Preoperative lipiodol marking and its role on survival and complication rates of CT-guided cryoablation for small renal masses
Hongo et al. BMC Urology
Preoperative lipiodol marking and its role on survival and complication rates of CT- guided cryoablation for small renal masses
Fumiya Hongo 0
Yasuhiro Yamada 0
Takashi Ueda 0
Terukazu Nakmura 0
Yoshio Naya 0
Kazumi Kamoi 0
Koji Okihara 0
Yusuke Ichijo 1
Tsuneharu Miki 0
Kei Yamada 1
Osamu Ukimura 0
0 Department of Urology, Kyoto Prefectural University of Medicine , 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566 , Japan
1 Department of Radiology, Kyoto Prefectural University of Medicine , Kyoto , Japan
Background: Partial nephrectomy for small renal masses (SRM) may be useful for preserving renal function, but is technically more difficult than radical nephrectomy. Cryoablation may be performed under local anesthesia. The objective of the present study is to assess the safety and therapeutic efficacy of cryoablation with lipiodol marking for SRM. Methods: Cryoablation therapy was performed on 42 patients under local anesthesia. Their median age was 74 years (31-91). The median tumor diameter was 21 mm (10-42). Responses to the treatment were evaluated using modified Response Evaluation Criteria in Solid Tumors (mRECIST) by contrast-enhanced CT. In six patients (14.3%) for whom it was not possible to use contrast medium, plain CT findings were assessed according to Response Evaluation Criteria in Solid Tumors (RECIST). Results: Twenty-nine (69%) and five (12%) patients achieved complete responses (CR) and partial responses (PR), respectively, while four (10%) and four (10%) patients each had stable disease (SD) and progressive disease (PD) after the first course of therapy. A second course of cryoablation therapy with lipiodol marking was performed on three out of four patients with PD after the first course of therapy, and resulted in a total of 32 patients achieving CR (76%). Four (36.4%) out of 11 patients for whom lipiodol marking was not conducted had PD, whereas none of the 31 patients for whom lipiodol marking was conducted had PD. All grade complications were reported in 11 (24.4%) patients while grade 3 in two (4.4%) patients. 11 (24.4%) A significant difference was observed in postoperative hemorrhagic events in all grades (18% in patients undergoing cryoablation without lipiodol marking vs. 0% in patients undergoing cryoablation without lipiodol marking). Conclusions: Although further studies involving more patients are needed in order to evaluate long-term results, cryoablation therapy appears to be a useful treatment option for SRM. Preoperative marking with lipiodol was helpful for improving complication and survival rates with cryoablation.
Ablation; Cryoablation; Lipiodol marking; Renal cell cancer; Small renal mass
Renal function-preserving surgery has recently been
recommended as a treatment for small renal cancer [1–3].
Percutaneous cryoablation therapy, which includes
thermal ablation, for humans was initially reported by
Uchida . Laparoscopic cryoablation was subsequently
conducted, and favorable outcomes were reported . In
Japan, cryoablation has been covered by national health
insurance since 2011. We started to perform
percutaneous cryoablation therapy for SRM in March 2013, and
herein report our initial experience with this procedure.
Computed tomography (CT)- or magnetic resonance
imaging (MRI)-guided puncture is conducted in
cryoablation therapy. One of the advantages of CT-guided
puncture is that it provides a broader space for puncture
than MRI-guided puncture; however, it is more difficult
© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
to recognize tumor margins with CT-guided puncture
than with MRI-guided puncture. Plain CT-guided
puncture is performed in our hospital. In some patients with
submerged tumors or tumor margins that are difficult to
recognize, marking with lipiodol is conducted prior to
Lipiodol is a lipid-soluble contrast material that is used
for lymphangiography , hysterosalpingography ,
and transcatheter arterial chemoembolization (TACE) of
hepatocellular carcinoma . Since lipiodol remains in
place for several days, it is easy to localize nodules using
X-ray or CT fluoroscopy during surgery. In the present
study, we examined the efficacy of cryoablation therapy
for SRM and the usefulness of preoperative lipiodol
In March 2013, our hospital started to perform
cryoablation therapy on patients who were not indicated for
radical surgery under general anesthesia because of active
double cancer or complications or on those who did not
wish to undergo surgery due to the presence of only one
kidney or for some other reason. A preoperative staging
imaging evaluation (chest to abdominal CT) was routinely
performed on all patients. We retrospectively examined
the efficacy of this procedure, adverse events, and
posttreatment changes in renal function. Pre- and
postoperative serum creatinine levels and adverse events in patients
aged 75 years or older were compared with those in
patients aged 74 years or younger. The present study was
conducted in accordance with the Principles of Helsinki.
This study protocol was approved by Institutional Review
Board of Kyoto Prefectural University of Medicinw. The
Ethics board approval number was ERB-C-54-1. All
patients included in this study provided informed consent
for cryosurgery, accompanying standard care and the use
of their data in research.
The treatment plan was made by performing CT before
ablation. A CryoHit® device (Galil Medical USA; Hitachi
Medical Corporation, Japan) was employed. IceSeed® or
IceRod® needles were used in accordance with the tumor
diameter. One to three needles were used for ablation
as one IceSeed® for less than 10 mm, 2 IceSeeds® for
10–12 mm, 3 IceSeeds® or 2 IceRods® for 13–20 mm, 3
IceRods® for 21–30 mm, and 4 IceRods® for 31–40 mm.
The cryoprobe was introduced under CT fluoroscopic
guidance (Vigor Laudator, Toshiba Medical System,
Tokyo, Japan) after local anesthesia had been
administered by a subcutaneous injection of 1% lidocaine.
The tumor site was cooled with argon gas and thawed
with helium gas. The cryoablation area was monitored
at appropriate times during puncture or cryoablation.
Two cycles of cryoablation were then performed, with
the first cycle typically lasting 10–15 min and the second
10 min. Passive thaw was performed between the
ablation cycles, and active thaw was performed after the
When the tumor was adjacent to peripheral organs,
such as the intestinal tract, hydrodissection with
physiological saline was performed in order to avoid injury.
Transdiaphragmatic puncture with an artificial
pneumothorax was conducted for transthoracic puncture. When
the tumor was adjacent to the renal pelvis, a ureteral
catheter was inserted in some patients, and the tumor
site was perfused with warm physiological saline to avoid
injury to the renal pelvic mucosa.
As a rule, percutaneous tumor biopsy using 18-gauge
Max-Core® (BARD, USA) was performed for a
histopathological diagnosis before or at the time of cryoablation
because the tumor histology and grade of preoperative
biopsy predicted the oncological outcomes of renal
cryoablation . Local anesthesia and the prophylactic
administration of antibiotics were permitted as combined and
Transarterial lipiodol marking was performed 1–3
days before cryoablation therapy when difficulties were
associated with identifying the tumor location on plain
CT. Transfemoral visceral arteriography was conducted
using a standard angiographic approach. Selective
catheterization of the tumor-feeding arteries was
performed under fluoroscopic guidance. After confirming
the presence of the catheter tip in the branches of the
renal arteries feeding the tumor, lipiodol (Laboratoire
Guerbet, Roissy, France) was manually injected (range,
0.2–0.4 mL) under fluoroscopy to make a lipiodol spot.
Evaluation of efficacy
Responses to the treatment were evaluated by
performing contrast-enhanced CT after 6 months. Efficacy was
evaluated based on the tumor response rate, namely, a
complete response (CR) or partial response (PR), using the
modified Response Evaluation Criteria in Solid Tumors
(mRECIST) criteria [10, 11]. The mRECIST criteria
incorporate amendments to the original RECIST criteria. Tumor
responses were defined as: (i) CR: the disappearance of any
intratumoral arterial enhancement in all target lesions; (ii)
PR: at least a 30% decrease in the sum of diameters of
viable (enhancement in the arterial phase) target lesions,
taking the baseline sum of the diameters of target lesions
as the reference; (iii) stable disease (SD): any cases that do
not qualify for either PR or progressive disease (PD); (iv)
PD: An increase of at least 20% in the sum of the diameters
of viable (enhancing) target lesions, taking the smallest
sum of the diameters of viable (enhancing) target lesions
recorded since the treatment started as the reference.
Efficacy was evaluated based on the tumor response
rate, namely, CR or PR, using the mRECIST criteria.
The Clavien Classification of Surgical Complications was
used for surgically related complications .
Relationships between clinicopathological characteristics
and response rates were examined using the χ2 test.
Changes in serum creatinine levels were examined using
the t-test. Test results were considered significant at
P < 0.05. All analyses were performed using JMP 10.0.2
Cryoablation therapy was performed on a total of 42
patients before December 2014 (Table 1). Their median
age was 74 years (range, 31–91). The median tumor
diameter was 24.1 mm (range, 10–42 mm).
Percutaneous renal biopsy was performed on 86% of
patients (36/42), but was not mandatory. Biopsy data are
shown in Table 1. A pathological diagnosis of renal cell
cancer (RCC) was reached in 30 out of the 36 patients
and benign tumor (AML) in one patient who underwent
biopsy. In the other five patients, biopsy specimens were
insufficient to make a pathological diagnosis.
Treatment responses were evaluated using mRECIST
based on contrast-enhanced CT findings (Table 2). In six
patients (14.3%) for whom it was not possible to use
contrast medium, plain CT findings were assessed
according to RECIST. After the first course of therapy,
29 (69%) and five (12%) patients achieved complete
responses (CR) and partial responses (PR), respectively,
while four (10%) and four (10%) patients each had stable
disease (SD) and progressive disease (PD). A second
course of cryoablation therapy with lipiodol marking
was performed on three out of the four patients with PD
after the first course of therapy. CR was achieved in two
patients and PR in 1. Final treatment responses were
evaluated in 42 patients, including three who underwent
two courses of cryoablation therapy. CR and PR were
achieved in 32 and five patients, respectively. SD and PD
were noted in four and one patients, respectively. one
patient proved to have AML. The technical success rate
There were 11 episodes (24.4%) of complications during
a total of 45 courses of cryoablation therapy regardless
of the grade. Grade 3 or higher adverse events were
observed in two patients (4.4%). Intra- and postoperative
complications included fever, hematoma, hematuria, pleural
effusion, hydronephrosis, and ureter perforation in 5, 1, 2,
1, 1, and 1 patient, respectively (Table 3). Grade 3 or higher
adverse events were observed in two patients: G3a
hydronephrosis and G3a ureteral injury. There were no
lipiodol marking-related adverse events.
Renal function after cryoablation
Postoperative renal function was investigated based on
serum creatinine levels 3 months after the treatment.
Preoperative serum creatinine levels were 0.95 ± 0.4 in
patients aged 74 years or younger and 1.19 ± 0.61 in
those aged 75 years or older. These values 3 months
Table 1 The characteristics and outcomes of patients underwent cryopablation with or without preoperativeliiodol marking
Preoperative lipiodol marking
Mean age (year, range)
Biopsy performed in 36/42 (85.7%)
Post ablative hemorrhagic event (%)
Table 2 Efficacy of cryoablation. In three of four patients with
PD after the first therapy, second cryoablation therapy with
lipiodol marking was performed
after surgery were 0.96 ± 0.46 and 1.20 ± 0.55, respectively.
The rates of changes were −1 ± 10 and 3 ± 15%,
respectively, which were not significantly different (p = 0.3282).
We conducted preoperative lipiodol marking before
cryoablation therapy on 31 patients with guidance
difficulties under plain CT. Baseline patient demographics
and operative outcomes are listed in Table 1. No
significance differences were observed in mean age (71.5 vs.
71.1), gender (male/female) (27/5 vs. 6/4), or tumor
laterality (15/16 vs. 6/5). On the other hand, significant
differences were detected in tumor sizes (27.8 mm (10–42)
vs. 21.3 (15–34) mm).
A case of cryoablation therapy with preoperative
lipiodol marking was shown (Fig. 1). The red circle indicates
the primary tumor. (A) The right renal tumor was
detected by a preoperative dynamic CT scan. (B) The
tumor was easily detected by intraoperative plain CT
after lipiodol marking. (C) A postoperative CT scan
showed no enhancement in the cryoablated area. CR
was achieved by cryoablation according to mRECIST.
Among all 42 patients, relapse was detected in four
(36.4%) out of 11 patients for whom lipiodol marking
was not conducted and was not observed in any (0%) of
the 31 patients for whom lipiodol marking was conducted
showed relapse, with a significant difference between with
and without marking (p = 0.01). Moreover, a significant
difference was detected in postoperative hemorrhagic
events (18% vs. 0%) (p < 0.05) (Table 1).
No deaths occurred within 1 month of cryoablation
therapy. Although one patient died during the follow-up
period, her death was not related to cryoablation therapy;
she died of primary disease (malignant lymphoma)
20 months after cryoablation therapy.
Patient survival was evaluated at a mean follow-up
time of 17 (range, 6–26) months (SD, 6.13 months).
One- and 2-year overall survival rates were 100 and
Nephrectomy has been performed as a standard
treatment for renal cancer for a long time. However, the
detection rate of SRM has increased with recent advances
in diagnostic imaging procedures. A paradigm shift in
treatment approaches to renal masses is underway,
leading the AUA to release guidelines for the management
of clinical stage 1 renal masses in 2009 for the first time
. Partial nephrectomy or ablative therapy for T1a
renal cancer may be useful for preventing
nephrectomyrelated chronic kidney disease (CKD) [13, 14]. In elderly
patients or patients with comorbidities, who are likely
have a lower estimated glomerular filtration rate (eGFR),
rapid reductions in renal function have been implicated
in early death . Therefore, not only partial
nephrectomy, but also ablative therapy including cryoablation
therapy, which may be performed under local anesthesia
without renal ischemia, thereby facilitating the
preservation of renal function, may be useful for patients with
comorbidities and the elderly. In the present study, the
impact of cryoablation therapy on renal function in
patients aged 75 years or older was not significant.
Treatment options for SRM include ablation therapy.
In our hospital, RFA therapy has been performed as
advanced medical care and its usefulness has been reported
[16, 17]. However, in Japan, RFA for renal tumors is not
yet covered by national health insurance. Therefore,
cryoablation therapy, which is covered by national health
insurance, is primarily performed in our hospital.
CT- or MRI-guided puncture is optional as a
percutaneous approach. Plain semi-real-time CT-guided
puncture is performed in our hospital. However, the major
limitation of plain CT is the difficulty associated with
the localization of the tumor, when the tumor resembles
Table 3 Postoperative complication in 45 sessions of cryoablation according to Clavien-Dindo classification
Fig. 1 A case of cryoablation with preoperative lipiodol marking. The red circle indicates the primary tumor. a The right renal tumor was detected by
a preoperative dynamic computed tomography (CT) scan. b The tumor was easily detected by intraoperative plain CT after lipiodol marking.
c A postoperative CT scan showed no enhancement in the cryoablated area. A complete response was achieved by cryoablation according
to the mRECIST criteria
the renal parenchyma, and, importantly, patients
indicated for ablative therapy may have renal dysfunctions
that are a contraindication for the frequent
intraoperative use of a CT contrast agent. In order to overcome
these limitations, we evaluated the usefulness of lipiodol
marking to identify the tumor center prior to
percutaneous cryoablation with plain CT guidance. In the selected
patients with submerged tumors or those in whom the
tumor margin was difficult to recognize, marking with
lipiodol was conducted prior to cryoablation therapy. We
previously reported the usefulness of preoperative lipiodol
marking prior to the ablation of lung cancer . The use
of cryoablation therapy for renal cancer has facilitated
accurate evaluations of target tumors, thereby improving the
accuracy of the treatment. In contrast, cryoablation
therapy may also be performed with the confirmation of
tumor contours by administering contrast medium.
However, the use of contrast medium needs to be avoided in
patients with renal hypofunction. Furthermore, a previous
study indicated that embolization prior to cryoablation
therapy was useful for reducing the incidence of
complications related to cryoablation therapy .
Regarding lipiodol marking, lipiodol with a gelatin sponge is
transarterially infused. It may be useful for identifying
the tumor location or its margin on CT-guided probe
insertion and preventing hemorrhage-associated
complications because it reduces intra-tumor blood flow.
When the tumor was adjacent to peripheral organs,
such as the intestinal tract, hydrodissection , which
is useful for avoiding thermal ablation-related intestinal
injury, was performed. There were no intestinal injuries
in any patients (0%).
In 115 tumors were treated using PCA, technical
success rate was achieved in 97% by post-procedure CT
(with and without IV contrast or MRI on POD 1). There
was no evidence of local recurrence in 80 tumors that
were followed for a mean of 13.3 months by CT imaging
. Kapoor et al. reported that the maximal and
minimal percentages of cancer-specific survival were
100% and 84.3% in follow-ups of 11.4 months (median)
and 64 months (mean), respectively, by reviewing a
total of 2104 analyzed tumors from 2038 patients in the
On the other hand, the timing of follow-ups after
cryoablation therapy has not yet been established. One
exception was the series by Gill and colleagues; the authors
routinely performed biopsies 6 months post-CA. In this
series, two out of 56 tumors were positive 6 months
post-CA, at a rate of 3.6% . In our hospital,
followups are performed using dynamic CT 1, 3, 6, 9, and
12 months after the treatment. In the present study,
treatment responses were evaluated after 6 months.
The success rate for the treatment was 98%, which was
consistent with previous findings. When biopsies revealed
no malignancy, follow-up CT was performed 6 and
12 months after the treatment.
Primary complications include hemorrhage. Hemorrhage
or significant bleeding requiring blood transfusion has
a reported incidence of 1–8% .
In the present study, postoperative hemorrhage was
observed in two patients (4%) in whom it was impossible
to discontinue anticoagulant therapy. However, these
patients did not require blood transfusions. There were no
cases of hemorrhage requiring blood transfusion (0%).
This percentage is lower than that previously reported
and may be attributed to the artery-embolizing effects of
preoperative marking with lipiodol, which is conducted
in our hospital where necessary, thereby decreasing the
incidence of postoperative hemorrhage. Transcatheter
renal arterial embolization with a mixture of ethanol and
lipiodol for unresectable RCC has been reported ,
and this study is the first to demonstrate the efficacy of
cryoablation with lipiodol marking. A previous study
showed that embolization before cryoablation therapy
reduced the rate of complications . In the present
study, there were no intestinal injuries. However, based
on previous findings, we prepared preventive strategies,
such as cryoablation therapy after hydrodissection, for
patients for whom the anterior surface of the kidney was
suspected to be in contact with the intestinal tract .
Regarding complications in the urinary tract, ureteral
perforation was noted in one patient. However, the
insertion of a Double J stent catheter for 6 months led to
improvements. The thermal ablation of renal tumors in
close proximity to or abutting the renal pelvis,
ureteropelvic junction (UPJ), or proximal ureter represents a
higher risk scenario for ureteral or collecting system injury,
with resultant obstruction or renal loss . Cryoablation
is more likely to be recommended than RF ablation for the
treatment of a renal tumor in proximity to the ureter
because the former procedure has been shown to result in
fewer urinary tract injuries than the latter, as demonstrated
in a porcine model .
According to a recent review on treatments for
localized renal masses in the United States, nephrectomy still
accounts for a high proportion, but its rate has decreased.
Partial nephrectomy and thermal ablation, such as
cryoablation and RFA, have been indicated for an increasing
number of patients . This may also be the case in
Japan in the future. Partial nephrectomy is now primarily
performed as a renal function-preserving treatment;
however, cryoablation therapy may be useful for elderly
patients and those with complications. A percutaneous
thermal ablation procedure for renal cancer appears to
be a useful treatment option for SRM. In the present
study, preoperative marking with lipiodol was helpful
for achieving successful cryoablation.
There were several limitations in the present study. The
total number of cases was too small to reach definite
conclusions. In addition, complete preoperative histological
information was unavailable, limiting the oncological
outcomes. Furthermore, this was a retrospective study.
Therefore, controlled randomized trials need to be designed
that compare preoperative lipiodol marking followed by
cryoablation and cryoablation without lipiodol marking.
The results of the present study suggest that cryoablation
with preoperative lipiodol marking improves the safety
and success rate of CT-guided cryoablation for SRM. This
approach was even shown to be useful for patients with
renal dysfunctions, who were likely contraindicated for
the intraoperative use of a contrast agent to visualize renal
CA: Cryoablation; CKD: Chronic kidney disease; CT: Computed tomography;
eGFR: Estimated glomerular filtration rate; HCC: Hepatocellular carcinoma;
Lipiodol: Ethiodized oil; mRECIST: Modified Response Evaluation Criteria in
Solid Tumors; MRI: Magnetic resonance imaging; PCA: Percutaneous cryoablation;
POD 1: Post operative day 1; RCC: Renal cell cancer; SRM: Small renal masses;
TACE: Transcatheter arterial chemoembolization; UPJ: Ureteropelvic junction
FH carried out cryosurgery on patients, collected and analyzed data, and wrote
and drafted the manuscript, YY, TU, and YI carried out cryosurgery on patients,
YN and KK participated in the acquisition of data, TN and KO participated in the
design of the study and performed the statistical analysis, and TM, KY, and OU
conceived the study, participated in its design and coordination, and helped to
draft the manuscript. All authors read and approved the final manuscript.
Consent for publication
Ethics and consent to participate
This study protocol was approved by Institutional Review Board of Kyoto
Prefectural University of Medicine. The Ethics board approval number is
ERB-C-54-1. All patients included in this study provided informed consent
for the use of their data in research.
1. Campbell SC , Novick AC , Belldegrun A , et al. Guideline for management of the clinical T1 renal mass . J Urol . 2009 ; 182 : 1271 - 9 .
2. Ljungberg B , Bensalah K , Canfield S , et al. EAU Guidelines on renal cell carcinoma: 2014 update. Eur Urol . 2015 ; 67 : 913 - 24 . doi:10.1016/j.eururo. 2015 . 01.005. Epub 2015 Jan 21.
3. Fujioka T , Obara W , Committee for Establishment of the Clinical Practice Guidelines for the Management of Renal Cell Carcinoma; Japanese Urological Association. Evidence-based clinical practice guidelines for renal cell carcinoma (Summary-JUA 2007 Edition) . Int J Urol . 2009 ; 16 : 339 - 53 . doi:10.1111/j.1442- 2042 . 2008 .02242.x.
4. Uchida M , Imaide Y , Sugimoto K , et al. Percutaneous cryosurgery for renal tumours . Br J Urol . 1995 ; 75 : 132 - 6 . discussion 136 - 137 .
5. Gill IS , Novick AC , Meraney AM , et al. Laparoscopic renal cryoablation in 32 patients . Urology . 2000 ; 56 : 748 - 53 . doi.org/10.1016/S0090-4295(00)00752- 4 .
6. Matsumoto T , Yamagami T , Kato T , et al. The effectiveness of lymphangiography as a treatment method for various chyle leakages . Br J Radiol . 2009 ; 82 : 286 - 90 .
7. Johnson NP , Farquhar CM , Hadden WE , et al. The FLUSH trial-flushing with lipiodol for unexplained (and endometriosis-related) subfertility by hysterosalpingography: a randomized trial . Hum Reprod . 2004 ; 19 : 2043 - 51 .
8. Ikeda M , Arai Y , Park SJ , et al. Prospective study of transcatheter arterial chemoembolization for unresectable hepatocellular carcinoma: an Asian cooperative study between Japan and Korea . J Vasc Interv Radiol . 2013 ; 24 : 490 - 500 .
9. Beksac AT , Rivera-Sanfeliz G , Dufour CA , et al. Impact of tumor histology and grade on treatment success of percutaneous renal cryoablation World J Urol , 2016 Aug 2 [Epub ahead of print]
10. Llovet JM , Decaens T , Raoul JL , et al. Modified RECIST (mRECIST) assessment for hepatocellular carcinoma . Semin Liver Dis . 2010 ; 30 : 52 - 60 . doi:10.1055/s0030- 1247132 . Epub 2010 Feb 19 . Review .
11. Lencioni R. New data supporting modified RECIST (mRECIST) for hepatocellular carcinoma . Clin Cancer Res . 2013 ; 19 : 1312 - 4 . doi:10.1158/ 1078 - 0432 . CCR-12- 3796. Epub 2013 Feb 4.
12. Dindo D , Demartines N , Clavien PA . Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey . Ann Surg . 2004 ; 240 : 205 - 13 .
13. Huang WC , Huang WC , Elkin EB , et al. Partial nephrectomy versus radical nephrectomy in patients with small renal tumors-is there a difference in mortality and cardiovascular outcomes ? J Urol . 2009 ; 181 : 55 - 61 . doi:10.1016/ j.juro. 2008 .09.017. discussion 61-2. Epub 2008 Nov 13.
14. Van Poppel H , Da Pozzo L , Albrecht W , et al. European Organization for Research and Treatment of Cancer (EORTC ); National Cancer Institute of Canada Clinical Trials Group (NCIC CTG); Southwest Oncology Group (SWOG); Eastern Cooperative Oncology Group (ECOG) A prospective randomized EORTC intergroup phase 3 study comparing the complications of elective nephron-sparing surgery and radical nephrectomy for low-stage renal cell carcinoma . Eur Urol . 2007 ; 51 : 1606 - 15 . Epub 2006 Nov 15.
15. Rifkin DE , Shlipak MG , Katz R , et al. Rapid kidney function decline and mortality risk in older adults . Arch Intern Med . 2008 ; 168 : 2212 - 8 . doi:10.1001/archinte.168. 20.2212.
16. Ukimura O , Kawauchi A , Fujito A , et al. Radio-frequency ablation of renal cell carcinoma in patients who were at significant risk . Int J Urol . 2004 ; 11 : 1051 - 7 .
17. Hiraoka K , Kawauchi A , Nakamura T , et al. Radiofrequency ablation for renal tumors: our experience . Int J Urol . 2009 ; 16 : 869 - 73 . doi:10.1111/j.1442- 2042 . 2009 .02378.x. Epub 2009 Sep 3.
18. Miura H , Yamagami T , Tanaka O , et al. CT findings after lipiodol marking performed before video-assisted thoracoscopic surgery for small pulmonary nodules . Acta Radiol . 2016 ; 57 : 303 - 10 . doi:10.1177/0284185115576047. Epub 2015 Mar 19.
19. Miller JM , Julien P , Wachsman A , et al. The role of embolization in reducing the complications of cryoablation in renal cell carcinoma . Clin Radiol . 2014 ; 69 : 1045 - 9 . doi:10.1016/j.crad. 2014 .05.110. Epub 2014 Jul 16.
20. Bodily KD , Atwell TD , Mandrekar JN , et al. Hydrodisplacement in the percutaneous cryoablation of 50 renal tumors . Am J Roentgenol . 2010 ; 194 : 779 - 83 .
21. Atwell TD , Farrell MA , Leibovich BC , et al. Percutaneous renal cryoablation: experience treating 115 tumors . J Urol . 2008 ; 179 : 2136 - 41 .
22. Kapoor A , Touma NJ , Dib RE . Review of the efficacy and safety of cryoablation for the treatment of small renal masses . Can Urol Assoc J . 2013 ; 7 : E38 - 44 . doi:10.5489/cuaj.12018.
23. Gill IS , Remer EM , Hasan WA , et al. Renal cryoablation: outcome at 3 years . J Urol . 2005 ; 173 : 1903 - 7 . http://dx.doi.org/10.1097/01.ju. 0000158154 .28845.c9.
24. Park JH , Kim SH , Han JK , et al. Transcatheter arterial embolization of unresectable renal cell carcinoma with a mixture of ethanol and iodized oil . Cardiovasc Intervent Radiol . 1994 ; 17 : 323 - 7 .
25. Finley DS , Beck S , Box G , et al. Percutaneous and laparoscopic cryoablation of small renal masses . J Urol . 2008 ; 180 : 492 - 8 . discussion 8 .
26. Lee SJ , Choyke LT , Locklin JK , et al. Use of hydrodissection to prevent nerve and muscular damage during radiofrequency ablation of kidney tumors . J Vasc Interv Radiol . 2006 ; 17 : 1967 - 9 .
27. Brashears III JH , Raj GV , Crisci A , et al. Renal cryoablation and radio frequency ablation: an evaluation of worst case scenarios in a porcine model . J Urol . 2005 ; 73 : 2160 - 5 .
28. Woldrich JM , Palazzi K , Stroup SP , et al. Trends in the surgical management of localized renal masses: thermal ablation, partial and radical nephrectomy in the USA , 1998 - 2008 . BJU Int . 2013 ; 111 : 1261 - 8 . doi:10.1111/j.1464-410X. 2012.11497.x. Epub 2013 Mar 7.