An efficient temperature estimation using optical-flow in ultrasound B-mode digital images

Abstract

A two-dimensional temperature estimation method has been proposed based on the detection of shifts in speckle pattern location of ultrasound B-Mode digital images from a region of tissue undergoing thermal therapy. The speckle pattern shifts were due to the local temperature dependence of sound speed and thermal expansion in the heated region. Here in this paper we made use of optical-flow in order to achieve a better accuracy and lower computational burden. The accuracy of measurement of the temperature has been tested on simulated images and it is experimentally validated using tissue mimicking phantom. Good agreement was obtained from the simulated sequences (mean difference=0.1 and pick error was 0.6). The proposed method was found computationally faster compared to our previous work which was based on the cross correlation algorithm.

Thermometry and ablation monitoring with ultrasound

“…In later work, Mehrabani et al utilized the Horn-Shunck method for visualizing optical flow to estimate the speckle displacement (76). Their B-mode ultrasound thermometry technique was ultimately tested in a sheep model where occlusion of the renal segmental artery led to a decreased renal lobular temperature (77).…”

In Vivo Noninvasive Temperature Measurement by B-Mode Ultrasound Imaging

“…A preliminary study indicates improved accuracy and a shortened computational time when optical flow, as opposed to cross-correlation, is used to track speckle displacement. 37 The use of a high-sensitivity thermocouple array, rather than a single thermocouple, would contribute to optimization of the tracking algorithm by evaluating the spatial accuracy of temperature change estimation. In addition, more systematic characterization of the material-dependent parameters of various tissue types would promote the applica-tion of this velocimetric image-processing approach to an increased number of clinical scenarios.…”

Optical Flow-Based Tracking of Needles and Needle-Tip Localization Using Circular Hough Transform in Ultrasound Images

“…This algorithm is advantageous since it is computationally efficient, and can run on a CPU. Optical flow algorithm has been previously used for temperature estimation in ultrasound images [19], estimation of muscle thickness during contraction [20], and myocardial strain analysis [21] to name a few. While the optical flow algorithm has been applied in other applications, to the best of our knowledge, this is the first time the optical flow algorithm is applied to ultrasound images to track the features of a needle.…”