AJR 2004; 182:990-992
© American Roentgen Ray Society
Acute Cerebral Infarction After Radiofrequency Ablation of an Atypical Carcinoid Pulmonary Tumor
Gong Yong Jin1,
Jeong Min Lee2,
Yong Chul Lee3 and
Young Min Han1
1 Department of Diagnostic Radiology, Chonbuk National University Hospital,
Chonju, Chonbuk 561-712, South Korea.
2 Department of Radiology, Seoul National University Hospital, 28 Yongon-Dong,
Chongno-Gu, Seoul 110-744, South Korea.
3 Department of Internal Medicine, Chonbuk National University Hospital, Chonju,
Chonbuk 561-712, South Korea.
Received March 10, 2003;
accepted after revision September 2, 2003.
Address correspondence to J. M. Lee
(leejm{at}radcom.snu.ac.kr).
Introduction
Radiofrequency ablation has been used to treat patients with lung
malignancies [1]. Although
complications have been reported during these radiofrequency ablations, most
were minor ones such as pleural effusion, pneumothorax, and self-limited
hemoptysis
[1–6].
We report our experience with a major complication: acute cerebral infarction
after radiofrequency ablation of an atypical carcinoid tumor.
Case Report
A 69-year-old woman presented with a nonproductive cough of 1-month
duration. Her medical history was significant for diabetes mellitus of 2-years
duration. Physical examination and laboratory findings indicated no
abnormalities. Chest radiography showed a 4 x 4 cm ill-defined round
radiopacity in the right lower lobe of the lung. Unenhanced CT showed a 4
x 4 cm irregular round homogeneous mass in the right lower lobe of the
lung, and contrast-enhanced CT showed heterogeneous enhancement of the mass
(Fig. 1A). We performed a
percutaneous needle biopsy that confirmed the tumor to be an atypical
carcinoid tumor. On several occasions we recommended that the patient undergo
surgery; however, she and her family strongly objected because of her age,
history of diabetes mellitus, and their fear of possible complications after
surgery. Therefore, radiofrequency ablation treatment was recommended as an
alternative therapy.
After instillation of 1% lidocaine, a 17-gauge internally cooled tip
radiofrequency electrode (Cool-tip, Radionics) with a 3-cm tip was inserted
into the lesion (Fig. 1B) and
was connected to a 200-W radiofrequency generator (CC1, Radionics).
Radiofrequency was applied with maximum allowable output (120–140 W) for
6–12 min per treatment
[3]. To achieve complete tumor
necrosis with radiofrequency ablation, we created multiple overlapping
ablations with three changes of tip position within the mass. After ablation,
the electrode was withdrawn without cauterizing the probe track. After the
radiofrequency electrode was removed, we recommended that the patient change
from the prone position to the supine position. At this point, the patient
inadvertently raised her head. She immediately experienced slurred speech and
showed left hemiparesis with hyperreflexia. We immediately performed brain CT
but noted no distinctive findings of cerebral infarction or hemorrhage.
However, at neurologic examination, she had a depressed mental status, left
hemifacial palsy, motor weakness to the left arm and leg (grade III), and gait
disturbance. Therefore, we thought that a cerebral infarct might have
occurred. A hyperintense area was also noted in the right middle cerebral
artery on T2-weighted MR images obtained 12 hr after radiofrequency ablation
(Fig. 1C). The patient received
a 1-week systemic treatment with heparin sodium. After the treatment for
cerebral infarction, her depressed mental status and left hemifacial palsy
completely disappeared and her motor weakness improved mildly (grade II).
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Fig. 1B. —69-year-old woman with atypical carcinoid tumor in right
lower lobe of lung. Unenhanced CT scan obtained during radiofrequency ablation
shows that 17-gauge single radiofrequency electrode (arrow) was
placed in mass.
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Fig. 1C. —69-year-old woman with atypical carcinoid tumor in right
lower lobe of lung. T2-weighted MR image obtained after radiofrequency
ablation shows ill-defined high signal intensity and effacement of sulci
(arrows) in right posterior parietal lobe.
|
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Two months after the radiofrequency ablation, contrast-enhanced CT showed a
change in configuration, a decrease in the size of the treated tumor, and
right pleural thickening. On the follow-up CT examination performed using
mediastinal window setting (Fig.
1D) 9 months after radiofrequency thermal therapy, no growth of
the atypical carcinoid tumor was apparent and the right pleural thickening had
completely disappeared. Fibrotic change rather than tumor appeared on the
images using the lung window settings. Nine months after initial ablation, the
patient still had motor weakness (grade II) of the left upper extremity
only.
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Fig. 1D. —69-year-old woman with atypical carcinoid tumor in right
lower lobe of lung. Contrast-enhanced CT scan using mediastinal window setting
obtained at 9-month follow-up shows that size of previously identified
atypical carcinoid tumor (arrows) in right lower lobe has
significantly decreased.
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Discussion
Percutaneous radiofrequency ablation has received much attention as an
effective minimally invasive approach for the treatment of a variety of
malignant neoplasms, especially for primary and secondary lung malignancies
[1,
4–6].
Despite promising early results for the treatment of liver malignancies,
radiofrequency ablation for treatment of lung malignancy has been investigated
by few researchers
[2–6].
Previous studies [2,
3] showed that radiofrequency
ablation for treating lung VX2 tumor in rabbits was feasible, and some
researchers
[4–6]
reported successful application of radiofrequency ablation for patients with
primary lung malignancy or metastasis. Although no reports of neurologic
complications during radiofrequency ablation of lung malignancies have
surfaced, Rose et al. [7]
reported that flow of microemboli to cerebral circulation occurred during
radiofrequency ablation of lung tumors.
Radiofrequency ablation could be used as a minimally invasive alternative
to surgery for patients with a small lung malignancy. From May 2000 to July
2003 at our institution, 45 patients with pulmonary malignancies underwent
transthoracic radiofrequency ablation under CT guidance. A few patients in our
clinical application of radiofrequency ablation for lung tumors developed
significant pneumothorax or hemoptysis, as in other reports
[4–6],
but acute cerebral infarction occurred in only one patient (1/45, 2.2%).
However, the incidence of cerebral infarction is rare, and no report of
cerebral infarction related to radiofrequency ablation in cases of lung
radiofrequency ablation has been presented at international meetings or in
published articles [1,
4–6].
Cerebral air embolism is recognized as a complication of diagnostic and
therapeutic procedures of the lung, including lung fine-needle aspiration and
biopsy [8].
In our case, although we were unable to determine the definitive cause of
our patient's cerebral infarction, we suspect that it might have been caused
by microbubbles because the cerebral infarction occurred immediately after
completion of the radiofrequency ablation. We speculate that because of injury
to the pulmonary vasculature around an atypical carcinoid tumor, a microbubble
passed from the pulmonary vein into the cardiac chambers during radiofrequency
ablation. After the patient was placed in the upright position, the gas bubble
was mobilized into the aorta and subsequently into the great vessels,
resulting in an embolic event.
On the basis of previous experience of radiofrequency ablation in other
organs [4], imaging-guided
radiofrequency thermal ablation for lung malignancies has some advantages in
that it can be used for repeated treatment, can shorten the patient's hospital
stay, and is associated with lower morbidity and mortality rates compared with
surgical techniques. However, additional studies to investigate the safety
issues of radiofrequency ablation in the lung are warranted because of the
possible risk of acute cerebral infarction, in spite of that risk seeming very
low.
Acknowledgments
We thank Bonnie Hami, department of radiology, University Hospitals of
Cleveland, for her editorial assistance in the preparation of this
manuscript.
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Introduction
Case Report
