Thoracic Imaging 2003 - Society of Thoracic Radiology

epositioned until all the tumor area has been treated.
The extent of the heat induced tissue damage is about
3 cm; therefore, the electrode must be repositioned
more than once for any lesion larger than 1.5 cm so
that a satisfactory margin is achieved.
The needle electrode is advanced into the lesion using
either a single needle puncture method or via a coaxial
system. There are 3 major vendors who produce
RFA equipment and each has a slightly different needle
electrode configuration. Irrespective of the equipment
vendor, once the needle electrode is confirmed
to be satisfactorily positioned by imaging, the generator
is turned on and energy is applied. One vendor
allows periprocedural monitoring by indicating the
temperature at the needle tip. Other vendors permit
periprocedural monitoring by measuring the delivery
of energy into tissue as watts. The body core temperature
of the patient is monitored during the procedure.
During prolonged procedures rises in core body temperature
may cause sweating which can result in
grounding pad detachment, therefore the pads should
be regularly checked to avoid burns.
G. Follow-up imaging recommendations:
Chest radiographs are obtained, at 1 and 2 hours following
the procedure, and again on the morning of
the day after the procedure. The majority of patients
leave hospital the day following the procedure.
Further follow-up imaging can be obtained with CT
and/or PET imaging. A baseline study can be
obtained at 1 month. Then further follow-up imaging
at 3 monthly intervals initially, gradually lengthening
the interval to annual surveillance examinations.
Results:
Overall, RFA for the treatment of primary and secondary
malignancies in the chest is a safe technique. Complication
rates are less than with conventional surgery. Reported adverse
effects include
• Pleural effusions occur in up to 30% of patients.
About half of these will require catheter drainage or
needle thoracocentesis.
• COPD exacerbation; IPF exacerbation has also been
reported.
• Bronchopleural fistula.
• Pulmonary embolism.
• Mental status changes (reversible) have been reported,
possibly due to an embolic phenomenon.
• Hemorrhage – rates are similar to percutaneous needle
biopsy of lung nodules. While perilesional hemorrhage
is commonly identified on post-procedural
CTs, the rate of symptomatic bleeding is considerably
less, and severe hemoptysis is rare.
• Pneumothorax – while small pneumothoraces are
common, those requiring treatment is similar to the
rate is no higher than that seen with percutaneous
needle biopsy of lung nodules.
• Pain – some patients experience pain, possibly due to
a tumor destruction syndrome. It is managed similar
to post-embolization syndrome with liberal use of
analgesic agents.
• Subcutaneous emphysema.
Early results indicate that RFA is highly effective in treating
bronchogenic carcinoma. 1-year survival rates greater than 70%
have been reported. 3-year survival rates exceed 50% in some
series. This compares very favorably with other conventional
treatment modalities. As RFA is a relatively new technique, long
term outcome data is not yet available. Failures of local treatment
occur more commonly with mediastinal and perihilar
lesions where the ‘heat sink’ effect may operate. Success rates
are higher with more peripheral lesions. RFA is a safe and
effective management tool for controlling patients with more
advanced primary bronchogenic cancer. It is also an effective
palliative technique in treating pulmonary metastatic disease.
Future directions:
RFA technology is rapidly improving and newer, more powerful
delivery systems will allow the treatment of larger lesions.
RFA may be synergistic with other treatments and combination
therapies may prove superior to any single method.
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