In the present study, we used multimodal imaging to investigate biodistribution in rats after intravenous administration of a new ^sup 99m^Tc-labeled delivery system consisting of polymer-shelled ...microbubbles (MBs) functionalized with diethylenetriaminepentaacetic acid (DTPA), thiolated poly(methacrylic acid) (PMAA), chitosan, 1,4,7-triacyclononane-1,4,7-triacetic acid (NOTA), NOTA-super paramagnetic iron oxide nanoparticles (SPION), or DTPA-SPION. Examinations utilizing planar dynamic scintigraphy and hybrid imaging were performed using a commercially available single-photon emission computed tomography (SPECT)/computed tomography (CT) system. For SPION containing MBs, the biodistribution pattern of ^sup 99m^Tc-labeled NOTA-SPION and DTPA-SPION MBs was investigated and co-registered using fusion SPECT/CT and magnetic resonance imaging (MRI). Moreover, to evaluate the biodistribution, organs were removed and radioactivity was measured and calculated as percentage of injected dose. SPECT/CT and MRI showed that the distribution of ^sup 99m^Tc-labeled ligand-functionalized MBs varied with the type of ligand as well as with the presence of SPION. The highest uptake was observed in the lungs 1 h post injection of ^sup 99m^Tc-labeled DTPA and chitosan MBs, while a similar distribution to the lungs and the liver was seen after the administration of PMAA MBs. The highest counts of ^sup 99m^Tc-labeled NOTA-SPION and DTPA-SPION MBs were observed in the lungs, liver, and kidneys 1 h post injection. The highest counts were observed in the liver, spleen, and kidneys as confirmed by MRI 24 h post injection. Furthermore, the results obtained from organ measurements were in good agreement with those obtained from SPECT/CT. In conclusion, microbubbles functionalized by different ligands can be labeled with radiotracers and utilized for SPECT/CT imaging, while the incorporation of SPION in MB shells enables imaging using MR. Our investigation revealed that biodistribution may be modified using different ligands. Furthermore, using a single contrast agent with fusion SPECT/CT/MR multimodal imaging enables visualization of functional and anatomical information in one image, thus improving the diagnostic benefit for patients.
Background: In the present study, we used multimodal imaging to investigate biodistribution in rats after intravenous administration of a new super(99m)Tc-labeled delivery system consisting of ...polymer-shelled microbubbles (MBs) functionalized with diethylenetriaminepentaacetic acid (DTPA), thiolated poly(methacrylic acid) (PMAA), chitosan, 1,4,7-triacyclononane-1,4,7-triacetic acid (NOTA), NOTA-super paramagnetic iron oxide nanoparticles (SPION), or DTPA-SPION. Methods: Examinations utilizing planar dynamic scintigraphy and hybrid imaging were performed using a commercially available single-photon emission computed tomography (SPECT)/computed tomography (CT) system. For SPION containing MBs, the biodistribution pattern of super(99m)Tc-labeled NOTA-SPION and DTPA-SPION MBs was investigated and co-registered using fusion SPECT/CT and magnetic resonance imaging (MRI). Moreover, to evaluate the biodistribution, organs were removed and radioactivity was measured and calculated as percentage of injected dose. Results: SPECT/CT and MRI showed that the distribution of super(99m)Tc-labeled ligand-functionalized MBs varied with the type of ligand as well as with the presence of SPION. The highest uptake was observed in the lungs 1 h post injection of super(99m)Tc-labeled DTPA and chitosan MBs, while a similar distribution to the lungs and the liver was seen after the administration of PMAA MBs. The highest counts of super(99m)Tc-labeled NOTA-SPION and DTPA-SPION MBs were observed in the lungs, liver, and kidneys 1 h post injection. The highest counts were observed in the liver, spleen, and kidneys as confirmed by MRI 24 h post injection. Furthermore, the results obtained from organ measurements were in good agreement with those obtained from SPECT/CT. Conclusions: In conclusion, microbubbles functionalized by different ligands can be labeled with radiotracers and utilized for SPECT/CT imaging, while the incorporation of SPION in MB shells enables imaging using MR. Our investigation revealed that biodistribution may be modified using different ligands. Furthermore, using a single contrast agent with fusion SPECT/CT/MR multimodal imaging enables visualization of functional and anatomical information in one image, thus improving the diagnostic benefit for patients.
In recent years, ever more workers are employed in sedentary jobs spending many hours sitting at video terminals. Discomfort office furniture and incorrect video screen positioning, as well as bad ...postural attitudes lead to the occurrence of back musculoskeletal disorders. Low back pain is one of the most widespread disease which causes a heavy socio- economic burden as it leads to absence from workplace and use of the National Health Service. In this scenario, being able to continuously evaluate poor postural attitudes may be beneficial to correct postural habits, and so to reduce the incidence of such a disease. For this purpose, many technologies capable to detect the spinal range of motions (ROMs) have been developed. Among others, the use of optical fiber sensors is gaining momentum, since these sensors allow the development of wearable, light and non-invasive monitoring systems. The present work aims at assessing the capability of a custom-made smart textile based on FBG sensors in detecting back dorsal flexion-extension (F/E) movements. Experimental results show high sensitivity to strain of the smart textile and confirm the system capability of monitoring back dorsal F/E movements in time.
Ultrasound contrast agents (UCA) have been used for years in the clinical field, for applications such as blood pool enhancement, characterization of liver lesions or perfusion imaging 12–15, 20. The ...contrast agents are generally in the form of spherical voids or cavities filled by a gas, called microbubbles (MB). MBs are stabilized by a coating material such as phospholipids, surfactants, denatured human serum albumin or synthetic polymers. As gas is less dense than liquids or solids, sound travels more slowly in gas than it does in liquid. The difference in the sound speed in the microbubbles creates an acoustic mismatch between tissue and blood surrounding a microbubble, making it an efficient reflector of ultrasound energy. The ability to produce strong signals from microbubbles depends on the stability of the gas particle. Stability has been enhanced by varying the gas composition (air, nitrogen, sulphur hexafluoride, perfluorocarbons) and/or by chemical modification of the microbubble shell 20. As microbubbles stay in the vascular space and have a behavior similar to red blood cells in the microcirculation, they can be used as intravascular tracers. The possibility to introduce a targeting ligand for a specific interaction with its receptor onto the microbubble shell can be a way to selectively accumulate the contrast agent in the deseased region. Moreover, targeted MBs can be used to carry different drugs to the desired sites and release them after their destruction/cavitation with ultrasound radiation or by chemical/enzymatic cleavage.
PDF
