The effect of hepatic inflow occlusion on laparoscopic radiofrequency ablation using simulated tumors

Navigated laparoscopic microwave ablation of tumour mimics in pig livers: a randomized ex-vivo experimental trial

BACKGROUND

In order to efficiently perform laparoscopic microwave ablation of liver tumours precise positioning of the ablation probe is mandatory. This study evaluates the precision and ablation accuracy using the innovative laparoscopic stereotactic navigation system CAS-One-SPOT in comparison to 2d ultrasound guided laparoscopic ablation procedures.

METHODS

In a pig liver ablation model four surgeons, experienced (n = 2) and inexperienced (n = 2) in laparoscopic ablation procedures, were randomized for 2d ultrasound guided laparoscopic or stereotactic navigated laparoscopic ablation procedures. Each surgeon performed a total of 20 ablations. Total attempts of needle placements, time from tumor localization till beginning of ablation and ablation accuracy were analyzed.

RESULTS

The use of the laparoscopic stereotactic navigation system led to a significant reduction in total attempts of needle placement. The experienced group of surgeons reduced the mean number of attempts from 2.75 ± 2.291 in the 2d ultrasound guided ablation group to 1.45 ± 1.191 (p = 0.0302) attempts in the stereotactic navigation group. Comparable results could be observed in the inexperienced group with a reduction of 2.5 ± 1.50 to 1.15 ± 0.489 (p = 0.0005). This was accompanied by a significant time saving from 101.3 ± 112.1 s to 48.75 ± 27.76 s (p = 0.0491) in the experienced and 165.5 ± 98.9 s to 66.75 ± 21.96 s (p < 0.0001) in the inexperienced surgeon group. The accuracy of the ablation process was hereby not impaired as postinterventional sectioning of the ablation zone revealed.

CONCLUSION

The use of a stereotactic navigation system for laparoscopic microwave ablation procedures of liver tumors significantly reduces the attempts and time of predicted correct needle placement for novices and experienced surgeons without impairing the accuracy of the ablation procedure.

A novel very simple laparoscopic hepatic inflow occlusion apparatus for laparoscopic liver surgery

BACKGROUND

Control of bleeding is extremely important for laparoscopic liver resection. We introduce a new and operationally simple laparoscopic hepatic inflow occlusion apparatus (LHIOA) and its successful application in laparoscopic surgery for patients with cirrhosis.

METHODS

The self-designed LHIOA was constructed using a tracheal catheter (7.5#) and infusion set. The tracheal catheter and infusion set were trimmed to 30 and 70 cm, to serve as an occlusion tube and occlusion tape, respectively. After establishment of pneumoperitoneum, the occlusion tape was inserted to encircle the hepatoduodenal ligament. The occlusion tube was then introduced and the ends of the occlusion tape were pulled out of it to occlude the hepatic inflow. Under intermittent vascular occlusion with the LHIOA, the liver parenchyma was transected using an ultrasonic scalpel and monopolar electrocoagulation. Outcomes of the application of the LHIOA in hepatocellular carcinoma patients with cirrhosis (LHIOA group, n = 46) were compared with patients undergoing laparoscopic hepatectomy without LHIOA (non-LHIOA group, n = 46), using one-to-one propensity case-matched analysis.

RESULTS

The LHIOA effectively occluded the hepatic inflow while showing no damage to the hepatoduodenal ligament. The time required for presetting the LHIOA is 6.8 ± 0.6 min. The conversion rate in the non-LHIOA group was 13.0% while there was no conversion in the occlusion group (P < 0.001). The median blood loss of patients in the LHIOA group (60 ml, range 50-200 ml) was significantly less than that of patients in the non-LHIOA group (250 ml, range 100-800) (P < 0.001). Transfusion was required in 8 patients in the non-LHIOA group while no transfusion was required in the LHIOA group. The median operative time in the LHIOA group (157 min, range 80-217 min) was significantly shorter than that in the non-LHIOA group (204 min, range 105-278 min) (P < 0.001).

CONCLUSIONS

The new LHIOA is effective, safe, and simple. It can significantly reduce conversion rate, blood loss, and operative time. It facilitates laparoscopic liver resection and is recommended for use.

Transarterial chemoembolization using drug eluting beads and subsequent percutaneous MR-guided radiofrequency ablation in the therapy of intermediate sized hepatocellular carcinoma

OBJECTIVE

To evaluate safety, efficacy, survival and recurrence-free survival of transarterial chemoembolization (TACE) with drug eluting (DC) beads combined with MR-guided radiofrequency (RF) ablation for the treatment of hepatocellular carcinomas (HCC) larger than 3 cm.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board. 20 patients (69.6 years ± SD 8.8) with HCC underwent DC Bead TACE and subsequent MR-guided RF ablation. Treatment interval varied between 5 and 15 days. Mean HCC diameter was 39 mm ± SD 7 mm (range 31-50mm). Rates of recurrence-free survival and overall survival were estimated using the Kaplan-Meier method.

RESULTS

Technical success rate, primary and secondary technical effectiveness rate were 100%, 90% and 95%, respectively. Local tumour progression developed in one patient. Cumulative survival rates at 1, 3 and 5 years were 90% (Confidence Interval [CI]: 67%-97%), 50% (CI: 29%-70%), 27% (CI: 11%-51%) respectively. Median survival time was 37.4 months. During follow up (mean: 39.1 months ± SD 22.4; range 5-84 months), tumour progression in untreated liver developed in 14 cases. Cumulative recurrence-free survival rates at 1, 3 and 5 years were 48% (CI: 27-69%), 16% (5-39%), 16% (5-39%) respectively. Median recurrence-free survival time was 10.7 months. One major complication occurred due to misdiagnosed local recurrence.

CONCLUSION

In conclusion, we demonstrated that MR-guided RF ablation with subsequent DC Bead TACE is safe and effective in local tumour control in patients with intermediate sized HCC.

Thermal tumor ablation therapy for colorectal cancer hepatic metastasis

Surgical resection for colorectal hepatic metastases (CRHM) is the preferred treatment for suitable candidates, and the only potentially curative modality. However, due to various limitations, the majority of patients with CRHM are not candidates for liver resection. In recent years, there has been an increasing interest in the role of thermal tumor ablation (TTA) as a component of combined resection-ablation strategies, staged hepatic resections, or as standalone adjunct treatment for patients with CRHM. Thus, ablative approaches have expanded the group of patients with CRHM that may benefit from liver-directed treatment strategies.

Outcome after laparoscopic radiofrequency ablation of technically resectable colorectal liver metastases

BACKGROUND

There continues to be controversy surrounding the appropriate use of radiofrequency ablation (RFA) for the treatment of colorectal liver metastases (CRLM). This study analyzes outcomes data of CRLM patients who underwent laparoscopic RFA. Outcomes of patients determined to be technically resectable were compared to patients with unresectable disease.

METHODS

Data from all patients with CRLM who underwent laparoscopic RFA between 1996 and 2006 were retrospectively reviewed. A blinded independent hepatobiliary-trained surgical oncologist reviewed preoperative diagnostic imaging studies to determine resectability. Outcomes data for patients with disease deemed anatomically resectable and unresectable were analyzed and compared. Survival was calculated by the Kaplan-Meier method. The log rank test was performed to assess significance in survival.

RESULTS

A total of 113 patients who underwent laparoscopic RFA for CRLM were identified. Twelve patients who underwent concurrent hepatic resection were excluded. Of the remaining patients, 64 were determined to have disease that was be technically resectable and 37 unresectable as a result of tumor number and/or distribution. Median and 5-year survival of the potentially resectable group was 4.3years and 48.7%, compared to 2.2 years and 18.4% in the unresectable group (P = 0.002). Median disease-free survival in the resectable group was 15.0 months, compared to 16.4 months in the unresectable group (P = 0.796). No postoperative mortality was reported in the technically resectable group, and the rate of major complications was 3.1%.

CONCLUSIONS

Laparoscopic RFA of resectable CRLM can produce comparable long-term survival to hepatic resection in carefully selected patients, with favorable morbidity and mortality.

The safety and efficacy of ablative techniques adjacent to the hepatic vasculature and biliary system

Ablative techniques may provide an alternative to resection in treating awkwardly placed hepatic malignancy adjacent to major vascular and biliary structures. The heat-sink effect may reduce efficacy adjacent to major vascular structures. Vascular occlusion improves efficacy but is associated with increased vascular and biliary complications. The safety and efficacy of ablation in these situations remain to be defined. Further studies comparing both safety and efficacy are needed.

Open surgical is superior to percutaneous access for radiofrequency ablation of hepatic metastases

PURPOSE

This study was designed to determine the best approach to radiofrequency ablation (RFA) in the liver.

METHODS

From a total of 41 procedures, 37 patients with 47 tumors were treated with RFA for metastatic disease. Indications included colorectal cancer (n=28, 68%), neuroendocrine tumors (n=2, 5%), gynecological primaries (n=4, 10%), pancreatic/duodenal cancer (n=2, 5%), and miscellaneous entities (n=5, 12%). Mean follow-up period was 18 (median, 18) months. All ways of approach to RFA were applied: percutaneous was chosen in 17 (41.5%), laparoscopic and hand-assisted laparoscopic in 5 (12.2%), and open surgical in 19 cases (46.3%), and in 10 cases, RFA was combined with hepatic resection. The average maximum tumor size was 2.3 (range, 0.8-6) cm, and the mean number of nodules treated per patient in a single session was 1.3 (range, 1-3).

RESULTS

Overall survival was 59.5% at 2 years, recurrence-free 2-year survival was 12.6%, local tumor recurrence rate was 34%, and overall recurrence was 75.6%. Local tumor recurrence and disease-free survival were significantly improved in the open surgically treated patients compared with the percutaneous treatment group (15.8% [n=3] vs. 58.8% [n=10] and 11.5 vs. 7.9 months, p<0.01 [chi2 test] and p<0.05 [log-rank test], respectively).

CONCLUSIONS

Open surgical approach is superior to percutaneous access for RFA in metastatic hepatic disease.

A family of new instruments for laparoscopic radiofrequency ablation of malignant liver lesions

Primary and secondary liver tumors may be treated with radiofrequency ablation (RFA) to improve tumor control and to increase patient survival. Lesions are punctured percutaneously or during open surgery. However, not all of the lesions are accessible percutaneously due to their localization: Adjacent structures could be endangered and/or the treatment would cause severe pain. Open surgery is an option in these cases but significantly more invasive. Laparoscopic RFA (LRFA) is an additional possibility in those cases: It offers a better access to difficult lesions than via the percutaneous route and is also less invasive than open surgery. The precision of targeting, however, in LRFA still has to be improved. In an in-vivo feasibility study we used a tumor mimic model in pigs to examine the applicability of laparoscopic RFA in combination with laparoscopic ultrasound using a set of dedicated new instruments to handle the RFA probe. To increase the ablation volume, the liver blood flow was reduced performing a Pringle maneuver. It is demonstrated that this set of specially designed instruments is indeed applicable and facilitates the targeting of liver lesions of any localization. Accordingly, it could significantly enlarge the applicability of LRFA.

Effect of vascular occlusion on radiofrequency ablation of the liver in a rabbit VX2 tumor model

AIM: To evaluate the effects of vascular occlusion of hepatic blood flow on radiofrequency lesion and liver injury in rabbit VX2 tumor model.

METHODS: Rabbit VX2 liver tumor models were successfully established, and than they were assigned to two groups: radiofrequency ablation alone group and radiofrequency ablation with hepatic blood flow occlusion (vascular-occluded RFA) group. Radiofrequency lesions were created in vivo using a cool-tip radiofrequency electrode (radiofrequency parameters were 8 min in time and 30 W in power). The hepatic blood flow occlusion was got by pringle maneuver. Serum ALT, AST, AKP and GGT were detected before the operation and the 1^st, 3^rd, 7^th day after the operation, and the adverse events were observed. The animals were sacrificed one week later. The size, volume of necrosis lesions in the two groups were then analyzed.

RESULTS: Volume and vertical diameter of the coagulated area were significantly greater with the pringle maneuver. The parallel diameter was larger than that coagulated by standard RFA, but there were no significantly differences between the groups. Serum ALT, GGT was higher in radiofrequency ablation combined with Pringle maneuver group than radiofrequency ablation alone group at each time after the operation (P < 0.05), and serum GGT lever was gradually increased postoperatively. Differences in serum AST, AKP between the two groups at each time postoperatively were not significant. One case of vascular-occluded RFA group was complicated with mild bile leakage, one case died on the 1^st day for hemorrhage, and one case died for liver injury on the 4^th day.

CONCLUSION: Radiofrequency ablation combined with occlusion of the hepatic artery and portal vein increases the volume of necrosis when compared with radiofrequency ablation alone, but much more serious liver injuries are found, careful attention should be paid when this technique is used in clinical practice.

Influence of approach on outcome in radiofrequency ablation of liver tumors

In this article some recent data concerning the approach on radiofrequency ablation (RFA) of liver tumors are reviewed. Specifically, several critical statements between surgical and percutaneous approach are raised and discussed: (1) Open approach may lead to a higher complication rate; (2) Temporary occlusion of hepatic inflow during surgical approach may lead to a higher rate of ablation of the liver tumors; (3) Surgical approach may permit better targeting of the tumor to be ablated. (4) Surgical approach may discover additional liver tumors. Finally, several conclusions and recommendations are also addressed.

[Effectiveness of radiofrequency ablation of lung tumours ]

BACKGROUND

There has been great success in the treatment of primary and secondary tumours of the liver using radiofrequency ablation (RFA) therapy, resulting in this method being used for other solid tumours such as in the lung. However, concerning lung cancer only few data are available about the histomorphological effects of this method. The aim of this study was to analyse the effects of RFA therapy in tumours of the lung.

PATIENTS AND METHODS

Eleven patients with non-small-cell lung cancer and one with a lung metastasis (primary tumour identified as urothelial carcinoma) underwent RFA therapy followed by resection of the affected lobe. One patient with a metastasis of the liver was included for comparison of treatment effects. Histomorphological analysis of the collected material was used to measure the amount of necrosis.

RESULTS

None of the treated tumours of the lung showed complete necrosis after applying RFA therapy. In contrast, this method with the control metastasis of the liver resulted in complete thermal destruction.

CONCLUSION

Our results indicate that RFA therapy is not adequate for successful induction of necrosis in tumours of the lung. Therefore the use of this method has to be considered extremely carefully as a palliative treatment option in tumours of the lung.

Laparoscopic radiofrequency ablation of hepatocellular carcinoma: A critical review from the surgeon's perspective

BACKGROUND

The treatment of choice for hepatocellular carcinoma (HCC) is surgical resection but only a small percentage of patients are operative candidates. Percutaneous radiofrequency interstitial thermal ablation (RFA) has proved to be effective in the treatment of unresectable HCC. However, there is a sub-group of patients who may benefit from a laparoscopic rather than a percutaneous approach. Laparoscopic RFA offers the combined advantages of improved tumor staging based on the intracorporeal ultrasound examination and safer access to liver lesions that are difficult or impossible to treat with a percutaneous approach. The aim of our review was to evaluate the advantages and limitations of the laparoscopic approach, according to the criteria of evidence-based medicine.

CONCLUSIONS

Laparoscopic RFA of HCC proved to be a safe and effective technique, at least in terms of the short- and mid-term results. This technique may be indicated in selected cases of HCC when percutaneous RFA is very difficult or contraindicated.

Laparoscopic radiofrequency of hepatocellular carcinoma using ultrasound-guided selective intrahepatic vascular occlusion

BACKGROUND

The optimal treatment for hepatocellular carcinoma (HCC) is surgical resection. However, only a small percentage of patients are operative candidates. The authors aimed to assess a novel operative combination of laparoscopic radiofrequency (LRF) with a selective intrahepatic vascular occlusion (SIHVO) to obtain an increased rate of total necrosis and a reduced rate of local HCC recurrences.

METHODS

For this study, 37 patients with HCC in liver cirrhosis were submitted to LRF with SIHVO. An LRF was indicated for patients not amenable to liver resection who evidenced at least one of the following criteria: severe impairment of the coagulation tests, large tumors (but <5 cm) or multiple lesions requiring repeated punctures, superficial lesions adjacent to visceral structures, deep-sited lesions with a very difficult or impossible percutaneous approach, and short-term recurrence of HCC after percutaneous loco-regional therapies.

RESULTS

Laparoscopic ultrasound identified seven new malignant lesions (19%) undetected by preoperative imaging. There was no operative mortality. Of the 37 patients, 31 experienced no complications (84%). Computed tomography (CT) evaluation 1 month after treatment showed that a complete response with 100% necrosis had been achieved for all the patients (100%). During the follow-up period (mean, 11.8 +/- 8.2 months), new malignant nodules developed in 14 patients (42%), and 36% of these recurrences were located in the same treated segment of the HCC.

CONCLUSIONS

The combined LRF and SIHVO procedure proved to be a safe and effective technique at least in the short and mid term. In fact, it permitted the treatment of lesions not treatable using the percutaneous approach with a complete clearance, and it had a low morbidity rate.

Laparoscopic liver resection for hepatocellular carcinoma

BACKGROUND

Single, small hepatocarcinomas (HCC) are still an indication for partial liver resection in patients ineligible for transplantation. Anatomical resections are recommended for oncological reasons. The mini-invasive approach of laparoscopy should minimize hepatic and parietal injury, thereby decreasing the risk of liver failure and ascites. However, the oncological results of this approach and its presumed benefits remain undemonstrated. We evaluated the short- and midterm results of laparoscopic liver resections for HCC.

METHODS

Between 1999 and 2006, we performed 32 laparoscopic liver resections for HCC. Mean tumor size was 3.8 +/- 2 cm and the mean age of the patients was 65 +/- 11 years. Twenty-two patients had cirrhosis (21 Child A and one Child C). Operative and postoperative results were analyzed, together with recurrence and survival rates.

RESULTS

We carried out 13 unisegmentectomies, nine bisegmentectomies, one trisegmentectomy, two right hepatectomies, one left hepatectomy, and six atypical resections. The duration of the operation was 231 +/- 101 minutes. Conversion to laparotomy was required in three patients (9%), none in emergency situations. Mean blood loss was 461 ml, with five patients (15.6%) requiring blood transfusion. The mean surgical margin was 10.4 mm. One cirrhotic patient (Child C) underwent surgery for a partially ruptured tumor and died of liver failure. Two patients had ascites and no transient liver failure occurred in the other 19 cirrhotic patients. Mean hospital stay was 7.1 days. During a mean follow-up of 26 months, 10 patients (31%) presented recurrence within the liver. None of the patients had peritoneal carcinomatosis or trocar site recurrence. Three-year overall and disease-free survival rates were 71.9% and 54.5%, respectively.

CONCLUSIONS

Laparoscopic liver resection for HCC is feasible and well tolerated. Midterm survival and recurrence rates are similar to those after laparotomy.

Indications for hand-assisted laparoscopic radiofrequency ablation for liver tumors

PURPOSE

Radiofrequency ablation has established itself as the preferred treatment for irresectable liver tumors. It can be performed either percutaneously, laparoscopically, or by open surgery. The choice of approach depends on the patient and tumor-related variables. The laparoscopic approach appears to be the safest and most effective method for small tumors on the liver surface. It also provides additional information on the intrahepatic tumor burden with the use of intraoperative ultrasound and staging laparoscopy. Furthermore, the pneumoperitoneum reduces the flow of the portal vein and increases the efficacy of the ablation. Depending on the location of the tumor, mobilization of the liver or lysis of adhesions from previous surgery can require open surgery. Our aim was to study the combined use of laparoscopy and laparotomy by using hand-assisted laparoscopic radiofrequency ablation.

MATERIALS AND METHODS

We performed hand-assisted laparoscopy to ablate nine tumors in seven patients, enabling us to combine most of the advantages of laparoscopy and open surgery. The radiofrequency ablation was technically simple to perform. A laparoscopy of the entire abdominal cavity and a thorough examination of the entire liver via ultrasound was also performed.

RESULTS

The electrode was accurately placed in all patients. In four patients, a complete mobilization of the right lobe was performed to obtain the easiest possible access to the tumor. In three patients, severe adhesions from previous surgeries were removed prior to insertion of the laparoscopic tools. The ablation was completed safely and successfully in all patients.

CONCLUSION

Our overall impression of the hand-assisted laparoscopic approach is that it seems to have a major advantage in comparison with simple laparoscopy, specifically for adhesions from previous surgeries and when the right liver lobe requires mobilization. Also, needle placement seems to be far more accurate than with simple laparoscopy.

Technical Aspects And Feasibility of Laparoscopic Ultrasound Navigation in Radiofrequency Ablation of Unresectable Hepatic Malignancies

PURPOSE

Laparoscopic radiofrequency ablation is safe, practicable, and combines minimally invasive surgery with the advantages of laparotomy. However, application of the laparoscopic freehand puncture is restricted because of capnoperitoneum and the consequent fixation of the needle on two different points. The use of a laparoscopic ultrasound probe with a canal for puncture can solve this problem and improve precision. However, a stiff needle limits the necessary angulation that is needed to reach right-lateral and cranial liver metastases. Therefore we present a new navigation tool for laparoscopic interventions.

MATERIALS AND METHODS

The US Guide 2000 (Ultra Guide, Tirat Hacarmel, Israel) is an independent navigation system compatible with all ultrasound machines and has six degrees of freedom. After proper evaluation of this system under operating room conditions during transcutaneous radiofrequency ablation, we used this technique in laparoscopic radiofrequency ablation. A special adapter was developed to attach the ultrasound-based navigation system to a laparoscopic ultrasound probe. After calibrating the system with an ultrasound phantom, laparoscopic navigation in a liver organ model was studied.

RESULTS

Even in cases of angulation of the ultrasound probe no disturbances of the navigation system could be detected. Anatomic landmarks in the liver could be safely reached. No interaction between the navigation system and the laparoscopic ultrasound probe or operating instruments was observed.

CONCLUSION

Our preliminary results show the feasibility of this technique in laparoscopic radiofrequency ablation. The use of an ultrasound-based laparoscopic inline navigation system offers the possibility of out-of-plane needle placement and could combine the flexibility of freehand puncture with the accuracy of a canal for puncture. This could increase the safety and accuracy of punctures.

Experimental and Clinical Radiofrequency Ablation: Proposal for Standardized Description of Coagulation Size and Geometry

BACKGROUND

Radiofrequency (RF) ablation is used to obtain local control of unresectable tumors in liver, kidney, prostate, and other organs. Accurate data on expected size and geometry of coagulation zones are essential for physicians to prevent collateral damage and local tumor recurrence. The aim of this study was to develop a standardized terminology to describe the size and geometry of these zones for experimental and clinical RF.

METHODS

In a first step, the essential geometric parameters to accurately describe the coagulation zones and the spatial relationship between the coagulation zones and the electrodes were defined. In a second step, standard terms were assigned to each parameter.

RESULTS

The proposed terms for single-electrode RF ablation include axial diameter, front margin, coagulation center, maximal and minimal radius, maximal and minimal transverse diameter, ellipticity index, and regularity index. In addition a subjective description of the general shape and regularity is recommended.

CONCLUSIONS

Adoption of the proposed standardized description method may help to fill in the many gaps in our current knowledge of the size and geometry of RF coagulation zones.

Selective portal clamping to minimize hepatic ischaemia-reperfusion damage and avoid accelerated outgrowth of experimental colorectal liver metastases

BACKGROUND

Temporary vascular clamping during local ablation for colorectal liver metastases increases destruction volumes. However, it also causes ischaemia-reperfusion (IR) injury to the liver parenchyma and accelerates the outgrowth of microscopic tumour deposits. The aim of this study was to investigate the effects of selective portal clamping on hepatocellular damage and tumour growth.

METHODS

Mice carrying pre-established hepatic colorectal micrometastases underwent either simultaneous clamping of both the portal vein and the hepatic artery or selective clamping of the portal vein to the median and left liver lobes for 45 min. Sham-operated mice served as controls. Hepatic injury and tumour growth were assessed over time.

RESULTS

Standard inflow occlusion resulted in a rise in liver enzymes, a local inflammatory response and hepatocellular necrosis. The outgrowth of pre-established micrometastases was accelerated three- to fourfold in clamped compared with non-clamped liver lobes (27.4 versus 7.8 per cent, P < 0.010). Conversely, selective portal clamping induced minimal liver injury, tissue inflammation or hepatocellular necrosis, and completely stopped the accelerated outgrowth of micrometastases.

CONCLUSION

Selective portal clamping does not induce liver tissue damage or accelerate micrometastasis outgrowth and may therefore be the preferable clamping method during local ablative treatment of hepatic metastases.

The surgical approach for radiofrequency ablation of liver tumors

Radiofrequency ablation for the treatment of liver tumors is one of the best alternative treatment modalities when surgical resection is not possible. To find the right indication for the treatment, every patient should be treated in a high-volume center for the treatment of liver tumors in an interdisciplinary conference consisting of liver surgeons, interventional radiologists, medical oncologists, and gastroenterologists. With a multimodal approach including anatomic segmental and wedge resection of the liver, RFA, and chemotherapy, a median survival of 36 months was achieved in technically unresectable patients with colorectal liver metastases (Elias et al. 2005). This survival doubles the survival rate of any other treatment modality in this group of patients. These interdisciplinary conferences also serve to determine the approach for RFA, whether it should be percutaneous, laparoscopic, or open surgery. The safest ablation with the fewest adverse events from RFA is the open surgical approach, followed by the laparoscopic approach. The approach with the highest risk of injury to organs in proximity to the liver is the percutaneous approach. Therefore, many variables must be evaluated before making definite decisions. After choosing RFA as the best alternative treatment option after evaluation of all variables for a particular patient, it offers a treatment option with a potential cure. A major advantage is the possible combination with liver resection, which extends the indication for surgical or ablative therapy.

Radiofrequency ablation of rabbit liver in vivo: effect of the pringle maneuver on pathologic changes in liver surrounding the ablation zone

Objective

We wished to evaluate the effect of the Pringle maneuver (occlusion of both the hepatic artery and portal vein) on the pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone in rabbit livers.

Materials and Methods

Radiofrequency (RF) ablation zones were created in the livers of 24 rabbits in vivo by using a 50-W, 480-kHz monopolar RF generator and a 15-gauge expandable electrode with four sharp prongs for 7 mins. The tips of the electrodes were placed in the liver parenchyma near the porta hepatis with the distal 1 cm of their prongs deployed. Radiofrequency ablation was performed in the groups with (n=12 rabbits) and without (n=12 rabbits) the Pringle maneuver. Three animals of each group were sacrificed immediately, three days (the acute phase), seven days (the early subacute phase) and two weeks (the late subacute phase) after RF ablation. The ablation zones were excised and serial pathologic changes in the hepatic vessels, bile ducts and liver parenchyma surrounding the ablation zone were evaluated.

Results

With the Pringle maneuver, portal vein thrombosis was found in three cases (in the immediate [n=2] and acute phase [n=1]), bile duct dilatation adjacent to the ablation zone was found in one case (in the late subacute phase [n=1]), infarction adjacent to the ablation zone was found in three cases (in the early subacute [n=2] and late subacute [n=1] phases). None of the above changes was found in the livers ablated without the Pringle maneuver. On the microscopic findings, centrilobular congestion, sinusoidal congestion, sinusoidal platelet and neutrophilic adhesion, and hepatocyte vacuolar and ballooning changes in liver ablated with Pringle maneuver showed more significant changes than in those livers ablated without the Pringle maneuver (p < 0.05)

Conclusion

Radiofrequency ablation with the Pringle maneuver created more severe pathologic changes in the portal vein, bile ducts and liver parenchyma surrounding the ablation zone compared with RF ablation without the Pringle maneuver. Therefore, we suggest that RF ablation with the Pringle maneuver should be performed with great caution in order to avoid unwanted thermal injury.

Radiofrequency-ablation of unresectable primary and secondary liver tumors: results in 88 patients

BACKGROUND AND AIMS

Radiofrequency-ablation (RFA) is increasingly used for destruction of unresectable primary and secondary liver tumors. We report our experience in the use of RFA for the management of unresectable hepatic malignancies.

PATIENTS AND METHODS

Between February 2000 and December 2004 we have undertaken 120 RFA procedures to ablate 426 unresectable primary or metastatic liver tumors in 88 patients. RFA was performed via laparotomy (n=68), laparoscopy (n=9) or a percutaneous approach (n=43). Primary liver cancer was treated in seven patients (8%) and metastatic liver tumors were treated in 81 patients (92%). All patients were followed to assess complications, treatment response and recurrence of malignant disease.

RESULTS

Procedure-related complication rate was low (3.4%). During a mean follow-up of 21.2 months, 15 patients had local tumor progression (17%), 21 patients (23.9%) had new malignant disease and 27 patients (30.7%) died from intervention-unrelated complications of their malignant disease. Additional liver lesions were identified in 27 (35%) of 77 cases by intraoperative ultrasound. Thirty-six patients received simultaneous resection and RFA.

CONCLUSION

RFA is a safe, well-tolerated and effective treatment for patients with unresectable primary and secondary liver malignancies.

Influence of operator experience in radiofrequency ablation of malignant liver tumours on treatment outcome

AIMS

Radiofrequency ablation is gaining popularity as the interventional therapy of choice for unresectable hepatic malignancies. However, little attention has been paid to the importance of operator experience in this therapy. This study aims to evaluate the results of RFA treatment dependent on operator experience and learning curve.

PATIENTS AND METHODS

Between 2/2000 and 11/2004 we have undertaken 116 RFA procedures to ablate 404 unresectable primary or metastatic liver tumours in 84 patients. The clinical data of all patients were recorded prospectively and treatment results of the first 42 patients (group I) and the second 42 patients (group II) were compared. All patients were treated by the same surgeon or interventional radiologist.

RESULTS

RFA was performed percutaneously in 44 procedures (group I n = 35, group II n = 9), via laparotomy in 64 procedures (group I n = 27, group II n = 37) and via laparoscopy in eight procedures (group I n = 1, group II n = 7). The complication rate was comparable in both groups with 7.9% in group I and 7.5% in group II. Group II had a higher complete ablation rate (96.2 vs 93.7%) than group I. One- and two-year survival rates of 92 and 89% in group II were significantly higher than in group I with 69 and 46% (p = 0.015).

CONCLUSION

By the experience conditional optimization of indication and performance by a specialized RFA team the results could be improved significantly. The data on hand speak for a considerable learning curve in the RFA and demonstrate the importance of the experience of the therapist for the outcome of the patients.

Development of exophytic tumor model for laparoscopic partial nephrectomy: technique and initial experience

OBJECTIVES

To develop and test a porcine model to help teach the techniques needed to perform laparoscopic partial nephrectomy (LPN), which is a technically challenging procedure with necessary reconstructive skills that are difficult to transfer.

METHODS

A tumor model was created by unilateral subcapsular percutaneous injection of liquid plastic (Smooth-Cast 320) in five pig kidneys. Five Washington University urologists performed LPN and assessed the efficacy of the tumor model. Subsequently, the tumor model was evaluated as a tool for teaching LPN during the Washington University Advanced Laparoscopic and Robotic Urologic Oncology Course. Twenty-eight participants performed unilateral porcine LPN with the tumor model. Questionnaires were used to assess the utility of this tumor model.

RESULTS

Unilateral tumors were successfully created in five pigs and remained intact during all LPN procedures. Visually, the tumors appeared as white exophytic masses. Ultrasonography revealed a well-circumscribed, hypoechoic lesion and a mean diameter of 2.02 cm. The mean operative time was 32.4 minutes. In subsequent testing, 24 (86%) of the 28 participants returned the questionnaire, and 96% responded that the tumor model had enhanced their LPN learning experience. Seven course participants (29%) reported problems with hemostasis, ultrasonography, or laparoscopic instrumentation. Two tumor model-related complications occurred. During the initial evaluation, one pig experienced a fatal pulmonary embolism of the plastic. During the course, a second animal experienced extravasation of the solution into the renal collecting system.

CONCLUSIONS

For surgical education purposes, the Smooth-Cast model is an effective surgical tool for LPN. Most of the surgeons in this evaluation believed the model enhanced their learning experience.

Local recurrence after hepatic radiofrequency coagulation: multivariate meta-analysis and review of contributing factors

OBJECTIVE

The purpose of this study was to analyze the factors that influence local recurrence after radiofrequency coagulation of liver tumors.

SUMMARY BACKGROUND DATA

Local recurrence rate varies widely between 2% and 60%. Apart from tumor size as an important risk factor for local recurrence, little is known about the impact of other factors.

METHODS

An exhaustive literature search was carried out for the period from January 1, 1990 to January 1, 2004. Only series with a minimal follow-up of 6 months and/or mean follow-up of 12 months were included. Univariate and multivariate meta-analyses were carried out.

RESULTS

Ninety-five independent series were included, allowing the analysis of the local recurrence rate of 5224 treated liver tumors. In a univariate analysis, tumor-dependent factors with significantly less local recurrences were: smaller size, neuroendocrine metastases, nonsubcapsular location, and location away from large vessels. Physician-dependent favorable factors were: surgical (open or laparoscopic) approach, vascular occlusion, general anesthesia, a 1-cm intentional margin, and a greater physician experience. In a multivariate analysis, significantly less local recurrences were observed for small size (P < 0.001) and a surgical (versus percutaneous) approach (P < 0.001).

CONCLUSIONS

Radiofrequency coagulation by laparoscopy or laparotomy results in superior local control, independent of tumor size. The percutaneous route should mainly be reserved for patients who cannot tolerate a laparoscopy or laparotomy. The short-term benefits of less invasiveness for the percutaneous route do not outweigh the longer-term higher risk of local recurrence.

Modelling heating of liver tumours with heterogeneous magnetic microsphere deposition

Ferromagnetic embolization hyperthermia (FEH) is a novel treatment for liver cancer. Magnetic microspheres are injected into the hepatic artery and cluster in the periphery of tumours and are heated with externally applied magnetic fields. In order to more accurately simulate FEH, we modelled a three-dimensional heterogeneous distribution of heat sources. We constructed a fractal model of the vasculature in the periphery of a tumour. We used this model to compute the spatial distribution of the microspheres that lodge in capillaries. We used the distribution model as input to a finite-element heat transfer model of the FEH treatment. The overall appearance of the vascular tree is subjectively similar to that of the disorganized vascular network which encapsulates tumours. The microspheres are distributed in the tumour periphery in similar patterns to experimental observations. We expect the vasculature and microsphere deposition models to also be of interest to researchers of any targeted cancer therapies such as localized intra-arterial chemotherapy and selective internal radiotherapy. Our results show that heterogeneous microsphere distributions give significantly different results to those for a homogeneous model and thus are preferable when accurate results are required.

Survival and intra-hepatic recurrences after laparoscopic radiofrequency of hepatocellular carcinoma in patients with liver cirrhosis

BACKGROUND

The optimal treatment for hepatocellular carcinoma (HCC) is surgical resection. However, only a small percentage of patients are operative candidates. Percutaneous radiofrequency interstitial thermal ablation proved to be effective, too. Our objective was to assess a novel operative combination of laparoscopic ultrasound (LUS) with laparoscopic radiofrequency (LRF) in the treatment of HCC not amenable to liver resection.

METHODS

One hundred and four patients with HCC in liver cirrhosis were submitted to laparoscopic LRF. A LRF was indicated in patients not amenable to liver resection that had at least one of the following criteria: (a) severe impairment of the coagulation tests; (b) large tumors (but <5 cm) or multiple lesions requiring repeated punctures; (c) superficial lesions adjacent to visceral structures; (d) deep-sited lesions with a very difficult or impossible percutaneous approach; (e) short-term recurrence of HCC following percutaneous loco-regional therapies.

RESULTS

The LRF procedure was completed in 102 out of 104 patients (98% feasibility rate). LUS identified 26 new malignant lesions (25%) undetected by pre-operative imaging. There was no operative mortality. Seventy-six patients had no complication (73%). At 1-month computed tomography (CT) evaluation, a complete response with a 100% necrosis was achieved in 88 out of 101 patients (87%). During the follow-up (mean follow-up: 22.5 +/- 15.9 months), 55 patients (54%) developed new malignant nodules (42% of these recurrences were localized in the same segment of the HCC treated).

CONCLUSIONS

LRF of HCC proved to be a safe and effective technique at least in the short and mid-term: in fact it permits to treat lesions not treatable with the per cutaneous approach, to detect 25% of new HCC nodules and it has a low morbidity rate.

DEVELOPMENT OF A RENAL TUMOR MIMIC MODEL FOR LEARNING MINIMALLY INVASIVE NEPHRON SPARING SURGICAL TECHNIQUES

PURPOSE

New laparoscopic partial nephrectomy and tumor ablation techniques are continuously being developed and evaluated in large animal models. However, to our knowledge no reliable renal tumor model exists to evaluate procedure efficacy. We developed and assessed the reliability of a tumor mimic model to serve as a training tool for minimally invasive kidney surgery.

MATERIALS AND METHODS

An agarose based model was created using a mixture of 3% agarose, 3% cellulose, 7% glycerol and 0.05% methylene blue. It is liquid when heated, but solidifies after cooling to physiological temperatures. The agar was injected (0.7 cc) into porcine renal parenchyma to make endophytic or completely intraparenchymal lesions. Three-dimensional ultrasound images of the lesions were obtained during initial development to ensure spherical lesions. A group of 20 lesions was initially placed in an ex vivo setting to assess size consistency and define baseline impedance characteristics. An additional 20 tumor mimics each were established in a laparoscopic model in a laparoscopic box trainer and an in vivo laparoscopic model. They were ablated with a temperature based radio frequency generator to assess impedance characteristics but the efficacy of ablation was not assessed. The in vivo model consisted of placing the agar lesion percutaneously under direct laparoscopic vision.

RESULTS

The agarose mixture was easily injected and readily visible on ultrasound as hyperechoic distinct lesions. Lesions had a mean size of 10.8 +/- SD 1.3 mm on ultrasound and 10.9 +/- 1.2 mm grossly. The impedance of normal renal parenchyma and unablated lesions was similar. Mean lesion size in the ex vivo model after radio frequency ablation was 9.8 +/- 2.0 mm on ultrasound, which was similar to the gross mean lesion size of 9.7 +/- 1.0 mm. Similar results were obtained for the in vivo model with a mean size of 10.1 +/- 2.1 and 10.4 +/- 1.5 mm, respectively. The lesions were easily identified grossly as blue solid lesions that replaced renal parenchyma.

CONCLUSIONS

The described renal tumor mimic model reproducibly creates ex vivo and in vivo porcine kidney lesions. Lesion size and impedance do not change with the application of radio frequency energy. This model should be a valuable adjunct in the development, assessment and teaching of novel, nephron sparing, minimally invasive surgical techniques.

Surgery and angiogenesis

Surgery may be regarded as an angiogenesis-inducing condition since it evokes the release of many angiogenic factors. Regarding the mechanistic overlap between tumor-associated neovascularisation and (physiological) angiogenesis in response to injury and hypoxia, surgery may promote the uncontrolled growth of residual dormant tumor cells. With the advent of anti-angiogenic agents, surgeons will be faced with more patients undergoing surgery for primary and secondary tumors under anti-angiogenic treatment. This could present problems with regard to angiogenesis-dependent phenomena such as wound repair, healing of intestinal anastomoses and liver regeneration. In this review we will discuss these matters from a biomedical and clinical point of view.

Radiofrequency ablation: Effect of pharmacologic modulation of hepatic and renal blood flow on coagulation diameter in a VX2 tumor model

PURPOSE

To determine whether pharmacologic agents can be used to modulate blood flow in hepatic and renal tumors sufficiently to alter the extent of radiofrequency (RF)-induced coagulation.

MATERIALS AND METHODS

VX2 tumors (8-15 mm) were implanted in the liver (n = 25) or kidney (n = 8) of 33 New Zealand White rabbits. RF was applied to tumors for 6 minutes with use of conventional electrodes (125 mA +/- 35; 90 degrees C +/- 2 degrees C tip temperature). In the hepatic model, blood flow was modulated with use of halothane, epinephrine, or arsenic trioxide (2-6 mg/kg). Laser Doppler flowmetry was used to quantify changes in hepatic blood flow. Correlation of blood flow with induced coagulation diameter was performed. RF ablation was then performed in a renal model with and without arsenic trioxide.

RESULTS

For liver tumors, halothane and arsenic trioxide reduced blood flow to 40.3% +/- 17.8% and 29% +/- 15% of normal, respectively, whereas epinephrine increased blood flow to 207.8% +/- 97.9%. Correlation of blood flow to coagulation diameter was demonstrated (R(2) = 0.40). Coagulation measured 7 mm +/- 1 with epinephrine, 10 mm +/- 1 with normal blood flow, 12 mm +/- 3 with halothane, and 13 mm +/- 3 with arsenic trioxide (P <.04 compared with controls). In the renal model, arsenic trioxide decreased blood flow (44% +/- 16%) and increased coagulation diameter (10.9 mm +/- 1) compared with controls (84% +/- 11% and 7.6 mm +/- 1; P <.01, both comparisons).

CONCLUSIONS

RF-induced coagulation necrosis in rabbit hepatic and renal tumors is affected by tumor blood flow. Pharmacologic modulation of tumor blood flow may provide a noninvasive way to decrease blood flow during thermally mediated ablation therapy, potentially enabling the creation of larger zones of coagulation necrosis.

Non-resection approaches for colorectal liver metastases

The field of in situ destruction of liver tumors has expanded rapidly with various institutions' results suggesting that these methods represent viable palliative options, primarily because of the low associated morbidity and mortality. Despite this enthusiasm, clinical trials are needed to determine the true nature and degree of palliation. Treating a systemic disease such as colorectal liver metastases with local therapy strategies alone is of dubious value. In fact, it has been shown by most reports that the limiting factor inpatient outcome is disease progression rather than technical failure. For optimal results, physicians performing in situ ablation of liver lesions should be familiar with tumor biology and the natural history of the malignancy, and possess expertise in proper integration of other therapeutic modalities (eg, systemic chemotherapy and hepatic artery chemotherapy). Patients with liver metastases from colorectal carcinoma should therefore be evaluated for curability by a surgical oncologist within the context of a multidisciplinary team, as surgical resection remains the best treatment to achieve long-term survival. Such an assessment offers the patient the opportunity of a tailored therapy that may consist of hepatic resection, intravenous or regional chemotherapy, and local ablative therapy. Furthermore, results of RF ablation should be reported in terms of well-established oncological outcomes (eg, overall survival, disease-free survival, progression-free survival) that are more meaningful to the patient, rather than lesion-oriented outcomes. Because most of the ablative techniques have not yet been validated, it is imperative that well-designed clinical trials are conducted under the auspices of national cooperative groups. To consider them standard independent therapies otherwise would be premature.

Size and geometry of hepatic radiofrequency lesions

AIM

To report and compare the size and geometry of hepatic radiofrequency (RF) lesions using the currently available commercial devices.

METHODS

A literature search was carried out for the period from January 1st 1990 to June 15th 2003. The commercial suppliers were asked to provide all available data. For each electrode and protocol, size and geometry of single-cycle thermal lesions were registered.

RESULTS

No information at all on size and geometry of the inducible lesions was available for 17 of the 28 current commercial electrodes. Many descriptions of RF lesions are limited to the mean transverse diameter. With normal blood flow, diameter of lesions is often smaller than suggested by the length of the electrode tip or the diameter of the deployed prongs. Lesions are rarely perfect spheres but either ellipses or flattened spheres. Distortion of the RF lesion by nearby blood vessels is very common. Fusion of thermal zones between prongs of expandable electrodes can be incomplete. Blood flow interruption using a Pringle maneuver yields larger lesions that are less distorted and more complete.

CONCLUSIONS

There is insufficient experimental data for many electrodes that are currently used in patients. RF companies should provide these data before releasing electrodes for use. For those electrodes for which data exist, coagulation lesions are often smaller, less spherical, less complete and less regular than generally presumed. Accurate knowledge of size and geometry of RF lesions is crucial to prevent local recurrence.