Extent Of Coagulation Necrosis Research Articles

Balloon-assisted laser application for endoscopic treatment of biliary stricture.

Malignant biliary stricture is a ductal narrowing of the bile duct that is often diagnosed at an advanced stage, leading to difficulty in resection. The current study aims to evaluate the feasibility of endobiliary laser treatment by quantifying the extent of coagulative necrosis in tissue under various conditions. Ex vivo and in vivo porcine bile tissues were used for endobiliary laser treatment to characterize the dosimetric responses of the tissue to various treatment conditions: power level, irradiation time, and number of treatments. 532 nm laser light was coupled with a balloon-integrated diffusing applicator (BDA) to deliver the laser light endoscopically for tissue coagulation. The coagulated regions (maximum length and depth) in the treated tissues were evaluated histologically for quantitative comparison. Dosimetric evaluations with ex vivo liver tissue confirmed that both maximum length and depth of coagulative necrosis (CN) increased with applied power and number of treatments. Ex vivo bile duct tests demonstrated that BDA-assisted laser treatment at 10 W for 12 s reproducibly yielded CN with a length of 5.8 ± 1.6 mm and a depth of 0.6 ± 0.2 mm. In vivo tests presented that endoscopic laser treatment using the BDA created CN on the ductal surface without any perforation. Microscopic examinations revealed that a dense inflammatory cell infiltration and eosinophilic area in the in vivo treated tissue. The extent of CN in the in vivo tissue was 40% longer and 120% deeper (length: 8.1 ± 0.7 mm; depth: 1.3 ± 0.2 mm), compared to that in the ex vivo tissue. BDA-assisted laser treatment could be a feasible option for endoscopic treatment of biliary stricture with uniform ablation at the circumference of bile duct. Further in vivo studies will be performed in a large number of stricture-developed porcine models to examine both efficacy and safety of the proposed endobiliary laser treatment for clinical translations.

Preliminary experience using high intensity focused ultrasound for treating liver metastasis from colon and stomach cancer

Purpose: To determine the efficacy and safety from our preliminary results of using high intensity focused ultrasound (HIFU) to treat liver metastasis from colon and stomach cancer.Materials and methods: Ten patients with liver metastasis from colon cancer and three from stomach cancer underwent HIFU under general anesthesia. HIFU was performed using an extracorporeal, ultrasound-guided focused system. Complications during the study, extent of coagulative necrosis at two-week follow up, and evidence of tumor on further follow up were analyzed. Patients were divided into four categories: (I) complete ablation with no evidence of recurrence on follow up; (II) apparent complete ablation of target mass with new foci of disease in the target organ or distant malignancy and no local tumor progression; (III) local tumor progression after apparent complete ablation; (IV) partial ablation.Results: Mean follow-up period was 22 weeks in the colon cancer group and 58 weeks in the stomach cancer group. The sum of total lesion size was between 1.8 cm and 21.4 cm (mean: 8.4 cm ± 6.7 cm) for the colon cancer group and between 1.7 and 16.3 cm (mean: 8.8 cm ± 7.3 cm) for the stomach cancer group. In the colon cancer group, one patient was categorized as category I, one as category II, three as category III, and the remaining five as category IV. The stomach cancer group showed two patients as category I, and one as category II.Conclusion: For treating liver metastasis from colon and stomach cancer HIFU seems safe but its efficacy is questionable. Further research is warranted.

Double radiofrequency ablation is more extensive with a spherical zone shape compared to single ablation in a pig liver model

We compared the duration of ablation and the area of coagulation necrosis between a single ablation method (SAM) and a double ablation method (DAM) with a 'multitined expandable' electrode (LeVeen 2 cm) for radiofrequency ablation (RFA) using pig liver. In the SAM group, ablation was completed after the first roll-off. In the DAM group, an additional ablation was performed to achieve a second roll-off. The comparison was made of the time required for roll-off and the extent of coagulation necrosis between the both groups. The Ellipticity index (EI) quantitatively describes the shape of the general RF ablation zone in the axial plane. There was no statistically significant difference in the interval until the first roll-off between both groups (SAM group: 100.7+/-24.7 seconds vs DAM group: 103.2+/-37.7 seconds, P=0.43). In the DAM group, the interval from the start of the additional ablation until the second roll-off was 154.0+/-86.9 seconds, longer than the interval for the first roll-off (P=0.023). The extent of coagulation necrosis was significantly more extensive in the DAM group (axial diameter, mean+/-SD, 26.2+/-2.8mm) x (maximal diameter: 29.3+/-1.6mm) x (minimal diameter: 26.5+/-3.6mm) compared to the SAM group with (23.0+/-3.3mm) x (23.7+/-3.1mm) x (20.0+/-2.5mm), respectively. Although there was no statistically significant difference in the EI between both groups, macroscopically, the shape of coagulation necrosis tended to be non-spherical in the SAM group and spherical in the DAM group. The DAM with a 'multitined expandable' electrode was more extensive with a spherical zone shape compared to the SAM.

Percutaneous radiofrequency ablation for inoperable non-small cell lung cancer and metastases: preliminary report.

To assess technical feasibility, efficacy, and complications of percutaneous computed tomography (CT)-guided transthoracic radiofrequency (RF) ablation for treating inoperable non-small cell lung cancer (NSCLC) and lung metastases. Twenty-six patients with 27 NSCLCs and four patients with five lung metastases underwent RF ablation with cooled-tip electrodes with CT guidance. Patients were not candidates for surgery because of either advanced-stage disease (n = 20) and/or comorbid processes (n = 4) or refusal to undergo surgery (n = 6). The procedure was performed with the intent to cure in 10 (33%) patients with stage I tumors and as palliative therapy in 20 (67%) patients. Contrast material-enhanced CT was performed immediately, 1 month, and then every 3 months after RF ablation to evaluate the response to therapy. Time to death for each patient was calculated with Kaplan-Meier analysis, and the effect of tumor size and the extent of coagulation necrosis on time to death were determined. Complete necrosis was attained in 12 (38%) of 32 lesions; partial (>50%) necrosis, in the remaining 20 (62%) lesions. Tumor size was a major discriminator in achieving complete necrosis. Complete necrosis was attained in all six (100%) tumors smaller than 3 cm but only in six (23%) of 26 larger tumors (P <.05). Mean survival of patients with complete necrosis (19.7 months) was significantly better than that of patients with partial necrosis (8.7 months) (P <.01). There were three (in 30 patients, 10%) major complications, which included acute respiratory distress syndrome, and two pneumothoraces that required thoracostomy. RF ablation appears to be a safe and promising procedure for the treatment of inoperable NSCLC and metastases.

Morphological and functional integrity of precision-cut rat liver slices in rotating organ culture and multiwell plate culture: effects of oxygen tension.

We examined the maintenance of functional and morphological integrity of precision-cut rat liver slices cultured in various incubation systems and conditions for 72 h. Slices were incubated (37 degrees C) for 6, 24, 48, and 72 h in supplemented Williams E medium in 6-well plastic culture plates on a gyratory shaking platform (WPCS) or in a rotating organ culture system (ROCS) using 5% CO2--95% air (WPCS/air or ROCS/air) or 5% CO2--70% O2--25% N2 (WPCS/O2 or ROCS/O2). Biochemical and functional parameters of slices maintained in WPCS/air or WPCS/O2 were almost totally inhibited after 24 h, in keeping with the extensive and diffuse coalescing coagulative necrosis typical of post-ischemic injury affecting almost all the slice surface after 48 h. As compared to freshly isolated slices, slices maintained in ROCS/air for 72 h showed stable ATP and GSH content, increased protein synthesis, and a slight steady decrease in GST activity, while ATP and GST activity remained stable and protein synthesis and GSH content increased in slices incubated in ROCS/O2 for 72 h. The extent of coagulative necrosis was markedly lower in longitudinal sections from slices incubated for 72 h in ROCS/O2 than in ROCS/air. Transversal sections from slices kept in ROCS/air for 72 h showed a thick central band of necrotic cells edged by two peripheral layers of viable hepatocytes, whereas most of the slice was composed of viable hepatocytes lined by two thin layers of necrotic cells after 72 h in ROCS/O2. ROCS/O2 emerged as the system best preserving the histological and functional integrity of rat liver slices in long-term culture.

Histopathological Evaluation of Laser Thermocoagulation in the Human Prostate: Optimization of Laser Irradiation for Benign Prostatic Hyperplasia

We have previously shown in a canine prostate model that a noncontact low power neodymium: YAG laser regimen of 15 watts for 180 seconds yields a larger volume of coagulation necrosis than the currently recommended high power regimen of 50 watts for 60 seconds. These 2 regimens have not yet been compared in humans. The objective of this study was to evaluate histopathologically the thermocoagulation effect of these 2 laser regimens in the human prostate and the effect of the spatial distribution of the laser lesions on the extent of coagulation necrosis. The study was conducted in 10 patients undergoing radical prostatectomy or cystoprostatectomy. The laser treatment was given transurethrally 1 hour before removal of the specimen. There were no fractures of the prostate. The coagulation necrosis did not reach the peripheral zone and it was minimal in areas rich in fibromuscular tissue, such as the bladder neck. At times, nodular benign prostatic hyperplasia was unaffected. A 4-quadrant treatment in the same plane often yielded small nonconfluent lesions. Confluent lesions in the same plane yielded approximately 30 percent greater depth of coagulation necrosis, which was achieved when 3 or 4 lesions were created on each side of the prostate (per single transverse plane). Likewise, coagulation necrosis observed with 15 watts for 180 seconds was approximately 40 percent greater than that noted with the 50 watts for 60 seconds regimen. Our findings suggest that noncontact laser prostatectomy is a safe procedure that can be improved by modifying the laser regimen and the spatial distribution of lesions.

Histologic evaluation of rat mammary tumor necrosis by interstitial Nd:YAG laser hyperthermia.

The extent of coagulative necrosis caused by interstitial laser hyperthermia was measured for different quantities of laser energy in a rat mammary tumor model. Continuous wave Nd:YAG laser at a power level of 5 W was focused onto a 600 mu diameter bare tip quartz fiber and placed inside a 19-gauge needle, which allowed the para-axial flow of normal saline at 1 cc/min. A microthermocouple soldered to the outside of the probe continuously provided the interstitial temperature. After the probe was inserted into the tumor, it was withdrawn as laser energy was administered at a rate sufficient to maintain the temperature within 42-45 degrees C. Tumors were excised after 48 hours, fixed in formalin, cut in 3 mm slices, and the coagulated surfaces measured microscopically. Laser fiber transmission loss was 1% per 1,000 J of laser energy and the average time required to coagulate 1 cc of tumor was 2 minutes. There was a statistically significant correlation between the volume of tumor necrosis and the level of laser irradiation (r = 0.71, P less than 0.001). It is concluded that the described technique is an efficient method of tumor coagulation by interstitial laser hyperthermia and proportionally larger volumes of necrosis are created with greater amounts of laser energy.

Experimental electrocoagulation of dog esophageal and duodenal mucosa

Lesions produced in the dog esophagus and duodenal bulb using the Cameron-Miller electrocoagulation probe and coagulator unit were evaluated as to size of alteration and depth of coagulation necrosis. The safesl electrocoagulation settings were 4,5 to 5.5 for 1 to 3 seconds in the duodenal bulb and were 4.5 to 6.0 for 1 second in the esophagus. The size of ulcers did not correlate with depth of injury. Hyperamylasemia was noted after duodenal electrocoagsulation hut did not correlate with extent of coagulation necrosis.