5-minute Thaw Research Articles

SAT312 CT-guided Cryoablation Of Hereditary Pheochromocytoma

Abstract Disclosure: E. Griffing: None. B. Reading: None. F. De Luca: None. Background: Guidelines surrounding the management of hereditary pediatric pheochromocytomas (PHEO) are lacking. This is the first report of a pediatric patient with bilateral hereditary PHEO treated with right adrenalectomy and computed tomography (CT) percutaneous-guided cryoablation (CRA) of the left-sided lesion.Clinical case: A previously healthy 15 years-old male presented to a tertiary care hospital with a months-long history of episodic chest pain, flushing, shortness of breath, diaphoresis, and tremulousness. Paternal family history was significant for PHEO and brain stem hemangioblastoma in grandmother and PHEO in the great-grandfather. Targeted familial mutation analysis of the von Hippel-Lindau tumor suppressor gene was positive for pathogenic mutation c.500G>A (p.R167Q). Plasma free normetanephrine level was 4,625 pg/mL (nl: <145 pg/mL), while free metanephrines were normal. Magnetic-resonance imaging of the abdomen visualized a 4.4 x 3.4 x 5.3 cm right adrenal mass and a 1.4 x 1.4 x 1.4 cm left adrenal mass, consistent with bilateral PHEO. He underwent right adrenalectomy after initiation of alpha-receptor blockade and later addition of beta-receptor blockade due to heart rates in the 150’s. After discussion with parents, it was decided to observe the smaller left-sided adrenal lesion. Plasma free normetanephrines initially decreased to 338 pg/mL, but then increased to 507 pg/mL five months post-operatively. Six months after surgery, due to the persistence of hypertension with systolic blood pressure in the 140’s as well as tachycardia with heart rates in the 150’s, he underwent CT-guided CRA of the left-sided PHEO. A 12-minute freeze, 5-minute thaw, and 10-minute freeze, followed by an active thaw were performed. There was an increase in blood pressure during the initial thaw with systolic blood pressure in the 230s, accompanied by bradycardia to the 30s, treated with nitroprusside, phentolamine, and increased sedation. He required continuation of nitroprusside infusion for five hours post-procedure. He was discharged the following day with normal blood pressure and heart rate. He was able to completely wean off anti-hypertensive medications within one month and symptoms of chest pain and tachycardia resolved. In the four years since his procedure, he has not had a recurrence of PHEO nor development of adrenal insufficiency. Plasma free normetanephrines and metanephrines have remained within normal limits. Conclusion: Percutaneous ablation of hereditary PHEO has not been reported before in the pediatric population and may represent a novel treatment strategy that reduces the risk of adrenal insufficiency. Presentation: Saturday, June 17, 2023

Breast Cancer Cryoablation: Assessment of the Impact of Fundamental Procedural Variables in an In Vitro Human Breast Cancer Model.

Introduction:Breast cancer is the most prominent form of cancer and the second leading cause of death in women behind lung cancer. The primary modes of treatment today include surgical excision (lumpectomy, mastectomy), radiation, chemoablation, anti-HER2/neu therapy, and/or hormone therapy. The severe side effects associated with these therapies suggest a minimally invasive therapy with fewer quality of life issues would be advantageous for treatment of this pervasive disease. Cryoablation has been used in the treatment of other cancers, including prostate, skin, and cervical, for decades and has been shown to be a successful minimally invasive therapeutic option. To this end, the use of cryotherapy for the treatment of breast cancer has increased over the last several years. Although successful, one of the challenges in cryoablation is management of cancer destruction in the periphery of the ice ball as the tissue within this outer margin may not experience ablative temperatures. In breast cancer, this is of concern due to the lobular nature of the tumors. As such, in this study, we investigated the level of cell death at various temperatures associated with the margin of a cryogenic lesion as well as the impact of repetitive freezing and thawing methods on overall efficacy.Methods:Human breast cancer cells, MCF-7, were exposed to temperatures of −5°C, −10°C, −15°C, −20°C, or −25°C for 5-minute freeze intervals in a single or repeat freeze-thaw cycle. Samples were thawed with either passive or active warming for 5 or 10 minutes. Samples were assessed at 1, 2, and 3 days post-freeze to assess cell survival and recovery. In addition, the modes of cell death associated with freezing were assessed over the initial 24-hour post-thaw recovery period.Results:Exposure of MCF-7 cells to −5°C and −10°C resulted in minimal cell death regardless of the freeze/thaw conditions. Freezing to a temperature of −25°C resulted in complete cell death 1 day post-thaw with no cell recovery in all freeze/thaw scenarios evaluated. Exposure to a single freeze event resulted in a gradual increase in cell death at −15°C and −20°C. Application of a repeat freeze-thaw cycle (dual 5-minute freeze) resulted in an increase in cell death with complete destruction at −20°C and near complete death at −15°C (day 1 survival: single −15°C freeze/thaw = 20%; repeated −15°C freeze/thaw = 4%). Analysis of thaw interval time (5 vs 10 minute) demonstrated that the shorter 5-minute thaw interval between freezes resulted in increased cell destruction. Furthermore, investigation of thaw rate (active vs passive thawing) demonstrated that active thawing resulted in increased cell survival thereby less effective ablation compared with passive thawing (eg, −15°C 5/10/5 procedure survival, passive thaw: 4% vs active thaw: 29%).Conclusions:In summary, these in vitro findings suggest that freezing to temperatures of 25°C results in a high degree of breast cancer cell destruction. Furthermore, the data demonstrate that the application of a repeat freeze procedure with a passive 5-minute or 10-minute thaw interval between freeze cycles increases the minimal lethal temperature to the −15°C to −20°C range. The data also demonstrate that the use of an active thawing procedure between freezes reduces ablation efficacy at temperatures associated with the iceball periphery. These findings may be important to improving future clinical applications of cryoablation for the treatment of breast cancer.

Percutaneous CT–Guided Cryoablation of the Salivary Glands in a Porcine Model

PurposeTo evaluate the imaging, histologic changes and safety of computed tomography (CT)–guided cryoablation of the parotid glands in a porcine model. Materials and MethodsUnilateral CT–guided parotid gland cryoablation was performed in 5 juvenile miniature pigs. The ablated parotid glands underwent 2 cycles of 10-minute freeze and 5-minute thaw using three 17-g cryoprobes. The animals were monitored daily for complications including pain, frostbite, infection, and sialocele or fistula formation. Follow-up CT was performed at 6 weeks postcryoablation. Pathologic evaluation was performed on 2 of the ablated parotid glands. ResultsAll cryoablations in 5 right parotid glands, with 3 sites in each gland, were technically successful. No symptoms suggestive of facial nerve damage were observed during 6-week follow-up. One pig developed an infected sialocele, which was treated with percutaneous drainage and oral antibiotic therapy. No CT evidence of sialocele or other abnormality was identified at the 6-week follow-up in all pigs. Histologic evaluation was performed on 2 of the parotid gland specimens, 1 with the treated sialocele, and 1 of the remaining pigs without sialocele. Both glands demonstrated postprocedural intraglandular lymph nodes and reactive changes without evidence of sialocele or abscess on histopathology. ConclusionsCryoablation of parotid glands was technically feasible in a porcine model. Only 1 pig developed sialocele, which was successfully treated. Further research is warranted to determine the potential use of salivary gland cryoablation to treat patients with drooling.

Experimental Study on Pulmonary Cryoablation in a Porcine Model of Normal Lungs

Objective of this study is to analyze the range of necrosis after using different freezing times and freeze-thaw cycles during percutaneous cryosurgery, in order to create a suggestion for optimizing the technique for lung cryoablation. Six healthy pigs were given a CT scan and histological investigation after percutaneous cryosurgery on both lungs. Three cryoprobes were inserted into both the left and right lungs of each pig, respectively. Cryoablation was performed with two cycles of an active 10-minute freezing using argon in the left lung, each freeze followed by an active 5-minute thaw using helium. In contrast to the left lung cryoablation, the right lungs underwent 3 cycles of freeze/thaw, the first and second cycles consisted of an active 5-minute freezing followed by an active 5-minute thaw, and the third cycle of 10-minute freezing and an active 5-minute thaw. The CT imaging change of an ice ball was continuously observed. The lung tissues were taken 4 hours after cryosurgery on day 3 and on day 7, respectively, for pathological observation. One pig presented acute symptoms including bradycardia and hypothermia 30 minutes after cryosurgery, and died 4 hours after the freezing, and the other 5 pigs experienced a weak condition for 4-6 hours and then exhibited relatively normal behavior and regularly took food. The freezing area (ice ball) on CT imaging during the cryoablation grew gradually in relation to the increase over time, and along with the increase in the number of cycles. The size of the cryolesion on the lung samples became larger than the ice ball during cryosurgery, regardless of whether 2 or 3 freeze-thaw cycles were performed. The area of necrosis histologically gradually increased for the time being. Percutaneous cryosurgery on the lung can achieve complete ablation of targeted tissue. Three freeze-thaw cycles are recommended, and the range of cryoablation may not be mandatory "1 cm safe border" during cryosurgery in order to avoid harming the organ and tissue which is close to the cancer. Correct use of the technique is especially important to treat the lung neoplasms, especially the malignant tumors, which are close to the heart and large vessels.

Are Multiple Cryoprobes Additive or Synergistic in Renal Cryotherapy?

To investigate the relationship between multiple cryoprobes was investigated to determine whether they work in an additive or synergistic fashion in an in vivo animal model because 1.47 mm (17-gauge) cryoprobes have been introduced to the armamentarium for renal cryotherapy. Laparoscopic-guided percutaneous cryoablation was performed in both renal poles of 3 pigs using 3 IceRod cryoprobes. These 12 cryolesions were compared with 12 cryolesions using a single IceRod cryoprobe. Each cycle consisted of two 10-minute freeze cycles separated by a 5-minute thaw. The iceball volume was measured using intraoperative ultrasonography. The kidneys were harvested, and cryolesion surface area was calculated. The lesions were fixed and excised to obtain a volume measurement. Statistical analysis was used to compare the single probe results multiplied by 3 to the multiple probe group for iceball volume, cryolesion surface area, and cryolesion volume. The iceball volume for the first freeze cycle for the single cryoprobe multiplied by 3 was 8.55 cm3 compared with 9.79 cm3 for the multiple cryoprobe group (P=.44) and 10.01 cm3 versus 16.58 cm3 for the second freeze (P=.03). The cryolesion volume for the single cryoprobe multiplied by 3 was 11.29 cm3 versus 14.75 cm3 for the multiple cyroprobe group (P=.06). The gross cryolesion surface area for the single cryoprobe multiplied by 3 was 13.14 cm2 versus 13.89 cm2 for the multiple probe group (P=.52). The cryolesion created by 3 simultaneously activated 1.47-mm probes appears to be larger than that of an additive effect. The lesions were significantly larger as measured by ultrasonography and nearly so (P=.06) as measured by the gross cryolesion volume.

Optimal Freeze Cycle Length for Renal Cryotherapy

To our knowledge the optimal freeze cycle length in renal cryotherapy is unknown. Ten-minute time based freeze cycles were compared to temperature based freeze cycles to -20C. Laparoscopic renal cryotherapy was performed on 16 swine. Time based trials consisted of a double 10-minute freeze separated by a 5-minute thaw. Temperature based trials were double cycles of 1, 5 or 10-minute freeze initiated after 1 of 4 sensors indicated -20C. A 5-minute active thaw was used between freeze cycles. Control trials consisted of cryoneedle placement for 25 minutes without freeze or thaw. Viability staining and histological analysis were done. There was no difference in cellular necrosis between any of the temperature based freeze cycles (p = 0.1). Time based freeze cycles showed more nuclear pyknosis, indicative of necrosis, than the 3 experimental freeze cycles for the renal cortex (p = 0.05) but not for the renal medulla (p = 0.61). Mean time to -20C for freeze cycle 1 was 19 minutes 10 seconds (range 9 to 46 minutes). In 4 of 21 trials (19%) -20C was never attained despite freezing for 25 to 63 minutes. There was no difference in immediate cellular necrosis among double 1, 5 or 10-minute freeze cycles. Cellular necrosis was evident on histological analysis for trials in which -20C was attained and in freeze cycles based on time alone. With a standard 10-minute cryoablation period most treated parenchyma 1 cm from the probe never attained -20C. Cell death appeared to occur at temperatures warmer than -20C during renal cryotherapy.

THE EFFECTS OF INTENTIONAL CRYOABLATION AND RADIO FREQUENCY ABLATION OF RENAL TISSUE INVOLVING THE COLLECTING SYSTEM IN A PORCINE MODEL

Ablative techniques for the treatment of urological malignancy are gaining acceptance and they are likely to become more widely used in clinical practice. Indications and limitations of the technologies are still evolving. In a porcine model we evaluated the safety and efficacy of cryotherapy and radio frequency ablation (RFA) of cortical and deep renal tissue. In 11 swine argon gas based cryoablation or RFA of renal tissue adjacent to the collecting system was performed using a laparoscopic or percutaneous approach. Lesions created in renal units 30 days or 2 hours prior to harvest were termed chronic or acute. Using single or multiple 17 gauge cryoneedles or 3.0 mm cryoprobes and 2 freeze-thaw cycles (10-minute freeze and 5-minute thaw) 13 acute and 10 chronic cryolesions were made. Using a single 16 gauge umbrella-shaped RFA probe and 2 heating cycles to maximum impedance 13 acute and 4 chronic RFA lesions were made. Gross and microscopic tissue analysis was performed to assess lesion size and renal parenchymal, collecting system and arterial effects. Acute cryolesion size estimation by laparoscopic or transcutaneous ultrasound (US) was compared with pathological lesion size. Acute cryolesions on hematoxylin and eosin staining demonstrated uniform coagulative necrosis of renal parenchyma and chronic cryolesions demonstrated uniform necrosis with fibrous scar formation. Interlobar artery (adjacent to renal pyramid) preservation occurred in 7 of 13 acute and 5 of 9 chronic cryolesions. Urothelial architecture was preserved in 8 of 13 acute and 7 of 9 chronic cryolesions. Acute and chronic RFA lesions demonstrated indeterminate necrosis on hematoxylin and eosin staining, although triphenyl tetrazolium chloride staining of gross specimens confirmed necrosis most definitively in renal cortex. Interlobar artery preservation occurred in 6 of 13 acute and 3 of 4 chronic RFA lesions. Urothelial architecture was preserved in 1 of 13 acute and 2 of 4 chronic RFA lesions. Acute cryolesion dimensions measured by laparoscopic US equaled or underestimated lesion size measured grossly in all 6 cases. Lesion dimensions measured by transcutaneous US equaled or underestimated true lesion size in 3 of 6 cases. In 3 of 6 lesions transcutaneous US overestimated true lesion size by 20%, 76% and 260%, respectively. Renal cortical tissue can be effectively destroyed by cryoablation or RFA. However, treatment of deep parenchymal lesions with either modality may result in incomplete ablation. Cryosurgery but not RFA spares the collecting system in an acute setting. However, healing or regrowth of the urothelium may occur with time after RFA. Laparoscopic US is more accurate for cryolesion monitoring than transcutaneous US.

The Acute Effects of Transthoracic Cryoablation on Normal Lung Evaluated in a Porcine Model

Purpose Percutaneous transthoracic cryoablation of lung parenchymal tumors offers a potentially less invasive alternative to thoracoscopic tumor resection. In the present study, we investigated the feasibility of transthoracic cryoprobe insertion into the lung parenchyma. Description Cryoablation was performed in porcine lung through a thoracotomy. A 2-mm diameter cryoprobe was inserted to a depth of 3 cm from the pleura. Cryoablation was performed as one or two cycles of 15-minute freeze followed by 5-minute thaw. Bleeding time and amount, and air leakage pressure from the insertion site was measured and compared between cycles. Evaluation The bleeding time and amount significantly increased, and air leakage pressure significantly decreased with two cycles of cryoablation compared with one cycle. Histologically, the primary finding in the cryolesion was localized pulmonary hemorrhage. Conclusions Bleeding time, bleeding amount, and air leakage from the insertion site after two cycles (453 ± 202 s, 1.3 ± 0.6 g, and 28 ± 12 cm H 2O, resectively) were considered unlikely to cause acute serious complications. Although long-term studies are needed, the present study provides support for transthoracic cryoablation.

Laparoscopic cryosurgery of the kidney in the porcine model: an acute histological study

Objectives. To verify histologically whether cryosurgery of the kidney can be accomplished reproducibly without injuring adjacent structures, using a combination of ultrasound and laparoscopic guidance. Materials and Methods. Six kidneys from three domestic female farm pigs were utilized in the study. Under general anesthesia and after obtaining pneumoperitoneum, the lower pole of the kidney was mobilized laparoscopically and the ureter and adjacent bowel were protected with saline-soaked gauze. Two 3.8 mm-cryoprobes were placed percutaneously into the lower pole and cryoablation was carried out under laparoscopic and ultrasound guidance using a double-freeze technique (10-minute freeze and 5-minute thaw cycles to a probe temperature of −185°C to −196°C) in five kidneys (one control). The kidneys, adjacent ureter and bowel were harvested acutely, and macroscopic, histologic, and electron microscopic evaluation of all specimens was performed. Results. Macroscopically, clear margins of cryodestruction corresponded with the ultrasound images of the iceball. In all five treated kidneys, reproducible cell death corresponding to visible margins of cryodestruction were verified histologically. Cell death was further corroborated by electron microscopy. Adjacent structures (ureter and bowel) were sectioned and no significant damage was noted. Blood pressure remained constant throughout the procedure. A crack in the renal parenchyma of one kidney was noted during the thaw phase; at harvest that animal was found to have an intraperitoneal hemorrhage. Conclusion. Combined laparoscopic and ultrasound-guided cryoablation of the lower pole of the kidney can be accomplished reproducibly in the porcine model without injury to adjacent structures.

Needle Implantation Cryoprobes: Biophysical and Thermal Characteristics

There has been increased recent interest in hepatic cryosurgery for primary and metastatic tumors in the liver. This has been realized through technological advances in intraoperative ultrasound monitoring and cryoprobe technology. Purpose-designed needle implantable cryoprobes have been developed to freeze deep-seated tumors in the hepatic parenchyma. However, the biophysical and thermal characteristics of these implantable cryoprobes have not been studied. This article discusses the biophysical and thermal characteristics of recently developed high-efficiency, implantable needle cryoprobes that can be used laparoscopically. The cryolesion was formed along the whole length of the cryoprobe implanted into hepatic tissue. It was cylindrical in shape and extended 8 mm beyond the tip of the cryoprobe after 20 minutes of freezing. During this period of freezing, the volume of the cryolesion increased in a near constant manner, but the diameter increased in a logarithmic fashion. In addition, single-cycle freezing produced a larger cryolesion than a dual freeze cycle interrupted by a 5-minute thaw. Further, increasing the length of cryoprobe implantation increased the volume of the cryolesion, although the diameter was smaller. The rate of cooling at the tip of the cryoprobe was also faster with partial implantation of the cryoprobe than with complete implantation. The cooling rate varied vertically along the length of the cryoprobe, as well as horizontally from the cryoprobe.

Needle Implantation Cryoprobes: Biophysical and Thermal Characteristics.

There has been increased recent interest in hepatic cryosurgery for primary and metastatic tumors in the liver. This has been realized through technological advances in intraoperative ultrasound monitoring and cryoprobe technology. Purpose-designed needle implantable cryoprobes have been developed to freeze deep-seated tumors in the hepatic parenchyma. However, the biophysical and thermal characteristics of these implantable cryoprobes have not been studied. This article discusses the biophysical and thermal characteristics of recently developed high-efficiency, implantable needle cryoprobes that can be used laparoscopically. The cryolesion was formed along the whole length of the cryoprobe implanted into hepatic tissue. It was cylindrical in shape and extended 8 mm beyond the tip of the cryoprobe after 20 minutes of freezing. During this period of freezing, the volume of the cryolesion increased in a near constant manner, but the diameter increased in a logarithmic fashion. In addition, single-cycle freezing produced a larger cryolesion than a dual freeze cycle interrupted by a 5-minute thaw. Further, increasing the length of cryoprobe implantation increased the volume of the cryolesion, although the diameter was smaller. The rate of cooling at the tip of the cryoprobe was also faster with partial implantation of the cryoprobe than with complete implantation. The cooling rate varied vertically along the length of the cryoprobe, as well as horizontally from the cryoprobe.