Search

Cryosurgery of liver lesions is becoming increasingly accepted for the ablation of liver tumors. Attempts at laparoscopic cryosurgery have been very limited and often need to be converted to open laparotomy due to the complexity of the procedure.Seven domestic pigs were anesthetized, and 17 small (0.7 cm mean diameter) tumor mimicking agar "lesions" were percutaneously placed in the liver. Two small subcostal incisions ( approximately 2.0 cm) were placed, and an endocavitary ultrasound transducer (with a 2. 4-mm cryoprobe mounted on it) was placed on the liver surface. Lesions were localized and directly punctured with one or two cryoprobes under ultrasound guidance, and a single 15-min freeze was undertaken. The animals were then killed, and their livers were removed and serially sectioned.Total time for probe placement was approximately 10 min after incisions had been made. Animals tolerated the procedure well and all survived until they were killed. No intraabdominal complications were detected at exploration. Mean cryolesion dimensions were 3.0 cm (single probe) and 3.3 cm (dual probe) (p0.05). Positive margins were detected in one lesion treated with a single probe, and in none of the lesions treated with dual probes. Mean margins were 0.9 cm: 1.2 cm for the single probe and dual probe techniques, respectively. Liver surrounding control agar lesions demonstrated a thin rim of necrosis, approximately 0.5 mm wide.We conclude that minilaparotomy is an effective, safe, and simple method for performing hepatic cryosurgery in this animal model. This minimally invasive technique may benefit a subset of patients with lesions in accessible locations. Lesions in posterior locations may not be as amenable to this technique due to deterioration of ultrasound image quality in the far field.

Porcine urinary tract epithelium responds to systemic infections with an increase in mucin secretion that has been called “mucinous degeneration.” Here we describe similar changes in calyceal, pelvic, and ureteric urothelium in pig renal tracts 14 days after local embolism and cryoablation (four kidneys) or cryoablation alone (six kidneys). Large mucin-filled vacuoles surrounded by smaller cytoplasmic vesicles were present in the affected urothelium but were rare in calyceal urothelium of normal kidneys. These mucinous vacuolar changes were proportional to the extent of renal necrosis and could be important in the pathologic responses of xenotransplanted pig kidneys.

We compared color Doppler velocity sonography and color Doppler energy sonography for the diagnosis of spermatic cord torsion in a canine model and determined the degree of torsion necessary to acutely halt testicular blood flow.Spermatic cord torsion was created in five dogs by exposing and rotating the ipsilateral testis 0 degree, 180 degrees, 270 degrees, 360 degrees, 450 degrees, and 540 degrees. Detorsion followed. The testicles were scanned at each torsion stop using both color Doppler velocity sonography and color Doppler energy sonography. Doppler parameters were optimized (by phantom and test scans) and maintained at a tolerable noise level throughout the experiment. Readers who were unaware of the degree of torsion compared flow in the rotated and contralateral control testes.Flow became undetectable by color Doppler velocity sonography and color Doppler energy sonography at 450 degrees in four of five cases and at 540 degrees in one of five cases. We found no significant difference between the velocity and the energy techniques for detecting this absence of flow (p.05, Wilcoxon test). We found a significant difference in degree of flow for both techniques when comparing controls and all degrees of torsion combined (p.006, Mann-Whitney test), but significance was achieved at lesser degrees of torsion with the velocity technique than with the energy technique (180 degrees and 360 degrees, respectively, Wilcoxon test).Color Doppler energy sonography was not significantly more sensitive than color Doppler velocity sonography for the diagnosis of spermatic cord torsion in this model. Complete occlusion of arterial inflow occurred at 450-540 degrees of torsion.