FUDA CANCER HOSPITAL GUANGZHOU|Cryosurgery

Renal cancer (also called renal cell canceror or renal adenocarcinoma) is a disease in which malignant cells are originated from tubules in the kidney. The incidence of renal cancer is 31,200 cases per year, representing 2–3% of new cancers. Men are affected approximately twice as often as are women, and the mean age at diagnosis is approximately 60 years. Some 4,500 patients died of renal cancer in 1998.
Overview of treatment for renal cancer
Surgery is the preferred treatment for resectable renal cancer .Radical nephrectomy is useful for localized cancer and for palliation of intractable bleeding and pain. Partial nephrectomy, also known as nephron-sparing surgery, is adequate treatment for small localized cancer and also offers some value for bilateral synchronous cancer, cancer in a functionally or anatomically solitary kidney.

Adjuvant chemotherapy or radiation have not been shown to prevent or decrease relapse rates.Sometimes, postoperative irradiation is used and may be useful for patients with residual local cancer, extension of cancer into perinephric fat, regional lymph node involvement, renal vein invasion.

Biological therapy or immunotherapy offers favorable results with cytokines for patients with metastatic renal cancer.Interferon-a(IFN-a) can produce response rates of 12% to 15% for patients with renal cancer. Interleukin-2 as monotherapy has resulted in complete or partial responses in up to 70% of patients.Combination therapy consisting of interleukin-2 and tumor-infiltrating lymphocytes or interferon-α has provided promising results.

Approaches under investigation include combinations of cytokine therapy, use of new cytokines, combinations of cytokine modulation and autologous cancer vaccination. Activation of cytotoxic T lymphocytes may be the common mechanism of action of many of these disparate treatments, including gene therapy. Adoptive immunotherapy that exploits dendritic cells as effectors is actively being investigated.

As the detection of small renal masses by widespread abdominal imaging continues to increase, so will the demand for minimally invasive nephron-sparing procedures. Laparoscopic or percutaneous renal cryoablation has been proved to be a viable option for the treatment of small peripheral renal masses in patients with significant comorbidities.

Ultrasonography is usually employed to guide the cryoprobe placement into the center of the tumor such that the probe tip is positioned at, or just beyond, the deep margin of the tumor. The evolving cryolesion is then sonographically monitored real-time until complete ablation of the tumor is confirmed and the ice ball is noted to extend 1 cm beyond the tumor margins circumferentially. Distance of the edge of the cryolesion from the renal sinus is measured, thus minimizing chances of inadvertent cryoinjury to the collecting system.

It is suggested that magnetic resonance imaging(MRI) is a preferred modality for guidance of renal cryolesions, due to its superior soft tissue contrast resolution and multiplanar imaging capability. Successful renal cryoablation is visualized as nonenhancement of the lesion following gadolinium administration (Figure-3).Here MRI guidance is introduced in detail is as follows:
The patient is then positioned prone on the MRI docking table and advance into the magnet bore.(Figure 4) With the patient in prone position in the MRI, a flex-4 send and receive coil is positioned around the torso. (Figure 5) Axial fast spin echo images are obtained to localize the kidneys and the mass targeted.

The same images are used to identify the planned probe entry site and the skin site marked is then prepped and draped in normal sterile fashion. After anesthetizing the skin with 1% Xylocaine with Epinephrine, a 2-3 mm incision is made through which either a 2 mm or 3-mm diameter cryoprobe was inserted along with its corresponding pinnacle introducer sheath(Figure 1).

Axial fast spin echo images generates at up to two images per second were used to monitor the cryoprobe advancing toward the mass. (Figures 2 & 3) Axial, sagittal or coronal T-1 images are also utilized along with breath-hold technique for better spacial definition and minimalization of probe artifact.
The probe is advanced through the center of the mass until the tip was positioned along the distal inner border of the mass. For tumors that are located anteriorly the probe is directed through the parenchyma away from the collecting system. The angle of the approach is calculated to allow maximum distance away from the collecting system. The cryo-system is activated for a 1-minute freeze at which time repeat imaging is performed to access the growth rate of the ice ball in the mass and to avoid possible injury to the collecting system. (Figure 4)

The ice ball that developed is represented by a signal void on T-1 weighted images. The ice ball is allowed to increase in size until it completely envelopes the mass and the edge extended 5 mm beyond the mass.(Figures 5 & 6).If the mass is of such size or configuration that the maximum ice ball generates failed to obliterate the targeted tissue, the probe is thawed and repositioned using overlapping technique to cover the entire targeted tissue. Ultimately, three freeze/thaw cycles are performed throughout the entire mass targeted.

The probe is removed after the third thaw cycle and the access sheath is packed with Surgicel or Gelfoam pledgets to facilitate hemostasis. The incision is closed with one or two interrupted non-absorbable sutures. Antibiotic ointment and a bandage are applied to the incision site.

Post-cryoablation
The follow-up schedule consisted of an MRI or CT scan, BUN, serum creatinine, and physical exam at 1 week, 1, 3, 6, and 12 months.

It is best to routinely perform MRI,with and without gadolinium enhancement, on days 1, 30, 60, and 90 postoperatively, in order to assess the kidney and surrounding structures. All cryolesions are isointense to the adjacent normal renal parenchyma on T1 weighted images and hypointense on T2 weighted images. A hyperintense peripheral rim at the border between the cryolesion and the kidney
on day 1 MRI scans T1 weighted images is observed in some the cases. After 30 days, an increase in signal intensity on both T1 and T2 weighted images is constantly detected, but no gadolinium enhancement of the cryolesion occurrs. It is reported that a decrease in MRI size of the cryolesion by 14%, 23%, and 40% at 1, 2, and 3 months postoperatively in 10 initial patients.

Renal histology after cryoablation
Histologically, the cryoablated tissue reveals progressive changes over time, from typical findings of cell death and tissue non-viability to chronic signs of inflammation, fibrosis and scarring. Initially (1 hour), the renal cryolesion macroscopically demonstrates areas of dark red discoloration consistent with interstitial hemorrhage with an abrupt line of demarcation from the surrounding healthy renal parenchyma.

Microscopically, generalized vascular congestion is evident, with only subtle signs of early coagulation necrosis. Hemorrhagic glomeruli, fibrin deposition within capillaries and near complete exfoliation of the urothelium covering the cryoablated papillae is evident (35). The inflammatory response is minimal with only a mild infiltration of polymorphonuclear neutrophils (10).

Marked ultrastructural evidence of irreversible cell death is also shown on electron microscopy, such as partial fragmentation and cytoplasmic vacuolization of membranes, disruption of outer membranes and internal crystal of mitochondria, chromatin condensation and loss of nuclear membrane, hemorrhage into glomerular spaces and
disruption of epithelial podocytes of glomerulli (12).

A sharply demarcated, deep-red cryolesion is readily apparent macroscopically after 24 hours.On microscopic examination, complete coagulation necrosis is evident centrally, surrounded by a 0.3
mm-8 mm transitional zone of partial necrosis, which abuts normal renal parenchyma. Loss of cell borders, absence of cytoplasmic organelles, and ghost renal tubules are easily identified in the area of complete necrosis. Hyalinization of glomerular and tubular cellular structure is seen, while nuclear pyknosis is evident universally in the glomerulii and
blood vessels. When examined under electron microscopy,tubular cells appear as proteinaceous aggregates, completely devoid of membranes, while glomerulii are degenerated and glomerular spaces are filled with necrotic cellular debris. Capillary basement membranes remain intact with large intravascular thrombi (12). The zone of partial necrosis contains some viable cells, thus representing an area of sublethal injury. Glomerular architecture is lost and proteinaceous casts are visible in the collecting tubules. Considerable infiltration of polymorphonuclear leucocytes is seen.
Fibrotic changes and a typical contracted scar are eventually seen after 1 month following renal cryoablation, when chronic inflammation, fibrotic
glomerulii and tubules, and no evidence of viable renal parenchyma are observed under microscopic examination.

Clinical efficacy

Open cruoablation
The first reported clinical study of cryoablation as a nephron-sparing procedure was published by Delworth et al., who performed open
cryoablation in 2 patients with a solitary kidney (21).The first patient had a 3 cm renal cell cancer and the second had a 10 cm angiomyolipoma. Operative time was 3.5 hours and 4.5 hours, with a blood loss of 200
ml and 700 ml, respectively. Postoperative serum creatinine was 1.3 mg% in both patients and follow-up consisted of a MRI at one month, revealing a significant decrease of the renal carcinoma dimensions and
at 3 months, showing a 10% enlargement in size of the angiomyolipoma. Although no pathologic data were included in the study, the authors concluded that renal cryotherapy could be performed safely with
minimal loss of renal function.

Rukstalis []evaluated the safety and efficacy of open renal cryoablation of small solid renal masses. A total of 29 patients were treated with open renal cryoablation. The median preoperative lesion size was 2.2 cm, with 22 solid renal masses and 7 complex renal lesions. Five serious adverse events occurred in 5 patients, with only one event directly related to the procedure. One patient experienced a biopsy-proven local recurrence, and 91.3% of patients (median follow-up 16 months) demonstrated a complete radiographic response with only a residual scar or small, nonenhancing cyst. Authors considered that open renal cryoablation appears to be a safe technique for the in situ destruction of solid or complex renal masses. However, inadequate freezing of renal cell carcinoma may result in local disease persistence.
Laparoscopic cryoablation
Gill et al reported oncological followup data on 56 patients undergoing laparoscopic renal cryoablation, of whom each completed a 3-year followup. The postoperative followup protocol comprised serial magnetic resonance imaging (MRI) at 1 day, months 1, 3, 6, 12, 18 and 24, and yearly thereafter for 5 years. Computerized tomography guided needle biopsy of the cryolesion was performed 6 months postoperatively and repeated if MRI findings were abnormal. Followup data were obtained prospectively. For a mean renal tumor size of 2.3 cm mean intraoperative size of the created cryolesion was 3.6 cm. Sequential mean cryolesion size on MRI on postoperative 1 day, and at 3 and 6 months, and 1, 2 and 3 years was 3.7, 2.8, 2.3, 1.7, 1.2 and 0.9 cm, representing a 26%, 39%, 56%, 69% and 75% percent reduction in cryolesion size at 3 and 6 months, and 1, 2 and 3 years, respectively. At 3 years 17 cryolesions (38%) had completely disappeared on MRI. Postoperative needle biopsy identified locally persistent/recurrent renal tumor in 2 patients. In the 51 patients undergoing cryotherapy for a unilateral, sporadic renal tumor 3-year cancer specific survival was 98%. There was no open conversion, kidney loss, urinary fistula, dialysis requirement, or perirenal or port site recurrence in any patients.
Powell et al[] reviewed the biology, techniques and outcomes of laparoscopic renal cryotherapy. 25 patients were treated with transperitoneal laparoscopic cryotherapy for small peripheral renal lesions between 2002 and 2003. Mean pretreatment creatinine of 1.06 was unchanged after treatment. Mean tumor size was 2.4 cm (range 1.5-3.6 cm). Pathology revealed 72% RCC, 2 oncocytomas, one each arterio-nephrosclerosis, inflammatory tissue, focal-segmental glomerulosclerosis, angiomyolipoma and one normal tissue specimen. Average tumor grade was 2.3 (range 2-4). Mean hospital stay was 2.3 days (range 1-5). Three cases were converted to open. Two complications included transfusion and hydronephrosis, both managed conservatively. Mean follow-up is 16.2 months (range 6-36 months). There have been no recurrences to date despite a rigorous surveillance protocol. It is showed that renal cryotherapy is a viable option for nephron sparing surgery in small, peripheral, renal lesions. The procedure is well tolerated, may be considered in patients who are not good candidates for open surgical approaches, results in minimal morbidity, and has very encouraging treatment results.

Gore et al[] reviewed their initial experience with laparoscopic cryoablation utilizing 17-gauge cryoneedles. Four patients aged 21 to 78 years underwent laparoscopy-assisted percutaneous cryotherapy. The tumor size ranged from 1.5 to 2.5 cm. The procedure involved transperitoneal exposure of the tumor utilizing three 5- or 10-mm ports. The cryoprobes were placed percutaneously, without the need for tract dilation. Two freeze-thaw cycles were performed with cooling to below -70 degrees C. In all patients, the procedure was completed without complication. The mean operative time was 125 minutes. The mean blood loss was 29 mL. No perioperative complications occurred. In follow-up, one patient with a tumor suspected of being renal-cell carcinoma demonstrated residual enhancement and underwent percutaneous radiofrequency ablation. Authors showed that laparoscopy-assisted percutaneous cryotherapy is a feasible treatment option in patients with small renal tumors. Laparoscopy allows mobilization of both anterior and posterior tumors. Direct viewing of the mass may facilitate accurate placement of the cryoneedles. The small size of the cryoneedles minimizes bleeding at the entry site.

Lee et al[] presented experience with laparoscopic renal cryoablation with up to 3 years of follow-up. Twenty patients with small renal masses (1.4 to 4.5 cm) underwent laparoscopic renal cryosurgery at our institution. A retroperitoneal laparoscopic approach was used to expose the kidney. Intraoperative ultrasound guidance was used to localize the lesions and monitor iceball formation. A double-freeze technique was used.Renal biopsies revealed renal cell carcinoma in 11 of the 20 patients. Of these 11 patients, none had evidence of recurrent disease at last follow-up, and follow-up scans showed no enhancement of any lesions. Of the 8 patients with follow-up of 2 years or greater, 4 had complete resolution of the renal lesions. The remainder had lesions that were reduced and stable in size. Complications included surgical re-exploration to evaluate pancreatic injury in 1 patient and failure to ablate a lesion in another.

Percutaneous cryoablation

Patrick et al reported a total of 20 patients with 23 tumors who were treated with percutaneous cryoablation under MR guidance. One patient had bilateral tumors and a second patient had two tumors in one kidney. The mean age is 58 years (49-76) with 10 males and 10 females. The mean diameter of the tumor was 3.0 cm (1.8-7.0). Two patients with masses exceeding entry criteria (5.0 and 7.0 cm) who were not open surgical candidates were treated on a compassionate basis. The average treatment time was 97 minutes (56-172). The only complication was a superficial wound abscess. The mean follow-up period was 9.1 months (3-14) with no radiographic evidence of tumor recurrence or new tumor development.

Allaf et al[] retrospectively compared the pain control requirements of patients undergoing computed tomography (CT)-guided percutaneous radiofrequency(RF) ablation with those of patients undergoing CT-guided percutaneous cryoablation of small (< or = 4-cm) renal tumors. During the study period from June 19, 2003, to February 28, 2004,, 10 men underwent cryoablation of 11 renal lesions, and 14 patients underwent RF ablation of 15 renal tumors. Analgesic and sedative requirements during the procedure were compared. There was no difference in terms of patient demographics, tumor diameter, or distribution of central versus noncentral lesions between the two groups. Cryoablation was associated with a significantly lower dose of fentanyl and midazolam. In the RF group, one patient required general anesthesia, one patient required supplemental narcotics and sedatives, and one patient became apneic for a brief interval after receiving additional narcotics for pain during the procedure. No patients in the cryoablation group required any additional or alternate anesthetics. The results show that image-guided percutaneous cryoablation of small (< or = 4-cm) renal lesions appears to require less analgesia than RF ablation.

Kodama et al[] reported that a 35-year-old woman with five renal cell carcinomas (RCCs) was treated by percutaneous cryoablation. She had two RCCs in the left kidney and three in the right. Cryoablation was performed using a high-pressure argon-based system with 2- or 3-mm cryoprobes under magnetic resonance (MR) guidance. Three tumors were completely ablated. Two tumors were residual, as they were so close to nearby organs that we were forced to stop the freezing to avoid complications. No complications were encountered, and renal function was preserved. In conclusion, MR-guided cryoablation is a safe procedure even when RCCs are bilateral and multiple.

Discussion

Experience with laparoscopic renal cryoablation is still evolving. Nevertheless, cumulative data regarding its safety and efficacy has been presented. Comparatively to the prostate, the kidney is an ideal solid organ for cryoablation. It usually harbors unifocal malignancy and can be easily mobilized laparoscopically, enabling a higher degree of precision
in completely involving the targeted area.

Guidance of cryoablation
Renal cryoablation is usually guided with ultrasound,CT. It is suggested that the use of MRI as the primary imaging modality for this procedure has multiple advantages over CT or ultrasonography,as follows:

There is the ability with MRI to simultaneously image in sagittal and coronal planes. This allows accurate determination of probe position in the mass.
MRI offers a superior tissue contrast and spatial resolution as compared to CT or US. no ongoing radiation that occurs with CT use.
Technically, a superior image quality as compared to ultrasound and additionally is able to image distal to the ice ball that cannot occur with ultrasound secondary to the acoustic shadowing effect of the ice ball.
Intraoperative image guidance requires high soft-tissue contrast resolution and real volumetric visualization that MR provides.
Monitoring of ice ball formation is additionally enhanced with MRI.

Safety of cryoablation to kidneys

A lot of experimental studies show that cryoablation is no negative effects to non-cancerous tissue and function of kidneys. The size of a renal cryolesion contracts over time. While on postoperative day 8 a large central area of coagulative necrosis surrounded by a narrow zone of sublethal injury is observed, at 3 months, the area of necrosis is completely absorbed and replaced by fibrosis. In a porcine study involving healthy kidneys, a macroscopic decrease in size of the renal cryolesion by 42% at day 7, 52% at day 30,and complete resorption of the lesion by day 90 (16)was noted.

Functional impact is determined by the amount of renal parenchyma ablated by the ice-ball.The selective destruction of target areas under precise intraoperative monitoring has been essential to preserve normal renal parenchyma. In a solitary kidney canine model (baseline serum creatinine 0.6-0.9 mg/dL), creation of a cryolesion (mean diameter 3.2
cm) resulted in a transient elevation of serum creatinine on postoperative day 2 (1.0-1.9 mg/dL), and a final serum creatinine of 1.0-1.5 mg/dL by day 28 (19). When renal cryoablation was performed bilaterally in the porcine model, mean serum creatinine levels at day 0, 1, 3, and 7 were 1.5, 2.3, 1.8, and 1.4 mg/dL, respectively (16).

Regarding the effect of the cryoinjury to the renal collecting system, an experimental study addressing this question has been recently presented by Sung et al. (39). In a porcine model, 18 kidneys were
submitted in vivo to intentional cryoinjury to the pelviocaliceal system under ultrasound and retrograde ureteropyelogram control, and the acute and long-term (3 months) sequelae were analyzed. After 1 month,
regrowth of normal urothelium was noted, with minimal scarring of the lamina propria and smooth muscle, while the adjacent parenchyma was replaced by fibrous scar. Ex-vivo retrograde pyelogram revealed
watertight healing of the caliceal system when no physical cryoprobe puncture injury to the renal pelvis was documented.

Renal cryoablation does not alter renal vein or renal arterial temperatures as well. Perlmutter et al. created renal cryolesions with a probe tip temperature of -147.7°C. Baseline renal artery and renal vein temperatures were 35.3°C and 34.9°C, respectively. Following cryoablation, mean renal artery and vein temperatures were 35.4°C and 34.5°C, respectively (38,40). A study showed that systemic (esophageal) temperature during renal cryoablation in a porcine model was noted to decrease only by 1°F to 3°F (16).

Future horizons
Longterm oncologic adequacy still needs to be documented before its widespread use recommendation, although recent results are promising. The followings should be paid a great attention:

Clinical and radiologic follow-up of these patients will be critical for determining local recurrence and the cancer-specific survival rate following renal cryoablation.

Although experimental data suggest adequate healing of the cryodamaged pelviocaliceal system, central tumors still constitute a contraindication for cryoablation.

Development of entirely percutaneous techniques make it possible to treat selected posteriorly located tumors.

Further development of three-dimensional ultrasound and MRI-compatible cryoprobes may allow improved imaging of the

acute and chronic renal cryolesion, establishing another
minimally invasive alternative for selected cases in an outpatient basis.

Conclusion

For patients with small (<4 cm) renal cell carcinomas, open partial nephrectomy offers comparable survival rates and preserves more renal function than radical nephrectomy. Because an increasing number of renal tumors are discovered incidentally, a less invasive nephron-sparing alternative treatment would be attractive to patients and urologists. With the development of supercooled minimally invasive cryodelivery systems and the availability of reliable real-time sonographic monitoring, laparoscopic or percutaneous renal cryoablation with ultrasound,CT or MRI guidance has proven to be technically feasible with minimal morbidity for patients with renal cancer. Currently, both renal cryoablation is being investigated as a minimally invasive alternative to open partial nephrectomy for the treatment of patients with small (<4 cm) unilateral localized renal cell carcinomas.

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Figure Laparoscopic renal cryoablation:1. Identify the lesion;2. Cryoablationneedles placed inside the lesion;3. Monitoring ice ball growth with real-time ultra-sound guidance;4. Lesion completely engulfed in ice

References
Erick M. Remer1, Jonathan C. Hale1, Charles M. O'Malley1, Karen Godec1 and Inderbir S. Gill2 Sonographic Guidance of Laparoscopic Renal Cryoablation AJR 2000; 174:1595-1596

Rukstalis DB ; Khorsandi M ; Garcia FU ; Hoenig DM ; Cohen JK Clinical experience with open renal cryoablation.Urology. 2001; 57(1):34-9

Lee DI, McGinnis DE, Feld R, Strup SE.Retroperitoneal laparoscopic cryoablation of small renal tumors: intermediate results. Urology. 2003 Jan;61(1):83-8.

Phelan MW, Perry KT, Gore J, Schulam PG.Laparoscopic partial nephrectomy and minimally invasive nephron-sparing surgery. Curr Urol Rep. 2003;4(1):13-20.

(Allaf ME, Varkarakis IM, Bhayani SB, Inagaki T, Kavoussi LR, Solomon SB.Pain control requirements for percutaneous ablation of renal tumors: cryoablation versus radiofrequency ablation--initial observations. Radiology. 2005 ;237(1):366-70.)

Kodama Y, Abo D, Sakuhara Y, Sawada A, Watanabe Y, Funakubo M, Shimizu T, Miyasaka K.MR-guided percutaneous cryoablation for bilateral multiple renal cell carcinomas.Radiat Med. 2005 Jun;23(4):303-7.

1. Smith SJ, Bosniak MA, Megibow AJ, Hulnick DH, Horii SC, Raghavendra BN.Renal cell carcinoma:earlier discovery and increased detection.Radiology 1989;170: 699-703.
2. Lerner SE.Editorial comment. Urology 1998;52: 33-4.
3. Zincke H, Dechet CB, Blute ML. Needle biopsy of solid renal masses. J Urol 1998;159: 169.
4. Bosniak MA, Krinsky GA, Waisman J.Management of small
incidental renal parenchymal tumors by watchful waiting in selected patients based on observation of tumor growth rates. J Urol 1996;155: 574 A.
5. Butler BP, Novick AC, Miller DP, Campbell SA, Licht MR. Management of small unilateral renal cell carcinomas: radical versus nephron-sparring surgery. Urology 1995;45: 34-41.
6. Licht MR, Novick AC.Nephron sparing surgery for renal cell carcinoma. J Urol 1993;149: 1-7.
7. Bird HM: James Arnott, MD (Aberdeen) 1797-1883.A pioneer in refrigeration analgesia. Anesthesia 1949;4: 10-7.
8. Gage AA.Cryosurgery in the treatment of cancer.Surg Gynecol Obstel 1992;174: 73-92.
9. Bush IM, Santoni E, Lieberman PH, Cahan WG,Whitmore WF.Some effects of freezing the rat kidney in situ. Cryobiology 1964;2:
163-70.
10. Breining H, Helpap B, Minderjahan A,Lumberpoulos S.Histologic and autoradiographic findings in cryonecrosis of the liver and kidney. Cryobiology 1974;11: 519-25.
11. Helpap B, Groules V, Lange O, Breining H,Lymberopoulos S. Morphologic and cell kinetic investigations of the spleen after repeated in situ freezing of liver and kidney. Pathol Res Pract,
1979;164: 167-77.
12. Sindelar WF, Javadpour N, Bagley DH.Histological and ultrastructural changes in rat kidney after cryosurgery. J Surg Oncol, 1981;18: 363-79.
13. Barone GW, Rodgers BM: Morphologic and functional effects of renal cryoinjury. Cryobiology 1988;25: 363-71.
14. Onik GM, Reyes G, Cohen JK, Porterfield B.Ultrasound characteristics of renal cryosurgery.Urology 1993; 42: 212-5.
15. Stephenson RA, King D, Rohr RL.Renal cryoablation in a canine model. Urology 1996;47: 772-76.
16. Gill IS, Matamoros A, Heffron TG, Miller C,Fidler M, Grune MT.Laparoscopic renal cryoablation.J Urol 1997;157: 210.
17. Chosy SG, Nicety SO, Lee FT, Warner T.Thermosensor-monitored renal cryosurgery in swine: predictors of tissue necrosis. J Urol 1996;157:250.
18. Nakada SY, Lee FT, Jr., Warner T, Chosy SG,Moon TD.
Laparoscopic cryosurgery of the kidney in swine: a comparison of puncture and contact techniques. J Urol 1996;157: 401.
19. Campbell SC, Krishnamurthy V, Chow G, Hale J, Myles J, Novick AC.Renal cryosurgery: experimental evaluation of treatment parameters.Urology 1998;52: 29-34
20. Uchida M, Imaide Y, Sugimoto K, Uehara H,Watanabe H. Percutaneous cryosurgery for renal tumors. Br J Urol 1995;745: 132.
21. Delworth MG, Pisters LL, Fornage BD, von Eschenbach AC.Cryotherapy for renal cell carcinoma and angiomyolipoma. J Urol 1996;155: 252-5.
22. Gill IS, Novick AC, Soble JJ, Sung GT, RemerE, Hale J, O’Malley C.Laparoscopic renal cryoablation: initial clinical series. Urology 1998;52:543-51.
23. Rodriguez R, Bishoff JT, Chen RB, Marshall FF.Renal ablative cryosurgery in select patients with peripheral renal masses. J Urol 1998;159: 151
24. Gage AA, Baust J. Mechanisms of tissue injury in cryosurgery. Cryobiology 1998;37: 171-186, 1998.
25. Mazur P: Cryobiology: the freezing of biological systems. Science, 1970;68: 939-949.
26. Lovelock JE: The mechnaism of the protective action of glycerol against hemolysis by freezing and thawing. Biochem Biophys Acta 1953;17: 28-36.
27. Bellman S, Ray JA.Vascular reactions after experimental
cold injury. Angiology 1956;7: 339-67.
28. Rubinsky B, Pegg DE. A mathematical model for the freezing process in biological tissue. Proc R Soc Lond [Biol] 1988;234: 343-58.
29. Baust J, Gage AA, Ma H, Zhang CM.Minimally invasive cryosurgery: technological advances.Cryobiology 1997;34: 373-84.
30. Saliken J, Cohen J, Miller R, Rothert M: Laboratory evaluation of ice around a 3 mm Accuprobe. Cryobiology 1995;32: 285-95.
31. Agustinowicz S, Gage A: Temperature and cooling rate variations during cryosurgical probe testing.Int J Refrig 1985;8: 198-208.
32. Neel H, Ketcham A, Hammond W. Requisites for successful cryogenic surgery of cancer. Arch Surg 1971;102: 45-8.
33. Tatsutani K, Rubinsky B, Onik G, Dahiya R.Effect of thermal variables on frozen human primary prostatic adenocarcinoma cells. Urology 1996;48: 441-7.
34. Shinohara K, Presti JC, Connolly JA, Matthies S, Lindenfield S, Carroll PR.Cryosurgery vs.Radical prostatectomy for localized prostate cancer:comparison of cost and quality of life
changes with treatment. J Urol 1996;155: 452A.
35. Nakada SY, Lee FT Jr., Warner T, Chosy SG, Moon TD: Laparoscopic cryosurgery of the kidney in the porcine model: an acute histologicalstudy. Urology 1998;51:161-6.
36. Soble JJ, Gill IS, Novick AC, Sung GT, Oto A,Hale J, OMalley CM, Remer EM: Ultrasound and MRI characteristics of renal cryolesions (submitted).
37. Orihuela E, van Sonnenberg E, Motamedi M,Bell B, Warren M: Thermodynamics of human renal cell cancer during cyrotherapy. J Endourol 1998;12: S87.
38. Long JP, Faller GT. Percutaneous cryoablation of the kidney in a porcine model. Cryobiology 1999;38: 89-93.
39. Remer E, Sung GT, Meraney A, Novick A,Skacel M, Gill IS.Effect of intentional cryoinjury to the renal collecting system. J Urol 2000;163: 113.
40. Perlmutter A, Schulsinger DA, Sosa RE, MarionD, Baughn Jr., ED. The effect of renal cryoablation on the renal parenchyma and renal
vasculature temperature. J Urol 1998;159: 152.
41. Shingleton WB, Sewell P, Jackson MS.Renal tumor cryoablation utilizing interventional magnetic resonance imaging (IMRI). J Urol 2000;163: 155.
42. de Jode M, Vale J, Gedroyc MW.MR-guided laser thermoablation of inoperable renal tumors in an open-configuration interventional MR scanner:preliminary clinical experience in three cases. J Magn Reson Imaging 1999;10: 545-549.
43. Sulman A, Resnick M, Oefelein M, Lewin JS.MRI-guided radiofrequency interstitial thermal ablation of renal tumors: a minimally invasive alternative to traditional surgical approaches. J
Urol 2000;163: 7.
44. Pavlovich C, Wood BJ, Choyke PL, Lyneham W,Walther MM.Radiofrequency interstitial thermal ablation (RITA) of small renal tumors in von hippel lindau disease. J Urol 2000;163: 8.
45. Savage S, Gill IS.Renal tumor ablation: energybased technologies. World J Urol, (In press).
46. Gill IS, Novick AC: Renal cryosurgery. Urology 1999;54: 215-9.
47. Rodriguez R, Chan DY, Bishoff JT, Kavoussi L,Choti M, Marshall FF. Renal ablative cryosurgery in selected patients with peripheral
renal masses. Urology 2000;55: 25-30.
48. Gill IS, Novick AC, Schweizer D, Chen RN,Hobart M, Meraney A, Sung GT, Hale J, RemerEM. Laparoscopic renal cryoablation in 32 patients(submitted).
49. Levin H, Meraney A, Novick A, Gill IS. Needle biopsy histology of renal tumors 3-6 months after laparoscopic renal cryoablation. J Urol, 2000;163:153.
50. Bishoff JT, Chan DY, Chen RB, Lee B, Kuszyk B, Huso D, Marshall FF, Kavoussi LR.Laparoscopic renal cryoablation: acute and longterm
clinical, radiolographic, and pathological effects in animal and human studies. J Endourol 1998;12: S88.
51. Hollister WR, Mathew AJ, Baust JG, van Buskirk RG: Effects of freezing on cell viability and mechanisms of cell death in a human prostate cancer cell line. Molecular Urology 1998;2: 13-8.