We demonstrate a method which incorporates state-of-the-art x-ray imaging with novel thermal therapy monitoring to enable improved minimally invasive thermal-therapy delivery for benign or malignant tumors. Thermal ablative techniques including RFA, microwave, and laser ablation are gaining acceptance. Incomplete treatments are common since there is no reliable method to monitor treatment zones during ablation. Treatment that doesn't encompass the entire tumor results in recurrence usually within one year. We describe a method to monitor tumor ablation zones during ablations performed under CT image guidance. This method allows the operator to predict necrosis while avoiding injury to critical structures. We validated the model using tissue and animal experiments. We also report on initial
clinical results from patients receiving RFA treatments for primary or metastatic lesions. Following CT image-guidance to position RFA devices in a patient's tumor, intraprocedural CT data was acquired and processed offline. In this paper we describe the methods to monitor and provide feedback on the ablation during the study. By demonstrating the creation of accurate thermal maps in tissue and animal models, and extending this in preliminary treatment of tumors in patients, we hope to encourage the broader adoption of these methods by improving both safety and efficacy.
In this paper, we discuss a unified theory for and performance evaluation of the ridge direction estimation through the minimization of the integral of the second directional derivative of the gray-level intensity function. The primary emphasis of this paper is on the ridge orientation estimation. The subsequent ridge detection can be performed using the traditional methods of using the zero crossing of the first directional derivative. The performance evaluation of the ridge orientation estimation is performed in terms of the mean orientation bias and orientation standard deviation given the true orientation and the same two measures given the noise standard deviation. We discuss two forms of our new ridge detector—first (ISDDRO-CN) using the noise covariance matrix estimation procedure under colored noise assumption, and the second (ISDDRO-WN) using the white noise assumption. ISDDRO-CN performs better than the ISDDRO-WN in the presence of strong correlated noise. When the noise levels are moderate it performs as well as ISDDRO-WN. ISDDRO-CN has superior noise sensitivity characteristics. We also compare both forms of our algorithm with the algorithm, Maximum Level Set Extrinsic Curvature (MLSEC) designed by A. López [IEEE Trans. Patter Anal. Mach. Intell. 21, 327–335 (1999)].
Arun Tirumalai, Lee Weng, Alexander Grassmann, Ming Li, Steve Marquis, Pat Sutcliffe, David Gustafson, Jin Kim, Chris Basoglu, Thomas Winter, Yongmin Kim
The narrow fields of view obtained from real-time ultrasound transducers, especially with linear array transducers, allow focused evaluation of a specific site but often without any anatomic reference. To allow medical ultrasound imaging to be used in more diverse clinical settings, we have created a new acquisition and display process that allows extended field of view (XFOV) imaging. To produce an XFOV image, extended acoustic slices are obtained by maneuvering the transducer along the body surface or inside. As the images are acquired, they are correlated, aligned, and spliced together into a long composite view, all without the use of a position sensor. This computationally intensive process involves image registration, geometric image transformation, panoramic image construction, and image display. The XFOV process executes in real-time on our programmable ultrasound processing subsystem, the programmable ultrasound image processor, which fits within an existing ultrasound system and supports native ultrasound signal and image processing.
We propose a scalable approach to ultrasound PACS. The general lack of any network interface capability on a large percentage of installed ultrasound scanners limits the solution available in the near term. A staged implementation beginning with a small number of ultrasound scanners interfaced to a single networked acquisition station is proposed. Initial mini-PACS may provide better utilization of the shared resources, such as archive and print servers and imagers, which would be cost prohibitive in a one-machine-per-scanner configuration. As the system requirements grow and ultrasound systems add direct network support, mini-PACS performances can overcome the initial single acquisition node bottleneck encountered with video-capture based systems, and ultrasound PACS can be integrated into a full hospital-wide PACS.
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