Magnetic-resonance-guided percutaneous cryoablation of hepatic tumours

Survival outcomes and quality of life after percutaneous cryoablation for liver metastasis: A systematic review and meta-analysis

BACKGROUND

Liver metastasis is present in a wide range of malignancies, with colorectal cancer as the most common site. Several minimally invasive treatments have been suggested for managing hepatic metastases, and cryoablation is among them, yet not widely used. In this systematic review, we aimed to assess the effectiveness of percutaneous cryoablation in all types of liver metastases.

METHODS

A systematic search was performed in international databases, including PubMed, Scopus, Embase, and Web of Science, to find relevant studies reporting outcomes for percutaneous cryoablation in liver metastasis patients. In addition to baseline features such as mean age, gender, metastasis origin, and procedure details, procedure outcomes, including overall survival, local recurrence, quality of life (QoL), and complications, were extracted from the studies. Random-effect meta-analysis was performed to calculate the mean difference (MD) and 95% confidence interval for comparison of QoL.

RESULTS

We screened 2131 articles. Fifteen studies on 692 patients were included. Mean overall survival ranged from 14.5-29 months. The rate of local recurrence in the included studies ranged from 9.4% to 78%, and local control progression-free survival ranged from 1 to 31 months. The total QoL decreased one week after the cryoablation procedure (-3.08 [95% Confidence interval: -4.65, -1.50], p-value <0.01) but increased one month (5.69 [3.99, 7.39], p-value <0.01) and three months (3.75 [2.25, 5.24], p-value <0.01) after the procedure.

CONCLUSION

Cryoablation is an effective procedure for the treatment of liver metastases, especially in cases that are poor candidates for liver resection. It could significantly improve QoL with favorable local recurrence.

Integrating interventional oncology in the treatment of liver tumors

Background

Percutaneous ablation techniques offer a vast armamentarium for local, minimally invasive treatment of liver tumors, nowadays representing an established therapeutic option, which is integrated in treatment algorithms, especially for non-resectable liver tumors. The results of ablative treatment compare very well to surgical treatment in liver lesions, and confirm that these techniques are a valuable option for bridging for transplantation. Different techniques have been established to perform tumor ablation, and the feasibility varies according to the procedure and technical skills of the operator, depending on the size and location of the liver lesion. In recent years, stereotactic multi-needle techniques using 3D trajectory planning, general anesthesia, and tube disconnection during needle placement have had a strong impact on the application range of ablation for liver tumors.

Conclusion

It is well known that creating a sufficient ablation margin and overlapping ablation zones is one key issue to enable ablation of large liver lesions with tumor-free margins (A0 ablation in analogy to R0 resection). Image fusion during treatment and follow-up assure highly accurate staging procedures and interventional planning.

Novel aspects

Review on the standards in ablation techniques for the treatment of liver tumors. Update on different ablation techniques, indications, and contraindications for percutaneous liver tumor treatment. Summary of recently published reports on liver tumor ablation.

Motion compensation for MRI-compatible patient-mounted needle guide device: estimation of targeting accuracy in MRI-guided kidney cryoablations

Patient-mounted needle guide devices for percutaneous ablation are vulnerable to patient motion. The objective of this study is to develop and evaluate a software system for an MRI-compatible patient-mounted needle guide device that can adaptively compensate for displacement of the device due to patient motion using a novel image-based automatic device-to-image registration technique. We have developed a software system for an MRI-compatible patient-mounted needle guide device for percutaneous ablation. It features fully-automated image-based device-to-image registration to track the device position, and a device controller to adjust the needle trajectory to compensate for the displacement of the device. We performed: (a) a phantom study using a clinical MR scanner to evaluate registration performance; (b) simulations using intraoperative time-series MR data acquired in 20 clinical cases of MRI-guided renal cryoablations to assess its impact on motion compensation; and (c) a pilot clinical study in three patients to test its feasibility during the clinical procedure. FRE, TRE, and success rate of device-to-image registration were 2.71 ± 2.29 mm, 1.74 ± 1.13 mm, and 98.3% for the phantom images. The simulation study showed that the motion compensation reduced the targeting error for needle placement from 8.2 mm to 5.4 mm (p  <  0.0005) in patients under general anesthesia (GA), and from 14.4 mm to 10.0 mm (p < 1.0 × 10(−5)) in patients under monitored anesthesia care (MAC). The pilot study showed that the software registered the device successfully in a clinical setting. Our simulation study demonstrated that the software system could significantly improve targeting accuracy in patients treated under both MAC and GA. Intraprocedural image-based device-to-image registration was feasible.

How to Perform a Routine Cryoablation Under MRI Guidance

In the last decade, the spectrum of interventional magnetic resonance imaging (MRI)-guided procedures, including percutaneous ablation, has substantially grown, and among the available MRI-compatible ablative techniques, cryoablation is progressively gaining a predominant position.The aim of the present narrative review is to discuss the technical requirements necessary to perform a percutaneous MRI-guided cryoablation in a closed-bore machine; to highlight the relative advantages and drawbacks; and to briefly summarize the results available in the literature.

Analysis of circulating tumor cells in colorectal cancer liver metastasis patients before and after cryosurgery

In this study, we determined the number of peripheral blood circulating tumor cells (CTCs) pre- and post-cryosurgery in patients with colorectal cancer liver metastasis as a reference for understanding the relevance of any changes to the efficacy of cryosurgery. CTC numbers and CTC-related gene expression were measured in the peripheral blood of 55 patients with colorectal liver metastasis at 1 day before and 7 and 30 d after cryoablation using magnetic activated cell sorting (MACS) and fluorescence activated cell sorting (FACS) combined with real-time quantitative PCR (RT-qPCR). The number of CTCs decreased significantly with postoperative time (P < 0.01). Delta cycle threshold values for the CTC-related genes CEA, Ep-CAM, CK18 and CK19 increased significantly after cryoablation. Furthermore, the expression of CEA, Ep-CAM, CK18 and CK19 decreased significantly with time after cryoablation (P < 0.01). RT-qPCR and FACS combined with MACS has significant diagnostic and prognostic value for evaluating the efficacy of cryosurgery in patients with advanced colorectal cancer.

Cryosurgery for Tumors — A Clinical Overview

Cryosurgery, a method of treating disease by the production of freezing temperatures in the tissue, is a useful technique for the treatment of tumors. When the modern era of cryosurgery began in the mid 1960's, the technique was used only for tumors easily accessible by direct observation or via endoscopy, such as those of the skin, oral cavity, and prostate gland. In general, the technique had limited usefulness in the next two decades. However, with the advent of intraoperative ultrasound as a method of monitoring the process of freezing and with the development of more effective cryosurgical apparatus, the cryosurgical treatment of tumors of the viscera and other deep tissues became practical in the 1990's. This review assesses the present day status of cryosurgery in the management of diverse tumors.

Liver Tumor Cryoablation: A Commentary on the Need of Improved Procedural Monitoring

Cryoablation is a method used for in situ destruction of liver tumors not eligible for surgical resection. Local recurrences following such treatment have been reported at rates of 5–44%. Insufficient procedural monitoring of the ablation is one plausible explanation for these recurrences. The cryoablative procedure is usually monitored by ultrasonography, but acoustic shadowing and loss of signals, compromise visualisation of the cryolesion circumference. Other monitoring modalities such as computer tomography and invasive methods like the use of thermocouples and impedance measurements have also been studied, but are not in common clinical use as single monitoring modalities. Thermodynamic conditions assumed adequate for tumor eradication are likely to occur only in parts of the cryolesion. This tumoricidal part of the cryolesion is not adequately depicted using any of these modalities.

Magnetic resonance imaging (MRI) provides a clear delineation of the cryolesion circumference. Noninvasive temperature measurements assisted by MRI indicate which parts of the cryolesion that may be subject to complete necrosis. In this article MRI monitored cryoablation of liver tumors is discussed. Improved peroperative monitoring as offered by MRI may reduce the rates of local recurrences after treatment, but further technological improvements are required.

Cryoablation plus chemotherapy in colorectal cancer patients with liver metastases

Cryoablation and surgery achieve similar removal rates for some colorectal cancer (CRC) liver metastasis removal, and systemic chemotherapy is accepted as the most important approach to improving overall survival (OS) in CRC patients with liver metastases. We aimed to evaluate the potential benefit of cryoablation plus chemotherapy in CRC patients with liver metastases. We retrospectively analyze 63 patients of CRC liver metastasis. There were 32 patients in group A, who have received cryoablation plus chemotherapy, and there were 31 patients in group B, who have received chemotherapy alone. We mainly observe the 2-year survival, the quality of life (QOL), and adverse effects. Patients in group A had a higher 2-year survival rate, better OS, better QOL, and better treatment response than patients in group B. Two-year survival rates were 71.9 and 51.6%,respectively, in group A and group B. The negative conversion rates of carcinoembryonic antigen and carbohydrate antigen 19-9 (CA199) were 57.1 and 61.5%, respectively, in group A, and 22.2 and 30%, respectively, in group B. The tumor shrinkage (a tumor volume reduction of ≥ 30%) rates were 62.5 and 22.6%, respectively, in groups A and B. Performance status remained stable or improved in 16 patients (50%) in group A and eight patients (25.81%) in group B. Cryoablation in combination with chemotherapy may increase the 2-year survival rate and improve QOL in CRC patients with liver metastasis.

Thermal ablation of lung tumors

Thermal ablation can be applied to treat any thoracic malignancy: primary lung cancers, recurrent primary lung cancers, metastatic disease, chest wall masses, and painful, bony metastases. Since the first reported use of thermal ablation for lung cancer in 2000 there has been an explosive use of the procedure, and by 2010 the number of procedures to treat thoracic malignancy is expected to exceed 150,000 per year. Presently, thermal ablation is best used for patients with early-stage lung cancers in patients who are not surgical candidates, patients with small and favorably located pulmonary metastases, and patients in whom palliation of tumor-related symptoms is the goal. Radiofrequency ablation, microwave ablation, and cryoablation are novel treatment modalities for lung cancer and can safely accomplish tumor destruction and even complete eradication of tumor in patients who are not candidates for surgical resection. In this article, we discuss technical considerations for each modality and the periprocedure and postprocedure management of patients with this disease.

Treatment of Prostate Cancer Local Recurrence After Radical Retropubic Prostatectomy with 17-Gauge Interstitial Transperineal Cryoablation: Initial Experience

OBJECTIVES

Interstitial transperineal cryoablation with 17-gauge cryoprobes is an accepted treatment modality for localized prostate cancer. The effectiveness of cryoablation in the treatment of local prostate cancer recurrence after radical retropubic prostatectomy (RRP) is unknown.

METHODS

We reviewed the outcome of cryoablative treatment in 15 patients for biopsy-proven locally recurrent prostate cancer after RRP. The follow-up data included prostate-specific antigen (PSA) level, imaging findings, side effects, and an assessment of voiding habits.

RESULTS

The mean follow-up time for the entire group was 20 months (range 4 to 32). Of the 15 patients, 6 (40%) had sustained declines in the PSA level (cryoablation success group) and 9 (60%) had disease progression (cryoablation failure group), defined as a PSA increase greater than 0.1 ng/mL from the PSA nadir, or the addition of external beam radiotherapy or androgen deprivation therapy. The pre-RRP PSA level and pre-cryoablation PSA level were similar for both groups. The pre-RRP biopsy Gleason scores (P = 0.03), RRP Gleason scores (P = 0.03), and lesion size on magnetic resonance imaging (P = 0.001) were lower in the success group than in the failure group. All patients who were recurrence free after cryotherapy had a biopsy and Gleason score of 6 or less. Of the 15 patients, 3 (20%) developed worsening of post-RRP incontinence.

CONCLUSIONS

Our preliminary results suggest that salvage cryoablation can be an effective and safe treatment modality and a possible alternative to external beam radiotherapy for targeted control of confirmed local recurrences after RRP, especially in those with favorable biopsy or pathologic Gleason scores before cryotherapy. Larger cohorts and longer follow-up are needed to assess the viability of this treatment.

Cryoablation of liver tumours -- a review of mechanisms, techniques and clinical outcome

Several techniques exist for in situ destruction or ablation of liver tumours not eligible for resection. Cryoablation, i.e. the use of low temperatures to induce local tissue necrosis, was among the first of the thermal ablative techniques widely used. The procedures have typically been performed by surgeons during laparotomy, but recently minimally invasive cryoablation has been reported feasible. The present review focuses on mechanisms of tissue destruction, techniques of ablation including procedural monitoring, and clinical outcome following cryoablation of liver tumours. Plausible causes of tumour persistence at the site of ablation, i.e. local treatment failure, are discussed. Shortcomings exist in monitoring of the freezing process and may be a main cause. The evidence for the long-term outcome following liver tumour cryoablation needs to be improved. Cryoablation has been challenged by other techniques of tumour ablation such as radiofrequency ablation. Randomised trials against these modern techniques may define the role of cryoablation in the treatment of liver tumours. With improved imaging technology and patient selection, cryoablation of liver tumours may hold promise for selected patients.

Current role of image-guided ablative therapies in lung cancer

Lung cancer is the leading cause of cancer-related mortality in the USA. Until recently, lung cancer treatment options (dependent upon the tumor grading and staging at presentation, and patient comorbidities) included surgical resection (lobar or sublobar), chemotherapy and external-beam radiation therapy. While these options are still viewed as the primary standard of care, newer minimally invasive percutaneous ablative techniques such as radiofrequency ablation, microwave ablation and cryoablation are currently being examined as treatment alternatives, especially in the setting of the nonsurgical candidate. This review will focus on these three distinct thermoablative techniques in the percutaneous setting of lung cancer treatment.

Interventional and intraoperative MRI at low field scanner--a review

Magnetic resonance imaging (MRI) is a cutting edge imaging modality in detecting diseases and pathologic tissue. The superior soft tissue contrast in MRI allows better definition of the pathology. MRI is increasingly used for guiding, monitoring and controlling percutaneous procedures and surgery. The rapid development of interventional techniques in radiology has led to integration of imaging with computers, new therapy devices and operating room like conditions. This has projected as faster and more accurate imaging and hence more demanding procedures have been applied to the repertoire of the interventional radiologist. In combining features of various other imaging modalities and adding some more into them, interventional MRI (IMRI) has potential to take further the interventional radiology techniques, minimally invasive therapies and surgery. The term "Interventional MRI" consists in short all those procedures, which are performed under MRI guidance. These procedures can be either percutaneous or open surgical of nature. One of the limiting factors in implementing MRI as guidance modality for interventional procedures has been the fact, that most widely used magnet design, a cylindrical magnet, is not ideal for guiding procedures as it does not allow direct access to the patient. Open, low field scanners usually operating around 0.2 T, offer this feature. Clumsy hardware, bad patient access, slow image update frequency and strong magnetic fields have been other limiting factors for interventional MRI. However, the advantages of MRI as an imaging modality have been so obvious that considerable development has taken place in the 20-year history of MRI. The image quality has become better, ever faster software, new innovative sequences, better MRI hardware and increased computing power have accelerated imaging speed and image quality to a totally new level. Perhaps the most important feature in the recent development has been the introduction of open configuration low field MRI devices in the early 1990s; this enabled direct patient access and utilization of the MRI as an interventional device. This article reviews the current status of interventional and intraoperative MRI with special emphasis in low field surrounding.

MR-guided interventional procedures: a review

Magnetic resonance imaging (MRI) has emerged as a potential guidance tool for a variety of procedures. Diagnostic and therapeutic procedures using either open surgical or percutaneous access are performed. They span from simple lesion targeting and biopsy to complex applications requiring multiple tasks performed simultaneously or in rapid succession. These tasks include instrument guidance and therapy monitoring as well as procedural follow-up. The interventional use of MRI (IMRI) is increasing steadily. This article reviews the prerequisites, systems, and clinical interventional procedures of IMRI.

Intra-operative visualisation of 3D temperature maps and 3D navigation during tissue cryoablation

Thermotherapeutic tools are increasingly used for tissue ablation, although the intra-operative monitoring is not adequate for such procedures. This is a main challenge for more extensive use of any ablative technique. The present work focuses on treatment of hepatic tumours by cryo therapy. For any thermotherapeutic tool there are specific thermal conditions that have to be met to ensure treatment adequacy. A software tool was made to calculate and visualise 3D temperature distributions during hepatic cryoablation combined with a 3D intra-operative navigation system. This system aids the user in placing the cryoprobe using an optical tracking system and 3D visualisation of the probe placement in relation to the target anatomy and the planned trajectory. 3D temperature distributions are calculated and visualized intra-operatively. The system is integrated with an interventional Magnetic Resonance 0.5T scanner. The system was tested in an animal experiment, exemplifying the usefulness of the navigation system and its ability to give intuitive feedback to the user on thermodynamic conditions induced in the target region. The system constitutes a novel tool for enhanced intra-operative control during cryoablative procedures, and motivates for studies using this tool to investigate predictors applied as indicators of treatment adequacy and patient outcome.

Radiofrequency Thermal Ablation: The Role of MR Imaging in Guiding and Monitoring Tumor Therapy

Performing RFA procedures under MR imaging involves two distinct processes: interactive guidance of the RF electrode into the targeted tumor and monitoring the effect of therapy. The justification for using MR imaging for electrode guidance is quite similar to its use to guide biopsy and aspiration procedures, where MR imaging offers advantages related to superior soft tissue contrast, multiplanar capabilities, and high vascular conspicuity that facilitate safe and accurate guidance in selected lesions. The major contribution of MR imaging to thermal ablation procedures is its ability to monitor tissue changes associated with the heating process instantaneously, an attribute that is not paralleled by any other currently available imaging modality. Such ability facilitates a controlled approach to ablation by helping to detect inadequately treated tumor foci for subsequent interactive repositioning of the RF electrode during therapy. As such, MR imaging guidance and monitoring enable treatment of the entire tumor on a single-visit basis while avoiding undue overtreatment and preserving often critically needed organ function. Although knowledge of interventional MR imaging concepts and familiarity with its technology and with the related safety issues are indispensable for interventional radiologists attempting thermal ablation procedures in the MR imaging environment, understanding the tissue basis of necrosis imaging is becoming an essential part of the knowledge base for the larger sector of general radiologists who are required to interpret the follow-up MR imaging scans of the increasing number of thermal ablation patients.

Percutaneous Cryoablation of Symptomatic Extraabdominal Metastatic Disease: Preliminary Results

OBJECTIVE

The objective of our study was to describe our initial experience using percutaneous cryoablation for palliation of symptomatic extraabdominal metastases or recurrent soft-tissue tumors.

CONCLUSION

Preliminary results suggest that percutaneous cryoablation may offer a minimally invasive alternative for relief of symptomatic metastatic disease in patients for whom conventional therapy failed.

Cryoablation of colorectal liver metastases: minimally invasive tumour control

BACKGROUND

Freezing is used for in situ destruction (ablation) of liver tumours not eligible for resection. The procedure is typically done during laparotomy. The objective of this report was to study tumour control at the site of freezing and a minimally invasive approach to cryoablation of colorectal liver metastases.

METHODS

A prospective study of 19 patients was conducted between 1999 and 2003. Twenty-five tumours were ablated during 24 procedures (i.e. 5 reablations). Sixteen procedures were performed percutaneously, 5 during laparotomy and 3 laparoscopically. Magnetic resonance imaging (MRI) was used for intraprocedural monitoring during most procedures. Nine patients had concomitant liver resections performed (5 during laparoscopy, 4 during laparotomy).

RESULTS

Out of 25 ablations, 18 (72%) were assumed adequate. Total ice-ball volume during percutaneous procedures was median 62 cm (range 32-114). Excellent imaging of the extent of freezing was achieved using MRI. Hospital stay for patients treated percutaneously was median 4 days (range 3-30). No perioperative mortality occurred. Tumour recurrence at the site of ablation occurred in 8 of 18 (44%) tumours adequately ablated. Actuarial 2-year tumour-free survival at site of ablation was 48%. At the time of analyses 12 out of 13 (92%) patients assumed to be adequately ablated were alive. Of all patients, 14 out of 19 (74%) survived.

CONCLUSIONS

Short-term tumour control can be achieved following cryoablation of colorectal liver metastases. A minimally invasive approach is feasible but the diameter of metastases considered for percutaneous cryoablation should not exceed 3 cm.

Use of optical coherence tomography to monitor biological tissue freezing during cryosurgery

The use of optical coherence tomography (OCT) for imaging skin during cryosurgery is evaluated. OCT provides high spatial resolution (5-10 microm) images of optical backscattering due to local variations in refractive index, such as the boundary between liquid and frozen water in tissue. Time resolved OCT images were acquired during freezing of water, Intralipid trade mark, and in vivo hamster skin. Subsurface morphological changes were evident only during freezing of Intralipid and skin. A simple thermal model was applied which predicted freezing times on the same order of magnitude as those observed in OCT images. OCT can be used as a feedback tool during cryosurgical procedures to monitor progression of the freezing front.

Utilization of Low-Field MR Scanners

The evident advantage of high-field MR (magnetic resonance) scanners is their higher signal-to-noise ratio, which results in improved imaging. While no reliable efficacy studies exist that compare the diagnostic capabilities of low- versus high-field scanners, the adoption and acceptance of low-field MRI (magnetic resonance imaging) is subject to biases. On the other hand, the cost savings associated with low-field MRI hardware are obvious. The running costs of a non-superconductive low-field scanner show even greater differences in favor of low-field scanners. Patient anxiety and safety issues also reflect the advantages of low-field scanners. Recent technological developments in the realm of low-field MR scanners will lead to higher image quality, shorter scan times, and refined imaging protocols. Interventional and intraoperative use also supports the installation of low-field MR scanners. Utilization of low-field systems has the potential to enhance overall cost reductions with little or no loss of diagnostic performance.

Hepatic vascular inflow occlusion enhances tissue destruction during cryoablation of porcine liver1

BACKGROUND

Local recurrences after cryoablation of liver tumors have been reported at rates from 5% to 44% and can be caused by inadequate coverage of the tumor by the frozen region. Hepatic vascular inflow occlusion may facilitate ablation by enlarging the size of the frozen region and the tissue necrosis induced by freezing. Few studies have documented these effects of inflow occlusion during liver cryoablation.

MATERIALS AND METHODS

Two cryolesions were induced in the liver of 12 pigs in a standardized set-up. Vascular inflow occlusion was used in six pigs during freezing. Two freeze cycles were performed at each location. Ice-ball volume was estimated by intraoperative magnetic resonance imaging. Cryolesion volume was estimated from histopathologic examination of the lesions 4 days after ablation.

RESULTS

The median volume of ice-balls produced during inflow occlusion was 107% larger than for ice-balls produced without occlusion (P < 0.001). The median volume of cryolesions made during inflow occlusion was 195% larger than for cryolesions induced without occlusion (P < 0.001). The geometry of the ice-balls was more regular if produced during inflow occlusion than if not. The ice-balls produced during the second freeze cycle were 17% and 20% larger than the ice-ball produced during the first freeze for lesions made with (P = 0.01) and without (P = 0.03) inflow occlusion.

CONCLUSIONS

Hepatic vascular inflow occlusion enables freezing of larger volumes of liver tissue andincreases the volume of tissue necrosis induced during cryoablation of porcine liver.

Intraoperative contrast-enhanced MR-imaging as predictor of tissue damage during cryoablation of porcine liver

This study evaluate intraoperative Magnetic Resonance Imaging (MRI) as predictor of tissue damage following cryoablation of porcine liver with and without concomitant hepatic vascular inflow occlusion. Inflow occlusion was used during freezing in 6 of 12 pigs included. The volumes of the procedural ice-balls were estimated from MR images. Immediately after thawing contrast (MnDPDP) enhanced MRI was performed to estimate the volume of the cryolesion. Four days after ablation MRI was repeated of the in-vivo and the ex-vivo liver. Photography was performed of the sliced liver specimens to estimate the volumes of the lesions. The intraoperative volume of the cryolesion as shown by contrast enhanced MRI corresponded well to the ice-ball volume for lesions made without vascular occlusion (difference 0.3 +/- 0.9 cm(3), p = 0.239). For lesions made during occlusion the volume of the intraoperative cryolesion was larger than the corresponding ice-ball (difference 7.5 +/- 3.3 cm(3), p = 0.003). The volume of the cryolesions as estimated from histopathology four days after freezing and contrast enhanced MRI immediately after freezing corresponded well for lesions made with (difference -2.6 +/- 4.5 cm(3), p = 0.110) and without vascular occlusion (difference -0.5 +/- 2.3 cm(3), p = 0.695). Intraoperative MnDPDP-enhanced MRI of the cryolesion is predictive of the tissue damage induced during cryoablation of porcine liver. The procedural ice-ball is not, if induced during inflow occlusion.

Percutaneous cryoablation in treatment of liver cancer: a report of 31 cases

AIM

To describe the indication, efficacy and clinical significance of percutaneous cryoablation in the treatment of liver malignancy.

METHODS

Total 31 patients with histologically or clinically confirmed primary or metastatic malignancies were treated pucutaneously under ultrasound guidance using the cryocare surgical system from July 2001 to January 2002. All patients were followed up to determine the serum tumor marker, and reveal CT scans, MRI images or utra-sound images.

RESULTS

This therapy was performed in 31 patients including 26 cases with Child A liver reserve, 4 cases with Child B and 1 cases with Child C. There were 21 cases of primary liver cancer and 10 metastastic liver cancer. AFP positive small liver cancer became AFP negative in 80% patients. The rate of completely concreted necrosis in small hepatic cancer with negative AFP was 66.7%, shown by CT or MRI. The curative rate for metastasis liver cancer was 50% at CT, MRI or tumor marker level.

CONCLUSION

Percutaneous cryoablation is a kind of new palliative treatment for liver carcinoma. It is minimally invasive, safe and effective especially for patients with unresectable liver cancer.

Percutaneous cryoablation of colorectal liver metastases: potentiated by two consecutive freeze-thaw cycles

Cryoablation may be beneficial for selected patients with liver tumours. Two freeze-thaw cycles at the same location have been recommended during treatment as this potentiate the effect of ablation in experimental studies. However, single freeze ablations are used by some as double freeze procedures are time-consuming and have been associated with increased risk of complications. Estimation of ice-ball volume is difficult using regularly used monitoring techniques. Magnetic resonance imaging, however, allows excellent and multiplanar visualisation of the frozen region during ablation. We comment on the effect of double freeze cycles in regard to ice-ball volume as estimated from magnetic resonance imaging during percutaneous cryoablation of colorectal liver metastases. The ice-ball volume at the end of the second freeze cycle was median 42% larger than the volume at the end of the first freeze. Double freeze cycles may thus facilitate tumour destruction.