American journal of nuclear medicine and molecular imaging最新文献

Radioiodine ablation is commonly performed after thyroidectomy for well-differentiated thyroid cancer (DTC). This study aimed to quantify thyroid remnant uptake in standardized uptake values (SUV) and evaluate its correlation with post-therapy Thyroglobulin (Tg) levels across different risk groups. We retrospectively quantified SUV uptake with attenuation, scatter, and resolution recovery corrections on post-therapy SPECT/CT in thyroid cancer patients referred to our centre between 2015 and 2017. Thyroid remnant was segmented with a maximum SUV of 0.5 as the threshold and total thyroid remnant uptake (SUV_total) was obtained. Patients were stratified into low-intermediate, high-intermediate, and high-risk groups based on clinical risk and therapeutic dose. The primary outcome was the correlation between SUV_total and post-therapy Tg levels. The cohort consisted of 174 adults (age: 50.7±16.0 yr, F:M=110:64). Moderate correlations were found between SUV_total and Tg levels in low-intermediate and high-intermediate groups (Spearman's ρ=0.65, P<0.001; ρ=0.61, P<0.001, respectively). No significant correlation was found in the high-risk group (ρ=0.12, P=0.33). Stimulated Tg levels increased (median Tg: 4, 7, and 13 pmol/L) and thyroid remnant uptake decreased (median SUV_total: 272, 51, and 33) across the low-intermediate, high-intermediate, and high risk groups. In conclusion, this study shows good correlations between the thyroid remnant uptake and thyroglobulin in subgroups of patients with low-intermediate and high-intermediate risk DTC. The rationales for lack of significant correlation in the high-risk group DTC were discussed. Thyroid uptake quantification may serve as a feasible substitute for Tg measurements in post-ablation follow-up, offering potential for predicting disease recurrence.

Renal artery aneurysms (RAAs) are rare vascular abnormalities that are often detected incidentally, as most patients are asymptomatic and the lesions are discovered during imaging for unrelated conditions. Differentiating intraparenchymal RAAs (IPRAAs) from renal tumors using non-invasive imaging techniques remains challenging. Misdiagnosis as a renal malignancy, such as renal cell carcinoma (RCC), poses a significant risk of catastrophic hemorrhage if inadvertently subjected to biopsy or surgical procedures. We reported the case of a 75-year-old female with an IPRAA that mimicked RCC on contrast-enhanced computed tomography (CECT). However, a suspicious feeding artery to the renal mass was identified on computed tomography angiography (CTA) images. Further evaluation with positron emission tomography/magnetic resonance imaging (PET/MR) suggests the diagnosis of IPRAA. This was confirmed by digital subtraction angiography (DSA), and the aneurysm was successfully treated with transcatheter embolization. This case highlights the importance of including IPRAA in the differential diagnosis of renal masses and emphasizes the need for careful imaging evaluation to avoid potentially life-threatening complications from misdiagnosis.

Theranostics is an interesting area of cancer research that describes the use of radiotracers to first diagnose and then treat cancer. By coupling a radioisotope to an agent that selectively targets malignant cells, one can distribute focused radiation to disease sites. There are a variety of different radiopharmaceutical vectors that have been utilized in this way, such as peptides, small molecules and antibodies. Because antibodies bind to highly specific antigens, radioimmunotherapy (RIT) offers a promising route to precisely targeted treatments with reduced systemic toxicity compared to conventional radiotherapy. Beta (β)-emitting isotopes (e.g., ¹³¹I, ⁹⁰Y) have been more commonly coupled in RIT, but the use of alpha (α)-emitters (e.g., ²²⁵Ac, ²¹²Pb), for RIT (α-RIT) has rising popularity due to their shorter tissue range and higher linear energy transfer. These characteristics decrease off-target effects in neighboring tissues and increase tumor cell destruction, respectively. However, there are several challenges to RIT. The production of daughter isotopes from α decay makes dosimetric assessments difficult and could potentially cause off target toxicities. Additionally, whole antibodies tend to accumulate in liver tissue and have long biological clearance times, which may cause excess radiation to the blood, marrow and liver. Yet, there are a variety of α-RIT agents currently in development to treat prostate cancer, hematologic malignancies, and other solid tumors. Many agents show promise, like ²²⁷Th-epratuzumab, a CD22-targeting antibody used in the treatment of relapsed or refractory acute myeloid leukemia (R/R AML). While notoriously deadly and difficult to treat, the disease control rate in patients with R/R AML taking ²²⁷Th-epratuzumab was 38%. Like many α-RIT therapies, follow-up studies are needed to continue to improve efficacy. Strategies to widen the therapeutic indices of these agents have been investigated such as pretargeting, use of antibody fragments, chelator optimization and combination therapies. This review describes the current landscape and clinical progress of targeted α radioimmunotherapy.

Meningiomas are the most common primary intracranial tumors, with treatment involving resection and radiation therapy. However, therapeutic options are limited for recurrent or progressive disease, particularly in higher World Health Organization (WHO) grade tumors. Somatostatin receptor (SSTR) expression in meningiomas has opened new therapeutic opportunities as the differential SSTR2 overexpression permits molecular targeting using radiolabeled somatostatin analogs. PRRT offers promising therapeutic efficacy in select meningioma patients, with clinical responses strongly correlated to WHO tumor grade and SSTR expression levels. Combining SSTR PET imaging, to evaluate receptor density, with radiomic analysis can reveal tumor heterogeneity patterns and quantitative imaging features that can guide clinical decision-making and monitor treatment response. Integrating machine learning and artificial intelligence (AI) into clinical workflows offer novel approaches to apply quantitative SUV parameters, image texture features, and histopathologic data in order to identify patients with WHO grade II and III meningiomas at greater risk of tumor recurrence. Given the heterogeneity in imaging and treatment protocols across institutions and the limited number of PRRT-treated meningioma cohorts, future research should prioritize prospective, multicenter studies that integrate histologic and molecular imaging data to refine patient selection strategies and establish PRRT's role within personalized, precision cancer treatment paradigms.

The purpose of this study is to evaluate the PSMA PET imaging parameters in association with outcomes among patients with oligorecurrent prostate cancer. This retrospective single-center study included 101 patients (median age 71; interquartile range 65-75) with biochemically recurrent prostate cancer who underwent PSMA PET between May 2021 and May 2022, revealing 5 or fewer sites of metastases (oligometastatic disease). Multiple variables including maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), and molecular tumor volume (MTV) were measured and analyzed on a per-patient basis, along with total MTV and molecular tumor burden (MTB). Multivariable Cox proportional-hazards regression models were used to identify factors associated with progression-free survival (PFS). PSMA PET revealed a total of 216 lesions across all patients, of which 134 (62.0%) involved the lymph nodes and 56 (25.9%) involved the bone. A total of 61 (60.4%) patients received combined metastasis-directed and hormone therapy, and 40 (39.6%) received hormone therapy only. The median subsequent follow-up from PSMA PET detection of oligorecurrent disease was 18.2 months (IQR 10.3-25.0). MTV on PSMA PET was associated with worse PFS (hazard ratio: 1.05, 95% CI 1.00-1.11; P = 0.04). Molecular tumor volume on PSMA PET is associated with worse clinical outcomes in patients with oligorecurrent prostate cancer.

Terbium-161 (¹⁶¹Tb) is emerging as a promising theranostic radionuclide for prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) in metastatic castration-resistant prostate cancer (mCRPC). Compared with lutetium-177 (¹⁷⁷Lu), ¹⁶¹Tb emits additional high-linear energy transfer Auger and internal conversion electrons, enabling superior tumor cell kill in micrometastatic disease. Early clinical studies demonstrate favorable safety, dosimetry, and efficacy profiles for ¹⁶¹Tb-labeled PSMA ligands. Ongoing trials and production advancements are critical to fully realizing the therapeutic potential of ¹⁶¹Tb-based RLT.

Poly(ADP-Ribose) Polymerase 1 (PARP1) is a key DNA repair enzyme and therapeutic target in cancer, with overexpression observed in several cancers, including basal cell carcinoma (BCC). Conventional diagnostic methods for BCC lack specificity and are invasive, highlighting the need for noninvasive alternatives. PARP-targeted molecular imaging, particularly with fluorescence probes, has shown strong potential for tumor detection and real-time visualization. PARPi-FL, a fluorescent derivative of Olaparib, enables rapid, specific, and high-contrast imaging of BCC in preclinical and ex vivo human studies. Optimized application protocols confirm its safety and translational promise for noninvasive diagnosis and image-guided surgery.

T-cell activation within the tumor microenvironment is a key determinant of response to immunotherapy, yet current biomarkers fail to capture its spatial and temporal dynamics. Traditional assays such as PD-L1 immunohistochemistry, tumor mutational analysis, and circulating cytokine profiling offer static or systemic snapshots that inadequately reflect localized immune engagement. Positron emission tomography (PET) provides a unique opportunity to visualize these processes in vivo. Among emerging tracers, CXCL9-targeted imaging stands out as a promising approach to quantify IFNγ-driven T-cell activation and recruitment. Jacobson et al. report the development of [¹⁸F]F-h2A12, a high-affinity nanobody PET tracer specific for CXCL9. Preclinical studies demonstrate robust uptake in CXCL9-expressing tumors, close correlation with intratumoral immune activation, and clear distinction from blood-based biomarkers. Compared with existing immune PET tracers that target cytotoxic enzymes, soluble cytokines, or surface activation markers, CXCL9 imaging offers an advantageous balance of specificity, localization, and functional relevance. By visualizing the chemokine gradients that govern T-cell trafficking, CXCL9 PET could serve as an early, noninvasive biomarker of immunotherapy response and a powerful tool for guiding adaptive treatment strategies.

The metabotropic glutamate receptor 3 (mGluR3) is a G-protein-coupled receptor (GPCR) involved in modulating glutamatergic neurotransmission and maintaining neural homeostasis. By inhibiting adenylyl cyclase activity, mGluR3 negatively modulates the activity of adenylyl cyclase via Gi/o protein coupling, reducing cyclic AMP (cAMP) levels and modulating downstream signaling pathways. Dysfunction of mGluR3 is associated with a range of neurological and psychiatric disorders, including depression, autism, cognitive impairment, bipolar affective disorder, schizophrenia, and neurodegenerative diseases. Despite its therapeutic relevance, no selective mGluR3 positron emission tomography (PET) radioligand is currently available to image this target in vivo. In this study, we report the radiosynthesis and preclinical evaluation of [¹⁸F]VU6010572 - a novel PET tracer based on a therapeutical drug candidate. VU6010572 exhibits potent binding affinity (IC₅₀ = 39.9 nM) and exceptional selectivity (>100-fold over other mGluR subtypes). Radiolabeling with fluorine-18 yielded [¹⁸F]VU6010572 with high radiochemical yield (48%, decay-corrected) and molar activity (59 GBq/µmol). While in vitro autoradiography demonstrated heterogeneous brain distribution, dynamic PET imaging in rodents revealed reasonable brain uptake in vivo yet modest binding specificity and rapid brain washout. While these findings support the potential of [¹⁸F]VU6010572 as a lead structure, further medicinal chemistry optimization is warranted to enhance the metabolic and pharmacokinetic properties.