Roy Carlson

High-intensity focused ultrasound (HIFU) multiple lesion imaging: comparison of detection algorithms for real-time treatment control

Imaging of HIFU-induced lesions provides non-invasive, real-time treatment monitoring and control. This work presents results obtained with HIFU-induced lesion detection algorithms specifically designed for multiple lesion detection. Algorithms sensitive to relative tissue changes during HIFU -measuring signal energy, tissue displacement, entropy, and tissue attenuation are compared for their ability to detect the creation of multiple and adjacent HIFU lesions. In vivo (N=4) canine prostate backscattered RF data was acquired with a custom Sonablate/spl reg/500 HIFU device during 7 treatments. A total of 815 sites were treated, forming the algorithm evaluation dataset. It was found that the algorithm based on signal energy performed best, detecting 82% of all HIFU lesions created, while showing false-alarm rates below 5%. All methods are completely non-invasive, and make use of tissue reference/normalization information obtained before, during, and after the HIFU treatment. Algorithm specifics, data acquisition methodologies, in vivo experimental results, and algorithm comparison results are shown.

The detection and exclusion of the prostate Neuro-Vascular Bundle (NVB) in automated HIFU treatment planning using a pulsed-wave doppler ultrasound system

Men with prostate cancer are likely to develop impotence after prostate cancer therapy if the treatment damages the neuro‐vascular bundles (NVB). The NVB are generally located at the periphery of the prostate gland. To preserve the NVB, a Doppler system is used to detect and localize the associated blood vessels. This information is used during the therapy planning procedure to avoid treatment surrounding the blood vessel areas. The Sonablate®500 (Focus Surgery, Inc.) image‐guided HIFU device is enhanced with a pulse‐wave multi‐gate Doppler system that uses the current imaging transducer and mechanical scanner to acquire Doppler data. Doppler detection is executed after the regular B‐mode images are acquired from the base to the apex of the prostate using parallel sector scans. The results are stored and rendered in 3‐D display, registered with additional models generated for the capsule, urethra, and rectal wall, and the B‐mode data and treatment plan itself. The display of the blood flow can be in 2‐D c...

Modeling prostate anatomy from multiple view TRUS images for image-guided HIFU therapy

Current planning methods for transrectal high-intensity focused ultrasound treatment of prostate cancer rely on manually defining treatment regions in 15-20 sector transrectal ultrasound (TRUS) images of the prostate. Although effective, it is desirable to reduce user interaction time by identifying functionally related anatomic structures (segmenting), then automatically laying out treatment sites using these structures as a guide. Accordingly, a method has been developed to effectively generate solid three-dimensional (3-D) models of the prostate, urethra, and rectal wall from boundary trace data. Modeling the urethra and rectal wall are straightforward, but modeling the prostate is more difficult and has received much attention in the literature. New results presented here are aimed at overcoming many of the limitations of previous approaches to modeling the prostate while using boundary traces obtained via manual tracing in as few as 5 sector and 3 linear images. The results presented here are based on a new type of surface, the Fourier ellipsoid, and the use of sector and linear TRUS images. Tissue-specific 3-D models will ultimately permit finer control of energy deposition and more selective destruction of cancerous regions while sparing critical neighboring structures.

Real‐Time Tissue Change Monitoring on the Sonablate® 500 during High Intensity Focused Ultrasound (HIFU) Treatment of Prostate Cancer

Sonablate® 500 (SB‐500) HIFU devices have been successfully used to treat prostate cancer non‐invasively. In addition, Visually Directed HIFU with the SB‐500 has demonstrated higher efficacy. Visually Directed HIFU works by displaying hyperechoic changes on the B‐mode ultrasound images. However, small changes in the grey‐scale images are not detectable by Visually Directed HIFU. To detect all tissue changes reliably, the SB‐500 was enhanced with quantitative, real‐time Tissue Change Monitoring (TCM) software. TCM uses pulse‐echo ultrasound backscattered RF signals in 2D to estimate changes in the tissue properties caused by HIFU. The RF signal energy difference is calculated in selected frequency bands (pre and post HIFU) for each treatment site. The results are overlaid on the real‐time ultrasound image in green, yellow and orange to represent low, medium and high degree of change in backscattered energy levels. The color mapping scheme was derived on measured temperature and backscattered RF signals fro...

Automated treatment planning for prostate cancer HIFU therapy

A framework for computer-assisted treatment planning for prostate cancer high intensity focused ultrasound (HIFU) treatments using 3D ultrasound images, user tracing, and 3D models of the prostate, urethra, and rectal wall was presented previously. This framework provides the input for the current research: the development of a general-purpose HIFU treatment planner module. This module is capable of automatically specifying the prostate HIFU treatment sites using given prostate anatomical information from 3D ultrasound images combined with information on HIFU probes, transducers, and elementary lesion parameters that are stored in a lesion library file. The output of the automatic planner module is a complete treatment plan that is executed after interactive physician review. Additional inputs to this module include clinically relevant parameters, such as inter-lesion spacing and treatment margins. Advantages of this approach include a reduction in the overall treatment time, the ability to easily and accurately plan treatments for complex prostate shapes, and the ability to adapt the planner to other systems and geometries simply by providing a different lesion library specific to that system. The automatic planner module has been integrated into the treatment software of the Sonablate 500 image-guided HIFU device (Focus Surgery, Inc). The entire treatment planning process is presented, highlighting the usefulness of the automatic planner module.

Real‐time tissue change monitoring during the treatment of prostate cancer using Sonablate 500 with high intensity focused ultrasound.

Tissue change monitoring (TCM) during HIFU is an essential required feedback during the HIFU treatment. The Sonablate 500 (SB500) HIFU is enhanced with quantitative, real‐time TCM software that estimate changes in tissue properties due to HIFU treatment of prostate cancer. TCM generates energy reading based on spectral analysis of the two‐dimensional rf backscattered ultrasound signals acquired during HIFU. These energy changes are correlated to tissue temperature. TCM results are overlaid on the real‐time ultrasound image in green, yellow, and orange to represent low, medium, and high degree of change in backscattered energy levels. To validate the TCM process five patients with histologically confirmed, organ confined prostate cancer were enrolled for the study. Needles containing three thermocouples were placed transperineally under TRUS guidance in the prostate to monitor temperatures from focal zone, posterior to the focal zone and on the lateral gland where no HIFU was applied. The measured temperat...

Design and in-vivo evaluation of next-generation laparoscopic HIFU kidney probe

Previously, we reported on the development and clinical evaluation of an ultrasound image-guided laparoscopic high-intensity focused ultrasound (HIFU) probe for kidney tumor ablation compatible with an 18mm trocar. Since then, the relentless march towards miniaturization of laparoscopic tools has led to the obsolescence of this trocar size, prompting a re-design of the probe to accommodate market realities and user expectations. Reducing the probe to be compatible with a 15mm trocar proved challenging, as simply scaling the existing design would have resulted in clinically unacceptable ablation performance.

MP100-14 HIGH INTENSITY FOCUSED ULTRASOUND KIDNEY ABLATION: PRE-CLINICAL SAFETY AND EFFICACY EVALUATION IN A PORCINE MODEL USING A 15MM LAPAROSCOPIC PROBE

INTRODUCTION AND OBJECTIVES: Irreversible Electroporation (IRE) is an emerging ablative modality for patients with renal tumors that are not candidates for surgery or conventional thermal ablation. This study aims to evaluate technical success, safety, and outcomes for IRE treated complicated renal tumors. METHODS: A single institution retrospective review of all renal tumors treatedwithComputed Tomography (CT) guided IREbetweenMay 2013 and February 2016 was performed. A total of 17 patients underwent IRE with NanoKnife (AngioDynamics, Queensbury, New York) for primary or secondary renal malignancies. Technical success was defined as delivery of all planned pulses during ablation and verifying complete ablation by immediatepost-procedureCT imaging. Local recurrencewasdefinedas residual enhancement or increased tumor size following technical success. Follow-up imaging was scheduled at 1, 3, 6, 12, 18, and 24 months. Complications were defined using Clavien-Dino (CD) classification. RESULTS: IRE was performed on 18 complicated renal tumors with median RENAL score of 6.5 ( 1st quartile 6, 3rd quartile 9) and median tumor size of 2.2 cm (1st quartile 2.0, 3rd quartile 3.1). Most were clear cell renal cell carcinomas (n1⁄413). Technical success was achieved in 17/18 tumor treatments (94.4%). One (5.6%) case was aborted due to bleeding (CD grade IIIb) requiring embolization. Minor CD grade one or two complications were present in 7/18 cases (38.9%), including post-procedural urinary retention (4/18, 22.2%), hypoglycemia (1/18, 5.6%), hematuria (1/18, 5.6%), and back pain (1/18, 5.6%). Patients lost to follow up were excluded (n1⁄43) from follow-up analysis. Median follow-up was 392 days, 1st quartile 203, 3rd quartile 696). Two local recurrences (14.2%) occurred on days 320 and 230 post-procedure with RENAL Scores of 9 and 8, respectively. Both cases were successfully treated with cryoablation and follow up showed no residual tumor at 723 and 617 days post cryoablation, respectively. CONCLUSIONS: IRE appears to be a safe and efficacious option for the treatment of renal tumors in patients that are not candidates for surgery or thermal ablation techniques. Further research is warranted with larger sample sizes and continued follow up.

Validation of tissue change monitoring (TCM) on the Sonablate® 500 during high intensity focused ultrasound (HIFU) treatment of prostate cancer with real-time thermometry

The Sonablate® 500 has quantitative, real-time Tissue Change Monitoring (TCM) software that estimates changes in tissue properties due to HIFU treatment of prostate cancer. This study validates the Sonablate 500 TCM system using real-time thermometry. Five patients with histologically confirmed, organ-confined prostate cancer were enrolled. Four patients with focal cancer had hemiablation and one had whole gland ablation. TCM generates energy reading based on spectral analysis on the RF backscattered ultrasound signals; results are used as an estimator of tissue temperature. Needle thermocouples were placed transperineally under TRUS guidance in the prostate to monitor temperatures from focal zone, posterior to the focal zone and on the lateral gland where no HIFU was applied. The HIFU treatments averaged 37, 35 and 19.7 Watts for the treatment for anterior, middle and posterior zones. The measured temperatures (Average, Max, and Min) in the HIFU treatment zones were 84, 114 and 70 degrees C. The temperat...