There are two forms of<unk> , untargeted (used in the clinic today) and targeted (under preclinical development). The two methods slightly differ from each other. Untargeted<unk>  Untargeted microbubbles, such as the aforementioned SonoVue, Optison, or Levovist, are injected intravenously into the systemic circulation in a small bolus. The microbubbles will remain in the systemic circulation for a certain period of time. During that time,<unk>  waves are directed on the area of interest. When microbubbles in the blood flow past the imaging window, the microbubbles’ compressible gas cores oscillate in response to the high frequency sonic energy field, as described in the<unk>  article. The microbubbles reflect a unique echo that stands in stark contrast to the surrounding tissue due to the orders of magnitude mismatch between microbubble and tissue echogenicity. The<unk>  system converts the strong echogenicity into a contrast-enhanced image of the area of interest. In this way, the bloodstream's echo is<unk> , thus allowing the clinician to distinguish blood from surrounding tissues. Targeted<unk>  Targeted<unk>  works in a similar fashion, with a few alterations. Microbubbles targeted with ligands that bind certain molecular markers that are expressed by the area of imaging interest are still injected systemically in a small bolus. Microbubbles theoretically travel through the circulatory system, eventually finding their respective targets and binding specifically.<unk>  waves can then be directed on the area of interest. If a sufficient number of microbubbles have bound in the area, their compressible gas cores oscillate in response to the high frequency sonic energy field, as described in the<unk>  article. The targeted microbubbles also reflect a unique echo that stands in stark contrast to the surrounding tissue due to the orders of magnitude mismatch between microbubble and tissue echogenicity. The<unk>  system converts the strong echogenicity into a contrast-enhanced image of the area of interest, revealing the location of the bound microbubbles. Detection of bound microbubbles may then show that the area of interest is expressing that particular molecular marker, which can be indicative of a certain disease state, or identify particular cells in the area of interest.
Contrast-enhanced ultrasound
Phase contrast magnetic resonance imaging
Radionuclide angiography
Angiography
Fluoroscopy
Angiology
Contrast CT
Magnetic resonance angiography