Frontiers in nuclear medicine (Lausanne, Switzerland)最新文献

[This corrects the article DOI: 10.3389/fnume.2025.1575026.].

Background: The characterization of solitary pulmonary nodules (SPNs) as malignant or benign remains a diagnostic challenge using conventional imaging parameters. The literature suggests using combined Positron Emission Tomography (PET) and Computed Tomography (CT) to characterise a SPN. Radiomics and machine learning are other promising technologies which can be utilised to characterise the SPN.

Purpose: This study explores the potential of PET radiomics signatures and machine learning algorithms to characterise the SPN.

Methods: This retrospective study aimed to characterize solitary pulmonary nodules (SPNs) using PET radiomics. A total of 163 patients who underwent PET/CT imaging were included in this study. A total of 1,098 features were extracted from PET images using PyRadiomics. To optimize model performance two strategies i.e., (a) feature selection and (b) feature reduction techniques were employed, including hierarchical clustering, RFE in feature selection, and PCA in feature reduction. To address outcome class imbalance, the dataset was statistically resampled (SMOTE). A random forest models was developed using original training set (RF-Model-O & RF-PCA-Model-O) and balanced training dataset (RF-Model-B & RF-PCA-Model-B) and validated on the test datasets. Additionally, 5-fold cross-validation and bootstrap validation was also performed. The model's performance was assessed using various metrics, such as accuracy, AUC, precision, recall, and F1-score.

Results: Of the 163 patients (aged 36-76 years, mean age 58 ± 7), 117 had malignant disease and 46 had granulomatous or benign conditions. In Strategy (a), five radiomic features were identified as optimal using hierarchical clustering and RFE. In Strategy (b), five principal components were deemed optimal using PCA. The model accuracy of RF-Model-O and RF-Model-B in the train-test validation, 5-fold cross-validation and bootstrap validation were found to be 0.8, 0.80 ± 0.07, 0.84 ± 1.11 and 0.8, 0.83 ± 0.10, 0.80 ± 0.07 in Strategy (a). Similarly, the model accuracy of RF-PCA-Model-O and RF-PCA-Model-B in the train-test validation, 5-fold cross-validation and bootstrap validation were found to be 0.84, 0.80 ± 0.07, 0.84 ± 07 and 0.74, 0.80 ± 0.08, 0.75 ± 0.08 in Strategy (b).

Conclusion: The PET radiomics demonstrated excellent performance in characterizing SPNs as benign or malignant.

Introduction: The COVID-19 pandemic has profoundly affected mental health, with lockdown periods particularly exacerbating negative emotions such as fear, sadness, and uncertainty. This study examines brain metabolic changes associated with the psychological context of the first French COVID-19 lockdown in vulnerable individuals.

Methods: As a proxy measure of the psychological context, we used a composite negative-emotion score derived from an open-source X/Twitter dataset ("The First French COVID-19 Lockdown Twitter Dataset"), designed to capture public sentiment over the 55-day lockdown. This score was day-by-day correlated with whole-brain voxel-based [18F]FDG PET imaging in 95 patients with neurological conditions, using statistical parametric mapping (SPM) (p-voxel < 0.001, k > 108).

Results: A significant negative correlation was found between daily negative-emotion scores and metabolism in the right ventromedial prefrontal cortex (vmPFC) and anterior cingulate cortex (ACC), key regions of the brain's fear circuit. Inter-regional correlation analysis (IRCA) of metabolic connectivity from the right vmPFC/ACC further revealed a right limbic-dominant network including the amygdala, hippocampus, thalamus, and basal ganglia.

Discussion: These findings highlight the sensitivity of the right vmPFC/ACC to societal emotional stressors, suggesting a potential cerebral substrate for the increase in psychological and psychiatric disorders observed during the pandemic. Further research is needed to validate these results in larger populations and to explore their longitudinal implications, to better understand the neurological impact of collective stress.

Kinetic modelling of brain PET data is crucial for estimating quantitative biological parameters, traditionally requiring arterial sampling. This study evaluated whether arterial samples could be omitted to estimate the image-derived input function (IDIF) using a long axial field-of-view PET scanner. The use of internal carotid arteries (ICA) for IDIF estimation, along with venous samples for plasma-to-whole blood ratios and plasma parent fractions, was also assessed. Six healthy volunteers underwent [¹⁸F]MC225 scans with manual arterial sampling. IDIFs were derived from the aortic arch (IDIF_AA) and calibrated using manual arterial samples (IDIF_{AA_CAL}). ICA-derived IDIF was also calibrated (IDIF_{CA_CAL}) and compared to IDIF_{AA_CAL}. In a separate group of six volunteers, venous and arterial samples were collected to evaluate plasma-to-whole blood ratios, plasma parent fractions, and IDIF calibration (IDIF_{CA_CAL_VEN}). Volume of distribution (V_T) of different brain regions was estimated for all IDIFs techniques, corrected for plasma-to-whole blood ratio and plasma parent fraction (IDIF_AA,P, IDIF_{AA_CAL,P}, IDIF_{ICA_CAL,P} and IDIF_{ICA_CAL_VEN_P}). Our findings revealed discrepancies between IDIF_AA and arterial samples, highlighting the importance of calibration. The differences between IDIF_AA,P and IDIF_{AA_CAL,P} were 9.2% for area under the curve and 4.0% for brain V_T. IDIF_{ICA_CAL,P} showed strong agreement with IDIF_{A_CAL,P}, with 1.2% V_T difference. Venous sampling showed consistent agreement with arterial sampling for plasma parameters but was unreliable for IDIF calibration, leading to 39% V_T differences. This study emphasises that arterial samples are still required for IDIF calibration and reliable V_T estimation for [¹⁸F]MC225 PET tracer. ICA-derived IDIF, when calibrated, provides reliable V_T estimates. Venous sampling is a potential alternative for estimating plasma parameters, but it is unsuitable for IDIF calibration.

Trial registry: NCT05618119 (clinicaltrials.gov/study/NCT05618119).

Background: Calcinosis is a morbid complication of dermatomyositis (DM) and systemic sclerosis (SSc) with no effective pharmacologic treatment or validated whole-body assessment modality. ¹⁸F-NaF PET/CT may help to quantify and characterize calcinosis.

Methods: In this pilot study, we enrolled three adults with DM and three with SSc, all with new calcinosis deposits. Each underwent ¹⁸F-NaF PET/CT and clinical examination with semi-quantitative scoring of calcinosis. We described the ¹⁸F-NaF PET/CT findings and compared these to CT imaging alone as well as to clinical examination.

Results: Calcinosis was noted on ¹⁸F-NaF PET/CT in the subcutaneous tissue in all patients and the muscle in three patients, including two with SSc. The average semi-quantitative score was 23.5 by ¹⁸F-NaF PET/CT and 20 by clinical exam. Wilcoxon signed rank test indicated greater scores by ¹⁸F-NaF PET/CT than by clinical exam (p = 0.0264). ¹⁸F-NaF uptake varied among calcinosis deposits and occurred without corresponding calcifications on CT.

Conclusions: ¹⁸F-NaF PET/CT appears to be a sensitive method of detecting and characterizing calcinosis that provides both quantitative and qualitative data beyond what can be obtained by physical examination or CT alone. ¹⁸F-NaF uptake occurs in muscle in both SSc and DM, suggesting the possibility that myositis may be driving calcinosis in a subset of patients with SSc.

[This corrects the article DOI: 10.3389/fnume.2024.1469487.].

Introduction: Fluorodeoxyglucose (FDG) PET/CT is typically the reference imaging method for assessing and tracking lymphomas. However, fibroblast activation protein inhibitor (FAPI) PET is being explored as a potentially useful option, especially when Fluorodeoxyglucose (FDG) scans do not show clear results.

Methods: For this systematic review, two researchers searched PubMed/MEDLINE and Cochrane CENTRAL for studies on FAPI PET/CT in lymphoma patients.

Results: The literature search initially retrieved 249 articles. After removing duplicates and screening titles and abstracts, and full text, there was a final selection of 15 articles (3 original studies and 12 case reports), encompassing a total of 270 patients. The three original studies were judged to have a low risk of bias according to the QUADAS-2 criteria. The systematic review reveals that FAPI PET/CT exhibits lower diagnostic sensitivity than [¹⁸F]FDG PET/CT in lymphomas characterized by low FAP expression. Nevertheless, FAPI PET/CT retains potential as a complementary imaging modality.

Discussion: [¹⁸F]FDG PET/CT remains the gold standard in lymphoma imaging, but FAPI PET/CT can potentially provide supplementary information regarding the molecular characteristics of lymphomas. FAPI PET/CT may have prognostic and therapeutic implications. In particular, it could help identify lymphoma subgroups with distinct stromal environments, potentially serving as a prognostic biomarker. Further large-scale prospective studies are warranted to validate its role in lymphoma management.

Background: Carbonic anhydrase-IX (CA-IX) is overexpressed in tumors due to hypoxic conditions and considered an attractive biomarker for tumor-targeting radioligands. The introduction of an albumin binder (ALB) to radioligands can delay their renal clearance, resulting in increased radioactivity delivered to tumors and decreased renal uptake of radioligands. In this study, we designed novel CA-IX-targeted trifunctional radioligands consisting of imidazothiadiazole sulfonamide (IS) as a CA-IX-targeted ligand, DOTA as a chelator with four free carboxylic groups, and lysine-conjugated 4-(p-iodophenyl)butyric acid (Lys-IPBA) as ALB, with IS-[¹¹¹In]In-DOTADG-ALB in a linear-chain arrangement and [¹¹¹In]In-DOTAGA-ALB-IS in a branched-chain arrangement. Fundamental properties of IS-[¹¹¹In]In-DOTADG-ALB and [¹¹¹In]In-DOTAGA-ALB-IS were evaluated by in vitro and in vivo assays.

Methods: IS-DOTADG-ALB and DOTAGA-ALB-IS were synthesized and radiolabeled with [¹¹¹In]InCl₃. The stability of IS-[¹¹¹In]In-DOTADG-ALB and [¹¹¹In]In-DOTAGA-ALB-IS was evaluated by HPLC analysis after incubation in murine plasma. A cell saturation binding assay using CA-IX-positive HT-29 cells and albumin-binding assay were performed for IS-[¹¹¹In]In-DOTADG-ALB and [¹¹¹In]In-DOTAGA-ALB-IS to evaluate their capacity to bind CA-IX and albumin. Biodistribution assays of IS-[¹¹¹In]In-DOTADG-ALB and [¹¹¹In]In-DOTAGA-ALB-IS were performed using HT-29 tumor-bearing mice to evaluate their pharmacokinetics.

Results: IS-[¹¹¹In]In-DOTADG-ALB and [¹¹¹In]In-DOTAGA-ALB-IS were successfully synthesized by ligand substitution reaction from their corresponding precursors. IS-[¹¹¹In]In-DOTADG-ALB and [¹¹¹In]In-DOTAGA-ALB-IS exhibited similar stabilities in murine plasma and affinities to CA-IX, although the affinities to albumin were higher for [¹¹¹In]In-DOTAGA-ALB-IS compared with IS-[¹¹¹In]In-DOTADG-ALB. In the biodistribution assays, [¹¹¹In]In-DOTAGA-ALB-IS showed higher blood retention and tumor accumulation and lower renal uptake than IS-[¹¹¹In]In-DOTADG-ALB, reflecting their albumin-binding affinities.

Conclusion: These data suggest that the branched-chain arrangement of DOTAGA-ALB-IS may be useful for the design of CA-IX-targeted radioligands consisting of an IS ligand, DOTA, and Lys-IPBA.

Hyperparathyroidism disrupts the balance of physiological bone formation and resorption by upregulating osteoclast activity. This leads to hypercalcemia, resulting in osteoporosis and eventually the formation of "brown tumors." Currently used radiological and nuclear medicine imaging for primary hyperparathyroidism face challenges in accurately diagnosing bone-related complications. Molecular bone imaging techniques routinely consist of bone scintigraphy, with possible addition of bone-SPECT/CT. Recently, renewed interest has emerged in the use of Na[¹⁸F]F-PET/CT. Both applications are highly sensitive to in vivo osteoblast activity. However, the latter technique offers improved spatial resolution and sensitivity, as well as shorter incubation and faster scanning. This article summarizes current limitations and potential improvements in bone-SPECT/CT and Na[¹⁸F]F-PET/CT imaging in selected patients with hyperparathyroidism, compared to other relevant techniques and clinical parameters.

In this case, we report the usefulness of bone scintigraphy in evaluating osteoarticular pain when the diagnosis is unclear after standard morphological imaging. A 24-year-old male patient exhibited mild left tibial pain that had been intensifying over a period of 2 years. The initial radiological evaluation suggested a diagnosis of pediatric tibial bone marrow osteosclerosis associated with periostitis, based on standard radiographs and MRI. However, a complementary bone scan was required for confirmation and showed moderate hyperemia and severe hyperfixation of the tibial lesion along with similar lesions on the left femur, both humeri, and the right ulna. These new findings led to a diagnosis of Ribbing disease, a rare sclerosing bone dysplasia.