Assessment of tissue perfusion by contrast-enhanced ultrasound

Abstract

Contrast-enhanced ultrasound (CEUS) with microbubble contrast agents is a new imaging technique for quantifying tissue perfusion.

201 Intraoperative Cerebral Glioma Characterization With Contrast Enhanced Ultrasound

“…Nondestructive US scanning, with specific algorithm performed with low acoustic power and sulfur hexafluoride, filled microbubble contrast agents, opens up to quantitative data analysis with dedicated software leading to real-time assessment and quantification of tumor contrast enhancement with microbubbles, measurement of organ transit time after microbubble injection, and analysis of tissue perfusion. Tissue perfusion may be quantified also by further evaluating the replenishment kinetics of the volume of microbubbles after their destruction in the imaged slice (using high mechanical index US), obtaining quantitative parameters related to local tissue perfusion [15,19]. However, we believe that the first step, as already performed for other organs and in our previous study [34], is the qualitative and semiquantitative analysis; timeintensity curves providing quantitative data require very large cohorts of patients in order to achieve a statistical relevance, so we feel that a quantitative analysis would be of little value in this study [28,29,32,33].…”

“…Contrast enhanced ultrasound (CEUS) is nowadays an established technique for many organs, as it allows, among other things, better detecting neoplastic lesions [14]. Furthermore, for their ability to highlight microcirculation, contrast agents are used in oncology in order to quantify the flow characteristics through an organ or tumor which differ according to the type of lesion and the organ involved [15][16][17][18][19]. The main clinically recognized application is the characterization of focal liver lesions [20]: CEUS with lowtransmit power insonation allows real-time assessment of contrast enhancement and vascularity of focal lesions during the different dynamic phases, after injection of an intravenous contrast agent.…”

“…Microbubbles are typically 5 micrometers in diameter, a similar size to red blood cells, and can therefore be transported into the smallest capillaries and across the lungs, thus allowing the visualization of the arterial system after venous injection. The pharmacokinetics of the microbubbles is quite different from that of contrast agents used for CT and MRI which generally diffuse in the interstitial space [15,16,23]. Second generation US contrast agents are clinically safe and well tolerated [24].…”

Crucial factors and emerging concepts in ultrasound-triggered drug delivery

“…Inertial cavitation can be useful in imaging, this to evaluate blood flow abnormalities by means of destruction replenishment imaging [6], but is particularly useful in drug delivery as it can trigger (a) release of drugs from the microbubbles and (b) uptake of the released drugs into the cells whose membranes become temporarily permeablized due to the localized mechanical effects related to microbubble implosion [7]. Since ultrasound is only applied at a certain location, time-and space-controlled drug delivery may become feasible.…”

Brain tumor surgery: supplemental intra-operative imaging techniques and future challenges

“…[51] The contrast agents containing microbubbles hit by low-acoustic power US waves resonate with a specific value that can be read by a US algorithm for contrast. [52,53] There is a good correlation between the preoperative MRI and iUS and can reach a small difference of 2 mm with the advantage of being intra-operative and dynamic [ Figure 4]. Nevertheless, neither iUS nor ICEUS can provide good borders for all LGG because of the similar echogenicity between the tumor and normal tissue.…”