Biomedical Engineering Reference
In-Depth Information
Wang et al. [70] reported on an extended population of 15
patients that included seven patients with lesions in the head
of the pancreas. Thirteen of the 15 patients had pain associated
with the cancer prior to treatment. Pain was fully alleviated in 11
patients and partly alleviated in the other two after HIFU treat-
ment. Using a USgHIFU device, Orsi et al.
[113] treated seven
patients with unresectable pancreatic cancer. All seven patients
were almost completely palliated in symptoms in 24 h after
treatment. The median survival time was 11 months. MDCT or
MRI performed 24 h after treatment did not detect any injury of
the surrounding organs. Portal vein thrombosis was observed in
one patient who was discharged 20 days later.
Recently, Wang
et al.
[143] published the clinical result of
using HIFU for treating 40 patients with advanced pancreatic
cancer, including 13 patients with stage III, and 27 patients with
stage IV. Pain relief was achieved in 87.5% of the patients, and
median pain relief time was 10 weeks. The median overall sur-
vival time was eight months in all patients, with 10 months in
stage III patients and six months in stage IV patients. Six- and
12-months survival rates were 58.8% and 30.1%, respectively.
HIFU was also combined with gemcitabine to treat 37 patients
with locally advanced pancreatic cancer [144]. The median
follow-up period was 16.5 months (range: 8.0-28.5 months).
Abdominal pain was relieved in 22 patients (78.6%) after HIFU
treatment. The overall therapeutic response rate was 43.6%,
including two cases with complete response and 15 cases with
partial response. The median time to progression and overall
survival were 8.4 months and 12.6 months, respectively. The
estimates of overall survival at 12 and 24 months were 50.6%
and 17.1%, respectively.
HIFU in the clinical management of solid malignancies. These
common and serious problems affect many thousands of people
every year and if HIFU can offer an option to even a small pro-
portion of these patients then it is vital to continue pushing the
technology forward. HIFU provides a noninvasive therapeutic
option that once perfected will add a useful extra string to the
cl i nicia n's bow.
However, until now, HIFU therapy for solid malignancies
has been mostly conducted in research settings for the assess-
ment of technical safety, efficacy, and feasibility, and a few of
those described herein have been used alone in clinical practice.
Where clinically appropriate, HIFU should give at least the same
results as surgical excision, with the extent of the negative sur-
gical margins being determined by imaging. Although recent
results have been very encouraging, multiple-central, long-term
follow-up trials are essential to evaluate the long-term efficacy
and cost-effectiveness of HIFU treatments in cancer. Not until
these issues have been resolved, and the results from prospec-
tive, randomized clinical trials worldwide become available, can
this noninvasive ablative technique be considered as a candidate
for conventional therapy for widespread clinical applications.
Similar to surgical removal, the goal of thermal ablation is
to eliminate a targeted cancer, which includes the cancer with a
margin of normal tissue. As the targeted tissue is destroyed and
left in place to be resorbed, using imaging techniques to iden-
tify the margin of a unifocal tumor and adjacent microsatellites
is more important in thermal ablation than surgery. With no
detailed pathology of the ablated tissue, the need for accurate
pre-ablation assessment of the extent of cancer is essential, par-
ticularly in core biopsy for histological evaluation.
HIFU technology continues to develop. Much supplementary
investigation is necessary to further evaluate the HIFU treatment
plans, the relationship between HIFU dosage and the extent of
coagulation necrosis, and factors that can influence focused
ultrasound energy deposition in target tissue including tissue
structure, movement, function, and perfusion. For instance, in
our animal studies, it has been indicated that when mechanical
and pharmacological means were used to manipulate tissue per-
fusion, perfusion-mediated tissue cooling could directly affect
the shape and size of tissue necrosis induced by HIFU ablation.
On the basis of these important findings, it seems that reduced
tissue perfusion causes an increase in the volume of coagulation
necrosis. Therefore, a better understanding of perfusion effects
and a new method of controlling its cooling forces are essential
to improve results.
Beyond optimization of technical and physiological param-
eters, it is clear that HIFU ablation should be undertaken when
there is precise knowledge not only of the number and location
of the lesions but also of the biological characteristics and natural
history of the tumor. The goal of tumor therapy is that all cancer
cells should be completely killed in the patient's body. For patients
with cancer, the therapeutic strategy for the disease should be a
multiple treatment plan, which includes local treatments such
as surgery and radiotherapy, and systemic therapy such as che-
motherapy and immunotherapy. A similar multidisciplinary
15.7.8 HIFU therapy for Soft tissue Sarcoma
From December 1997 to October 2001, a total of 77 patients with
soft tissue sarcoma received HIFU treatment in China [145].
Most
of the patients had recurrent soft tissue sarcoma after surgery.
Among them, 18 patients were treated with HIFU in Chongqing,
China. Before treatment, pathological examination showed lipo-
sarcoma in six patients, synovial sarcoma in two, fibrosarcoma in
two, malignant peripheral nerve sheath tumor in two, and other
soft tissue sarcomas in five. The tumor size ranged from 5.5 to 16
cm in diameter (mean 8.6 cm), and follow-up time varied from
11 to 39 months (median 21 months). After HIFU treatment,
contrast-enhanced MRI showed the complete ablation of the tar-
geted tumor. Of the total, 16 patients are still alive (survival rate,
90%), and two patients died of metastasis after HIFU treatment.
Three patients had local recurrence and then underwent a second
HIFU treatment for the purpose of control.
15.8 Conclusions
HIFU ablation has been shown to be technically feasible and
effective for the treatment of solid malignancies. It may offer
complete ablation of cancer, with less morbidity, less damage,
lower cost, and shorter hospital stay. There is clearly a place for
