^NatGa]Ga-NODAGA-estradiol significantly decreased the uptake of [¹⁸F]FES within ER-positive cells. In vivo imaging of [⁶⁸ Ga]Ga-NODAGA-estradiol revealed negligible tumor uptake and predominant hepatobiliary clearance.</p><p><strong>Conclusion: </strong>Two estradiol-derived radiotracers were successfully synthesized and tested, however neither showed selective binding towards ER in vitro or in vivo. The conjugation site of the cyclic macrocycle on 17β-estradiol is likely a key parameter to retain strong binding towards ER. These findings identify an important limitation for chelator-based ER tracer design.</p>","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148930593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative Evaluation of [^99mTc]Tc-HYNIC-FAPI-04 and [^99mTc]Tc-HYNIC-FAPI-46 for FAP-Targeted SPECT Imaging.","authors":"Yan Wang, Mengmeng Hu, Rundong Pi, Hua Shu, Yu Long, Wenzhu Hu, Yuan Feng, Rongmei Tang, Fan Hu, Chengpeng Gong, Xiaoli Wang, Kun Li, Yongkang Gai, Jia Hu","doi":"10.1007/s11307-026-02139-z","DOIUrl":"https://doi.org/10.1007/s11307-026-02139-z","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Purpose: &lt;/strong&gt;Fibroblast activation protein (FAP) is highly expressed in cancer-associated fibroblasts (CAFs) and has emerged as an important target for tumor imaging and therapy. Although numerous FAP-targeted PET tracers have demonstrated promising clinical performance, their high cost and limited accessibility restrict their widespread clinical application. In contrast, SPECT imaging is a more cost-effective and widely available alternative. Among the developed FAPI derivatives, FAPI-04 and FAPI-46 are two of the most extensively studied compounds with high translational potentials. In this study, we performed a systematic preclinical comparison of [&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-04 and [&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-46 to evaluate their imaging performance and provide guidance for optimal tracer selection in clinical SPECT.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Procedure: &lt;/strong&gt;Bioinformatic analyses were performed to evaluate FAP expression and its association with prognosis and CAF-related markers. [&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-04 and [&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-46 were synthesized and assessed for their radiochemical purity and in vitro stability. FAP expression in FAP-HT1080 and HT1080 cells was validated using western blotting and immunofluorescence. Cellular uptake and saturation binding assays were conducted to evaluate the tracer affinity, and blocking experiments were conducted to confirm specificity. Small-animal SPECT/CT imaging and biodistribution studies were performed using FAP-HT1080 xenograft mouse models to assess in vivo tumor targeting. Immunohistochemical staining was used to further validate FAP expression in the tumor tissue.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;[&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-04 and [&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-46 exhibited high radiochemical purity and stability. FAP overexpression in FAP-HT1080 cells was confirmed by western blotting, immunofluorescence, and immunohistochemistry, and both tracers showed a high affinity for FAP. The cellular uptake of FAPI-04 was slightly higher than that of FAPI-46, and blocking experiments confirmed specific binding. SPECT/CT imaging demonstrated strong tumor accumulation with prolonged retention for both tracers, enabling clear visualization even 24 h post-injection. Quantitative analysis revealed no significant differences in tumor uptake or tumor-to-normal tissue ratios, despite the slightly higher tumor uptake of FAPI-04 observed in biodistribution studies. Consistently, comparable T/M, T/B, T/K, and T/L ratios were observed, indicating similar overall imaging performance. Bioinformatic analyses further revealed that FAP was upregulated in multiple tumors and correlated with CAF markers (COL1A1 and ACTA2).&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;Both [&lt;sup&gt;99m&lt;/sup&gt;Tc]Tc-HYNIC-FAPI-04 and -46 showed high tumor uptake and clear visualization. Despite differences in pharmacokinetics, a similar tumor-to-normal tissue contrast was observed, supporting the suitability of bo","PeriodicalId":18760,"journal":{"name":"Molecular Imaging and Biology","volume":" ","pages":""},"PeriodicalIF":2.5,"publicationDate":"2026-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148911369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}