Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 4

molecular imaging Related Abstracts

4 Multifunctional Bismuth-Based Nanoparticles as Theranostic Agent for Imaging and Radiation Therapy

Authors: Azimeh Rajaee, Lingyun Zhao, Shi Wang, Yaqiang Liu

Abstract:

In recent years many studies have been focused on bismuth-based nanoparticles as radiosensitizer and contrast agent in radiation therapy and imaging due to the high atomic number (Z = 82), high photoelectric absorption, low cost, and low toxicity. This study aims to introduce a new multifunctional bismuth-based nanoparticle as a theranostic agent for radiotherapy, computed tomography (CT) and magnetic resonance imaging (MRI). We synthesized bismuth ferrite (BFO, BiFeO3) nanoparticles by sol-gel method and surface of the nanoparticles were modified by Polyethylene glycol (PEG). After proved biocompatibility of the nanoparticles, the ability of them as contract agent in Computed tomography (CT) and magnetic resonance imaging (MRI) was investigated. The relaxation time rate (R2) in MRI and Hounsfield unit (HU) in CT imaging were increased with the concentration of the nanoparticles. Moreover, the effect of nanoparticles on dose enhancement in low energy was investigated by clonogenic assay. According to clonogenic assay, sensitizer enhancement ratios (SERs) were obtained as 1.35 and 1.76 for nanoparticle concentrations of 0.05 mg/ml and 0.1 mg/ml, respectively. In conclusion, our experimental results demonstrate that the multifunctional nanoparticles have the ability to employ as multimodal imaging and therapy to enhance theranostic efficacy.

Keywords: Nanomedicine, radiotherapy, molecular imaging, Theranostics

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3 X-Ray Fluorescence Molecular Imaging with Improved Sensitivity for Biomedical Applications

Authors: Guohua Cao, Xu Dong

Abstract:

X-ray Fluorescence Molecular Imaging (XFMI) holds great promise as a low-cost molecular imaging modality for biomedical applications with high chemical sensitivity. However, for in vivo biomedical applications, a key technical bottleneck is the relatively low chemical sensitivity of XFMI, especially at a reasonably low radiation dose. In laboratory x-ray source based XFMI, one of the main factors that limits the chemical sensitivity of XFMI is the scattered x-rays. We will present our latest findings on improving the chemical sensitivity of XFMI using excitation beam spectrum optimization. XFMI imaging experiments on two mouse-sized phantoms were conducted at three different excitation beam spectra. Our results show that the minimum detectable concentration (MDC) of iodine can be readily increased by five times via excitation spectrum optimization. Findings from this investigation could find use for in vivo pre-clinical small-animal XFMI in the future.

Keywords: X-Ray Scattering, molecular imaging, X-Ray fluorescence, chemical sensitivity

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2 Generation Mechanism of Opto-Acoustic Wave from in vivo Imaging Agent

Authors: Hiroyuki Aoki

Abstract:

The optoacoustic effect is the energy conversion phenomenon from light to sound. In recent years, this optoacoustic effect has been utilized for an imaging agent to visualize a tumor site in a living body. The optoacoustic imaging agent absorbs the light and emits the sound signal. The sound wave can propagate in a living organism with a small energy loss; therefore, the optoacoustic imaging method enables the molecular imaging of the deep inside of the body. In order to improve the imaging quality of the optoacoustic method, the more signal intensity is desired; however, it has been difficult to enhance the signal intensity of the optoacoustic imaging agent because the fundamental mechanism of the signal generation is unclear. This study deals with the mechanism to generate the sound wave signal from the optoacoustic imaging agent following the light absorption by experimental and theoretical approaches. The optoacoustic signal efficiency for the nano-particles consisting of metal and polymer were compared, and it was found that the polymer particle was better. The heat generation and transfer process for optoacoustic agents of metal and polymer were theoretically examined. It was found that heat generated in the metal particle rapidly transferred to the water medium, whereas the heat in the polymer particle was confined in itself. The confined heat in the small particle induces the massive volume expansion, resulting in the large optoacoustic signal for the polymeric particle agent. Thus, we showed that heat confinement is a crucial factor in designing the highly efficient optoacoustic imaging agent.

Keywords: molecular imaging, in vivo imaging, nano-particle, opto-acoustic effect

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1 The Superiority of 18F-Sodium Fluoride PET/CT for Detecting Bone Metastases in Comparison with Other Bone Diagnostic Imaging Modalities

Authors: Mojtaba Mirmontazemi, Habibollah Dadgar

Abstract:

Bone is the most common metastasis site in some advanced malignancies, such as prostate and breast cancer. Bone metastasis generally indicates fewer prognostic factors in these patients. Different radiological and molecular imaging modalities are used for detecting bone lesions. Molecular imaging including computed tomography, magnetic resonance imaging, planar bone scintigraphy, single-photon emission tomography, and positron emission tomography as noninvasive visualization of the biological occurrences has the potential to exact examination, characterization, risk stratification and comprehension of human being diseases. Also, it is potent to straightly visualize targets, specify clearly cellular pathways and provide precision medicine for molecular targeted therapies. These advantages contribute implement personalized treatment for each patient. Currently, NaF PET/CT has significantly replaced standard bone scintigraphy for the detection of bone metastases. On one hand, 68Ga-PSMA PET/CT has gained high attention for accurate staging of primary prostate cancer and restaging after biochemical recurrence. On the other hand, FDG PET/CT is not commonly used in osseous metastases of prostate and breast cancer as well as its usage is limited to staging patients with aggressive primary tumors or localizing the site of disease. In this article, we examine current studies about FDG, NaF, and PSMA PET/CT images in bone metastases diagnostic utility and assess response to treatment in patients with breast and prostate cancer.

Keywords: Precision Medicine, molecular imaging, sodium fluoride, skeletal metastases, fluorodeoxyglucose, prostate cancer (68Ga-PSMA-11)

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