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P1217Zirconium-89 labelled probe for molecular imaging of inflammation in experimental atherosclerosis
摘要： Early detection of in?amed atherosclerotic lesions by molecular imaging might improve risk assessment beyond that of vascular stenosis and plaque morphology imaging, and improve the clinical management of high-risk patients. To target the key features of unstable atherosclerotic lesions, we studied the feasibility of our radiotracer, based on modi?ed human serum albumin (HSA), to identify in?amed atherosclerotic lesions by in vivo molecular imaging. We applied a maleylated HSA (Mal-HSA) probe, recognised by scavenger receptors on macrophages, in an experimental imaging study of atherosclerosis. Mal-HSA was coupled with a positron-emitting metal ion, Zirconium-89 (89Zr). The targeting potential of this probe was evaluated and compared with unspeci?c 89Zr-HSA and 18F-FDG in a mouse model of atherosclerosis (Apoe?/?, n=22) and compared with wild-type (WT) mice (C57BL/6, n=21) as controls. Radiotracer accumulation in the aortic arch was analysed in vivo by the fusion of positron emission tomography–magnetic resonance imaging (PET-MRI), radiotracer bio-distribution was measured ex vivo by gamma counter, and plaque uptake was evaluated by phosphor imaging (PI) autoradiography (ARG). PET-MRI, gamma counter measurements, and PI-ARG showed the accumulation of 89Zr-Mal-HSA in the atherosclerotic lesions of Apoe?/? mice. The maximum standardised uptake value (SUVmax) for 89Zr-Mal-HSA at 16 and 20 weeks were 26% and 20% higher (P<0.05) in Apoe?/? mice than control WT mice, whereas no difference in SUVmax was found for 18F-FDG in the same animals. 89Zr-Mal-HSA uptake in the aorta as evaluated by gamma counter 48 h post-injection was 32% higher (P<0.01) for Apoe?/? mice compared to WT mice, and the aorta-to-blood ratio was 10-fold higher (P<0.001) for 89Zr-Mal-HSA compared with unspeci?c 89Zr-HSA. HSA probes were mainly distributed to the liver, spleen, kidneys, bone and lymph nodes. The PI-ARG results corroborated the PET and gamma counter measurements, showing higher accumulation of 89Zr-Mal-HSA in the aortas of Apoe?/? mice compared to WT mice; 9.4±1.4 vs 0.8±0.3% (P<0.001). The modi?ed HSA-based radiotracer showed in vivo targeting of in?amed atherosclerotic lesions of mouse aorta, which could also be veri?ed ex vivo. 89Zr-Mal-HSA seems to be a promising diagnostic tool for the identi?cation of vascular in?ammation. Further methodological studies are needed to verify its applicability for detecting rupture-prone plaques.
关键词： atherosclerosis,inflammation,Zirconium-89,PET-MRI,molecular imaging,Nuclear cardiology
更新于2025-09-23 15:19:57
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Dual layer doI detector modules for a dedicated mouse brain PET/MRI
摘要： This work discusses two system geometries including their associated block detectors. Both configurations were based on a dual layer offset structure with small crystals sizes, in the order of 1×1×4/6 mm3, to provide discrete depth of interaction information. The detector for configuration “A” was based on a 4×4 silicon photomultiplier (SiPM) array attached to an optical diffusor, and a 12×12 as well as a 9×11 LSO crystal array, to achieve optimal system sensitivity. This configuration was evaluated by a double layer of 12×12 crystals. Configuration “B” was composed of three 2×2 SiPM arrays equipped with a 1 mm diffusor to read out an LSO stack of 20×6 and 19×5 individual crystals. The average peak-to-valley ratio of the inner/outer layer was 3.5/3.6 for detector “A”, and 3.4/2.8 for detector “B”. The average full width at half maximum (FWHM) energy resolution of the block detectors were 22.24±3.36% for “A” and 30.67±5.37% for “B”. The FWHM of the full block timing resolution of the inner/outer layer was 1.4 ns/1.2 ns for detector “A” and 1.8 ns/1.4 ns for “B”. The performance of the crystal position profile, the energy, and timing resolution indicate that configuration “A” is more appropriate for a mouse brain PET/MRI system.
关键词： PET/MRI,Depth of interaction,brain,small animal brain imaging,PET/RF,integrated MRI-coil,preclinical imaging,PET
更新于2025-09-19 17:15:36
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Quantitative comparison of pre-therapy 99mTc-macroaggregated albumin SPECT/CT and post-therapy PET/MR studies of patients who have received intra-arterial radioembolization therapy with 90Y microspheres
摘要： Objective: The aim of our study was to compare yttrium -90 (90Y) dosimetry obtained from pre-therapy 99mTc-macroaggregated albumin (MAA) SPECT/CT versus post-therapy PET/MRI imaging among patients with primary or metastatic hepatic tumors. Materials and methods: Prior to 90Y radioembolization (RE), 32 patients underwent a scan using MAA mimicking 90Y distribution. After RE with 90Y microspheres, the patients were imaged on a PET/MRI system. Reconstructed images were transferred to a common platform and used to calculate 90Y dosimetry. The Passing-Bablok regression scatter diagram and the Bland and Altman method were used to analyze the difference between dosimetry values. Results: For MAA and PET/MRI modalities, the mean liver doses for all 32 subjects were 43.0 ± 20.9 Gy and 46.5 ± 22.7 Gy, respectively, with a mean difference of 3.4 ± 6.2 Gy. The repeatibility coefficient was 12.1 (27.0% of the mean). The Spearman rank correlation coefficient was high (ρ = 0.92). Although, there was a substantial difference in the maximum doses to the liver between the modalities, the mean liver doses were relatively close, with a difference of 24.0% or less. Conclusions: The two main contributors to the difference between dosimetry calculations using MAA versus 90Y PET/MRI can be attributed to the changes in catheter positioning as well as the liver ROIs used for the calculations. In spite of these differences, our results demonstrate that the dosimetry values obtained from pre-therapy MAA SPECT/CT scans and PET/MRI post-therapy 90Y studies were not significantly different.
关键词： MAA,90Y PET/MRI,Dosimetry
更新于2025-09-10 09:29:36
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Metabolic Volumetric Parameters in <sup>11</sup> C-Choline PET/MR Are Superior PET Imaging Biomarkers for Primary High-Risk Prostate Cancer
摘要： Purpose. Positron emission tomography/magnetic resonance imaging (PET/MRI) can facilitate the use of noninvasive imaging biomarkers in clinical prostate cancer staging. Although multiparametric MRI is a widely used technique, the clinical value of simultaneous PET imaging remains unclear. This study aimed at investigating this issue. Methods. Between January 2015 and December 2016, 31 high-risk prostate cancer patients underwent 11C-choline PET/MRI for staging purposes. Clinical characteristics and imaging parameters, including the standardized uptake value (SUV) and metabolic volumetric parameters from PET imaging; apparent diffusion coefficient (ADC) values from diffusion-weighted imaging; and volume transfer rate constant (Ktrans), reflux rate constant (Kep), and initial area under curve (iAUC) in 60 seconds from dynamic contrast-enhanced (DCE) MRI were analyzed. Results. 11C-Choline PET imaging parameters were significantly correlated with prostate-specific antigen (PSA) levels, and metabolic volumetric parameters, including metabolic tumor volume (MTV) and uptake volume product (UVP), showed significant correlations with other MRI parameters. In our cohort analysis, the PET/MRI parameters UVP/minimal ADC value (ADCmin) and kurtosis of Kep (Kepkur)/ADCmin were significant predictors for progression-free survival (PFS) (HR = 1.01, 95% CI: 1.00–1.02, p = 0.031 and HR = 1.09, 95% CI: 1.02–1.16, p = 0.009, respectively) in multivariate Cox regression analysis. High UVP/ADCmin and Kepkur/ADCmin values were significantly associated with shorter PFS. Conclusions. Metabolic volumetric parameters such as MTV and UVP can be routinely used as PET imaging biomarkers to add prognostic value and show better correlations in combination with MR imaging parameters in high-risk prostate cancer patients undergoing 11C-choline PET/MRI.
关键词： 11C-choline,metabolic volumetric parameters,imaging biomarkers,PET/MRI,prostate cancer
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Bangalore, India (2018.9.19-2018.9.22)] 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Multi-Modal Medical Image Fusion Using Curvelet Algorithm
摘要： Medical image fusion is the process of combining images from different modalities to make the fused image more informative than any of the source images. Images of different modalities include PET, CT, SPECT and MRI. One input image will have high spatial resolution and low spectral information and another image will have high spectral resolution and vice versa. The aim of medical image fusion is to have a single image having both spatial and spectral resolution. Most commonly used transform domain methods like Curvelet transform is applied to extract more specific information from the source images. Experimental results demonstrate that fused image will have sharpened image resolution and the fusion performance is evaluated with image quality assessment metrics.
关键词： SPECT/PET,MRI,spatial and spectral resolution,Curvelet
更新于2025-09-04 15:30:14