Biomedical Engineering Reference
In-Depth Information
endorectal FUS transducer and a MR image of the transducer for
prostate cancer treatment.
The other major components, such as the system control elec-
tronics, the operator's workstation, and the MR scanner, are
standard, similar to the ExAblate 2000 described previously.
the designated treatment effect. Posttreatment contrast imaging
can be used to confirm the treatment effect.
The system has been used for treating patients with brain
tumors through the intact skull (without a prior craniotomy
procedure), and it has been demonstrated that the treatment
is safe without skull heating (which might cause damage to
the brain surface). Based on these results, the FDA approved a
continuation of the study with emphasis on efficacy (McDonald
et al. 2010).
10.2.3 Exablate 4000 (Exablate Neuro
transcranial [tc]) MrgFUS System
The ExAblate 4000, later named the ExAblate Neuro, is a tran-
scranial (tc) MRgFUS system (InSightec Ltd., Tirat Carmel,
Israel). The system is currently under evaluation for clinical
safety and efficacy in functional neurosurgery and tumor abla-
tion, stroke, and targeted drug delivery. This system is designed
for treating diseases in the brain only.
A hemispherical, helmet-like, multi-element (4000 elements)
phased array transducer (Figure 10.6) enables focal targeting of
brain tissue through the intact cranium. The system is integrated
with a standard GE 1.5 T or 3 T MRI system using a detachable
treatment table. In the treatment room, the patient lies on the table
with his or her head immobilized in a stereotactic frame, with
the helmet-like transducer positioned around his or her head. A
sealed water system with an active cooling and degassing capacity
maintains the skull and skin surface at a comfortably low tem-
perature to protect intervening skin and skull from overheating.
A series of conventional MRI scans are displayed on the
ExAblate workstation and analyzed by the physician/physicist
to determine the targeted regions. Preoperative CT and inter-
operative MR scans can be fused for reconstructing a model
of the skull and brain anatomy used in treatment planning.
The treatment is based on multiple sonications that cover the
targeted volume. Sublethal focal spots can be used to confirm
target localization accuracy and patient comfort prior to ultra-
sound treatment via the measurement of temperature using MR.
During energy delivery to each spot, thermal images were used
for real-time feedback control of the treatment, allowing the
physician/physicist to adjust parameters accordingly to reach
10.3 Haifu Systems
Research and development of the Haifu systems began in
Chongqing, China, in 1988. After extensive ex vivo and in vivo
animal studies with the improvement of key techniques, a proto-
type of the ultrasound-guided extracorporeal HIFU system was
successfully developed for clinical trials in Chongqing Medical
University, China, in 1997. From December 1997 to October
2001, a total of 1038 patients with solid tumors were treated with
HIFU in 10 Chinese hospitals through clinical trials. The tumors
included primary and metastatic liver cancers, malignant bone
tumors, breast cancers, soft tissue sarcomas, kidney cancers,
pancreatic cancers, abdominal and pelvic malignant tumors,
uterine fibroids, and benign breast tumors. In addition, the
US-guided HIFU system (Model JC, Focused Ultrasound Tumor
Therapeutic System, Chongqing Haifu [HIFU] Technology
Company, Ltd., Chongqing, China) was approved by China's
SFDA (the national agency similar to the FDA in the United
States) in 1999, followed by CE mark in Europe in 2005. A sec-
ond HIFU system, as shown in Figure 10.7, the JC200 Focused
Ultrasound Tumor Therapeutic System, was approved by both
China's SFDA and CE in 2007. To date, both US-guided extra-
corporeal HIFU systems have treated large numbers of patients
in 15 countries, including China, Japan, Korea, the United
Kingdom, Italy, Spain, Russia, Romania, Ukraine, and Saudi
Arabia. The clinical results are promising and support the safety,
feasibility, and efficacy of HIFU therapy for solid tumors.
FIGURE 10.6 The ExAblate Neuro transcranial (tc) MRgFUS system.
(Courtesy of InsighTec, Inc.)
FIGURE 10.7 Model JC200 Focused Ultrasound Tumor Therapy
System (Chongqing Haifu).
Search WWH ::




Custom Search