Radiofrequency ablation of small liver malignancies under magnetic resonance guidance: progress in targeting and preliminary observations with temperature monitoring

Objectives

To evaluate the feasibility and effectiveness of magnetic resonance (MR)-guided radiofrequency (RF) ablation for small liver tumours with poor conspicuity on both contrast-enhanced ultrasonography (US) and computed tomography (CT), using fast navigation and temperature monitoring.

Methods

Sixteen malignant liver nodules (long-axis diameter, 0.6–2.4 cm) were treated with multipolar RF ablation on a 1.5-T wide-bore MR system in ten patients. Targeting was performed interactively, using a fast steady-state free precession sequence. Real-time MR-based temperature mapping was performed, using gradient echo–echo planar imaging (GRE-EPI) and hardware filtering. MR-specific treatment data were recorded. The mean follow-up time was 19?±?7 months.

Results

Correct placement of RF electrodes was obtained in all procedures (image update, <500 ms; mean targeting time, 21?±?11 min). MR thermometry was available for 14 of 16 nodules (88%) with an accuracy of 1.6°C in a non-heated region. No correlation was found between the size of the lethal thermal dose and the ablation zone at follow-up imaging. The primary and secondary effectiveness rates were 100% and 91%, respectively.

Conclusions

RF ablation of small liver tumours can be planned, targeted, monitored and controlled with MR imaging within acceptable procedure times. Temperature mapping is technically feasible, but the clinical benefit remains to be proven.     

Threshold-based prediction of the coagulation zone in sequential temperature mapping in MR-guided radiofrequency ablation of liver tumours

Objective

To evaluate different cut-off temperature levels for a threshold-based prediction of the coagulation zone in magnetic resonance (MR)-guided radiofrequency (RF) ablation of liver tumours.

Methods

Temperature-sensitive measurements were acquired during RF ablation of 24 patients with primary (6) and secondary liver lesions (18) using a wide-bore 1.5?T MR sytem and compared with the post-interventional coagulation zone. Temperature measurements using the proton resonance frequency shift method were performed directly subsequent to energy application. The temperature maps were registered on the contrast-enhanced follow-up MR images acquired 4?weeks after treatment. Areas with temperatures above 50°, 55° and 60°C were segmented and compared with the coagulation zones. Sensitivity and positive predictive value were calculated.

Results

No major complications occurred and all tumours were completely treated. No tumour recurrence was observed at the follow-up examination after 4?weeks. Two patients with secondary liver lesions showed local tumour recurrence after 4 and 7?months. The 60°C threshold level achieved the highest positive predictive value (87.7?±?9.9) and the best prediction of the coagulation zone.

Conclusions

For a threshold-based prediction of the coagulation zone, the 60°C cut-off level achieved the best prediction of the coagulation zone among the tested levels.

Key Points

? Temperature monitoring can be used to survey MR-guided radiofrequency ablation ? The developing ablation zone can be estimated based on post-interventional temperature measurements ? A 60°C threshold level can be used to predict the ablation zone ? The 50°C and 55°C temperature zones tend to overestimate the ablation zone     

MR-guided microwave ablation in hepatic tumours: initial results in clinical routine

Objectives

Evaluation of the technical success, patient safety and technical effectiveness of magnetic resonance (MR)-guided microwave ablation of hepatic malignancies.

Methods

Institutional review board approval and informed patient consent were obtained. Fifteen patients (59.8 years?±?9.5) with 18 hepatic malignancies (7 hepatocellular carcinomas, 11 metastases) underwent MR-guided microwave ablation using a 1.5-T MR system. Mean tumour size was 15.4 mm?±?7.7 (7-37 mm). Technical success and ablation zone diameters were assessed by post-ablative MR imaging. Technique effectiveness was assessed after 1 month. Complications were classified according to the Common Terminology Criteria for Adverse Events (CTCAE). Mean follow-up was 5.8 months?±?2.6 (1-10 months).

Results

Technical success and technique effectiveness were achieved in all lesions. Lesions were treated using 2.5?±?1.2 applicator positions. Mean energy and ablation duration per tumour were 37.6 kJ?±?21.7 (9-87 kJ) and 24.7 min?±?11.1 (7-49 min), respectively. Coagulation zone short- and long-axis diameters were 31.5 mm?±?10.5 (16-65 mm) and 52.7 mm?±?15.4 (27-94 mm), respectively. Two CTCAE-2-complications occurred (pneumothorax, pleural effusion). Seven patients developed new tumour manifestations in the untreated liver. Local tumour progression was not observed.

Conclusions

Microwave ablation is feasible under near real-time MR guidance and provides effective treatment of hepatic malignancies in one session.

Key Points

? Planning, applicator placement and therapy monitoring are possible without using contrast enhancement ? Energy transmission from the generator to the scanner room is safely possible ? MR-guided microwave ablation provides effective treatment of hepatic malignancies in one session ? Therapy monitoring is possible without applicator retraction from the ablation site

     

Ultrasound-guided thermal radiofrequency ablation (RFA) as an adjunct to systemic chemotherapy for breast cancer liver metastases

Purpose

The aim of this study was to evaluate the effectiveness of radiofrequency thermal ablation (RFA) of liver metastases from breast cancer and its impact on survival.

Materials and methods

Thirteen female patients (age range 36?C82 years; median 54.5 years) underwent RFA for the treatment of 21 liver metastases from breast cancer. The procedures were performed under ultrasound (US) guidance using an RF 2000 or RF 3000 generator system and Le Veen monopolar needle electrodes. Follow-up was carried out by computed tomography (CT) after 1, 3, 6 and 12 months.

Results

Technical success was 100%. No major or minor complications occurred at the end of the procedure. In our series, 7/21 lesions in 7/13 patients increased in size at 7, 18, 19 and 38 months. This resulted in a mean disease-free interval of 16.6 months. Mean overall survival after RFA was 10.9 months.

Conclusions

RFA appears to be a useful adjunct to systemic chemotherapy and/or hormone therapy in the locoregional treatment of hepatic metastases from breast cancer. RFA may also be a less invasive alternative to surgery in the locoregional treatment of liver metastases from breast cancer     

Oblique approach for CT-guided liver radiofrequency ablation using multiplanar reformation images in hepatocellular carcinoma

Purpose

To evaluate the feasibility and safety of CT-guided radiofrequency (RF) ablation by caudal-cranial oblique insertion using multiplanar reformation (MPR) images for hepatocellular carcinomas (HCCs).

Materials and methods

Twenty-two HCCs in 19 patients that were difficult to demonstrate on ultrasound (mean tumor diameter was 17.5?mm) were treated with CT-guided RF ablation by caudal-cranial oblique insertion to avoid pneumothorax, using MPR images after transcatheter arterial chemoembolization. The insertion point and direction of insertion, avoiding aerated lung parenchyma, bones, large vessels, and intestine, were sought on the MPR images. Technical success was defined as complete eradication of tumor enhancement in the contrast-enhanced CT. Local tumor progression was defined by the appearance of enhanced tumor adjacent to the zone of ablation. The technical success rate, local tumor progression, and complications were investigated.

Results

The coronal plane was used for insertion in 18 tumors, the sagittal plane in 3 tumors, and the oblique plane in 1 tumor. RF electrode placement was successful and complete necrosis was obtained in all cases. During the mean follow-up period of 38.0?months, local tumor progression was not detected in any of the patients. There were no major complications, including pneumothorax.

Conclusion

CT-guided RF ablation by caudal-cranial oblique insertion using MPR images is a feasible and safe therapeutic option.     

Ablative zone size created by radiofrequency ablation with and without chemoembolization in small hepatocellular carcinomas

Purpose

We retrospectively evaluated whether combined use of chemoembolization expands ablative zone sizes created by radiofrequency (RF) ablation in patients with small hepatocellular carcinomas (HCCs).

Materials and methods

Fifty-seven patients treated with single RF ablation for solitary HCC measuring ??2?cm were assessed. RF ablation alone was done in nine patients and in 48 patients following chemoembolization, with an interval of 0?days in 6, 1?C14?days in 27, 15?C28?days in 6, and ??4?weeks in 9. Ablative zone sizes, disappearance of tumor enhancement, and creation of sufficient ablative margins (>5?mm) were evaluated on contrast-enhanced computed tomography (CT) images.

Results

Both mean long-axis (4.2?C4.7 vs. 3.6?±?0.4?cm, p?p?p?Conclusion Ablative zones created by RF ablation with chemoembolization become larger than RF ablation alone, leading to secure ablative margins.     

Image-guided microwave ablation of hepatic tumours: preliminary experience

Purpose

Microwave thermal ablation (MWA) opens up a new scenario in the field of image-guided tumour ablation thanks to its potential advantages over validated radiofrequency ablation (RFA). In this pilot study, we assessed the technical success, safety and efficacy of MWA in treating hepatic malignancies.

Materials and methods

After obtaining informed consent, we enrolled 15 inoperable patients, for a total of 19 lesions (ten metastases, nine hepatocellular carcinoma) with a mean diameter of 47 mm (range 14?C78 mm). Mean follow-up was 8 (range 1?C14) months.

Results

Technical success reached 100%. Complications (one major and one minor) occurred in two cases. Complete ablation, obtained in 68.4% of cases, showed no significant correlation with either cancer histological type or with lesion diameter. At follow-up, treatment failures occurred in 60% of cases; lesion diameter was the only prognostic factor for maintaining complete ablation.

Conclusions

Our preliminary results should encourage further trials of this technique. MWA proved to be feasible and safe in treating advanced-stage liver tumours and represented an additional therapeutic attempt to be validated in further and larger efficacy studies.     

High-resolution magnetic resonance-guided posterior femoral cutaneous nerve blocks

Objective

To assess the feasibility, technical success, and effectiveness of high-resolution magnetic resonance (MR)-guided posterior femoral cutaneous nerve (PFCN) blocks.

Materials and methods

A retrospective analysis of 12 posterior femoral cutaneous nerve blocks in 8 patients [6 (75 %) female, 2 (25 %) male; mean age, 47 years; range, 42–84 years] with chronic perineal pain suggesting PFCN neuropathy was performed. Procedures were performed with a clinical wide-bore 1.5-T MR imaging system. High-resolution MR imaging was utilized for visualization and targeting of the PFCN. Commercially available, MR-compatible 20-G needles were used for drug delivery. Variables assessed were technical success (defined as injectant surrounding the targeted PFCN on post-intervention MR images) effectiveness, (defined as post-interventional regional anesthesia of the target area innervation downstream from the posterior femoral cutaneous nerve block), rate of complications, and length of procedure time.

Results

MR-guided PFCN injections were technically successful in 12/12 cases (100 %) with uniform perineural distribution of the injectant. All blocks were effective and resulted in post-interventional regional anesthesia of the expected areas (12/12, 100 %). No complications occurred during the procedure or during follow-up. The average total procedure time was 45 min (30–70) min.

Conclusions

Our initial results demonstrate that this technique of selective MR-guided PFCN blocks is feasible and suggest high technical success and effectiveness. Larger studies are needed to confirm our initial results.     

Contrast-enhanced ultrasound (CEUS) follow-up after radiofrequency ablation or cryoablation of focal liver lesions: treated-area patterns and their changes over time

Objectives

To describe the early patterns of liver lesions successfully treated with radiofrequency ablation (RFA) or cryoablation (CA) and their changes over time.

Methods

Twenty-two RFA-treated and 17 CA-treated patients underwent CEUS from week 1 to year 3 post-ablation. Patterns, margins and volumes of RF-induced and cryolesions were evaluated and compared over time.

Results

After contrast enhancement, shortly after ablation, undefined margins with persistent enhancing small vessels penetrating >2 mm into the treated zone were significantly more frequent after CA (67 %) than RFA (22 %) (P?<?0.02). During the arterial phase, a thin, enhancing marginal rim was seen during week 1 (T1) in around 28 % of RF lesions, while 75 % of cryolesions had thick enhancing rims (P?<?0.02). The mean RF-induced lesion volume, maximum at T1 (44.1?±?37.5 ml), shrank slowly over time, remaining clearly visible at 1 year (8.3?±?7.4 ml). Cryolesions shrank faster (P?=?0.009), from an average of 16.6?±?7.1 ml at T1 to 1.7?±?1.3 ml 1-year post-ablation.

Conclusion

RF-induced and cryolesions differ, particularly their margins and shrinkage rates. Knowing these differences allows avoidance of incomplete treatment or falsely diagnosed recurrence, especially after CA.

Key Points

? Contrast-enhanced ultrasound (CEUS) provides new follow-up information following hepatic radiological inyervention. ? CEUS provides good visualisation of vascular modifications after thermoablation. ? RFA-induced lesions and cryoablated lesions differ. ? Knowledge about RF and cryolesion patterns is essential for correct CEUS follow-up. ? Cryolesions have thicker peripheral inflammatory reactions and shrink faster than RFA-induced lesions.     

Stereotactic Radiofrequency Ablation (SRFA) of Liver Lesions: Technique Effectiveness, Safety, and Interoperator Performance

Purpose

To evaluate technique effectiveness, safety, and interoperator performance of stereotactic radiofrequency ablation (SRFA) of liver lesions.

Methods

Retrospective review including 90 consecutive patients from January 2008 to January 2010 with 106 computed tomography-guided SRFA sessions using both single and multiple electrodes for the treatment of 177 lesions: 72 hepatocellular carcinoma (HCC) and 105 metastases with a mean size of 2.9?cm (range 0.5?C11?cm). Technique effectiveness and 1-year local recurrence were evaluated by computed tomographic scans. Complications, mortality, and hospital days were recorded. The performance between an experienced and inexperienced interventional radiologist was compared.

Results

The overall technique effectiveness after a single SRFA was 95.5% (93.1% for HCC and 97.1% for metastases). Four of the eight unsuccessfully treated lesions could be retreated (secondary technique effectiveness of 97.7%). Local recurrence at 1?year was 2.9%. Technique effectiveness was significantly different for lesions <5?cm (96.7%) and >5?cm (87.5%) (P?=?0.044) but not for lesions <3?cm (95.9%) and 3?C5?cm (100%). Compared to clear parenchymal property (97.3%), vessel vicinity (93.3%) (P?=?0.349) and subcapsular (95.2%) (P?=?0.532) had no, but hollow viscera vicinity (83.3%) had a significantly lower technique effectiveness (P?=?0.020). Mortality rate was 0.9%. Major complications and hospital days were higher for cirrhosis Child-Pugh B (20%, 7.2?days) than Child-Pugh A (3.1%, 4.7?days) patients and for metastases (5.1%, 4.3?days). There was no significant difference in interoperator performance.

Conclusion

SRFA allowed for efficient, reliable, and safe ablation of large-volume liver disease.     

Cementoplasty in the management of painful extraspinal bone metastases: our experience

Purpose

The aim of this study was to demonstrate the effectiveness of interventional techniques in the palliative management of painful extraspinal bone metastases.

Materials and methods

Cementoplasty alone or in combination with radiofrequency (RF) ablation was performed in 14 skeletal extravertebral segments in 13 patients with ages ranging from 50 to 74 (average 67) years. The primary tumours were myeloma (n=5), renal carcinoma (n=5), hepatocellular carcinoma (n=2) and bladder carcinoma (n=2). Metastases were located at the acetabulum (n=4), femur (n=5), humerus (n=1), scapula (n=2) and iliac bone (n=2). The clinical indication was a pain intensity score >4 on the visual analogue scale (VAS) partially or totally refractory to analgesic medication. Clinical evaluation was based on clinical and neurological conditions before and immediately after the procedure and during the follow-up.

Results

Technical success was achieved in all cases. Ten patients were treated by cementoplasty alone and four cases by cementoplasty combined with RF ablation. After treatment, all patients experienced improved symptoms, as demonstrated by the VAS score, which remained constant during follow-up. All patients were followed for between 2 and 14 (average 6.1) months. We had one major complication in a patient who developed an abscess, which was treated by percutaneous drainage.

Conclusions

In our experience, cementoplasty alone for small lesions or combined with RF ablation in larger lesions is an effective and safe therapy in the palliative management of painful extraspinal bone metastases.     

Microwave ablation of liver metastases to overcome the limitations of radiofrequency ablation

Purpose

The purpose of our study was to evaluate technical success, effectiveness and safety of microwave ablation (MWA) in patients with unresectable liver metastases, where radiofrequency ablation (RFA) presents some limits.

Materials and methods

Twenty-five patients (17 men, 8 women) with 31 liver metastases >3 cm or located near vessels (>3 mm) were treated in a total of 29 sessions. Tumours were subdivided as follows: colorectal metastases (n=21) and no colorectal metastases (n=10). All procedures were performed percutaneously under ultrasound (US) guidance. Follow-up was performed with computed tomography (CT) scan at 1, 3, 6 and 12 months after treatment; mean follow-up period was 12.04 (range, 3–36) months. Technical success, mean disease-free survival, effectiveness and safety were evaluated.

Results

Technical success was obtained in all cases. Mean disease-free survival was of 20.5 months. Local recurrence was recorded in 12.9% of metastases treated (4/31). No major complications were recorded. The rate of minor complications was 44.8% (13/29 sessions). Mortality at 30 days was 0%.

Conclusions

Percutaneous MWA of liver metastases >3 cm or located near vessels (>3 mm) can be considered a valid and safe option, probably preferable to RFA. Further studies are required to confirm these encouraging initial results.     

MR findings of steatotic focal nodular hyperplasia and comparison with other fatty tumours

Objectives

To correlate MR findings with pathology in steatotic FNHs and to compare the MR findings with those of other fatty tumours developed on noncirrhotic liver in a consecutive series of resected lesions.

Methods

Our population included resected FNH with intralesional steatosis (n?=?25) and other resected fatty tumours selected as controls (hepatocellular adenomas and angiomyolipomas, n?=?34). Lesions were classified into three groups: those with typical FNH without (group 1) or with (group 2) fat on MR and those with atypical lesions (group 3). In group 3, diagnostic criteria for other fatty tumours were applied.

Results

There were 9 lesions in group 1 (15.3 %), 4 in group 2 (16.8 %) and 46 in group 3 (77.9 %). Group 3 contained 12 FNHs (26 %) and all the other fatty tumours. In group 3, the association of lesion homogeneity, signal intensity similar to or slightly different from adjacent liver on in-phase T1- and T2-weighted sequences, and strong arterial enhancement was observed in 7/12 (58 %) of steatotic FNHs and 3/34 (9 %) of other tumours.

Conclusion

On MR, fat within a typical FNH should not reduce the diagnostic confidence. We recommend further investigations including liver biopsy if necessary when fatty tumours exhibit atypical MR findings.

Key Points

? MRI is increasingly used to assess hepatic lesions containing fat. ? Nodules of focal nodular hyperplasia often contain foci of fat. ? However, steatotic FNH does not always demonstrate typical fatty features on MRI. ? The main mimickers of steatotic FNHs are telangiectatic/inflammatory hepatocellular adenomas. ? We recommend liver biopsy when fatty tumours exhibit atypical MR findings.     

Radiofrequency ablation of benign non-functioning thyroid nodules: 4-year follow-up results for 111 patients

Objectives

To evaluate the clinical outcomes and safety of radiofrequency (RF) ablation for benign non-functioning thyroid nodules over a 4-year follow-up.

Methods

We evaluated 126 benign non-functioning thyroid nodules of 111 patients treated with RF ablation and followed-up more than 3 years. RF ablation was performed using the Cool-Tip RF system and an internally cooled electrode. Nodule volume and cosmetic and symptom scores were evaluated before treatment and during follow-up. Complications and factors related to efficacy were evaluated.

Results

The mean follow-up duration was 49.4?±?13.6 months. Thyroid nodule volume decreased significantly, from 9.8?±?8.5 ml before ablation to 0.9?±?3.3 ml (P?<?0.001) at final evaluation: a mean volume reduction of 93.4?±?11.7 %. The mean cosmetic (P?<?0.001) and symptom scores (P?<?0.001) improved significantly. Factors related to efficacy were initial solidity and volume. The overall recurrence rate was 5.6 % (7/126). The overall complication rate was 3.6 % (4/111).

Conclusions

RF ablation was effective in shrinking benign thyroid nodules and in controlling nodule-related problems over a 4-year follow-up. There were no life-threatening complications or sequelae. Therefore, RF ablation can be used as a non-surgical treatment for patients with benign non-functioning thyroid nodules.

Key Points

? Radiofrequency (RF) ablation provides a non-surgical option for benign non-functioning thyroid nodules ? RF ablation reduced non-functioning thyroid nodular volume by 93.5 % after 49 months ? Initial solidity and volume influenced the efficacy of RF ablation ? Larger thyroid nodules required more treatment sessions to achieve appropriate volume reduction ? Complete treatment of the periphery of the nodule is important in preventing marginal regrowth     

Radiofrequency ablation of renal cell carcinoma in patients with a solitary kidney: a retrospective analysis of our experience

Purpose

This study was done to evaluate the feasibility and safety of radiofrequency ablation (RFA) of renal cell carcinomas (RCCs) in patients with solitary kidney.

Materials and methods

Seven patients (two men, five women; age range 52?C70 years; mean age 59.7 years) were treated under computed tomography (CT) and ultrasound (US) guidance. Three patients had single lesions, and the remaining four had multiple lesions. Seventeen lesions (4 cortical, 13 exophytic, maximum diameter range 12?C40 mm, mean 21.0 mm) not located close to the renal pelvis were treated. CT or magnetic resonance (MR) imaging follow-up studies were obtained for all patients at the end of the procedure and at 1, 3, 6 and 12 months; serum creatinine was also monitored.

Results

Ten ablation sessions were performed. In two patients, a perinephric haematoma was detected, and one of these patients had two episodes of self-limiting haematuria. Contrast-enhanced CT and MR imaging at the end of the procedure and at 1 month demonstrated 100% technical success; these results were confirmed at 3, 6 and 12 month. Fisher??s test comparing serum creatinine obtained 1 day before and 1 day after the procedure showed no case of acute renal failure (mean serum creatinine 24 h before the procedure 1.02 mg/dl; mean serum creatinine 24 h after the procedure 0.95 mg/dl; p=0.114; not significant). Serum creatinine at follow-up was always within the normal range.

Conclusions

Radiofrequency ablation in the solitary kidney is a safe and effective procedure for treating RCC.     

Ablation of colorectal liver metastases by irreversible electroporation: results of the COLDFIRE-I ablate-and-resect study

Objectives

Irreversible electroporation (IRE) is a new ablation technique that relies on high-voltage electrical pulses. This clinical study evaluates the pathological response of colorectal liver metastases (CRLM) treated with IRE and the clinical safety and feasibility.

Methods

Ten patients with resectable CRLM were included. During laparotomy, the metastases were treated with IRE and resected 60 min later. Safety and feasibility were assessed based on adverse events, laboratory values, technical success and intra-operative ultrasound findings. Tissue response was assessed using triphenyl tetrazolium chloride (TTC) vitality staining and (immuno)histochemical stainings (HE, complement-3d and caspase-3).

Results

Ten lesions with a mean diameter of 2.4 cm were successfully electroporated and resected, on average, 84 min later (range 51–153 min). One minor transient cardiac arrhythmia occurred during IRE. Ultrasound showed a sharply demarcated hypoechoic ablation zone around the tumour. TTC showed avitality of all lesions, covering the complete tumour in 8/10 lesions. Although immunohistochemistry proved heterogeneous and difficult to interpret within the tumours, it confirmed irreversible cell damage in the tumour-free margin of all specimens.

Conclusions

This ablate-and-resect study demonstrated avitality caused by IRE of CRLM in humans. Further characterisation of tissue- and tumour-specific electrical properties is warranted to improve ablation protocols for maximised tissue ablation.

Key Points

? Irreversible electroporation induces cell death in colorectal liver metastases within 1 h. ? The ablation zone shows a sharp demarcation between avital and vital tissue. ? Apoptosis is involved in cell death of colorectal liver metastases after IRE. ? Effects of IRE can be monitored real-time using intraoperative ultrasound. ? Local electrical heterogeneities of tumour tissue may require tumour-specific ablation protocols.     

CT-guided Bipolar and Multipolar Radiofrequency Ablation (RF Ablation) of Renal Cell Carcinoma: Specific Technical Aspects and Clinical Results

Purpose

This study was designed to evaluate the clinical efficacy of CT-guided bipolar and multipolar radiofrequency ablation (RF ablation) of renal cell carcinoma (RCC) and to analyze specific technical aspects between both technologies.

Methods

We included 22 consecutive patients (3 women; age 74.2 ± 8.6 years) after 28 CT-guided bipolar or multipolar RF ablations of 28 RCCs (diameter 2.5 ± 0.8 cm). Procedures were performed with a commercially available RF system (Celon AG Olympus, Berlin, Germany). Technical aspects of RF ablation procedures (ablation mode [bipolar or multipolar], number of applicators and ablation cycles, overall ablation time and deployed energy, and technical success rate) were analyzed. Clinical results (local recurrence-free survival and local tumor control rate, renal function [glomerular filtration rate (GFR)]) and complication rates were evaluated.

Results

Bipolar RF ablation was performed in 12 procedures and multipolar RF ablation in 16 procedures (2 applicators in 14 procedures and 3 applicators in 2 procedures). One ablation cycle was performed in 15 procedures and two ablation cycles in 13 procedures. Overall ablation time and deployed energy were 35.0 ± 13.6 min and 43.7 ± 17.9 kJ. Technical success rate was 100 %. Major and minor complication rates were 4 and 14 %. At an imaging follow-up of 15.2 ± 8.8 months, local recurrence-free survival was 14.4 ± 8.8 months and local tumor control rate was 93 %. GFR did not deteriorate after RF ablation (50.8 ± 16.6 ml/min/1.73 m² before RF ablation vs. 47.2 ± 11.9 ml/min/1.73 m² after RF ablation; not significant).

Conclusions

CT-guided bipolar and multipolar RF ablation of RCC has a high rate of clinical success and low complication rates. At short-term follow-up, clinical efficacy is high without deterioration of the renal function.     

Radiofrequency ablation for colorectal liver metastases: prognostic factors in non-surgical candidates

Purpose

To determine prognostic factors in patients with colorectal liver metastases who were not surgical candidates and received liver radiofrequency (RF) ablation.

Materials and methods

RF ablation was done for 141 colorectal liver metastases in 84 patients. There were 63 (75.0?%, 63/84) males and 21 (25.0?%, 21/84) females, with a mean age of 64.6?±?10.3. The mean maximum tumor diameter was 2.3?±?1.4?cm (range 0.5?C9.0?cm). Extrahepatic metastases were associated at the time of liver RF ablation in 23 patients (27.4?%, 23/84), and 12 (14.3?%, 12/84) had lung metastases considered controllable by planned lung RF ablation. Prognostic factors were evaluated by univariate and multivariate analyses.

Results

There was no procedure-related mortality. The 1-, 3-, and 5-year overall survival rates were 90.6?% (95?%CI, 83.9?C97.2?%), 44.9?% (95?%CI, 31.8?C57.9?%), and 20.8?% (95?%CI, 7.3?C34.3?%), respectively, with a median survival of 34.9?months. The univariate analysis showed that tumor diameter larger than 3?cm, tumor multiplicity, uncontrollable extrahepatic disease, and previous chemotherapy history were significantly worse prognostic factors. The former three factors remained significant for worse prognosis in the multivariate Cox model. Extrahepatic disease was not a prognostic factor when it could be controlled.

Conclusion

Tumor size and number, and uncontrollable extrahepatic metastases were significant prognostic factors.     

MRI-guided core biopsy of the prostate in the supine position—introduction of a simplified technique using large-bore magnet systems

Objectives

To introduce a simplified technique for MRI-guided core biopsies (MRGB) of the prostate in the supine position using large-bore magnet systems.

Methods

Fifty men with a history of negative transrectal ultrasound-guided biopsies underwent MRGB in either a 1.5-T (13/50) or 3.0-T (37/50) wide-bore MRI unit. MRGBs were conducted with the patients in a supine position using a dedicated MR-compatible biopsy device.

Results

We developed a dedicated positioning device for the supine position. Using this device, the biopsies were performed successfully in all patients. Apart from minor rectal bleeding, only one patient developed a major side effect (urosepsis). Histology revealed prostate cancer in 25/50 (50 %) patients.

Conclusions

The new technique appears feasible. Its major advantage is the more comfortable and patient-friendly supine position during the biopsy without the need to modify the MRI system’s patient table.

Key Points

? A novel positioning device for MRI-guided prostate biopsies has been developed. ? Biopsies can be performed in the patient-friendly supine position. ? The positioning device can be utilised without modifying the MRI’s patient table.     

Microwave ablation therapy for treating primary and secondary lung tumours: technical note

Purpose

The purpose of our study was to retrospectively evaluate the feasibility, safety and effectiveness of microwave ablation (MWA) in nine patients with unresectable lung tumour.

Materials and methods

Ten lesions were treated in ten ablation sessions in nine patients. The treatments were performed with a microwave generator with 45 W and 915 MHz connected to a 14.5-gauge antenna for 10 min. Antenna placement was performed with computed tomography (CT) fluoroscopy guidance or XperGuide. All patients underwent CT follow-up at 1, 3 and 6 months from the procedure.

Results

Technical success was obtained in all cases; mortality at 30 days was 0%.

Conclusions

This study shows that in selected patients, MWA is a valid alternative to other ablative techniques. Further studies are required to demonstrate the short- and long-term effects of this technique and to make a comparison with other available ablation systems, especially with radiofrequency.