Modeling and predicting tissue movement and deformation for high intensity focused ultrasound therapy

Purpose

In ultrasound-guided High Intensity Focused Ultrasound (HIFU) therapy, the target tissue (such as a tumor) often moves and/or deforms in response to an external force. This problem creates difficulties in treating patients and can lead to the destruction of normal tissue. In order to solve this problem, we present a novel method to model and predict the movement and deformation of the target tissue during ultrasound-guided HIFU therapy.

Methods

Our method computationally predicts the position of the target tissue under external force. This prediction allows appropriate adjustments in the focal region during the application of HIFU so that the treatment head is kept aligned with the diseased tissue through the course of therapy. To accomplish this goal, we utilize the cow tissue as the experimental target tissue to collect spatial sequences of ultrasound images using the HIFU equipment. A Geodesic Localized Chan-Vese (GLCV) model is developed to segment the target tissue images. A 3D target tissue model is built based on the segmented results. A versatile particle framework is constructed based on Smoothed Particle Hydrodynamics (SPH) to model the movement and deformation of the target tissue. Further, an iterative parameter estimation algorithm is utilized to determine the essential parameters of the versatile particle framework. Finally, the versatile particle framework with the determined parameters is used to estimate the movement and deformation of the target tissue.

Results

To validate our method, we compare the predicted contours with the ground truth contours. We found that the lowest, highest and average Dice Similarity Coefficient (DSC) values between predicted and ground truth contours were, respectively, 0.9615, 0.9770 and 0.9697.

Conclusion

Our experimental result indicates that the proposed method can effectively predict the dynamic contours of the moving and deforming tissue during ultrasound-guided HIFU therapy.

MR-guided focused ultrasound surgery, present and future

MR-guided focused ultrasound surgery (MRgFUS) is a quickly developing technology with potential applications across a spectrum of indications traditionally within the domain of radiation oncology. Especially for applications where focal treatment is the preferred technique (for example, radiosurgery), MRgFUS has the potential to be a disruptive technology that could shift traditional patterns of care. While currently cleared in the United States for the noninvasive treatment of uterine fibroids and bone metastases, a wide range of clinical trials are currently underway, and the number of publications describing advances in MRgFUS is increasing. However, for MRgFUS to make the transition from a research curiosity to a clinical standard of care, a variety of challenges, technical, financial, clinical, and practical, must be overcome. This installment of the Vision 20∕20 series examines the current status of MRgFUS, focusing on the hurdles the technology faces before it can cross over from a research technique to a standard fixture in the clinic. It then reviews current and near-term technical developments which may overcome these hurdles and allow MRgFUS to break through into clinical practice.

First experience of high-intensity focused ultrasound combined with transcatheter arterial embolization as local control for hepatoblastoma

The purpose of this study was to assess the effectiveness of high-intensity focused ultrasound (HIFU) combined with transarterial chemoembolization (TACE) in treating pediatric hepatoblastoma. Twelve patients with initially unresectable hepatoblastoma were enrolled in the study. All patients received chemotherapy, TACE, and HIFU ablation. Follow-up materials were obtained in all patients. The tumor response, survival rate, and complications were analyzed. Complete ablation was achieved in 10 patients (83.3%), and the alpha-fetoprotein level was also decreased to normal in these patients. The mean follow-up time was 13.3 ± 1.8 months (range, 2-25 months). At the end of follow-up, two patients died from tumor progression, the other 10 patients were alive. One patient was found to have lung metastasis after HIFU and had an operation to remove the lesion. The median survival time was 14 months, and the 1- and 2-year survival rates were 91.7% and 83.3%, respectively. Complications included fever, transient impairment of hepatic function, and mild malformation of ribs.

CONCLUSION

HIFU combined with TACE is a safe and promising method with a low rate of severe complications. As a noninvasive approach, it may provide a novel local therapy for patients with unresectable hepatoblastoma.