Nuclear Medicine and Molecular Imaging最新文献

Fibroblast activation protein (FAP) has attracted growing interest as a promising target for cancer imaging and therapy due to its highly selective expression in the tumor stroma. This review summarizes the current development status of FAP-targeted radioligand therapy based on clinical evidence reported to date. Early therapeutic pipelines utilized quinoline-based compounds such as FAPI-04 and FAPI-46, predominantly investigated for PET imaging, by labeling them with beta-emitting radionuclides. Despite high tumor uptake, these early agents showed limited therapeutic efficacy due to short tumor retention and insufficient intratumoral radiation dose. To overcome this limitation, various structural modifications have been investigated to improve tumor retention, including cyclic peptides, dimers, and albumin binders. Several of these modified agents have been evaluated in clinical studies, showing improved tumor dosimetry while maintaining acceptable normal organ doses and toxicity profiles. However, therapeutic outcomes remain inconclusive, and evidence from large-scale, well-structured studies is still lacking. Currently, a few compounds are under investigation in early-phase clinical trials aimed at regulatory approval for clinical use. Evidence of therapeutic efficacy from those strictly designed clinical trials is awaited.

Cancer treatment has greatly benefited from advancements in radiopharmaceutical therapy, which requires precise dosimetry to enhance therapeutic efficacy and minimize risks to healthy tissues. This review investigated the role of artificial intelligence (AI) in theranostic radiopharmaceutical dosimetry, focusing on image quality enhancement, dose estimation, and organ segmentation. An in-depth review of the literature was conducted using targeted keywords searches in Google Scholar, PubMed, and Scopus. Selected studies were evaluated for their methodologies and outcomes. Traditional dosimetry techniques such as organ-level and voxel-based methods are discussed. Deep learning (DL) models based on U-Net, generative adversarial networks, and hybrid transformer networks for image synthesis and generation, image quality improvement, organ segmentation, and radiation dose estimation are reviewed and discussed. While DL shows great potential for enhancing dosimetry accuracy and efficiency, challenges such as the need for accurate dose estimation from theranostic pairs, lack of imaging data, and modeling of radionuclide decay chains must be addressed using DL models. In addition, the optimization and standardization of DL and AI models is crucial for ensuring clinical reliability and should be given high priority to support their effective integration into clinical practice.

This surveillance study examined the status of theranostics in West Asia, analyzing data from 15 countries. The research assessed availability, production, coverage, staff density, infrastructure density, financial and political impacts. All surveyed countries except Yemen offered theranostic services, with 452 centers and 1,426 theranostic physicians across the region. Over half of the countries reported densities exceeding one theranostician, nuclear medicine technologist, physicist, and nurse per million inhabitants. Scientific and social activities were available in nine and ten countries, respectively. Countries with gross domestic product (GDP) below $200 billion showed significantly lower infrastructure and manpower resources, particularly in cyclotron availability and theranostic agents (p < 0.05), compared to those with higher GDP. Politically stable countries demonstrated statistically higher densities of theranostic personnel than unstable nations (p < 0.05). The study emphasizes the importance of collaboration between model countries and those lacking adequate services to enhance theranostic practice and availability in West Asia.

Radiolabeled magnetic nanoparticles (MNPs), particularly superparamagnetic iron oxide nanoparticles (SPIONs), have gained significant attention in the field of cancer theranostics due to their potential in targeted therapy and molecular imaging. This review highlights recent advancements in the development of various radiolabeled SPIONs, including those functionalized with polyethylene glycol (PEG), DTPA, and other targeting agents. These nanoparticles are designed for multiple clinical applications, including hyperthermia, magnetic resonance imaging (MRI), and radiotherapy. However, the translation of these promising nanostructures into clinical practice faces several challenges, such as issues with surface functionalization, toxicity, stability, and the complexities of multimodal imaging. The review also explores creative approaches to overcome these challenges, such as designing multicomponent nanostructures, utilizing chelator-based and chelator-free radiolabeling techniques, employing click chemistry for radiolabeling, and enhancing biocompatibility methods. Ultimately, radiolabeled SPIONs have the potential to revolutionize cancer treatment and imaging, but further optimization is required to overcome existing obstacles and enhance their clinical applicability.

Purpose: To evaluate the value of thyroglobulin doubling time (Tg-DT) in predicting ¹⁸F-FDG PET/CT findings and clinical outcomes in differentiated thyroid cancer (DTC) patients with high thyroglobulin (Tg) level and negative ¹³¹I whole-body scan (¹³¹I WBS).

Materials and methods: 188 DTC patients with Tg levels ≥ 10 ng/ml and negative ¹³¹I WBS underwent ¹⁸F-FDG PET/CT scan. Three last consecutive values of unstimulated Tg were used to calculate Tg doubling time (Tg-DT). ROC curve analysis was performed to determine the optimal thresholds of Tg-DT in predicting ¹⁸F-FDG PET/CT results. Patients were followed up for at least 12 months after PET/CT scan. The Kaplan-Meier curve was used to estimate progression-free survival (PFS) and overall survival (OS). Cox regression analyses were conducted to identify factors significantly associated with PFS and OS.

Results: The specificity and positive predictive value of Tg-DT for predicting ¹⁸F-FDG PET/CT findings were 93.94%, and 92.6%, respectively, while those for Tg levels were 78.79% and 83.53% (p < 0.001). This study revealed that stimulated Tg and Tg-DT can predict disease progression and survival in DTC patients. Age > 55, distant metastasis on ¹⁸F-FDG PET/CT, and Tg-DT ≤ 12 months were independent predictors of PFS. Distant metastasis and Tg-DT ≤ 12 months were independent prognostic factors for OS.

Conclusion: Tg-DT is a valuable biomarker in predicting positive ¹⁸F-FDG PET/CT findings in DTC patients with high Tg level and negative ¹³¹I WBS. Along with distant metastases, Tg-DT ≤ 12 months is the only independent prognostic factor for PFS and OS.

Purpose: This study aimed to determine whether the PRIMARY Score on prostate specific membrane antigen (PSMA) positron emission tomography/compute tomography (PET/CT) can predict adverse pathology and prognosis in patients with intermediate-risk prostate cancer (PCa).

Materials and methods: This is a retrospective, multicenter analysis of patients diagnosed with intermediate risk PCa. Patients were staged using pelvic multiparametric magnetic resonance imaging (mpMRI) and radiolabeled PSMA PET/CT, either [68 Ga]Ga-PSMA-11 or [18F]F-PSMA1007, to evaluate the extent of disease before initiating appropriate treatment. PI-RADS Version 2.1 and PRIMARY score were used for a quantitative analysis, respectively for mpMRI and PSMA PET/CT. Biochemical recurrence of disease was defined as a post-operative serum PSA > 0.2 ng/ml on two separate occasions at minimum 2-week intervals.

Results: Seventy-eight intermediate-risk PCa patients were enrolled. PRIMARY scores > 3 was found in 62% of favorable (n = 50) and 71% of unfavorable cases (n = 28). Gleason score changes occurred in 20% of favorable-risk patients, with 90% having a PRIMARY score > 3. Biochemical recurrence was observed in 17% of patients during follow-up, predominantly among favorable-risk cases (13%), where most had Gleason score changes and a PRIMARY score > 3.

Conclusions: These results highlight the predictive value of the PRIMARY score for Gleason score changes.

Supplementary information: The online version contains supplementary material available at 10.1007/s13139-025-00920-6.

This study reports the first case of solitary brain metastasis from myxoid pleomorphic liposarcoma (MPLS) evaluated using ¹⁸F-FAPI-04 PET/CT. The imaging revealed a distinct "Halo Sign," reflecting the infiltration characteristics of cancer-associated fibroblasts (CAFs) within this rare tumor type. These findings highlight the utility of ¹⁸F-FAPI-04 PET/CT in characterizing tumor heterogeneity and underscore its potential to improve the diagnosis of rare brain metastases while informing future therapeutic strategies.

Purpose: Directed therapies employing small (SM) and large (LM) molecule drugs to target tumor antigens are used for treatment. Theranostics radiolabels them for imaging and radiation treatment. Poor radiopharmaceutical kinetics, prolonged circulating times, and high nontarget radiation to normal tissues after intravenous (i.v) injection limits translation. Intra-arterial (i.a.) procedures locally concentrate nonspecific chemotherapies or radiation to treat hepatic tumors (HT). Pseudovascular isolation (PVI), embolizes the HT arterioles, blocking efferent flow into capillaries isolating the HT from the systemic vasculature maximizing uptake to provide curative tumor specific absorbed radiation.

Methods: [¹⁸F]Fluorodeoxyglucose (FDG) SM and ^99mTc-labeled macroaggregated albumin (MAA) LM surrogates were used to assess biodistribution in a porcine HT. Injected dose per gram (%ID/g) of the tracers obtained from 1 to 120 min after control (i.v) and experimental i.a. infusion with PVI.

Results: SM drug delivered to HT was 290-366% greater for PVI vs. i.v (60 min %ID/g 31.26 ± 2.55 vs. 8.83 ± 0.55, p = 0.033; 120 min 29.28 ± 1.44 vs. 8.94 ± 0.96, p = 0.145). Mean HT uptake of LM with PVI was up to 760% greater than i.v. without washout (60 min %ID/g 80.01 ± 2.87 vs. 10.61 ± 0.96 p = 0.001; 81.72 ± 3.0 vs. 11.98 ± 0.3 p = 0.001 at 120 min).

Conclusion: PVI significantly increases the concentration of both SM and LM drugs within a HT compared to i.v. infusion. PVI with tumor specific drugs offers an opportunity to locally cure HT using a drug that specifically targets tumor antigens.

Introduction: The current gold standard for imaging to rule out extra-hepatic biliary atresia (EHBA) is hepatobiliary scintigraphy (HBS), which involves visually assessing the tracer appearance in the bowel. However, in cases where hepatic function is impaired, biliary-to-bowel transit may not be observable, even in neonatal hepatitis (NH) cases. This study aims to assess the utility of semi-quantitative parameters on HBS to distinguish biliary atresia (BA) from NH when there is a lack of biliary-to-bowel transit for up to 24 h.

Materials and methods: The study involved retrospective analysis of patients with the diagnosis of neonatal cholestasis where HBS failed to differentiate BA and NH. Histopathological examination was taken as the gold standard. Semiquantitative parameters calculated include: Liver: blood pool (LBR) and liver: kidney ratios (LKR) at 5 min, 30 min, 1 h and 24 h. Mean values for the two groups were calculated. Student's t-test was employed to assess the statistical significance of difference of mean between the two groups. Receiver operating characteristic (ROC) curve was also drawn to determine a cut-off of these ratios to differentiate between the two groups using SPSS v26.0. P-value < 0.05 was considered statistically significant.

Results: The study included 53 patients (37 males) with a median age of 3 months (range: 24 days to 10 months). Of these, 32 patients had a histopathological diagnosis of BA, while 21 had NH. Mean LBR and LKR at 24 h were statistically different in the two groups (p-value < 0.05). Receiver operating characteristic (ROC) curve analyses showed highest AUC for LBR at 24 h 0.683 (CI:0.532-0.834, p-value 0.017) and LKR at 24 h - 0.669 (CI: 0.511-0.827, p-value:0.036). For diagnosis of BA a cut-off value of ≤ 4.18 for LBR at 24 h (sensitivity and specificity of 62.5% and 61.9% respectively) and ≤ 4.64 for LKR at 24 h (sensitivity and specificity of 68.8% and 66.7% respectively) were found to be pertinent.

Conclusion: HBS serves as non-invasive imaging of choice to rule out EHBA. Semi-quantitative indices LBR and LKR at the 24-hour can differentiate between EHBA and NH even in cases with compromised hepatic function where traditional visual interpretation of tracer transit proves inadequate.

Supplementary information: The online version contains supplementary material available at 10.1007/s13139-025-00909-1.