A Comparative Study of Ablation Boundary Sharpness After Percutaneous Radiofrequency, Cryo-, Microwave, and Irreversible Electroporation Ablation in Normal Swine Liver and Kidneys.

PURPOSE: To compare ablation boundary sharpness after percutaneous radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA) and irreversible electroporation (IRE) ablation in normal swine liver and kidney. MATERIALS AND METHODS: Percutaneous CT-guided RFA (n = 5), CA (n = 5), MWA (n = 5) and IRE (n = 5) were performed in the liver and kidney of four Yorkshire pigs. Parameters were chosen to produce ablations 2-3 cm in diameter with a single ablation probe. Contrast-enhanced CT imaging was performed 24 h after ablation, and animals were killed. Treated organs were removed and processed for histologic analysis with hematoxylin and eosin, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Three readers independently analyzed CT, H&E and TUNEL stained images of the ablation boundary to delineate regions of (1) viable cells, (2) complete necrosis or (3) mixture of viable and necrotic cells which was defined as the transition zone (TZ). The width of TZ was compared across the techniques and organs. RESULTS: Ablations appeared as non-contrast-enhancing regions on CT with sharp transition to enhancing normal tissue. On TUNEL stained slides, the mean width (µm) of the TZ after MWA was 319 ± 157 in liver and 267 ± 95 in kidney, which was significantly lower than RFA (811 ± 477 and 938 ± 429); CA (452 ± 222 and 700 ± 563); and IRE (1319 ± 682 and 1570 ± 962) (all p < 0.01). No significant differences were observed between the organs. CONCLUSION: Under similar conditions, the width of the TZ at the ablation boundary varies significantly between different ablation techniques.

Normal Porcine Ureter Retains Lumen Wall Integrity but Not Patency Following Catheter-Directed Irreversible Electroporation: Imaging and Histologic Assessment over 28 Days.

PURPOSE: To evaluate the effect of catheter-directed irreversible electroporation (IRE) on the integrity, patency, and function of the normal porcine ureter. MATERIALS AND METHODS: A catheter-mounted electrode was used to perform fluoroscopy-guided IRE in 8 healthy pigs. Two unilateral ablations (90 pulses at 2,000 V, 100 µs) were performed in each animal in the proximal and distal ureter. Serum creatinine measurements and contrast-enhanced computed tomography imaging were performed at 1, 7, 14, 21, and 28 days after IRE, and findings were compared with baseline values by Student t test. Two animals each were euthanized at 1, 7, 14, and 28 days after IRE for histologic assessment of treatment effects. Quantitative histologic analysis of regeneration and healing of the ureteral wall was graded on a five-point scale. RESULTS: IRE was successfully performed in all animals. Preservation of ureteral wall integrity was confirmed by the leakage-free passage of contrast medium in the treated ureter of all animals through the observation period. Ureteral strictures and associated renal pelvicaliceal dilation were observed in all animals by study days 7 (P = .005) and 14 (P = .007) and did not resolve by day 28. Urothelial recovery was observed in tissue samples from day 7, with progressive replacement of the tunica muscularis with granulation tissue. Despite extensive scarring of the tunica muscularis, full recovery of the urothelium was observed by day 28. CONCLUSIONS: The normal porcine ureter retains lumen wall integrity and function following catheter-directed IRE. Scarring of the tunica muscularis in the treated ureter results in stricture formation and reduction of lumen patency.

Nonthermal Ablation by Using Intravascular Oxygen Radical Generation with WST11: Dynamic Tissue Effects and Implications for Focal Therapy.

Purpose To examine the hypothesis that vascular-targeted photodynamic therapy (VTP) with WST11 and clinically relevant parameters can be used to ablate target tissues in a non-tumor-bearing large-animal model while selectively sparing blood vessels and collagen. Materials and Methods By using an institutional animal care and use committee-approved protocol, 68 ablations were performed in the kidneys (cortex and medulla) and livers of 27 adult pigs. Posttreatment evaluation was conducted with contrast material-enhanced computed tomography in the live animals at 24 hours. Immunohistochemistry was evaluated and histologic examination with hematoxylin-eosin staining was performed at 4 hours, 24 hours, and 7 days. Intravenous infusion of WST11 (4 mg per kilogram of body weight) was followed by using near-infrared illumination (753 nm for 20 minutes) through optical fibers prepositioned in target tissues by using a fixed template. Treated areas were scanned, measured, and statistically analyzed by using the Student t test and two-way analysis of variance. Results Focal WST11 VTP treatment in the liver and kidney by using a single optical fiber resulted in well-demarcated cylindrical zones of nonthermal necrosis concentrically oriented around the light-emitting diffuser, with no intervening viable parenchymal cells. The radius of ablated tissue increased from approximately 5 mm at 150 mW to approximately 7 mm at 415 mW (P < .01). Illumination through fiber triads at 1-cm separation resulted in confluent homogeneous necrosis. Patterns of acute injury within 24 hours were consistent with microcirculatory flow arrest and collagen preservation (demonstrated with trichrome staining). In the peripheral ablation zone, blood vessels at least 40 µm in diameter were selectively preserved and remained functional at 7 days. Ablated tissues exhibited progressive fibrosis and chronic inflammatory cell infiltrates. No histologic changes consistent with thermal injury were observed in blood vessels or collagen. The renal hilum and collecting system did not show treatment effect, despite treatment proximity. Conclusion WST11 VTP induces nonthermal tissue ablation in target tissue while preserving critical organ structures and bystander blood vessels within solid organs. (©) RSNA, 2016 Online supplemental material is available for this article.

The Prognostic Impact of a Positive Vascular Margin on pT3 Clear Cell Renal Cell Carcinoma.

PURPOSE: We examined the impact of positive vascular margins in patients with pT3 clear cell renal cell carcinoma. MATERIALS AND METHODS: After excluding patients with nonvascular positive margins, metastasis, lymph node involvement, neoadjuvant therapy or nonclear cell histology, we identified 224 patients with venous tumor invasion through our institutional database from 1999 to 2013. Kaplan-Meier analysis and log rank tests were used to evaluate whether positive vascular margins were associated with progression-free survival or cancer specific survival. RESULTS: There were 41 patients (18%) with a positive vascular margin. Margin status was directly related to the level of invasion (p <0.0001). Compared to the negative vascular margin group the positive group had a significantly worse progression-free survival (p=0.01) but not cancer specific survival (p=0.3). Similarly the level of vascular thrombus invasion was significantly associated with worse progression-free survival (p=0.02) but not cancer specific survival (p=0.4). The 3-year progression-free survival was worst with inferior vena cava invasion and best with segmental/muscular venous branch invasion (54%, 95% CI 34-70 vs 76%, 95% CI 64-85). Among patients with only main renal vein thrombus, vascular margin status was not associated with progression-free survival (p=0.5) or cancer specific survival (p=0.2). CONCLUSIONS: In patients with pT3N0/XM0 clear cell renal cell carcinoma positive vascular margins are associated with risk of disease progression. However, the risk of relapse associated with positive vascular margins is driven by the extent of vascular thrombus invasion. These findings suggest that the clinical significance of vascular margin status as currently defined in pT3 clear cell renal cell carcinoma is minimal.

Improved Intraoperative Visualization of Nerves through a Myelin-Binding Fluorophore and Dual-Mode Laparoscopic Imaging.

The ability to visualize and spare nerves during surgery is critical for avoiding chronic morbidity, pain, and loss of function. Visualization of such critical anatomic structures is even more challenging during minimal access procedures because the small incisions limit visibility. In this study, we focus on improving imaging of nerves through the use of a new small molecule fluorophore, GE3126, used in conjunction with our dual-mode (color and fluorescence) laparoscopic imaging instrument. GE3126 has higher aqueous solubility, improved pharmacokinetics, and reduced non-specific adipose tissue fluorescence compared to previous myelin-binding fluorophores. Dosing and kinetics were initially optimized in mice. A non-clinical modified Irwin study in rats, performed to assess the potential of GE3126 to induce nervous system injuries, showed the absence of major adverse reactions. Real-time intraoperative imaging was performed in a porcine model. Compared to white light imaging, nerve visibility was enhanced under fluorescence guidance, especially for small diameter nerves obscured by fascia, blood vessels, or adipose tissue. In the porcine model, nerve visualization was observed rapidly, within 5 to 10 minutes post-intravenous injection and the nerve fluorescence signal was maintained for up to 80 minutes. The use of GE3126, coupled with practical implementation of an imaging instrument may be an important step forward in preventing nerve damage in the operating room.

The unidirectional barbed suture for renorrhaphy during laparoscopic partial nephrectomy: Stanford experience.

PURPOSE: Using barbed suture represents a novel technical modification in the performance of minimally invasive partial nephrectomy. Our purpose of this study was to evaluate the safety and efficacy of this suture for renorrhaphy during laparoscopic partial nephrectomy (LPN). PATIENTS AND METHODS: Thirteen consecutive patients underwent LPN using V-Loc™ 180 (Covidien, Dublin, Ireland) suture, and a nonconsecutive control group of 24 patients, matched according to tumor size and R.E.N.A.L. nephrometry score, underwent LPN using absorbable polyglactin suture. All 37 patients underwent LPN performed by a single surgeon. Perioperative and postoperative indicators of morbidity, estimated blood loss, and warm ischemia time (WIT) were compared between the groups. RESULTS: Baseline characteristics including age, body mass index, American Society of Anesthesiologists score, tumor size, laterality, and R.E.N.A.L nephrometry score were identical between the groups. On multivariable analysis, there were no significant differences between the two groups with regard to operative time, estimated blood loss, transfusion rates, rates of surgical complications, and length of hospital stay. However, mean WIT was significantly shorter in the V-Loc group compared with the control group (24.5±5.3 minutes versus 31.9±8.9 minutes, P=.01). CONCLUSIONS: The use of V-Loc sutures for renorrhaphy during LPN is safe and feasible and, in our series, significantly reduces WIT. Further studies are needed to corroborate these findings, but these results indicate a promising development in reducing WIT during minimally invasive partial nephrectomy.

Methods for registration of magnetic resonance images of ex vivo prostate specimens with histology.

PURPOSE: To evaluate two methods of scanning and tissue processing to achieve accurate magnetic resonance (MR)-histologic correlation in human prostate specimens. MATERIALS AND METHODS: Two prostates had acrylic paint markers injected to define the plane of imaging and serve as internal fiducials. Each was placed on a polycarbonate plane-finder device (PFD), which was adjusted to align the imaging and cutting planes. Three prostates were aligned by use of a plane finder key (PFK), a polycarbonate plate that locks the specimen in a cylindrical carrier. Markers were injected for registration analysis. Prostates were imaged, then sectioned. Imaging software was used to create registration maps of the MR and histology images. Measurements between control points were made and compared. RESULTS: Accurate correlation was achieved between MR and histologic images. The mean displacement (MD) between the corresponding registration points using the PFD technique ranged from 1.11-1.38 mm for each section. The MD for all sections was 1.24 mm. The MD using the PFK technique ranged from 0.79-1.01 mm for each section, and the MD across all sections for the PFK was 0.92 mm. CONCLUSION: We describe two methods that can achieve accurate, reproducible correlation between MR imaging and histologic sections in human prostatectomy specimens.

Novel technique for management of distal ureter and en block resection of bladder cuff during hand-assisted laparoscopic nephroureterectomy.

OBJECTIVES: To report our experience with a novel flexible cystoscopic approach to excise the en block bladder cuff and juxtavesical ureter during hand-assisted laparoscopic nephroureterectomy. The optimal technique for excising the distal ureter and bladder cuff during nephroureterectomy continues to evolve. METHODS: Hand-assisted laparoscopic nephroureterectomy was performed in 6 patients. A hand-assist device and two 5 to 12-mm ports were placed in the mid and upper abdomen. Two 10-mm clips were placed on the proximal ureter to occlude it, and the kidney was resected in the usual fashion. An additional 5 to 12-mm port was placed in the midline between the umbilicus and symphysis pubis. The ureter was dissected down into the pelvis to the level of the bladder. Without repositioning the patient, a flexible cystoscope was inserted into the bladder and a 2-cm bladder cuff excised using a 5F electrode on cutting current, with coagulating current used as needed. The specimen was removed intact through the hand port. RESULTS: The mean time to resect the distal bladder cuff was 30 minutes (range 22 to 35). The mean estimated blood loss was 254 mL. The mean operating room time was 264 minutes, mean hospital stay 6.3 days, and mean time to a general diet 2.6 days. All patients underwent cystography at 7 to 10 days postoperatively, with no extravasation or diverticula. Cystoscopic and computed tomography follow-up demonstrated no evidence of recurrence. CONCLUSIONS: This technique allows for complete resection of the kidney, distal ureter, and a cuff of bladder, avoiding repositioning.

Reconstitution of lethally irradiated adult mice with dominant negative TGF-beta type II receptor-transduced bone marrow leads to myeloid expansion and inflammatory disease.

TGF-beta regulation of immune homeostasis has been investigated in the context of cytokine knockout (TGF-beta null) mice, in which particular TGF-beta isoforms are disrupted throughout the entire organism, as well as in B and T cell-specific transgenic models, but to date the immunoregulatory effects of TGF-beta have not been addressed in the context of an in vivo mouse model in which multi-isoform TGF-beta signaling is abrogated in multiple leukocyte lineages while leaving nonhemopoietic tissue unaffected. Here we report the development of a murine model of TGF-beta insensitivity limited to the hemopoietic tissue of adult wild-type C57BL/6 mice based on retroviral-mediated gene transfer of a dominant negative TGF-beta type II receptor targeting murine bone marrow. Unlike the lymphoproliferative syndrome observed in TGF-beta1-deficient mice, the disruption of TGF-beta signaling in bone marrow-derived cells leads to dramatic expansion of myeloid cells, primarily monocytes/macrophages, and is associated with cachexia and mortality in lethally irradiated mice reconstituted with dominant negative receptor-transduced bone marrow. Surprisingly, there was a notable absence of T cell expansion in affected animals despite the observed differentiation of most cells in the T cell compartment to a memory phenotype. These results indicate not only that TGF-beta acts as a negative regulator of immune function, but that lack of functional TGF-beta signaling in the myeloid compartment of adult mice may trigger suppression of lymphocytes, which would otherwise proliferate when rendered insensitive to TGF-beta.