Effects of Temperature Change and Tissue Denaturation on the Texture of the Ultrasonic Nakagami Image

Project: National Science and Technology CouncilNational Science and Technology Council Academic Grants

Project Details

Abstract

Many clinical trials have shown significant improvement in treatment of cancer by combining conventional chemotherapy with hyperthermia. A successful tissue ablation by hyperthermia is dependent on temperature monitoring to assure an accurate thermal dose. Ultrasound is preferred over other imaging modalities for its low cost, non-ionizing radiation, non-invasiveness, and real-time capability. Currently, methods for using ultrasound as a noninvasive thermometer are mainly based on three types of measures, including attenuation coefficient, echo shift, and the change in the backscattered energy. Recently, it was found that the change in temperature produces medium contraction/expansion, which would cause variations in the relative position of scatterers to alter the backscattered waveform and the corresponding speckle pattern in the B-mode image. This interesting phenomenon provides a new point of view to develop ultrasonic methods to monitor the temperature distribution in a tissue. The recently proposed ultrasonic Nakagami image based on analyzing the probability density function of the backscattered envelopes has been demonstrated to be a pulse echo system-based functional ultrasound image to characterize the speckle pattern for quantifying the arrangements of scatterers in a tissue. Compared to the conventional texture analysis, the Nakagami image better reflects the scatterer properties and is less system-dependent because its construction is based on the ultrasound raw data. In this research project, we would like to study the temperature effects on the Nakagami image for well understanding the behaviors of ultrasonic backscattering, scatterer arrangements, and the speckle pattern with the variation in temperature. The objectives of this project are described as follows: (1) At the beginning, we would build up an ultrasound B-scan imaging system able to output the raw ultrasound data for constructing the B-mode and Nakagami images. (2) We will carry out phantom experiments to explore the relationship between the textures of the Nakagami image and the phantom temperature. Moreover, we will also study the effects of ultrasound frequency and scatterer concentration on the curve of the Nakagami parameter as a function of temperature. (3) Tissue scanning in vitro will be performed to investigate the relationship between temperature, tissue denaturation, and the Nakagami image textures. According to the behaviors of the Nakagami curve as a function of temperature, some appropriate mathematic functions will be used for curve fitting to explore the feasibility of using the Nakagami image to point out the watershed of tissue destruction during the process of increasing temperature. We expect to contribute two journal papers and one patent application in this research project.

Project IDs

Project ID:PB9912-1007
External Project ID:NSC99-2218-E182-009
StatusFinished
Effective start/end date01/12/1031/10/11

Keywords

  • Ultrasound temperature imaging
  • Nakagami distribution
  • backscatter statistics

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