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HIGH INTENSITY FOCUSED ULTRASOUND

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A PRIMTIVE ANALOGY ADVANTAGES OF HIFU Non-Invasive Preserve tissue integrity Relatively Infection Free Non ... Imaging-guided Focused US Ablation of Breast ... – PowerPoint PPT presentation

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Title: HIGH INTENSITY FOCUSED ULTRASOUND


1
HIGH INTENSITY FOCUSED ULTRASOUND
  • CESO Conference
  • April 29, 2004
  • Jason Smale
  • Clinical Engineering Student,
  • University of Toronto

2
A PRIMTIVE ANALOGY
ANALOGY FROM Gail R. ter Haar, Royal Marsden
HospitalUnited Kingdom PICTURE FROM
http//wmuma.com/tracker/skills/fire/magnifier/
3
ADVANTAGES OF HIFU
  • Non-Invasive
  • Preserve tissue integrity
  • Relatively Infection Free
  • Non-Ionizing Treatment
  • Minimal or no anesthesia required
  • Shorter recovery period
  • Shorter treatment time
  • 10-15 sec/treatment point
  • 60-600 sec/treatment point for other hyperthermia
    treatments
  • laser, RF or water

4
LIMITATIONS OF HIFU
  • Controlling of the Focal Spot
  • Patient shift or tissue motion
  • Cannot adequately control shape, size or location
  • Beam dosimetry
  • Unknown tissue temperatures
  • Possibility of acoustic cavitation
  • Local tissue thermal conductivity and perfusion
  • Tissue specific
  • Patient specific (Skin thickness, proportion of
    fat and muscle)
  • Growth specific (Malignant, Benign, and Healthy)

5
SOLUTIONS?
  • Couple With Diagnostic Ultrasound
  • Can monitor focal point position
  • Could not measure tissue temperature
  • Couple With Diagnostic MRI
  • Easily monitor soft tissue focal point
  • Can calculate tissue temperature
  • Proton resonant frequency is dependent of
    temperature
  • Must use a MRI compatible focused ultrasound
    system

6
MR GUIDED HIFU SYSTEM
UPPER PICTURE SOURCE http//www.insightec.com LEF
T PICTURE SOURCE http//www.surgeons.org/asernip-
s/net-s/information/mri_guided_focused_ultrasound.
htm RIGHT PICTURE SOURCE MRI Guided Focused
Ultrasound Surgery of Fibroadenomas in the
Breast A Feasibility Study, Hynynen et al.
7
MR GUIDED TEMP CONTROL
UPPER PICTURE SOURCE http//www.dkfz-heidelberg.d
e/mrphys/temperature/temperature.html LEFT
PICTURE SOURCE MR Imagingguided Focused
Ultrasound Surgery of Uterine Leiomyomas A
Feasibility Study, Tempany et al. RIGHT PICTURE
SOURCE MRI Guided Focused Ultrasound Surgery of
Fibroadenomas in the Breast A Feasibility Study,
Hynynen et al.
8
HIFUS TREATMENT TREND
  • 1960s Proved to be an effective treatment for
    Parkinsons Disease
  • Outdone by L-Dopa treatment
  • 1980s and 90s Proved to be an effective eye
    treatment
  • Outdone by eye-laser treatment
  • 1990s and 2000s Tumor ablation treatment
  • Hoping to be outdone by a cure for cancer?

9
HIFUS TUMOR ABLATION EFFECTIVENESS
  • Proven effective treatment for prostate tumors
  • Uses a trans-rectal transducer
  • Investigations are being performed to test safety
    and efficacy
  • 9 centers are performing clinical investigations
    worldwide
  • Phase III Benign Fibroadenomas
  • Paper published Hynynen (BWH)
  • Phase III Benign Uterine Fibroids
  • Paper published by Tempany (BWH)
  • Phase II Breast Cancer
  • Paper published by Gianfelice (St. Luc)
  • General Investigation into Brain Tumor ablation
  • Investigations underway at BWH

10
IMPORTANT POINTS FROM RESEARCH
  • Patients are released same day
  • Some patients suffered from
  • Skin burns, Abdominal Blistering, Scar Tissue
    burns
  • Approximately 17 of patients received 2nd degree
    burns
  • Mild discomfort as tumor site for 24-36 hours
    following ablation
  • 30 patients rated pain more severe than mild
    discomfort

11
TRANS-SKULL HIFU
  • Problems with using HIFU on the brain
  • Heterogeneous thickness and density of the skull
  • Very diverse acoustic velocities of the skull and
    brain tissue
  • Impedance matching
  • Results in Signal attenuation, overheating of
    tissue near the skull and requires a high number
    of transducers
  • Uses CT instead of MR
  • Able to measure heterogeneous internal density of
    skull
  • The magic of time reversal
  • Virtual source sends acoustical wave from focal
    point and amplitude and delay are calculated at
    HIFU transducer points
  • Measured signal is sent into the brain to create
    focal point

12
HIFU EFFECTS ON THE CLINICAL ENGINEER
  • Future roll of MR Guided HIFU is relatively
    unknown
  • Similar to lasers The solution without a
    problem
  • Since reporting on Phase 3 trials for benign
    tumors, implementation might be just over the
    horizon for some of the larger hospitals
  • Its better to lead the technology trend than to
    follow it. A. Dolan, University of Toronto

13
REFERENCES
  • MR Imaging-guided Focused Ultrasound Surgery of
    Uterine Leiomyomas, Tempany et al., Radiology
    (226), March 2003
  • MR Imaging-guided Focused Ultrasound Surgery of
    Fibroadenomas in the Breast, Hynynen et al.,
    Radiology (219), April 2001
  • MR Imaging-guided Focused US Ablation of Breast
    Cancer Histopathologic Assessment of
    EffectivenessInitial Experience, Gianfelice et
    al., Radiology (227), June 2003
  • High Intensity Focused Ultrasound for the
    Treatment of Tumors, Ter Haar, Echocardiography,
    Volume 18, No. 4, May 2001
  • New and Emerging Techniques Surgical Procedure
    Brief MRI-Guided Focused Ultrasound for Uterine
    Fibroids, Royal Australasian College of Surgeons,
    August 2003
  • Tissue Thermal Conductivity by Magnetic Resonance
    Thermometry and Focused Ultrasound Heating, Cheng
    et al., JOURNAL OF MAGNETIC RESONANCE IMAGING
    (16), 2002
  • Experimental demonstration of noninvasive
    transskull adaptive focusing based on prior
    computed tomography scans, Aubry et al., Journal
    of Acoustical Society of America, January 2003
  • Poster MR Guided Focused Ultrasound Surgery, R.
    Newman, Vice President, InSightec TxSonics
  • InSightec Website www.insightec.com
  • In-vivo MR Temperature Monitoring of Focused
    Ultrasound (HIFU) in Rabbit Muscle, Rademaker et
    al., http//www.dkfz-heidelberg.de/mrphys/temperat
    ure/temperature.html
  • QUESTIONS OR COMMENTS jason.smale_at_utoronto.ca
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