Ablation protocols and ancillary procedures in tumor ablation therapy: consensus from Japanese experts

Purpose

A panel of Japanese experts on tumor ablation therapy gathered to reach a general consensus on topics surrounding ablation therapy.

Materials and methods

Questionnaires relating to ablation protocols for radiofrequency ablation (RFA) and cryoablation, as well as ancillary procedures required for safe and secure ablation therapy, were sent to seven institutions. Experts from these institutions discussed each topic based on the evidence and the questionnaire data, and a consensus was reached at an annual meeting of the Japan Image-guided Ablation Group in Maebashi, Japan, in October 2015.

Results

A consensus was reached on each of six topics, including “management of antiplatelet and anticoagulation drug therapy”; “pain control in the perioperative period”; “arterial embolization combined with ablation therapy”; “protection of non-target organs”; “RFA and cryoablation protocols”; and “ablative margins.”

Conclusions

The consensus achieved here will serve as the framework for tumor ablation therapies in Japan.

     

RF Ablation of Giant Hemangiomas Inducing Acute Renal Failure: A Report of Two Cases

Objective

In patients that require treatment for hepatic giant cavernous hemangiomas (GCH), radiofrequency ablation (RFA) has been suggested to represent a safe and effective alternative to invasive surgery. In a recent report of bipolar RFA, using two expandable needle electrodes, was uneventfully performed in patients with large GCH (>10 cm). The objective of this report is to present two cases in which bipolar RFA of symptomatic GCH was complicated by acute kidney injury.

Materials and methods

In 2015 we treated two patients for very large symptomatic GCH (15.7 and 25.0 cm) with bipolar RFA during open laparotomy.

Results

In both patients the urine showed a red–brown discoloration directly after the ablation. They became anuric and presented with progressive dyspnea, tachypnea, and tachycardia, requiring hemodialysis for a period of 1 month in one case. Lab results revealed hemepigment-induced acute kidney. Both patients fully recovered and both showed a complete relief of symptoms at 3 months following the procedure.

Conclusion

RFA for large GCHs can cause hemepigment-induced acute kidney injury due to massive intravascular hemolysis. The presented cases suggest that caution is warranted and advocate an upper limit regarding the volume of GCHs that can be safely ablated.

     

Thermal ablation of thyroid nodules: are radiofrequency ablation,microwave ablation and high intensity focused ultrasound equally safe and effective methods?

Objectives

This study compares volume reduction of benign thyroid nodules three months after Radiofrequency Ablation (RFA), Microwave Ablation (MWA) or High Intensity Focused Ultrasound (HIFU) to evaluate which of these methods is the most effective and safe alternative to thyroidectomy or radioiodine therapy.

Material and Methods

Ninety-four patients (39 male, 55 female) with a total of 118 benign, symptomatic thyroid nodules were divided into three subgroups. HIFU was applied to 14 patients with small nodules. The other 80 patients were divided up into two groups of 40 patients each for RFA and MWA in the assumption that both methods are comparable effective. The pre-ablative and post-ablative volume was measured by ultrasound.

Results

RFA showed a significant volume reduction of nodules of 50 % (p<0.05), MWA of 44 % (p<0.05) and HIFU of 48 % (p<0.05) three months after ablation. None of the examined ablation techniques caused serious or permanent complications.

Conclusion

RFA, MWA and HIFU showed comparable results considering volume reduction. All methods are safe and effective treatments of benign thyroid nodules.

Key Points

? Thermal Ablation can be used to treat benign thyroid nodules ? Thermal Ablation can be an alternative to thyroidectomy or radioiodine therapy ? Radiofrequency Ablation, Microwave Ablation, High Intensity Focused Ultrasound are safe and effective

     

In vivo effects of radiofrequency ablation on long bones and the repair process in swine models

Purpose

To investigate in vivo effect of radiofrequency ablation (RFA) on swine long bones and the repair process.

Materials and methods

RFA was performed in six swine at the end and middle part of the tibia or femur. After RFA, radiological examinations were performed, and the swine were killed immediately and at different time points post-RFA for histopathological examination.

Results

All swine had successful RFA. The RFA-induced elliptical necrotic area ranged from 3.81–5.24 cm² (mean 4.08 ± 0.73 cm²) at the bone end but 5.60–8.98 cm² (mean 7.58 ± 1.41) at the middle part immediately after RFA until 10 days, with the necrosis area significantly smaller (P = 0.000) at the end than at the middle. RFA only damaged the cortical bone slightly (0.01 cm thick) with no damage to the soft tissues outside the compact bone at both the end and middle. Surrounding the elliptic pale zone of coagulative necrosis was a narrow brown band of hemorrhage and inflammatory exudate. From day 10 until week 12, tissue proliferation and repair became increasingly apparent, with proliferated granulation, fibrous tissue, and fresh and mature bone trabecula.

Conclusion

RFA can quickly and effectively destroy the cancellous bone tissue without affecting the cortical bone and activate bone remodeling.

     

Diagnostic Ability of Percutaneous Needle Biopsy Immediately After Radiofrequency Ablation for Malignant Lung Tumors: An Initial Experience

Purpose

To evaluate the safety and diagnostic ability of percutaneous needle biopsy performed immediately after lung radiofrequency ablation (RFA).

Materials and Methods

From May 2013 to April 2014, percutaneous needle biopsy was performed immediately after RFA for 3 patients (2 men and 1 woman, aged 57–76 years) who had lung tumors measuring 1.3–2.6 cm in diameter. All patients had prior history of malignancy, and all tumors were radiologically diagnosed as malignant. Obtained specimens were pathologically classified using standard hematoxylin and eosin staining.

Results

We completed three planned sessions of RFA followed by percutaneous needle biopsy, all of which obtained tumor tissue that could be pathologically diagnosed. Two tumors were metastatic from renal clear cell carcinoma and rectal adenocarcinoma, respectively; one tumor was primary lung adenocarcinoma. There was no death or major complication related to the procedures. Although pneumothorax occurred in two patients, these resolved without the need for aspiration or chest tube placement. Tumor seeding was not observed, but 21 months after the procedure, one case developed local tumor progression that was treated by additional RFA.

Conclusion

Pathologic diagnosis was possible by needle biopsy immediately after RFA for lung tumors. This technique may reduce the risks and efforts of performing biopsy and RFA on separate occasions.

     

Effectiveness and safety of computed tomography-guided radiofrequency ablation of renal cancer: a 14-year single institution experience in 203 patients

Objectives

To define effectiveness and safety of CT-guided radiofrequency ablation (RFA) of renal tumours and prognostic indicators for treatment success.

Methods

Patients with a single treatment of a solitary, biopsy-proven renal tumour with intent to cure over a 14-year period were included (n?=?203). Probability of residual disease over time, complication rates and all-cause mortality were assessed in relation to multiple variables.

Results

Mean tumour size was 2.5 cm (range 1.0–6.0). Mean follow-up was 34.1 months (range 1–131). There was an increase in likelihood of residual disease for tumours ≥3.5 cm (P?<?0.05), clear cell subtype of renal cell carcinoma (P?≤?0.005) and maximum treatment temperature ≤70 °C (P?<?0.05). There was a decrease in likelihood of residual disease for exophytic tumours (P?=?0.01) and no difference based on age, gender, tumour location or type of radio freqency (RF) electrode used. Major complications occurred in 3.9 %. Median post-treatment survival was 7 years for patients with tumours <4 cm, and 5-year overall survival was 80 %. Probability of minor complication increased with tumour size (P?=?0.03), as did all-cause mortality (P?=?0.005).

Conclusions

CT-guided RFA is safe and effective for early-stage renal cancer, particularly for exophytic tumours measuring <3.5 cm. Overall 5-year survival with tumours <4 cm is comparable to partial nephrectomy.

Key points

? Prognostic indicators for success of CT-guided RFA of renal tumours are reported. ? Tumour size ≥3.5 cm confers an increased risk for residual tumour. ? Clear cell renal cell carcinoma subtype confers increased risk for residual tumour. ? Tmax <70 °C within the ablation zone confers increased risk for residual tumour. ? Exophytic tumours have a lower probability of residual disease.

     

Magnetic resonance imaging with gadoxetic acid for local tumour progression after radiofrequency ablation in patients with hepatocellular carcinoma

Objectives

To develop and validate a prediction model using magnetic resonance imaging (MRI) for local tumour progression (LTP) after radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC) patients.

Methods

Two hundred and eleven patients who had received RFA as first-line treatment for HCC were retrospectively analyzed. They had undergone gadoxetic acid-enhanced MRI before treatment, and parameters including tumour size; margins; signal intensities on T1-, T2-, and diffusion-weighted images, and hepatobiliary phase images (HBPI); intratumoral fat or tumoral capsules; and peritumoural hypointensity in the HBPI were used to develop a prediction model for LTP after treatment. This model to discriminate low-risk from high-risk LTP groups was constructed based on Cox regression analysis.

Results

Our analyses produced the following model: ‘risk score?=?0.617?×?tumour size?+?0.965?×?tumour margin?+?0.867?×?peritumoural hypointensity on HBPI’. This was able to predict which patients were at high risk for LTP after RFA (p?<?0.001). Patients in the low-risk group had a significantly better 5-year LTP-free survival rate compared to the high-risk group (89.6 % vs. 65.1 %; hazard ratio, 3.60; p?<?0.001).

Conclusion

A predictive model based on MRI before RFA could robustly identify HCC patients at high risk for LTP after treatment.

Key points

? Tumour size, margin, and peritumoural hypointensity on HBPI were risk factors for LTP.? The risk score model can predict which patients are at high risk for LTP.? This prediction model could be helpful for risk stratification of HCC patients.

     

Percutaneous Intraductal Radiofrequency Ablation for Extrahepatic Distal Cholangiocarcinoma: A Method for Prolonging Stent Patency and Achieving Better Functional Status and Quality of Life

Purpose

The clinical efficacy of intraductal radiofrequency ablation (RFA) with Habib? EndoHPB catheter, a newly developed intervention for malignant extrahepatic biliary obstruction, remains uncertain. The aim of this study was to investigate the clinical efficacy of intraductal RFA.

Methods

Data from 71 patients with extrahepatic distal cholangiocarcinoma were retrospectively analyzed. The study patients were divided into RFA and control groups. The RFA group had undergone percutaneous transhepatic intraductal RFA with a Habib? EndoHPB catheter, followed by placement of covered or uncovered biliary self-expandable metallic stents (SEMs) whereas the control group had undergone percutaneous transhepatic covered or uncovered SEMs placement. Procedure-related complications, stent patency, patient survival, and postoperative serum bilirubin concentrations were compared between the two groups. The Functional Assessment of Cancer Therapy-Hepatobiliary (FACT-Hep) questionnaire was administered to evaluate functional status, improvement in clinical manifestations, and quality of life.

Results

The RFA group had a longer median stent patency than the control group (p = 0.001 for uncovered SEMs placement). Higher functional well-being, hepatobiliary-specific cancer subscale, Trial Outcome Index, and total FACT-Hep scores were observed during post-procedure follow-up in the RFA group. However, median survival did not differ significantly between the two groups (p > 0.05).

Conclusions

Prolongation of stent patency and better functional status and quality of life, which are all important clinical endpoints, were observed in patients treated with intraductal RFA. Prospective randomized controlled clinical trials are necessary to further investigate the clinical efficacy and long-term benefits of intraductal RFA.

     

Feasibility of Intraoperative Nerve Monitoring in Preventing Thermal Damage to the “Nerve at Risk” During Image-Guided Ablation of Tumors

Purpose

To assess feasibility of intraoperative neurophysiologic monitoring (IONM) during image-guided, percutaneous thermal ablation of tumors.

Materials and Methods

From February 2009 to October 2013, a retrospective review of all image-guided percutaneous thermal ablation interventions using IONM was performed and data was compiled using electronic medical records and imaging studies.

Results

Twelve patients were treated in 13 ablation interventions. In 4 patients, real-time feedback from the monitoring neurologist was used to adjust applicator placement and ablation settings. IONM was technically feasible in all procedures and there were no complications related to monitoring or ablation. All nerves at risk remained intact and of the 11 patients who could be followed, none developed new nerve deficit up to a minimum of 2 months after ablation.

Conclusion

IONM is safe and feasible for use during image-guided thermal ablation of tumors in the vicinity of nerves. Outcomes in this study demonstrate its potential utility in image-guided ablation interventions.

     

Radiofrequency ablation versus magnetic resonance guided focused ultrasound surgery for minimally invasive treatment of osteoid osteoma: a propensity score matching study

Objectives

To compare outcomes in pain relief and motor functional recovery in patients with an osteoid osteoma treated by magnetic resonance guided focused ultrasound surgery (MRgFUS) or radiofrequency ablation (RFA) using a propensity score matching study design.

Methods

Thirty patients with osteoid osteomas were included in this institutional review board (IRB)-approved study. MRgFUS was performed in 15 subjects. These subjects were matched by propensity analysis with a group of 15 subjects treated by RFA. Pain relief in terms of complete response (CR) and motor functional recovery were measured.

Results

A similar proportion of subjects treated by MRgFUS (94 %) or RFA (100 %) experienced CR 12 weeks after treatment, with no significant difference. The improvement in pain control following MRgFUS or RFA paralleled with improved motor functional recovery. The treatment failure rate was 6.6 % in the MRgFUS group and 0 % in the RFA group. No major complications were observed following either ablative treatment.

Conclusions

Although this study involved a limited number of patients, MRgFUS favourably improves perceived pain and motor functional recovery, with no major complications. No difference was found in the achievement of primary and secondary outcome measures with respect to RFA.

Key Points

? To demonstrate the effectiveness of a recent technique for treating osteoid osteoma ? MRgFUS results compared with results of the gold standard treatment (RFA) ? MRgFUS is effective both from a clinical and functional point of view ? No significant side effects compared with RFA

     

Clinical utility of radiofrequency ablation following transarterial injection of miriplatin-iodized oil suspension in small hepatocellular carcinoma

Purpose

To retrospectively evaluate the clinical utility of radiofrequency ablation (RFA) following transarterial injection of miriplatin-iodized oil suspension (MPT–RFA) for hepatocellular carcinoma treatment.

Materials and methods

We evaluated clinical outcomes of MPT–RFA for three or fewer hepatocellular carcinomas. Twenty-one patients with 30 tumors (maximum diameter: mean 1.4 ± 0.4 cm, range 0.7–2.2 cm) received MPT–RFA.

Results

Nineteen patients (90.5 %, 19/21) achieved complete ablation at the first RFA session. Two patients (9.5 %, 2/21) required a second RFA session but achieved complete ablation. Primary and secondary technical success rates were 90.5 and 100 %. There were no deaths related to the procedures performed. Grade 3 or 4 increases in the serum aspartate aminotransferase, alanine aminotransferase, and bilirubin levels were found in six patients (38.1 %, 8/21). There were no liver infarctions. During the median follow-up period of 24.1 months (mean ± SD 24.7 ± 6.9 months, range 13.8–38.9 months), the local tumor progression rate and overall survival rate at 2 years was 5.0 % (95 % confidence interval 0.3–20.6 %) and 86.7 % (95 % confidence interval 56.3–96.5 %), respectively. The mean hospital stay was 8.4 ± 3.1 days (range 5–18 days).

Conclusion

MPT–RFA is a safe therapeutic option that initially provides therapeutic results.

     

Radiation Exposure of Interventional Radiologists During Computed Tomography Fluoroscopy-Guided Renal Cryoablation and Lung Radiofrequency Ablation: Direct Measurement in a Clinical Setting

Introduction

Computed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking.

Materials and Methods

Radiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator’s finger skin was measured using thermoluminescent dosimeter rings.

Results

The mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator’s finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA.

Conclusion

Radiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.

     

Radiofrequency ablation versus cryoablation for T1b renal cell carcinoma: a multi-center study

Purpose

To compare the clinical outcomes between radiofrequency ablation (RFA) and cryoablation for the treatment of clinical T1b (cT1b) renal cell carcinoma (RCC).

Materials and methods

The data of 46 patients [(39 men and 7 women, median age; 73 years, range 39–87 years)] were gathered from 3 institutions. RFA and cryoablation were performed on 23 patients each. The median number of ablation needle was 2 (range 1–4) and 4 (range 3–5, p?<?0.0001) in RFA and cryoablation, respectively. Technique efficacy defined as coverage of the tumor by ablative zone, adverse events, local tumor progression, and survival were compared between the RFA and cryoablation groups.

Results

The primary technique efficacy rate was significantly higher in the cryoablation group (96%, 22/23) than in the RFA group (65%, 15/23, P?=?0.02). There was no significant difference in the secondary technique efficacy rate after additional RFA and cryoablation [21/23 (91%) vs. 23/23 (100%); P?=?0.24]. The incidence of grade 3 or higher adverse events was similar between the 2 groups (P?>?0.99). There was no significant difference between local tumor progression rate after RFA and cryoablation [3/21 (14%) vs. 2/23 (9%); P?=?0.66]. The 5-year overall survival rates were comparable between RFA and cryoablation (78 vs. 82%; P?=0.82).

Conclusion

Other than primary technique efficacy, the clinical outcomes between RFA and cryoablation were similar in patients with cT1b RCC.

     

Percutaneous Endovascular Radiofrequency Ablation for Malignant Portal Obstruction: An Initial Clinical Experience

Purpose

The Habib? VesOpen Catheter is a new endovascular radiofrequency ablation (RFA) device used to treat malignant portal obstruction. The purpose of this study was to evaluate the clinical feasibility and safety of RFA with this device.

Methods

We collected the clinical records and follow-up data of patients with malignant portal obstruction treated with percutaneous endovascular portal RFA using the Habib? VesOpen Catheter. Procedure-related complications, improvement of symptoms, portal patency, survival, and postoperative biochemical tests were investigated.

Results

The 31 patients enrolled in the study underwent 41 successful endovascular portal RFA procedures. Patients were divided into a portal-stenting (PS) group (n = 13), which underwent subsequent portal stenting with self-expandable metallic stents, and a non-stenting (NS) group (n = 18), which did not undergo stenting. No procedure-related abdominal hemorrhage or portal rupture occurred. Postablation complications included abdominal pain (n = 26), fever (n = 13), and pleural effusion (n = 15). Improvements in clinical manifestations were observed in 27 of the 31 patients. Of the 17 patients experiencing portal restenosis, 10 underwent successful repeat RFA. The rate of successful repeat RFA was significantly higher in the NS group than in the PS group. Median portal patency was shorter in the PS group than in the NS group. No mortality occurred during the 4 weeks after percutaneous endovascular portal RFA.

Conclusions

Percutaneous endovascular portal RFA is a feasible and safe therapeutic option for malignant portal obstruction. Prospective investigations should be performed to evaluate clinical efficacy, in particular, the need to evaluate the necessity for subsequent portal stenting.

     

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

     

Retrospective review of thoracic neural damage during lung ablation – what the interventional radiologist needs to know about neural thoracic anatomy

Background and Purpose

Radiofrequency ablation (RFA) is associated with low neural morbidity compared with surgery, which commonly causes debilitating long-term pain. The purpose was to review the thoracic neural anatomy relevant to percutaneous RFA and to retrospectively review symptomatic nerve injury after lung RFA at our institution.

Materials and Methods

We retrospectively examined all symptomatic nerve injuries occurring after computed tomography (CT)-guided RFA treatment of lung tumors for 462 patients/509 procedures/708 lesions treated at our large tertiary referral centre during 10 years.

Results

Eight patients experienced neurological complications after heating during the RFA procedure. These complications occurred in the phrenic (n = 1), brachial (n = 3), left recurrent (n = 1), and intercostal nerves (n = 2) and the stellate ganglion (n = 1). Three were grade 2, four grade 3 and one grade 4 injuries (CTCAE v3).

Conclusion

Although rare, neurological complications can occur after RFA, and they can occasionally be severe. To prevent these complications, it is important for the interventional radiologist to be aware of the anatomy of nervous structures and to attempt to identify nerves on CT scans during the RFA procedure. Creating a pneumothorax can be useful to avoid nerve damage and related clinical complications.

     

Percutaneous Microwave Ablation of Renal Angiomyolipomas

Purpose

To evaluate the safety and efficacy of US-guided percutaneous microwave (MW) ablation in the treatment of renal angiomyolipoma (AML).

Materials and Methods

From January 2011 to April 2014, seven patients (5 females and 2 males; mean age 51.4) with 11 renal AMLs (9 sporadic type and 2 tuberous sclerosis associated) with a mean size of 3.4 ± 0.7 cm (range 2.4–4.9 cm) were treated with high-powered, gas-cooled percutaneous MW ablation under US guidance. Tumoral diameter, volume, and CT/MR enhancement were measured on pre-treatment, immediate post-ablation, and delayed post-ablation imaging. Clinical symptoms and creatinine were assessed on follow-up visits.

Results

All ablations were technically successful and no major complications were encountered. Mean ablation parameters were ablation power of 65 W (range 60–70 W), using 456 mL of hydrodissection fluid per patient, over 4.7 min (range 3–8 min). Immediate post-ablation imaging demonstrated mean tumor diameter and volume decreases of 1.8 % (3.4–3.3 cm) and 1.7 % (27.5–26.3 cm³), respectively. Delayed imaging follow-up obtained at a mean interval of 23.1 months (median 17.6; range 9–47) demonstrated mean tumor diameter and volume decreases of 29 % (3.4–2.4 cm) and 47 % (27.5–12.1 cm³), respectively. Tumoral enhancement decreased on immediate post-procedure and delayed imaging by CT/MR parameters, indicating decreased tumor vascularity. No patients required additional intervention and no patients experienced spontaneous bleeding post-ablation.

Conclusion

Our early experience with high-powered, gas-cooled percutaneous MW ablation demonstrates it to be a safe and effective modality to devascularize and decrease the size of renal AMLs.

     

Experience of neuroprotective air injection during radiofrequency ablation (RFA) of spinal osteoid osteoma

Purpose

To assess the usefulness of epidural air injection during the RFA treatment of spinal osteoid osteoma.

Methods

A retrospective review of 17 patients who underwent RFA for spinal osteoid osteoma between September 2006 and May 2017 was performed. All the procedures were performed by a single radiologist. We reviewed the perioperative CT studies to assess the distribution of air relative to the osteoid osteoma. The clinical outcome of each patient group was evaluated during routine follow-up.

Results

Seventeen patients were treated for spinal OO (male:female 13:4; mean age was 16, ranging from 4 to 42). The nidus size ranged from 5.8 to 17.2 mm (mean 11.2). In nine cases epidural air injection was performed. In three cases the neuroprotective air was deemed satisfactory with a clear layer of air between the osteoid osteoma and the dural sac being visualised. In six patients adherence between the cortical bone immediately adjacent to the osteoid osteoma and the dural sac in contact was observed.In 15 patients the procedure was successful in terms of pain relief. No neural damage or other complication was reported in either group.

Conclusion

RFA is a safe treatment for spinal osteoid osteoma. Neuroprotective air injection does not appear to be necessary when performing the treatment in the spine.

Key Points

? Seventeen patients with spinal OO were treated with RFA, nine with air injection and eight without. Clinically successful treatment was achieved in 15 patients, with 2 subsequently undergoing surgery ? In 6/9 cases the injected air failed to achieve separation between the osteoid osteoma and the thecal sac because of inflammatory adhesion ? No complications were observed, regardless of whether neuroprotective air was instilled. Neuroprotective air injection appears unnecessary when treating spinal OO

     

Renal Angiomyolipoma: Mid- to Long-Term Results Following Embolization with Onyx

Purpose

Percutaneous transcatheter embolization is currently the preferred treatment for ruptured or enlarging renal angiomyolipoma (AML), although the optimum choice of embolic material has not yet been established. We present mid- to long-term outcomes following embolization of AMLs with Onyx.

Materials and Methods

Ten AMLs in seven patients (including two with tuberous sclerosis) were embolized with Onyx. Patients were followed-up clinically, with tumour size and renal function measured pre- and post-procedure.

Results

Mean pre-treatment AML size was 63.4 mm (range 42–100). Mean clinical follow-up was 431.4 days (range 153–986) and imaging follow-up 284.2 days (range 30–741). There was no haemorrhage from treated lesions within the follow-up period. Of patients who had cross-sectional imaging pre- and post-procedure, mean decrease in AML size of 22 mm was seen after Onyx embolization (p = 0.0058, 95 % CI 9.13–34.87). No significant difference between serum creatinine was seen pre- and post-procedure (p = 0.54, 95 % CI 8.63–4.85).

Conclusions

Onyx embolization of renal AMLs is effective in the medium to long term, with theoretical benefits in safety and durability of result.