Characterization of tumor vasculature distributions in central and peripheral regions based on Doppler ultrasound

Abstract

Although the tumor perfusion and vascular density estimates showed good temporal correlations during tumor progression, they did not show good spatial correlations due to tumor perfusion patterns changing from homogeneous to heterogeneous. In contrast to the perfusion patterns, the vascular density of the tumor remained uniformly distributed. In the present study, no necrosis regions were found in the tumor experiments. Furthermore, the measurement of γ value is a simple method for assessing the vasculatures of spatial distribution within tumors.

Skin-scanning technique for superficial blood flow imaging using a high-frequency ultrasound system

“…Approximately 10 6 cells in 100 lL of phosphate-buffered saline (pH 7.4) were injected subcutaneously into the lower limb of the mouse. Eleven days after inoculation, when the tumor reached about 8 mm in diameter, an ultrasound examination was performed; this time point was chosen since the tumor neovasculature is distributed more in the periphery and necrosis has not yet occurred [7]. The mouse was anesthetized with isoflurane gas at a dose of 1% in pure oxygen with a flow rate of 1 L/min, and the body temperature was maintained at 37 ± 1°C by a heating pad (model THM100, Indus Instruments, Houston, TX, USA).…”

“…The high-frequency ultrasound imaging system used in this study was developed previously in our laboratory [7,21,22]. Briefly, …”

“…During tumor progression the distribution of the neovasculature will spread more in the periphery than in the center of the tumor due to the higher interstitial fluid pressure within the tumor, even though necrosis has not yet occurred [4,5]. Therefore, evaluating the distribution of the neovasculature in peripheral regions of a tumor is helpful for assessing both drug delivery and prognosis [6,7].…”

“…In this technique the ultrasonic signals are continuously acquired from close intervals along each scanline in order to maintain a strong correlation between adjacent pairs of ultrasonic signals. An interval of 1-2 lm is usually adopted for estimating the blood flow rate and velocities in preclinical studies [7,10,[20][21][22].…”

High-frequency Ultrasound Imaging of Mouse Cervical Lymph Nodes

“…HFUS has been adapted for visualization of tumor formation in conventional brightness (B)-mode, as well as with a number of general and specialized contrast enhancement agents9. Using power Doppler with HFUS provides the ability to monitor blood flow within mouse tumors, allowing a comprehensive assessment of angiogenic perfusion in live mice 10,11 . HFUS has been used to visualize diseased mouse lymph nodes within the main body cavity, demonstrating parallel utility of this technology to clinical practice.…”