DOI:10.2214/AJR.04.1220
AJR 2005; 185:890-893
© American Roentgen Ray Society
Radiofrequency Ablation Combined with CO2 Injection for Treatment of Retroperitoneal Tumor: Protecting Surrounding Organs Against Thermal Injury
Shuji Kariya1,
Noboru Tanigawa1,
Hiroyuki Kojima1,
Atsushi Komemushi1,
Yuzo Shomura1,
Yasuhiro Ueno1,
Tomokuni Shiraishi2 and
Satoshi Sawada1
1 Department of Radiology, Kansai Medical University, 10-15 Fumizono, Moriguchi,
Osaka, Japan 570-8507.
2 Department of Radiology, Ishikiri Seiki Hospital, Osaka, Japan 579-8026.
Received August 2, 2004;
accepted after revision December 7, 2004.
Address correspondence to S. Kariya
(shuuji{at}ops.dti.ne.jp).
Abstract
OBJECTIVE. The objective of this study was to separate target tumors
from adjacent structures by injecting carbon dioxide (CO2) around
the tumor to avoid thermal injury and the heat-sink effect from the blood
vessel during percutaneous radiofrequency ablation.
CONCLUSION. We successfully achieved complete ablation of a
retroperitoneal tumor without thermal injury. Imaging-guided percutaneous
CO2 injection is useful for preventing thermal injury while
achieving complete ablation of the tumor during radiofrequency ablation.
Introduction
Radiofrequency ablation is a minimally invasive treatment for renal and
adrenal tumors [1]. However,
treatment of renal or adrenal tumors adjacent to the pancreas, digestive
tract, or spleen risks thermal injury to these adjacent structures. The
indications for radiofrequency ablation are thus limited. In such cases,
attempts have been made to inject sterile water or air between the tumor and
adjacent structures
[2-3].
We successfully performed radiofrequency ablation after percutaneous injection
of carbon dioxide (CO2) around the target tumor to physically
separate the tumor from adjacent structures and allow ablation of the tumor,
including the margin, without causing thermal injury to any adjacent
structures.
Subjects and Methods
Written informed consent was obtained from all patients. Treatment was
performed on an in-patient basis. The procedure was performed using conscious
sedation (hydroxyzine and morphine hydrochloride) with local anesthesia in all
patients.
Case 1
A 62-year-old man presented with a metastatic left adrenal tumor
originating from primary lung cancer. Right lower lobectomy had been performed
1 year earlier to treat primary pulmonary adenocarcinoma, but brain and
intrapulmonary metastases were confirmed 10 months after surgery. A cerebral
metastasis of 2-cm diameter in the frontal lobe was treated by external
radiation therapy, and no recurrence was identified. A 3-cm diameter pulmonary
metastasis in the right upper lung was treated by external radiation therapy,
and tumor control was achieved without an increase in tumor size.
Around this time, a 55 x 38 mm left adrenal tumor was detected on CT.
Sonography-guided needle biopsy revealed the tumor as metastasis from the
primary lung cancer. The adrenal tumor was adjacent to the stomach on the
superior side; the splenic vein, splenic artery, and pancreas on the ventral
side; and the spleen on the left side (Fig.
1A). A risk of thermal injury to adjacent structures was
considered present, and the heat-sink effect of the splenic vein and artery
might have resulted in unsuccessful ablation of the target tumor. Carbon
dioxide (CO2) was therefore injected into the perirenal space to
separate the tumor from adjacent structures. CO2 was insufflated by
hand injection; no insufflator was used.
View larger version (145K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A —62-year-old man with metastatic adrenal tumor originating
from primary lung cancer. Preoperative unenhanced CT image shows left adrenal
gland swollen (black arrow) and adjacent to splenic vein (white
arrow) and pancreas.
|
|
The patient was placed in a prone position, and radiofrequency ablation was
performed. CO2 was injected using a 20-gauge, 15-cm PTCD needle
(Medikit), comprising an outer Teflon (Dupont) cannula and an inner stainless
steel needle. The needle tip was placed in the perirenal space on the dorsal
side of the target tumor under sonographic guidance, and 400 mL of
CO2 was injected. The CO2 diffused into the perirenal
space and separated the tumor from adjacent structures
(Fig. 1B).
View larger version (155K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B —62-year-old man with metastatic adrenal tumor originating
from primary lung cancer. Intraoperative unenhanced CT image (prone position)
after injection of 400 mL CO2 (asterisks) into perirenal
space shows left adrenal gland physically separated from splenic vein and
pancreas. In left adrenal gland, 3-cm single-tip active electrode (black
arrowhead) is seen.
|
|
Thermal ablation was completed in 22 min using a 3-cm single-tip active
electrode attached to the Cool-tip radiofrequency system (Radionics). During
ablation, CT was performed every 5 min to confirm sufficient separation
between the tumor and adjacent structures. When separation was insufficient,
more CO2 was injected. An additional 700 mL of CO2 was
injected during ablation, with 100, 200, 200, and 200 mL of CO2
injected at 5, 10, 15, and 20 min after starting ablation, respectively. A
total of 1,100 mL of CO2 was thus used. Contrast-enhanced CT was
performed 2 days after ablation, confirming complete ablation of the tumor
without any evidence of damage to adjacent structures (Figs.
1C and
1D). Most of the CO2
was absorbed, and only minute amounts of gas remained.
View larger version (143K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C —62-year-old man with metastatic adrenal tumor originating
from primary lung cancer. Contrast-enhanced CT performed 2 days after ablation
shows no enhancement in left adrenal gland (black arrow) or area of
left adrenal gland adjacent to splenic vein (white arrow), confirming
absence of heat-sink effect from splenic vein.
|
|
View larger version (141K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1D —62-year-old man with metastatic adrenal tumor originating
from primary lung cancer. Contrast-enhanced CT performed 2 days after ablation
reveals nothing of concern in left adrenal gland (black arrow) or
area of left adrenal gland adjacent to splenic artery (white
arrowhead), confirming absence of heat-sink effect from splenic
artery.
|
|
Case 2
A 72-year-old man presented with left renal cell carcinoma. The patient was
diagnosed with stage IV sigmoid colon cancer accompanied by multiple pulmonary
metastases and subsequently underwent sigmoidectomy and systemic chemotherapy.
During follow-up, a 30-mm tumor was discovered at the superior pole of the
left kidney, and sonography-guided needle biopsy confirmed renal cell
carcinoma. At the request of the patient, radiofrequency ablation was
performed to excise the renal cell carcinoma. Preoperative CT showed the left
renal tumor adjacent to the spleen (Figs.
2A and
2B). To avoid thermal injury to
the spleen, CO2 was injected into the perirenal space (Figs.
2C and
2D).
View larger version (178K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A —72-year-old man with renal cell carcinoma. Intraoperative
unenhanced CT image before CO2 injection shows tumor (white
arrow) protruding on dorsal side from superior pole of left kidney and
electrode (white arrowhead) placed at center of tumor. 20-gauge percutaneous
transhepatic cholangiodrainage (PTCD) needle (black arrow) was placed
on right side of tumor for CO2 injection.
|
|
View larger version (83K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B —72-year-old man with renal cell carcinoma. Multiplanar
reconstruction of intraoperative unenhanced CT findings before CO2
injection shows tumor (white arrow) adjacent to spleen (black
arrowhead). 20-gauge PTCD needle (black arrow) and electrode
(white arrowhead) placed at center of tumor was placed. Tip is out of
image.
|
|
View larger version (160K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C —72-year-old man with renal cell carcinoma. Intraoperative
unenhanced CT image (prone position) immediately after injection of 400 mL
CO2 into the perirenal space shows tumor (white arrow)
separated from surrounding organs by CO2 (asterisks)
injected in perirenal space.
|
|
View larger version (81K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2D —72-year-old man with renal cell carcinoma. Multiplanar
reconstruction of intraoperative unenhanced CT shows tumor (white
arrow) and left kidney separated from spleen (black arrowhead)
and surrounding organs after CO2 (asterisk) injection into
perirenal space.
|
|
The patient was placed in the abdominal position and radiofrequency
ablation was performed. A 20-gauge PTCD needle was used to inject 400 mL of
CO2. Placing the tip of the PTCD needle between the target tumor
and spleen was difficult. The tip was therefore placed on the right side of
the tumor under sonographic guidance to inject the CO2, which
diffused into the perirenal space and separated the tumor from the spleen.
Thermal ablation was completed in 15 min using a 3-cm single-tip active
electrode attached to the Cool-tip radiofrequency system. During ablation, CT
was performed every 5 min to confirm sufficient separation between the tumor
and spleen. Additional injections were not necessary during the procedure.
Contrast-enhanced CT was performed 1 week after ablation, confirming complete
ablation of the tumor without any evidence of injury to the spleen.
Slight, dull pain was reported by both patients during CO2
injection. However, no medication was required and the procedure could be
continued. After CO2 injection was completed, neither patient
reported any symptoms, and there were no complications caused by the
CO2 injection.
Discussion
Radiofrequency ablation is a minimally invasive treatment for renal and
adrenal tumors in nonsurgical candidates
[1]. Percutaneous
radiofrequency ablation can be performed, provided that an applicator can be
placed percutaneously. However, tumor location adjacent to important organs
results in a risk of thermal injury to these structures, and the indications
are therefore limited. Furthermore, insufficient ablation may be achieved in
tumors adjacent to vessels of less than 1-mm diameter because of the heat-sink
effect [4].
Thermal injuries by radiofrequency ablation to adjacent structures have
been reported in patients with not only renal tumors but also other tumors
[5]. Hansen and colleagues
[6] conducted experiments using
pig livers and documented that when the edge of ablation was less than 1 cm
from the liver surface, full-thickness burns were noted in adjacent structures
such as the stomach, small intestine, and colon.
To separate tumors from adjacent structures, we injected CO2
around the target tumor. We chose to use CO2 for three primary
reasons. First, CO2 is a gas that features poor heat conduction and
high heat insulation. Second, the safety of intraabdominal CO2
injection has been proven by laparoscopic studies
[7], and because CO2
is used as a negative contrast medium in angiography, it can be safely
injected into vessels [8].
Third, a relatively large amount of CO2 can be injected, so even
when the tip of the injection needle cannot be placed between a tumor and an
adjacent organ, the tumor and adjacent organ can be separated if sufficient
CO2 is injected into the compartment.
Sterile water and quantities of air have been used to separate tumors from
adjacent structures [2,
3]. Farrell and colleagues
[2] injected sterile water to
separate a renal tumor from the intestinal tract, allowing successful
radiofrequency ablation in three renal cancer patients. Liddell and Solomon
[3] injected 3 mL of air
between a renal cell carcinoma and the loop of the small bowel, again allowing
successful ablation. We injected a mean CO2 volume of 400 to 1,100
mL, markedly more than the amount of air injected by Liddell and Solomon.
Rendon and colleagues [9]
performed radiofrequency ablation using normal porcine kidneys by injecting
either CO2 or sterile normal saline between the kidney and Gerota's
fascia. No difference in the level of thermal protection was identified
between CO2 and sterile normal saline. However, in cases where a
tumor can only be separated from adjacent structures by a small distance,
differences in insulation between CO2 and sterile normal saline may
result in marked differences in thermal protection.
In case 1, the left adrenal tumor was adjacent to the splenic vein and
artery, so the heat-sink effect represented a concern. However, the left
adrenal tumor was physically separated from the splenic artery and vein after
CO2 injection, and ablation was a complete success. One factor
behind this success could have been the high-heat insulation effect of
CO2.
CO2 pulmonary embolization during laparoscopic surgery has been
reported [10]. In laparoscopic
surgery, CO2 is continuously injected while monitoring pressure in
the retroperitoneal cavity. The volume of CO2 used during
laparoscopic surgery is much greater than that used in the present cases. The
possibility of complications involving CO2 pulmonary embolization
thus seems low using our method.
Conclusion
Imaging-guided percutaneous CO2 injection is useful for
preventing thermal injury to adjacent structures during percutaneous
radiofrequency ablation.
References
- Farrell MA, Charboneau JW, DiMarco DS, el al. Imaging-guided
radiofrequency ablation of solid renal tumors. AJR2003; 180:1509
-1513[Abstract/Free Full Text]
- Farrell MA, Charboneau JW, Callstrom MR, Reading CC, Engen DE,
Blute ML. Paranephric water instillation: a technique to prevent bowel injury
during percutaneous renal radiofrequency ablation. AJR2003; 181:1315
-1317[Free Full Text]
- Liddell RP, Solomon SB. Thermal protection during radiofrequency
ablation. AJR 2004;182
: 1459-1461[Free Full Text]
- Lu DS, Raman SS, Vodopich DJ, Wang M, Sayre J, Lassman C. Effect of
vessel size on creation of hepatic radiofrequency lesions in pigs: assessment
of the "heat sink" effect. AJR2002; 178:47
-51[Abstract/Free Full Text]
- Livraghi T, Solbiati L, Meloni WF, Gazelle GS, Halpern EF, Goldberg
SN. Treatment of focal liver tumors with percutaneous radio-frequency
ablation: complications encountered in a multicenter study.
Radiology 2002;441
-451
- Hansen PD, Rogers S, Corless CL, Swanstrom LL, Siperstien AE.
Radiofrequency ablation lesions in a pig liver model. J Surg
Res 1999; 87:114
-121[CrossRef][Medline]
- Chantigian RC, Chantigian PDM. Anesthesia for laparoscopy. In:
Conform RS, Diamond MP, DeCherney A, eds. Laparoscopy and
hysteroscopy. Oxford, England: Blackwell Scientific Publications,1993
: 11-21
- Durant TM, Stauffer HM, Oppenheimer MJ, Paul RE Jr. The safety of
intravascular carbon dioxide and its use for roentgenologic visualization of
intracardiac structures. Ann Intern Med1957; 47:191
-201
- Rendon RA, Gertner MR, Sherar MD, et al. Development of a
radiofrequency based thermal therapy technique in an in vivo porcine model for
the treatment of small renal masses. J Urol2001; 166:292
-298[CrossRef][Medline]
- Dion YM, Levesque C, Doillon CJ. Experimental carbon dioxide
pulmonary embolization after vena cava laceration under pneumoperitoneum.
Surg Endosc 1995;9
: 1065-1069[Medline]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
Top
Abstract
Introduction
