Thuroff.qxp 25/9/08 10:32 am Page 29
Prostate Cancer High-intensity Focused Ultrasound
Local Therapy of Prostate Cancer with High-intensity Focused Ultrasound
Using Ablatherm
®
Integrated Imaging
a report by
Christian G Chaussy
1
and Stefan Thüroff
2
1. Professor of Urology, University of Munich, and Chairman, Department of Urology, Harlaching Clinic;
2. Vice Chairman, Department of Urology, Harlaching Clinic
It has been known for decades that high-intensity focused ultrasound larger tissue volumes, in the future phased-array transducers may be
(HIFU) enables the destruction of tissue from a distance; however, in used to move the focal area without the need for mechanical
its early stages the technique did not find any clinical application movement of the transducer. The main criteria for treatment are
because of the lack of a suitable imaging system to monitor the acoustic intensity, duration of the impulse and the interval between
procedure. Nowadays, ultrasound and magnetic resonance imaging the impulses. In order to determine the ultrasound parameters for a
(MRI) allow the treatment to be carried out under realtime control. As specific therapeutic application, in vitro and in vivo experiments and
a result, HIFU has begun to be used in many surgical fields as a non- computer simulations have been performed.
5–10
Other ultrasound-
invasive extracorporeal method for the destruction of deep tissues, based techniques, such as contrast-enhanced power Doppler, as well
allowing ablation without incision. The increasing number of studies as various other techniques for characterisation of the acoustic tissue
and publications has led to gradual validation and acceptance of properties have been proposed for localisation and guidance of the
transrectal HIFU therapy for prostate cancer. There are also many therapy and to assess the extent of HIFU-induced lesions.
11–14
ongoing studies into the use of HIFU in other benign and malignant
tumours, such as kidney cancer, breast cancer, liver cancer, thyroid Results
nodules, fibroids of the uterus, brain tumours and glaucoma.
Experimental
Materials and Methods The destruction of tissue has been examined in various experimental
As early as 1942, intensive focused ultrasound was introduced for local tumour models. In vivo experiments on the effects of HIFU on tumour
tissue destruction.
1
When high-energy ultrasound is focused on tissue, tissue have been performed in murine glioma,
15
hamster
it causes a mechanical alteration of the cells and initiates changes medulloblastoma
16
and rat Morris hepatoma.
17,18
For prostate cancer
within biological structures. The destruction of tissue is mainly due to experimental models, DUNNING R3327 cell lines implanted in rats and
mechanical, thermal and cavitation effects. The thermal effect is
caused by the absorption of ultrasound energy as it passes through
Christian G Chaussy is a Professor of Urology at the
tissue. The grade of thermal coagulation depends on the absorption
University of Munich and Chairman of the Department of
co-efficient of the tissue and the size, shape and thermal response of Urology at the University-associated Harlaching Clinic. In
the heated region. The biological changes induced by heating are
1975 he initiated pre-clinical and clinical research into
extracorporeal shock-wave lithotripsy at the Institute for
determined by the temperature reached and the duration of the
Surgical Research at the University of Munich, and in 1980
exposure. With thermal doses above a certain threshold, irreversible
was the first person in the world to use this technique on a
patient. In 1996 he introduced high-intensity focused
tissue damage is induced, causing coagulation necrosis. For thermal
ultrasound for the treatment of localised prostate cancer,
doses below the threshold, the effects depend on the sensitivity of the and has since treated 2,000 patients – the highest figure worldwide. Professor Chaussy has
tissue to heat.
2
The generated ultrasound has a very high intensity in
received many awards and honorary memberships of various national and international
surgical and urological societies, including an Honorary Fellowship of the Royal College of
the focal area, whereas the impact on the surrounding tissue is only
Surgeons, Edinburgh and the Lifetime Achievement Award from the Endourological Society.
marginal. Focused ultrasound waves can cause large temperature rises
He is a member of several medical societies and international committees and President of
(70–100°C) within a few seconds, destroying a well-defined area of
the German Lithotripsy Society.
the tissue. The tissue volume destroyed by a single ultrasound impulse
E: CHAU1@aol.com
is known as the ‘primary lesion’. To destroy large lesions, multiple
Stefan Thüroff is Vice Chairman of the Department of
primary lesions have to be made side by side by mechanically moving
Urology at the Harlaching Clinic, a position he has held
the transducer or by electronically positioning the focal point if a
since 2001. His research activities are mainly in lithotripsy
phased array is available.
2–4
and renal cancer, and he supervises extracorporeal shock-
wave lithotripsy (ESWL) treatments at the clinic. His main
research interest is high-intensity focused ultrasound
Several parameters are essential for the development of a HIFU system
(HIFU). Dr Thüroff leads national and international training
courses in ESWL and HIFU, and since 2006 has been
for a specific application. The most important criteria are selection of
teaching courses for the European School of Urology. He is
the transducer, sonication parameters and imaging guidance. The a member of several national and international societies, as well as the European School of
therapeutic transducer is defined by its operating frequency, geometry
Urology. His academic work includes nine videos and more than 130 posters, oral
presentations, articles and book chapters. In 2000 he received, together with Professor
and physical dimensions. Piezoelectric systems can operate at various
Chaussy, the Bavarian Hospital Development Award. Dr Thüroff studied medicine at the
power densities with different reproducibility and long-term stability
Universities of Pisa, Aachen and Heidelberg.
according to therapeutic needs. While current urological HIFU
E: urologie@khmh.de
applications use mechanical single-focus transducers in order to treat
© TOUCH BRIEFINGS 2008 29