American journal of nuclear medicine and molecular imaging最新文献

Gallium-68 labeled fibroblast activation protein inhibitor ([68Ga]Ga-FAPI-04) can be visualized just 15 min post-injection. However, the appearance of imaging at 15 and 60 min remains unclear. This study aimed to explore the relationship between quantitative values in [68Ga]Ga-FAPI-04 PET, specifically at 15 and 60 minutes post-injection, in patients with various tumor. We enrolled 30 patients with cancer who underwent [68Ga]Ga-FAPI-04 PET/CT scan between January 2021 and February 2025 at our institute. Image acquisition was performed using a PET/CT scanner at 15 min and 60 min after [68Ga]Ga-FAPI-04 injection. The maximum, mean and peak standardized uptake value (SUV_max, SUV_mean and SUV_peak), tumor-to-liver ratio (TLR), and uptake tumor volume (UTV) were measured in the region of interest of the target lesion, liver SUV_mean (SUV_liver) was also measured. Correlation coefficients of the between-image variables were evaluated by Spearman's rank correlation test. Agreement between the variables was evaluated by Bland-Altman plots with 95% limits of agreement. The SUV_max, SUV_mean, SUV_peak and UTV in tumors of all examinations were decreased from 15 min to 60 min. The SUV_max, SUV_mean, SUV_peak, TLR, and UTV at 15 min and 60 min were highly correlated (r_s = 0.945, 0.949, 0.959, 0.943, and 0.958; P < 0.001). The 95% limits of agreement ranged from -27.8 to 29.1 with a mean of 0.7 and -24.1 to 29.5 with a mean of 2.7 for SUV_max and SUV_mean, respectively. Other PET metrics demonstrated that all limits are above ± 30% between 15 min and 60 min. We observed a high correlation between the quantitative values at 15 min and 60 min. Meanwhile, 15 min and 60 min [68Ga]Ga-FAPI-04 PET SUV_max and SUV_mean have clinically acceptable reproducibility, and 15 min scan is feasible for all patients, but SUV_peak, TLR and UTV should not be used interchangeably.

Phosphodiesterase 4B (PDE4B) is an enzyme that hydrolyzes cyclic adenosine monophosphate (cAMP), a critical signaling molecule involved in various cellular processes. Dysregulated PDE4B activity has been implicated in psychiatric diseases like depression and schizophrenia. In this report, a PDE4B-targeted PET tracer, [¹⁸F]PF-06445974, was synthesized using an automated synthesis module. [¹⁸F]PF-06445974 demonstrated high brain specificity, robust uptake, and excellent stability. In vivo metabolic studies confirmed that its radioactive metabolites did not cross the blood-brain barrier, and no abnormal bone uptake was observed in PET imaging. Furthermore, PET studies and quantitative autoradiography revealed significantly increased expression of PDE4B in the hippocampus and cortex of depression model rats compared to normal controls. The findings highlight the potential of in vivo PDE4B PET imaging as a valuable tool for monitoring PDE4B changes in depression, providing insights into its pathophysiological processes and paving the way for clinical translational research in this domain.

Objective: The heterogeneity of gastric cancer (GC) poses significant challenges for the detection capabilities of monomeric fibroblast activation protein inhibitor (FAPI) tracers, particularly in cases with low FAP expression. To address this limitation, a dual-target heterodimeric radiotracer, ¹⁸F-FAPI-42-RGD, was designed to target both FAP and integrin αvβ3. This study aimed to evaluate the efficacy of ¹⁸F-FAPI-42-RGD in GC models and compare its performance with the mono-specific radiotracer, ¹⁸F-FAPI-42.

Methods: ¹⁸F-FAPI-42-RGD was synthesized, and its radiochemical properties and stability were assessed. Micro-PET imaging and biodistribution studies were conducted in BALB/C nude mice bearing MKN-45, N87-18.2, NUGC4 tumors, and GC patient-derived xenografts (PDX). The results were compared with those obtained from ¹⁸F-FAPI-42.

Results: ¹⁸F-FAPI-42-RGD demonstrated excellent stability in saline and fetal bovine serum (FBS) for at least 2 hours. Compared to ¹⁸F-FAPI-42, ¹⁸F-FAPI-42-RGD exhibited significantly enhanced tumor uptake in MKN-45, N87-18.2, NUGC4, and GC-PDX tumors at all time points. Biodistribution studies revealed that ¹⁸F-FAPI-42-RGD had markedly higher tumor uptake in GC models compared to ¹⁸F-FAPI-42, particularly in the MKN-45, N87-18.2, and GC-PDX tumor models. The uptake of ¹⁸F-FAPI-42-RGD in these tumors was significantly greater than that of ¹⁸F-FAPI-42 (4.97 ± 1.36 vs. 2.18 ± 1.26, 7.02 ± 0.97 vs. 2.34 ± 0.11, and 4.49 ± 1.29 vs. 1.09 ± 0.46 %ID/g in MKN-45, N87-18.2, and GC-PDX, respectively, at 4 h post-injection).

Conclusion: The dual-targeting PET tracer ¹⁸F-FAPI-42-RGD demonstrated significantly enhanced tumor uptake in GC models, along with a clearer background compared to ¹⁸F-FAPI-42. This indicates its superior diagnostic performance, suggesting its potential for clinical translation in the imaging and diagnosis of GC.

To evaluate the safety and VEGFR-3 imaging effects of [⁶⁸Ga]Ga-NOTA-(TMVP1)₂ in ovarian cancer patients. 13 patients with ovarian cancer were recruited and underwent radionuclide imaging with [⁶⁸Ga]Ga-NOTA-(TMVP1)₂. The safety of [⁶⁸Ga]Ga-NOTA-(TMVP1)₂ was assessed in vivo (including vital signs, biochemical indices, ECG, allergic reactions, etc.) and its imaging effect on VEGFR-3 was explored. A total of 1 patient with primary ovarian cancer and 12 patients with recurrent ovarian cancer, with an age range of 41-54 years, were included in the study. 13 ovarian cancer patients had a total of 49 ¹⁸F-FDG-positive lesions, 63.3% of which were positive for [⁶⁸Ga]Ga-NOTA-(TMVP1)₂. The higher expression of VEGFR-3 in [⁶⁸Ga]Ga-NOTA-(TMVP1)₂-positive ovarian cancer lesions was found by immunohistochemical staining, which was positively correlated. Meanwhile, [⁶⁸Ga]Ga-NOTA-(TMVP1)₂ is a safe radiotracer as no significant side effects have been found in the human. In conclusion, [⁶⁸Ga]Ga-NOTA-(TMVP1)₂ enables precise molecular imaging of VEGFR-3 in ovarian cancer patients with a favourable safety profile, providing a new tool for the in vivo assessment of VEGFR-3 in ovarian cancer.

Radiopharmaceuticals targeting fibroblast activation protein (FAP) have rapidly emerged as innovative agents for cancer imaging and therapy. By selectively binding to cancer-associated fibroblasts (CAFs), radiolabeled FAP inhibitors (FAPIs) enable high-contrast PET/CT imaging across diverse tumor types. This article highlights recent advances in FAPI PET/CT imaging, with particular focus on the influence of multivalency effect in radiotracer development.

Clear cell renal cell carcinoma (ccRCC), accounting for 65%-70%, is the most common subtype of renal cell cancers. Contrast-enhanced CT and MRI are still the predominant diagnostic modalities for renal carcinoma in clinical practice, but they cannot provide accurate diagnosis and staging, and molecular information related to tumor microenvironment. Carbonic anhydrase IX (CAIX), a transmembrane metalloenzyme on the cell surface and associated with hypoxia within the tumor, is emerging as a potential molecular target for both diagnosis and therapy in ccRCC. CAIX-targeted molecular imaging enables non-invasive visualization of ccRCC and guides treatment decision-making.

Purpose: This study aims to explore the diagnostic performance of ¹⁸F-FDG PET/CT in distinguishing collecting duct carcinoma (CDC) from clear cell renal cell carcinoma (ccRCC).

Methods: A retrospective analysis was conducted on 11 patients with CDC and 27 patients with ccRCC who underwent ¹⁸F-FDG PET/CT examinations. Clinical indicators and the SUVmax, tumor-to-liver standardized uptake value ratio (TLR), tumor-to-kidney standardized uptake value ratio (TKR), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) values of the primary tumor, whole-body MTV (WBMTV), and whole-body TLG (WBTLG) based on a baseline PET scan, were recorded and compared between the two groups. To assess the discriminative power of these metabolic parameters between CDC and ccRCC, we performed a receiver operating characteristic (ROC) curve analysis.

Results: The median age of the 11 CDC patients was 59 years. All CDC patients were in advanced stages (18% stage III and 82% stage IV). Compare with ccRCC patients, CDC patients had higher lymph node metastases rates (72.7% vs. 22.2%, P = 0.008) and distant metastases rates (81.8% vs. 22.2%, P = 0.001). The primary tumor in CDC also showed higher SUVmax (10.5 vs. 4.0, P < 0.001), TLR (3.9 vs. 1.4, P < 0.001), TKR (4.4 vs. 1.5, P < 0.001), MTV (53.2 vs. 9.5, P = 0.021), and TLG (305.7 vs. 30.4, P = 0.0069) than ccRCC. The WBMTV and WBTLG of CDC patients were also higher than the ccRCC group (144.1 vs. 9.5, P = 0.0013 and 528.4 vs. 30.4, P = 0.0013, respectively). ROC curve analysis revealed no significant differences in the ability of SUVmax, TLR and TKR to differentiate CDC from ccRCC. Median survival for CDC was 36 months, worse for older patients.

Conclusion: The utilization of ¹⁸F-FDG PET/CT can assist to detect the metastases and provide guidance for diagnosis and staging. Metabolic parameters obtained from ¹⁸F-FDG PET/CT hold promise for distinguishing CDC from ccRCC.

Neuroendocrine tumors (NETs) can affect several organ systems and present a variety of clinical symptoms, which are difficult to diagnose by conventional methods. Somatostatin receptor (SSTR) is a group of specific receptors expressed on the well-differentiated NET cell membrane. [⁶⁸Ga]-labeled somatostatin analogues (SSAs) PET/CT, endogenous ligands targeting SSTR, is widely used in currently clinical NETs diagnosis. The dual-tracer strategy ([⁶⁸Ga]Ga-SSAs + [¹⁸F]FDG) allows for a more detailed evaluation of tumor metabolism and receptor expression. The NETPET score, integrating [⁶⁸Ga]Ga-SSAs PET/CT and [¹⁸F]FDG PET/CT results, enhances the accuracy of predicting treatment response and prognosis. In addition, novel isotopes ([¹⁸F]/[⁶⁴Cu]) labeled SSAs and SSTR antagonists outperformed [⁶⁸Ga]-SSAs in lesion detection, tumor uptake, and tumor-to-background ratio. Due to undifferentiated or dedifferentiated NETs, SSTR may not be expressed. [⁶⁸Ga]Ga-Pentixafor and [¹⁸F]-FDG PET/CT are applicable for SSTR-negative NET diagnosis. [¹⁸F]-MFBG and [¹⁸F]-DOPA have a higher sensitivity for identifying non-metastatic pheochromocytoma and paraganglioma (PPGL) than other radiotracers. This review addressed NET diagnosis with conventional imaging techniques, the clinical application of novel radiotracers, and the merits and limitations of the various radiotracers.

Single-photon emission computed tomography (SPECT) is widely used in myocardial perfusion imaging (MPI) in clinic. However, conventional dual-head SPECT scanners require lengthy scanning times and gantry rotation, which limits the application of SPECT MPI. In this work, we proposed a deep learning-based approach to reconstruct dual-view projections, aiming to reduce acquisition time and enable non-rotational imaging for MPI based on conventional dual-head SPECT scanners. U-Net was adopted for the dual-view projection reconstruction. Initially, 2D U-Nets were used to evaluate various data organization schemes for dual-view projection as input, including paved projection, interleaved projection, and stacked projection, with and without an attenuation map. Subsequently, we developed 3D U-Nets using the optimal data organization scheme as input to further enhance reconstruction performance. The dataset consisted of a total of 116 SPECT/CT scans with ^99mTc-tetrofosmin tracer acquired on a GE NM/CT 640 scanner. Reconstruction performance was assessed using quantitative metrices and absolute percentage errors, while the reconstruction images from the full-view projection were used as reference images. The 2D U-Nets provided reasonable transverse view images but exhibited slight axial discontinuity compared to the reference images, regardless of the data organization schemes. Incorporating the attenuation map reduced this axial discontinuity. Quantitatively, the 2D U-Net trained using both stacked projection and attenuation map achieved the best performance, with a normalized mean absolute error of 0.6%±0.3% and a structural similarity index measure (SSIM) of 0.93±0.04. The 3D U-Net further improved the performance with less axial discontinuity and a higher SSIM of 0.94±0.03. The localized absolute percentage errors were 1.8±16.8% and -2.0±6.3% in the left ventricular (LV) cavity and myocardium, respectively. We developed a deep learning-based image reconstruction approach for dual-view projection from a conventional SPECT scanner. The 3D U-Net, trained with the stacked projection with an attenuation map is effective for non-rotational imaging and could benefit dynamic myocardium perfusion imaging.

Primary cutaneous anaplastic large cell lymphoma (pcALCL) is a type of skin T-cell lymphoma with a favorable prognosis. Some patients may experience recurrence, but systemic involvement is rare. Some studies suggest that systemic progression is associated with poor prognosis. The value of ¹⁸F-FDG PET/CT in diagnosing lymphoma has been recognized, but there is often controversy over the application value of ¹⁸F-FDG PET/CT in pcALCL. We present a rare case of pcALCL involving multiple systemic lesions, monitored and evaluated using ¹⁸F-FDG PET/CT to assist in clinical treatment decisions. Through this case, we consider that ¹⁸F-FDG PET/CT has significant value in diagnosing pcALCL. However, more clinical cases are needed to confirm whether high FDG uptake is associated with the invasiveness of pcALCL and the impact of high FDG uptake and Ki-67 expression on the progression and prognosis of pcALCL.