Ablation Margin Research Articles

Thermally sensitive fluorescence imaging system for radiofrequency ablation guidance

Radiofrequency ablation (RFA) has been clinically used as a minimally invasive procedure for the treatment of many solid tumors. However, the current imaging techniques have some shortages in RFA guidance, especially for the assessment of the margin of ablation. Herein, we developed a novel optical imaging platform to guide RFA utilizing fluorescence resonance energy transfer from a thermally sensitive fluorescent protein conjugated to a near-infrared fluorescent dye. Additionally, attaching receptor-targeting ligands further equipped the system with high specificity to tumors overexpressing the targeted receptor.

Technique to evaluate the ablation margin area using fusion markers during radiofrequency ablation/microwave ablation for hepatocellular carcinoma

Technique to evaluate the ablation margin area using fusion markers during radiofrequency ablation/microwave ablation for hepatocellular carcinoma

Stereotactic radiofrequency ablation of a variety of liver masses in children

Background and aims Surgical resection is currently the cornerstone of liver tumor treatment in children. In adults radiofrequency ablation (RFA) is an established minimally invasive treatment option for small focal liver tumors. Multiprobe stereotactic RFA (SRFA) with intraoperative image fusion to confirm ablation margins allows treatment for large lesions. We describe our experience with SRFA in children with liver masses. Methods SRFA was performed in 10 patients with a median age of 14 years (range 0.5–17.0 years) suffering from liver adenoma (n = 3), hepatocellular carcinoma (n = 1), hepatoblastoma (n = 2), myofibroblastic tumor (n = 1), hepatic metastases of extrahepatic tumors (n = 2) and infiltrative hepatic cysts associated with alveolar echinococcosis (n = 1). Overall, 15 lesions with a mean lesion size of 2.6 cm (range 0.7–9.5 cm) were treated in 11 sessions. Results The technical success rate was 100%, as was the survival rate. No transient adverse effects higher than grade II (Clavien and Dindo) were encountered after interventions. The median hospital stay was 5 d (range 2–33 d). In two patients who subsequently underwent transplant hepatectomy complete ablation was histologically confirmed. Follow-up imaging studies (median 55 months, range 18–129 months) revealed no local or distant recurrence of disease in any patient. Conclusions SRFA is an effective minimal-invasive treatment option in pediatric patients with liver tumors of different etiologies.

Simplified Non-Thermal Tissue Ablation With a Single Insertion Device Enabled by Bipolar High-Frequency Pulses.

To demonstrate the feasibility of a single electrode and grounding pad approach for delivering high frequency irreversible electroporation treatments (H-FIRE) in in-vivo hepatic tissue. Ablations were created in porcine liver under surgical anesthesia by adminstereing high frequency bursts of 0.5-5.0μs pulses with amplitudes between 1.1-1.7 kV in the absence of cardiac synchronization or intraoperative paralytics. Finite element simulations were used to determine the electric field strength associated with the ablation margins (ELethal) and predict the ablations feasible with next generation electronics. All animals survived the procedures for the protocol duration without adverse events. ELethal of 2550, 1650, and 875V/cm were found for treatments consisting of 100x bursts containing 0.5μs pulses and 25, 50, and 75μs of energized-time per burst, respectively. Treatments with 1μs pulses consisting of 100 bursts with 100μs energized-time per burst resulted in ELethal of 650V/cm. A single electrode and grounding pad approach was successfully used to create ablations in hepatic tissue. This technique has the potential to reduce challenges associated with placing multiple electrodes in anatomically challenging environments. H-FIRE is an in situ tumor ablation approach in which electrodes are placed within or around a targeted region to deliver high voltage electrical pulses. Electric fields generated around the electrodes induce irrecoverable cell membrane damage leading to predictable cell death in the relative absence of thermal damage. The sparing of architectural integrity means H-FIRE offers potential advantages compared to thermal ablation modalities for ablating tumors near critical structures.

The effects of the no-touch gap on the no-touch bipolar radiofrequency ablation treatment of liver cancer: A numerical study using a two compartment model

The no-touch bipolar radiofrequency ablation (RFA) for cancer treatment is advantageous primarily because of its capability to prevent tumour track seeding (TTS). In this technique, the RF probes are placed at a distance (no-touch gap) away from the tumour boundary. Ideally, the RF probes should be placed sufficiently far from the tumour in order to avoid TTS. However, having a gap that is too large can lead to ineffective ablation. This paper investigates how the selection of the no-touch gap can affect the tissue electrical and thermal responses during the no-touch bipolar RFA treatment. Simulations were carried out on a two compartment model using the finite element method. Results obtained indicated that a gap that is too large may lead to incomplete ablation and failure to achieve significant ablation margin. However, keeping the gap to be too small may not be clinically practical. It was suggested that the incomplete ablation and the insufficient ablation margin observed in some of the cases may require the placement of additional probes around the tumour. The present study stresses on the importance of identifying the optimal no-touch gap that can avoid TTS without compromising the treatment outcome.

Intraprocedural Assessment of Ablation Margins Using Computed Tomography Co-registration in Primary Liver Tumor Treatment With Percutaneous Ablation

Intraprocedural Assessment of Ablation Margins Using Computed Tomography Co-registration in Primary Liver Tumor Treatment With Percutaneous Ablation

Tailoring ablation strategies for colorectal liver metastases based upon rat sarcoma viral oncogene mutation status

Rat sarcoma viral oncogene (RAS) is one of the most well-known tumor genes implicated in the oncological and surgical management of patients with colorectal liver metastases (CLM). More recently, RAS mutational status has also emerged as a relevant factor affecting the oncological outcomes of CLM treated with ablation procedures, a well-established local therapy modality routinely utilized in the oligometastatic disease (OMD) setting. Available evidence suggests that RAS mutation is a prognosticator of shorter local tumor progression free survival (LTPFS) following liver ablation, and that mutant RAS patients with CLM treated with ablation should have wider minimal ablation margins. In this review, we aim to discuss the current literature on the influence of RAS mutational status on ablation outcomes, as well to provide a perspective on the future research on the impact of tumor molecular biology on liver ablation procedures and the potential synergies between local and systemic therapies.

Quantitative Volumetric Assessment of Ablative Margins in Hepatocellular Carcinoma: Predicting Local Tumor Progression Using Nonrigid Registration Software.

Purpose After radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC), pre- and postinterventional contrast-enhanced CT (CECT) images are usually qualitatively interpreted to determine technical success, by eyeballing. The objective of this study was to evaluate the feasibility of quantitative assessment, using a nonrigid CT-CT coregistration algorithm. Materials and Methods 25 patients treated with RFA for HCC between 2009 and 2014 were retrospectively included. Semiautomated coregistration of pre- and posttreatment CECT was performed independently by two radiologists. In scans with a reliable registration, the tumor and ablation area were delineated to identify the side and size of narrowest RFA margin. In addition, qualitative assessment was performed independently by two other radiologists to determine technical success and the anatomical side and size of narrowest margin. Interobserver agreement rates were determined for both methods, and the outcomes were compared with occurrence of local tumor progression (LTP). Results CT-CT coregistration was technically feasible in 18/25 patients with almost perfect interobserver agreement for quantitative analysis (κ = 0.88). The interobserver agreement for qualitative RFA margin analysis was κ = 0.64. Using quantitative assessment, negative ablative margins were found in 12/18 patients, with LTP occurring in 8 of these patients. In the remaining 6 patients, quantitative analysis demonstrated complete tumor ablation and no LTP occurred. Conclusion Feasibility of quantitative RFA margin assessment using nonrigid coregistration of pre- and postablation CT is limited, but appears to be a valuable tool in predicting LTP in HCC patients (p=0.013).

Percutaneous ultrasound guided radiofrequency and microwave ablation in the treatment of hepatic metastases. A monocentric initial experience.

Percutaneous radiofrequency (RFA) and microwave ablation (MWA) are currently the best treatment options forpatients with liver metastases (LM) who cannot undergo a liver resection procedure. Presently, few studies have evaluated theefficacy of tumor ablation in beginner's hands but none at all in hepatic metastasis. Our aim was to report the initial experiencewith ultrasound as a tool to guide tumor ablation in a low volume center with no experience in tumor ablation. We conducted a retrospective cohort study, on a series of 61 patients who had undergone percutaneous US-guided ablations for 82 LM between 2010 and 2015. Long term outcome predictors were assessed using univariate and multivariate analysis. Complete ablation was achieved in 86.9% of cases (53/61). All MWA sessions (20/20) attained ablation margins >5mm, compared to 79% (49/62) for RFA sessions (p=0.031). Ablation time was significantly shorter for MWA, with a median duration of 10 minutes (range: 6-12) vs. 14 minutes (range: 10-19.5, p=0.003). There was no statistically significant difference in local tumor progression (LTP)-free survival rates between MWA and RFA (p=0.154). On univariate analysis, significant predictors for local recurrence were multiple metastases (p=0.013) and ablation margins <5 mm (p<.001), both retaining significance on multivariate analysis. Significant predictors for distant recurrence on both univariate and multivariate analysis were multiple metastases (p<0.001) and non-colorectal cancer metastases (p<0.05). A larger than 5 mm ablation size is critical for local tumor control. We favor the use of MWA due to its ability to achieve ablation in significantlyshorter times with less incomplete ablations.

Quantitative margin assessment of radiofrequency ablation of a solitary colorectal hepatic metastasis using MIRADA RTx on CT scans: a feasibility study

BackgroundCompared to surgery, radiofrequency ablation(RFA) for colorectal liver metastasis(CRLM) is associated with higher local recurrence(LR) rates. A wide margin (at least 5 mm) is generally recommended to prevent LR, but the optimal method to assess ablation margins is yet to be established. The aim of our study was to evaluate the feasibility and reproducibility of CT-CT co-registration, using MIRADA software, in order to assess ablation margins of patients with CRLM.MethodsIn this retrospective study, pre- and post-ablation contrast-enhanced CT scans of 29 patients, treated with percutaneous RFA for a solitary CRLM, were co-registered. Co-registration was performed by two independent radiologist, based on venous structures in proximity to the tumor. Feasibility of CT-CT co-registration and inter-observer agreement for reproducibility and ablation margins was determined. Furthermore, the minimal ablation margin was compared with the occurrence of LR during follow-up.ResultsCo-registration was considered feasible in 18 patients (61% male, 63.1(±10.9) year), with a perfect inter-observer agreement for completeness of ablation: κ = 1.0(p < 0.001). And substantial inter-observer agreement for measurement of the minimal margin (≤ 0 mm, 1-5 mm, ≥ 5 mm): κ = 0.723(p-value < 0.001). LR occurred in eight of nine(88.9%) incompletely ablated CRLM and in one of the nine completely ablated CRLM(11.1%).ConclusionCo-registration using MIRADA is reproducible and potentially a valuable tool in defining technical success. Feasibility of co-registration of pre- and post-ablation CT scans is suboptimal if scans are not acquired concordantly. Co-registration may potentially aid in the prediction of LR after percutaneous ablation.

Radiofrequency ablation for hepatocellular carcinoma: Clinical value of ultrasound-ultrasound overlay fusion for optimal ablation and local controllability.

To retrospectively investigate the potential benefit of ultrasound-ultrasound (US-US) overlay fusion guidance for local controllability of radiofrequency ablation (RFA) in the treatment of hepatocellular carcinoma (HCC). Patients (n = 101) with 121 HCCs (mean ± SD, 1.8 ± 0.7cm) who underwent RFA guided by US-US overlay fusion were included in the retrospective study. By overlaying pre/postoperative US, the tumor image could be projected onto the ablative hyperechoic zone. The ablative margin could thereby be evaluated three-dimensionally during the RFA procedure. As a control group, all 325 patients with 453 HCCs who underwent conventional RFA during the same study period were selected. The total number of RF needle insertions per tumor for ablation was significantly more in the US overlay fusion group (mean 1.9 vs. 1.2; P < 0.01). The technical success rates of ablation after a single session were 100% (101/101) and 96.6% (314/325) for the US overlay fusion group and the control group, respectively. For early assessment of RFA response, 5-mm safety margins were achieved in 89.3% (108/121) and 47.0% (213/453) of nodules in the US overlay fusion group and the control group, respectively (P < 0.01). During the follow-up period (median 19months), the 2-year local tumor progression rates were 0.8% (1/121) and 6.0% (27/453) in the US overlay fusion group and the control group, respectively (P = 0.022, log-rank test). US-US overlay fusion guidance can be highly effective for safety margin achievement in RFA for HCC, providing a lower risk of local tumor progression.

Rectal wall saline displacement for improved margin during MRI-guided cryoablation of primary and recurrent prostate cancer.

To describe safety, efficacy, and added oncologic margin of saline displacement of the rectal wall during MRI-guided cryoablation of primary and recurrent prostate cancer. A retrospective review was conducted for patients who underwent MRI-guided cryoablation with saline displacement of the rectal wall for treatment of primary and recurrent prostate cancer over a 2-year period. Saline displacement was used when the distance from the edge of the ablation area to the rectal wall was insufficient to provide at least a 5-mm treatment margin. Pre- and post-ablation rectal wall displacement distances as well as ablative zone margins were assessed with MRI. Saline displacement distance was measured from the rectal wall to the edge of the lesion for focal lesion ablation and from the edge of the prostate for hemi-gland ablation. Immediate and intermediate-term complications were assessed. Saline displacement was used in 25 patients undergoing MRI-guided cryoablation. Twenty-one patients underwent salvage cryoablation, while four patients had it as primary treatment for prostate cancer. Median pre- and post- saline displacement rectal wall displacement distances were 6.0 and 11.2mm, respectively (P < 0.0001). Median-added oncologic margin achieved by saline displacement was 4.6mm (range 0.6-26.5). Median follow-up was 14months (range 5-29). There were no intra-procedural complications and 3 patients experienced minor (Clavien-Dindo grade I) complications. One rectal complication occurred in a patient undergoing salvage cryotherapy with a history of extensive pelvic surgery and radiation. Saline infusion at the time of MRI- guided cryoablation for prostate cancer resulted in increased distances between the target lesion and rectum. This is a useful technique in providing an added oncologic margin when treating lesions close to the rectal wall.

Irreversible electroporation ablation of end-stage metastatic retroperitoneal lesions: Report on three cases and literature review.

Metastatic retroperitoneal tumors constitute an end-stage disease with poor prognosis that represents a heavy global health burden. The present study aimed to explore the efficacy of irreversible electroporation ablation (IRE) therapy in patients with end-stage retroperitoneal tumors. Between April 2016 and September 2017, three patients with unresectable retroperitoneal malignant tumors were enrolled. Among these cases, ultrasound (US)-guided IRE was palliatively performed for targeting 3 tumors (1 tumor per patient) located around the abdominal aorta. Post-treatment contrast-enhanced US (CEUS) and contrast-enhanced computed tomography (CECT) scans were subsequently performed to evaluate the area adjacent to the ablation zone and determine the prognosis. During the follow-up, the cases experienced a reduction of pain (mean score of 5.8 decreased to 2.2, based on the visual analogue scale), and had an overall survival rate ranging from 2 to 11 months. Case 1 remained alive at the time of submission of this study, but case 2 died within 2 months and case 3 within 11 months due to liver metastases of the primary tumor. At the 3-week follow-up, the CEUS image for case 1 exhibited a contrast defect with a sufficient ablation margin, in accordance with the CECT at 1.5 months following IRE, exhibiting complete tumor necrosis without contrast enhancement. Overall, these results suggest that US-guided percutaneous IRE may be effective in the treatment of end-stage retroperitoneal tumors. However, further studies are required to substantiate the conclusions of the present study. The present clinical trial was registered at clinicaltrials.gov (ID: NCT02822066) on June 20th, 2016.

The interaction between irreversible electroporation therapy (IRE) and embolization material using a validated vegetal model: an experimental study.

Irreversible electroporation (IRE) is a nonthermal tumor ablation technique that induces cell apoptosis while preserving extracellular architecture. Surgical clips and embolic agents may lie adjacent to, or within, the target lesion. It is unknown to date if IRE causes degradation to the embolic agents or surgical clips that may have adverse effects to patients. We aimed to examine the effects of the IRE on the morphology of various embolic agents and the effects of these agents to the ablation field using a previously validated vegetal model. Metallic surgical clips and various metallic and nonmetallic embolic agents were inserted within the center of the tuber ablation field. Additionally, clips were inserted on the edge and outside the ablation field. One tuber was ablated as a control. Ablation settings were based on previous published experiments. Tubers were imaged with magnetic resonance imaging (MRI) 18-24 hours after ablation and the ablated field dimensions were measured. Nonmetallic embolic agents were examined microscopically by the pathologist. Nonmetallic agents did not affect the ablation pattern. Metallic implants, however, caused arcing of the ablation margins. There was no macroscopic or microscopic degradation to the agents after IRE. The ablation zone arced in the presence of surgical clips at the edge or outside the ablation margins; therefore, nearby critical structures may be susceptible to the effects of IRE. Furthermore, there was no physical degradation of the embolic agents or surgical clips, and this may have importance when considering IRE ablation of previously embolized lesions in vivo.

An Noninvasive and Impedance-Ignored Control Strategy of the Ablation Zone in Radiofrequency Ablation Therapy.

This study proposed a control strategy of the ablation margin using the temperature of the probe, without causing additional damage. Compared with other methods, the proposed strategy is real time and impedance-ignored, thus has a better performance in practice. A theoretical model was established to obtain the temperature distribution during the treatment. Several functions were obtained by fitting the results of the simulation model, with which a preset central temperature curve corresponding to a desired ablation zone was determined to regulate the temperature of the control point. Considering the various impedances in practice, a voltage adjustment method according to the error between the preset central temperature and the practical central temperature was proposed to minimize the effect of impedances. At last, the strategy was verified with phantom experiments. The results show that all the temperatures of the control points reached to 50°C at a specific time and kept for a while, which demonstrated the strategy had a good performance within the error range allowed.

Ablation in Primary Liver Tumors

Minimal invasive thermal ablation techniques have a key role in the treatment regimen of primary liver tumors. These relatively low-risk procedures are established in nonresectable liver tumors and even challenge the surgical approach, which is regarded as first-line treatment in eligible patients.The location and size of the liver tumor, the applied ablation, and guidance technique are crucial for treatment outcome. The confirmation of an adequate ablation zone including sufficient tumor overlap and a safety margin (A0 ablation analogous to R0 resection) is crucial to minimize local recurrence rates and improve survival. A variety of different ablation devices is available. The outcome of conventional computed tomography- or ultrasound-guided thermal ablation in small lesions is well comparable to surgery. However, in liver lesions with large diameter overlapping ablation zones are required to ensure an adequate ablation margin. Therefore, stereotactic techniques in combination with a multiple needle approach, three-dimensional trajectory planning, and image fusion for intraoperative treatment evaluation have been successfully introduced.

Use of Transthoracic Transdiaphragmatic Approach Assisted with Radiofrequency Ablation for Thoracoscopic Hepatectomy of Hepatic Tumor Located in Segment VIII

BackgroundResection of segment VIII remains challenging despite the widespread laparoscopic hepatectomies in past decades,1,2 especially for patients with cirrhosis. In this case, we combined radiofrequency ablation (RFA) with transthoracic approach, which was a novel approach for laparoscopic-guided hepatectomy of segment VIII in a cirrhotic patient. PatientA 42-year-old male patient with a body mass index of 22.0 kg/m2 suffered from HBV-related cirrhosis was admitted to our institution. The preoperative MRI showed a 1.3 cm liver mass located in segment VIII. The preoperative AFP is 192 ng/ml. The patient was considered to have hepatectomy using transthoracic transdiaphragmatic approach with the assist of RFA. TechniqueThe patient was placed in a left lateral position with artificial pneumothorax in the right lung and left side ventilation. Three trocars were placed into the right thoracic space. Transdiaphragmatic intraoperative ultrasonography (IOUS) was performed to confirm the size and location of the lesion. In order to decrease the blood loss during parenchymal dissection and to reach tumor-free margins, the RFA was performed around the tumor before hepatectomy. After that the resection was carried out along the ablative margin. After the specimen was removed, the diaphragm was sutured and a closed thoracic drainage tube was placed. The operative time was 210 min with an estimated blood loss of 50 mL. The postoperative course was uneventful. Antibiotics was used in the first 24 h post-operation to prevent thoracic infection. Drainage tube was pulled out on the fourth day post-operation when we observed the daily fluid volume was less than 100 ml for 2 days and X-ray showed no gases and effusion in chest cavity. The pathology confirmed the diagnosis of hepatocellular carcinoma and the surgical margin was negative. The patient was discharged on the 8th day after surgery. DiscussionLesions in the postero-superior segments still be challenging as we know.3 Previous studies showed that the procedure’s results, such as the blood loss and operative time, were similar between thoracoscopic hepatectomy and laparoscopic hepatectomy, even the former was better.2,4 Thus, for the superficial lesions in the postero-superior segments, and not more than 3 cm in diameter, thoracoscopic hepatectomy is recommended. Furthermore, a patient with a hostile abdomen who has a lesion in S7 or S8, transthoracic approach may be particularly helpful. However, functional lung is required due to the unilateral ventilation. Besides, anatomic resections are difficult to perform from the top.5 In this case, we used RFA before liver resection, and the tumor cells were destroyed to ensure the negative margin of the cut, and the bleeding blood vessels were also closed. This method can make a significant reduction of blood loss in the patients with cirrhosis compared with conventional hepatectomy (whether through thoracoscopic6 or laparoscopic7 approach). ConclusionThe novel approach for transthoracic hepatectomy was safe and feasible for lesions of segment VIII in selected patients with cirrhosis,8 which was associated with reduced blood loss and a safe surgical margin.

Safety margin of radiofrequency ablation for hepatocellular carcinoma: a prospective study using magnetic resonance imaging with superparamagnetic iron oxide.

In radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), it is difficult to assess the ablative margin (AM) precisely by comparing pre- and post-RFA CT images. We prospectively studied the AMs using magnetic resonance imaging (MRI) with pre-administered superparamagnetic iron oxide (SPIO). SPIO is safe for kidney disease patients. Hepatocellular carcinoma patients were treated with RFA within 8h of SPIO administration. On T2*-weighted MRI performed 4-7days later, AM was visualized as a hypointense rim. The ablation status was classified as AM(+) if the rim completely surrounded the tumor, AM(0) if the rim was partly discontinuous without tumor protrusion, and AM(-) if the rim was partly discontinuous with tumor protrusion. The minimal thickness of AM was measured. AM(-) tumors were re-treated consecutively. In total, 85 HCCs ablated in 76 patients were evaluated. The local recurrence rate at 3years was 2% for AM(+) tumors and 34% for AM(0) tumors (p < 0.01). In addition, no local recurrence was seen in the tumors with an AM of ≥ 2mm. MRI with pre-administered SPIO is useful for determining the AM precisely, and an AM of ≥ 2mm is recommended for curative RFA. This study was registered with UMIN Clinical Trials Registry (UMIN 000025406).

3-D Contrast-Enhanced Ultrasound Fusion Imaging: A New Technique to Evaluate the Ablative Margin of Radiofrequency Ablation for Hepatocellular Carcinoma

To investigate the feasibility of assessing the ablative margin (AM) of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) with 3-D contrast-enhanced ultrasound fusion imaging (3-DCEUS-FI), pre- and post-RFA 3-DCEUS images of 84 patients with HCC were fused for two radiologists to independently assess the AMs. The success rate, duration and influencing factors for registration; inter-observer agreement for AM classification; and local tumor progression (LTP) rate were evaluated. The success rate of the automatic registration (AR), which was completed within 4–12 s, was 57.1% (48/84). The duration and success rate of the interactive registration (IR) were 4.2 ± 1.8 min and 91.7% (77/84) for radiologist A and 4.8 ± 2.1 min and 91.7% (77/84) for radiologist B, respectively. The multivariate analysis demonstrated that the pre-RFA image quality, number of vessels (≥3 mm) and presence of acoustic shadow were independent factors for AR (p < 0.05), while the number of vessels was an independent factor for IR (p = 0.001). The agreement between observers was excellent (kappa = 0.914). LTP rate was significantly higher for AMs <5 mm than for AMs ≥5 mm (p = 0.024). Quantitatively evaluating the AM immediately after RFA for HCC with 3-DCEUS-FI was feasible.

Assessment of the cryoablation margin using MRI–CT fusion imaging in hepatic malignancies

To demonstrate the feasibility of magnetic resonance imaging (MRI)-computed tomography (CT) fusion imaging for the assessment of the ablative margin after cryoablation in hepatic malignancies. This retrospective study analysed 35 patients with 47 liver tumours treated with CT-guided cryoablation. Fusion images of pre-ablation MRI and intraoperative CT data were created on a workstation. Minimal ablative margin (MAM) assessment was categorised into three groups: (I) MAM <0 mm (tumour protruded through the ablation zone), (II) MAM 0-5 mm, and (III) MAM ≥5 mm. Local tumour progression (LTP) was assessed during follow-up. MRI-CT fusion imaging was successfully achieved in 46 (97.9%) of 47 lesions. LTP was detected in 67.4% (31/46) of cases. Twenty-four (77.4%) of 31 LTPs occurred in the subcapsular region of the liver. Using fusion images, the MAM was classified as groups I, II, and III in 18, 25, and three tumours, respectively. In group I, LTP was found in 15 (83.3%) of 18 lesions, whereas in group II, LTP was detected in 16 (64%) of 25 lesions. The cumulative LTP rate in group II was significantly lower than that in group I (p=0.012). Pre-ablation MRI and intraoperative CT fusion imaging is feasible and useful for evaluating the MAM of cryoablation in hepatic malignancies.