Härmark Johan, Hebert Hans, Koeck Philip J B
School of Technology and Health, KTH Royal Institute of Technology and Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden.
Micron. 2016 Jun;85:39-43. doi: 10.1016/j.micron.2016.03.009. Epub 2016 Apr 1.
Intravenously injected microbubbles (MBs) can be utilized as ultrasound contrast agent (CA) resulting in enhanced image quality. A novel CA, consisting of air filled MBs stabilized with a shell of polyvinyl alcohol (PVA) has been developed. These spherical MBs have been decorated with superparamagnetic iron oxide nanoparticles (SPIONs) in order to serve as both ultrasound and magnetic resonance imaging (MRI) CA. In this study, a mathematical model was introduced that determined the shell thickness of two types of SPIONs decorated MBs (Type A and Type B). The shell thickness of MBs is important to determine, as it affects the acoustical properties. In order to investigate the shell thickness, thin sections of plastic embedded MBs were prepared and imaged using transmission electron microscopy (TEM). However, the sections were cut at random distances from the MB center, which affected the observed shell thickness. Hence, the model determined the average shell thickness of the MBs from corrected mean values of the outer and inner radii observed in the TEM sections. The model was validated using simulated slices of MBs with known shell thickness and radius. The average shell thickness of Type A and Type B MBs were 651nm and 637nm, respectively.
静脉注射的微泡（MBs）可作为超声造影剂（CA）使用，从而提高图像质量。一种新型的造影剂已被开发出来，它由填充空气的微泡组成，并用聚乙烯醇（PVA）外壳进行稳定化处理。这些球形微泡已用超顺磁性氧化铁纳米颗粒（SPIONs）进行了修饰，以便同时用作超声和磁共振成像（MRI）造影剂。在本研究中，引入了一个数学模型来确定两种类型的SPIONs修饰微泡（A型和B型）的外壳厚度。微泡的外壳厚度对于确定来说很重要，因为它会影响声学特性。为了研究外壳厚度，制备了塑料包埋微泡的薄片，并使用透射电子显微镜（TEM）进行成像。然而，切片是从微泡中心随机距离处切割的，这影响了观察到的外壳厚度。因此，该模型根据在TEM切片中观察到的外半径和内半径的校正平均值确定了微泡的平均外壳厚度。该模型使用具有已知外壳厚度和半径的微泡模拟切片进行了验证。A型和B型微泡的平均外壳厚度分别为651nm和637nm。
