Brunolf W. Lagerveld

Contrast-enhanced ultrasonography in the follow-up of cryoablation of renal tumours : a feasibility study

To determine whether evaluating perfusion patterns with contrast‐enhanced ultrasonography using contrast‐pulse sequence imaging (CPS; a new imaging method that enables selective visualization of perfusion) is possible at different times after cryoablation of renal tumours, and to describe the characteristics of CPS in a small group of patients.

Immediate Effect of Kidney Cryoablation on Renal Arterial Structure in a Porcine Model Studied by Imaging Cryomicrotome

PURPOSE Injury to blood microvessels has a crucial role in effective cryoablation for renal masses. We visualized vascular injury induced by a clinically applied cryoablation instrument and established a microvascular diameter threshold for vascular damage. MATERIALS AND METHODS In 5 anesthetized pigs 1 kidney each was exposed and 3, 17 gauge cryoneedles were inserted in 1 pole. Tissue was exposed to freezing for 2 x 10 minutes with a 10-minute thaw between freezes. After nephrectomy the arteries were injected with fluorescence dyed casting material and the kidney was frozen to -20C and cut in 40 to 60 micron slices in the imaging cryomicrotome, where fluorescent images of the cutting plane of the bulk were obtained. This resulted in a 3-dimensional image of the arterial tree that was segmented, resulting in unbranched vessel segments. Histograms were constructed with the total segment length per diameter bin plotted as function of diameter. RESULTS The ablated zone was sharply demarcated on fluorescent and normal light images. Mean +/- SD diameter at the peak of the histogram from control areas was 152.4 +/- 5.3 micron. Compared to control areas the peak diameter of ablated areas was shifted to a larger diameter by an average of 25.4 +/- 2.6 micron. CONCLUSIONS Immediate renal cryoablation injury destroys arteries smaller than 180 micron. Branching structures of larger arteries remain anatomically intact and connected to vascular structures in surrounding tissue.

Vascular fluorescence casting and imaging cryomicrotomy for computerized three-dimensional renal arterial reconstruction

Authors from the Netherlands studied the use of a casting technique, cryomicrotome imaging and three‐dimensional computer analysis to visualise and reconstruct the arterial anatomy in a porcine kidney model. They found that this could be done satisfactorily to a resolution of 50 µm.

Gradient Changes in Porcine Renal Arterial Vascular Anatomy and Blood Flow After Cryoablation

PURPOSE We quantified temporal changes in vascular structure and blood flow after cryosurgery of the porcine kidney in vivo. MATERIALS AND METHODS We studied 5 groups of 4 kidneys each with a survival time of 20 minutes, 4 hours, 2 days, and 1 and 2 weeks after cryoablation, respectively. Before harvesting the kidneys, fluorescently labeled microspheres were administrated in the descending aorta. After harvest the kidney and its vasculature were casted with fluorescently dyed elastomer, frozen and processed in an imaging cryomicrotome to reveal the 3-dimensional arterial branching structure and microsphere distribution. In regions of interest vessels were segmented by image analysis software and histograms were constructed to reveal the total summed vessel length as a function of diameter. A characteristic diameter of the ablated area was measured. RESULTS The 20-minute survival group histograms showed a significant shift of the peak to larger diameters (p<0.002), indicating that smaller vessels were destroyed. Microsphere density was decreased to 2% in the ablated region but not in the nonablated border zone, depending on the remaining crater crossing larger vessels. After 2 weeks neither vessels nor microspheres were left in the ablated area, which had shrunk by about 40% in diameter. Study limitations are the lack of histological confirmation and the use of normal rather than cancerous tissue. CONCLUSIONS Larger vessels remain patent just after ablation and transport blood to the border of the ablation crater but perfusion within the crater is halted instantly. Characteristic crater diameter increases initially but decreases thereafter. Destruction of vessels and tissue is complete 2 weeks after cryoablation.

Oncological outcomes and complication rates after laparoscopic-assisted cryoablation: a European Registry for Renal Cryoablation (EuRECA) multi-institutional study

To assess complication rates and intermediate oncological outcomes of laparoscopic‐assisted cryoablation (LCA) in patients with small renal masses (SRMs).

The performance of 17-gauge cryoprobes in vitro.

In cryosurgery it is crucial that the performance of cryoprobes is predictable and constant. In this study we tested the intra- and interneedle variation between 17-gauge cryoprobes in two homogeneous mediums. Also, a multiprobe setup was tested. Cryoprobe performance was defined as the time it takes one cryoprobe to lower the temperature from 0 to −20 °C as measured by four thermosensors each at 3 mm distance from the cryoprobe. In agar eight cryoprobes were tested during six freeze cycles, and in gel four cryoprobes during four freeze cycles; each freeze cycle in a different cup of agar or gel. Using more accurate ‘bare’ thermosensors three cryoprobes were tested in gel during two freeze cycles. A multiprobe configuration with four cryoprobes was tested during two freeze cycles in both agar and gel. Statistical analyses were done using ANOVA for repeated measures. There was no significant intraneedle variation, whereas both in agar and gel there was a significant interneedle variation (p<0.05). Mean performance in gel was better than in agar (p<0.001). Also, there was a significant variation between the four thermosensors (p< 0.001). Using bare thermosensors mean performance was 2.7 times faster compared to measurements by regular thermosensors (p<0.001). In a multiprobe configuration, overall performance seems less variable and more reproducible compared to a single cryoprobe. In conclusion, the performance of cryoprobes differs depending on the medium and measuring device used. Cryoprobes deliver reproducible freeze cycles, although there is variation between different cryoprobes. In a multiprobe configuration performance seems less variable.

Preoperative Aspects and Dimensions Used for Anatomical Score Predicts Treatment Failures in Laparoscopic Cryoablation of Small Renal Masses.

OBJECTIVES To determine the potential of the preoperative aspects and dimensions used for anatomical (PADUA) classification score as a predictive tool in relation to residual unablated tumor and disease-free survival (DFS) following laparoscopy-assisted cryoablation (LCA) of small renal masses. PATIENTS AND METHODS A multi-institutional cohort of 212 patients with biopsy-verified T1N0M0 renal malignancies treated with LCA between August 2005 and September 2014 were retrospectively investigated with respect to oncologic outcomes. RESULTS The preoperative PADUA score was found to be low (6-7 points) in 70 patients (33%), moderate (8-9 points) in 86 patients (40.6%), and high (10-14 points) in 56 patients (26.4%). The mean PADUA score was significantly higher in cases (n = 11) with residual unablated tumor (10.4 vs 8.1, p < 0.001) and in cases (n = 8) with local tumor recurrence (9.8 vs 8.1, p < 0.001) at a mean follow-up of 37 (95% confidence interval: 34-40) months. The estimated 2-, 3-, and 5-year DFS for patients with a moderate PADUA score was 96%, 94%, and 94% compared with 95%, 87%, and 81%, respectively, for patients with a high PADUA score (log-rank, p = 0.003). The PADUA score did not predict overall survival. CONCLUSION The PADUA score significantly predicts residual unablated tumor and DFS following LCA. Further studies are needed to validate the efficacy of the PADUA score in relation to oncologic outcomes following ablative procedures.

Crioablación laparoscópica de las pequeñas masas renales

Resumen Objetivos Revision del estado actual de la crioblacion de las pequenas masas renales y descripcion preliminar de la serie del AMC. Material y metodos Busqueda bibliografica (PubMed/Medline/Embase) y analisis de las series mas importantes. La presente serie incluye 13 pacientes portadores de masas renales unicas de pequeno tamano tratados mediante crioablacion laparoscopica con sondas ultrafinas (1,5 mm diametro). El seguimiento postoperatorio se realizo mediante CT y/o RMI trimestralmente durante el primer ano y semestralmente durante el segundo. Resultados No existen estudios randomizados comparando la crioablacion de las masas renales de diametro ≤ 4 cm con la cirugia parcial o radical. La tasa de complicaciones es baja y la tasa de recurrencia o persistencia, a corto plazo, minima salvo en una serie de crioablacion guiada por la imagen (8%). El diametro tumoral maximo tratado en nuestra serie es de 3,2 cm. Los tumores se abordaron retro o transperitonealmente dependiendo de su situacion. El tiempo quirurgico medio fue de 208 minutos (106-379) y el tiempo medio de exposicion a temperaturas inferiores a -20oC en la periferia tumoral fue de 10 minutos. A tiempo medio de seguimiento de 8 meses no se objetivo recurrencia tumoral. Conclusion La crioablacion laparoscopica o guiada mediante imagen de las masas renales de pequeno tamano parece una alternativa aceptable si bien el tiempo medio de seguimiento es todavia corto en la mayoria de las series.

Renal cryoablation: Multidisciplinary, collaborative and perspective approach

Renal cryoablation is becoming an established treatment option for small renal masses. It allows preservation of renal function without compromising cancer control. The technique has evolved considerably since it was first reported using liquid nitrogen over 20 years ago. We describe the modern technique for both laparoscopic and image guided renal cryoablation. Renal cryoablation is performed either laparoscopically or percutaneously depending on tumour characteristics. Common features include biopsy of the mass, protection of adjacent organs, and the use of compressed argon gas for freezing and helium for thawing. Dynamic monitoring is used to ensure adequate treatment. The shape of the iceball can be modified by adding extra needles or changing their positions. A double freeze/thaw is necessary for confident ablation of all cancer cells. The laparoscopic approach includes exposure of the tumour and may involve extensive mobilisation of the kidney. Laparoscopic ultrasound is essential for correct localisation of the tumour, needle placement, and monitoring the treatment. A Temperature probe is placed at the edge of the tumour to record treatment temperature. The percutaneous approach is typically performed with CT guidance. Adjacent organs can be protected by injecting saline or carbon dioxide. Early imaging is helpful to detect or rule out incomplete treatment. Post-operative follow-up is structured at specific intervals (e.g. 3, 6, 12 months then annually) and perhaps tailored or modified based on the degree of suspicion of inadequate treatment.

Laparoscopic vs Percutaneous Cryotherapy for Renal Tumors: A Systematic Review and Meta-Analysis.

BACKGROUND Cryoablation has emerged as an alternative to the more invasive partial nephrectomy for small renal masses. The approach can be carried out by two techniques, either laparoscopic cryoablation (LCA) or percutaneous cryoablation, (PCA) with CT guidance. We aimed to compare between the two procedures. MATERIALS AND METHODS A systematic review and meta-analysis was conducted, including studies comparing the two techniques. Outcomes included incomplete ablation, late local recurrence, cancer-specific survival, procedure time, transfusion rates, hospital stay, and complications. RESULTS A total of 1475 patients were included, 788 patients in the laparoscopic group and 687 patients in the percutaneous group. There was statistical difference favoring the laparoscopic group with regard to having less incomplete ablation (p = 0.0008) and higher cancer-specific survival patients (p = 0.04). However, there was longer hospital stays in the LCA group (p < 0.00001) and was found to be more costly than the PCA group. There was significantly more Clavien-I complications in the PCA group (p = 0.001) and more Clavien-III complications in the LCA group (p = 0.001). Otherwise, there were no differences in any other outcome parameter. CONCLUSION LCA was found to have less incomplete tumor ablation rates and higher cancer-specific survival rates, however, higher hospitalization time, more major complications (Clavien III), and was costlier compared with PCA.