A new versatile MR-guided high-intensity focused ultrasound (HIFU) device for the treatment of musculoskeletal tumors.

Magnetic Resonance (MR) Imaging-guided High Intensity focused Ultrasound (MRgHIFU) is a non-invasive, non-ionizing thermal ablation therapy that is particularly interesting for the palliative or curative treatment of musculoskeletal tumors. We introduce a new modular MRgHIFU device that allows the ultrasound transducer to be positioned precisely and interactively over the body part to be treated. A flexible, MR-compatible supporting structure allows free positioning of the transducer under MRI/optical fusion imaging guidance. The same structure can be rigidified using pneumatic depression, holding the transducer rigidly in place. Targeting accuracy was first evaluated in vitro. The average targeting error of the complete process was found to be equal to 5.4 ± 2.2 mm in terms of focus position, and 4.7° ± 2° in terms of transducer orientation. First-in-man feasibility is demonstrated on a patient suffering from important, uncontrolled pain from a bone metastasis located in the forearm. The 81 × 47 × 34 mm3 lesion was successfully treated using five successive positions of the transducer, under real-time monitoring by MR Thermometry. Significant pain palliation was observed 3 days after the intervention. The system described and characterized in this study is a particularly interesting modular, low-cost MRgHIFU device for musculoskeletal tumor therapy.

Estrogen Receptor-Beta2 (ERß2)-Mutant p53-FOXM1 Axis: A Novel Driver of Proliferation, Chemoresistance, and Disease Progression in High Grade Serous Ovarian Cancer (HGSOC).

High grade serous ovarian cancer (HGSOC) is the most common and lethal subtype of epithelial ovarian cancer. Prevalence (~96%) of mutant p53 is a hallmark of HGSOC. Estrogen receptor-beta (ERß) has been reported to be another important player in HGSOC, although the pro-versus anti-tumorigenic role of its different isoforms remains unsettled. However, whether there is functional interaction between ERß and mutant p53 in HGSOC is unknown. ERß1 and ERß2 mRNA and protein analysis in HGSOC cell lines demonstrated that ERß2 is the predominant isoform in HGSOC. Specificity of ERß2 antibody was ascertained using cells depleted of ERß2 and ERß1 separately with isoform-specific siRNAs. ERß2-mutant p53 interaction in cell lines was confirmed by co-immunoprecipitation and in situ proximity ligation assay (PLA). Expression levels of ERß2, ERα, p53, and FOXM1 proteins and ERß2-mutant p53 interaction in patient tumors were determined by immunohistochemistry (IHC) and PLA, respectively. ERß2 levels correlate positively with FOXM1 levels and negatively with progression-free survival (PFS) and overall survival (OS). Quantitative chromatin immunoprecipitation (qChIP) and mRNA expression analysis revealed that ERß2 and mutant p53 co-dependently regulated FOXM1 gene transcription. The combination of ERß2-specific siRNA and PRIMA-1MET that converts mutant p53 to wild type conformation increased apoptosis. Our work provides the first evidence for a novel ERß2-mutant p53-FOXM1 axis that can be exploited for new therapeutic strategies against HGSOC.

Interventional Radiology Outpatient Clinics (IROC): Clinical Impact and Patient Satisfaction.

PURPOSE: To retrospectively analyze our interventional radiology outpatient clinics (IROC) for referral patterns, impact on interventional practice, and patient satisfaction. MATERIALS AND METHODS: Consultations performed between 2011 and 2019 were extracted. The two consecutive years with the highest number of consultations (n2018 = 1426; n2019 = 1595) were compared for unattended consultations (i.e., scheduled consultations with patients not showing-up); initial/follow-up consultations; hospital clinician/general practitioner referrals; initial consultations with radiologists not recommending interventions; procedural conversion rate (PCR; i.e., No. initial consultations resulting in interventions over the total number of initial consultations performed for the same clinical indication). A survey was conducted in 159 patients to determine their satisfaction. RESULTS: Consultations increased from 2011 to 2019 by 130%. In 2018-2019, the number of unattended consultations was stable (7.0% vs 6.6%; P = .68). The referrals were for back pain (42.2%), interventional oncology (40.5%), and arteriovenous malformations (9.0%). For back pain, in 2019, there were fewer consultations with radiologists not recommending interventions and increased PCR compared to 2018 (11.9% vs. 17.7%; 88.1% vs. 82.3%; respectively; P = .01). For interventional oncology, follow-up consultations and general practitioner referrals increased in 2019 compared to 2018 (43.0% vs 35.3%; P = .01; 24.4% vs. 12.7%; P < .01; respectively). No other changes were noted. Cumulative 2018-2019 PCR was ≥ 85.4%. 99.2% responders highly appreciated their IROC experience. Quality of secretarial and medical services were the main aspects evaluated to rate the experience with IROC. CONCLUSION: IROC results in high PCR. Recent changes in referral/impact on IR practice were noted with patients referred for back pain and interventional oncology. LEVEL OF EVIDENCE IV: Level 4, Case Series.

Percutaneous vertebroplasty of the cervical spine performed via a posterior trans-pedicular approach.

OBJECTIVES: Percutaneous vertebroplasty (PV) of the cervical spine has been traditionally performed with a trans-oral or antero-lateral approach. The posterior trans-pedicular approach (PTPA) has been sporadically reported. Therefore, the aim of this study is to retrospectively assess the technical feasibility, safety, and clinical outcomes of cervical PV performed with a PTPA. METHODS: All consecutive patients undergoing PV in cervical levels with PTPA (under general anesthesia and computed tomography [CT] guidance) from January 2008 to November 2019 were identified. The following data were collected: patients' demographics; indication for PV; vertebral level features; procedure-related variables; and clinical outcomes including complications and pain relief. RESULTS: Thirty-two patients (18 females, 14 males; mean age 61.1 ± 13.2 years, range 36-88) were included accounting for 36 vertebrae. Three vertebrae (3/36, 8%) were referred due to an underlying traumatic fracture, the remaining (33/36, 92%) due to a painful lytic tumor. Technical success was 97% (35/36 levels). Mean time required to deploy the trocar was 23 ± 11 min (range 7-60). Extra-vertebral asymptomatic cement leakage was observed in 3/35 (9%) vertebral levels. One patient (1/32, 3%) developed an acute cardiogenic pulmonary edema requiring admission in the intensive care unit; another patient (1/32, 3%) developed localized infection to the skin entry site, which was managed conservatively. At 1-month follow-up, the mean pain in the study population was 1.0 ± 1.1 (range 0-4/10) vs 6.2 ± 1.4 (range 4-9/10) at baseline (p < 0.05). CONCLUSIONS: Cervical PV performed via a CT-guided PTPA is technically feasible, safe, and results in effective pain relief. KEY POINTS: • Percutaneous vertebroplasty (PV) is a well-established technique for the treatment of benign and malignant compression fractures. • Common PV approaches used for cervical vertebrae include the trans-oral, antero-lateral, lateral, and sporadically the posterior trans-pedicular approach. • Retrospective analysis of our 11-year experience with the posterior trans-pedicular approach used for cervical vertebrae proved that such approach was safe and effective.

Musculoskeletal interventional oncology: current and future practices.

Management of musculoskeletal (MSK) tumours has traditionally been delivered by surgeons and medical oncologists. However, in recent years, image-guided interventional oncology (IO) has significantly impacted the clinical management of MSK tumours. With the rapid evolution of relevant technologies and the expanding range of clinical indications, it is likely that the impact of IO will significantly grow and further evolve in the near future.In this narrative review, we describe well-established and new interventional technologies that are currently integrating into the IO armamentarium available to radiologists to treat MSK tumours and illustrate new emerging IO indications for treatment.

Is percutaneous image-guided renal tumour ablation ready for prime time?

In the last few decades, thermal ablation (TA) techniques have been increasingly applied to treat small localised renal cell carcinomas. Despite this trend, there is still an underuse of TA compared to surgery and a substantial lack of high-quality evidence derived from large, prospective, randomised controlled trials comparing the long-term oncologic outcomes of TA and surgery. Therefore, in this narrative review, we assess published guidelines and recent literature concerning the diagnosis and management of kidney-confined renal cell carcinoma to understand whether percutaneous image-guided TA is ready to be proposed as a first-line treatment.

Spinal Tumor Ablation: Indications, Techniques, and Clinical Management.

Percutaneous thermal ablation has proven to be safe and effective in the management of patients with spinal tumors. Such treatment is currently proposed following the decision of a multidisciplinary tumor board to patients with small painful benign tumors such as osteoid osteoma or osteoblastoma, as well as carefully selected patients presenting with spinal metastases. In both scenarios, in order to provide a clinically effective procedure, ablation is often tailored to the specific patients' clinical needs and features of the target tumor. In this review, we present the most common clinical contexts in which spine ablation may be proposed. We scrutinize technical aspects and challenges that may be encountered during the procedure, as well as offering insight on follow-up and expected outcomes.

Large nearly spherical ablation zones are achieved with simultaneous multi-antenna microwave ablation applied to treat liver tumours.

AIM: To investigate the shape and the volume of ablation zones obtained with microwave ablation (MWA) performed with multiple antennas in liver tumours. MATERIALS AND METHODS: Tumour volume, number of antennas, size (long diameter (Dl), along the antenna axis; short diameter (Ds), perpendicular to the antenna axis; vertical diameter (Dv), vertical to both Dl and Ds) and shape (roundness index (RI); 1 corresponds to a sphere) of the ablation zone, ablation volume, and complications were evaluated. RESULTS: Mean Dl, Ds, and Dv were 4.7 ± 1.4 cm, 3.9 ± 1.4 cm, and 3.8 ± 1.0 cm, respectively. Mean RIs (Ds/Dl, Dv/Dl, and Dv/Ds) were 0.83 ± 0.13, 0.83 ± 0.17, and 1.02 ± 0.23, respectively, without any difference between the mean RI obtained with the double (0.84 ± 0.01) and that with the triple-antenna (0.93 ± 0.13) approach (p = 0.25). Mean ablation volume was 41 ± 32 cm3 (vs. mean tumour volume 13 ± 10 cm3; range 1-40; p < 0.001). No complications were noted. CONCLUSIONS: Simultaneous multi-antenna MWA of liver tumours results in large nearly spherical ablation zones. KEY POINTS: • Simultaneous multi-antenna microwave ablation of liver tumours results in nearly spherical ablation zones. • The multi-antenna approach generates oversized ablation volumes compared with the target tumour volume. • The multi-antenna approach is safe.

GPU-based 3D iceball modeling for fast cryoablation simulation and planning.

PURPOSE: The elimination of abdominal tumors by percutaneous cryoablation has been shown to be an effective and less invasive alternative to open surgery. Cryoablation destroys malignant cells by freezing them with one or more cryoprobes inserted into the tumor through the skin. Alternating cycles of freezing and thawing produce an enveloping iceball that causes the tumor necrosis. Planning such a procedure is difficult and time-consuming, as it is necessary to plan the number and cryoprobe locations and predict the iceball shape which is also influenced by the presence of heating sources, e.g., major blood vessels and warm saline solution, injected to protect surrounding structures from the cold. METHODS: This paper describes a method for fast GPU-based iceball modeling based on the simulation of thermal propagation in the tissue. Our algorithm solves the heat equation within a cube around the cryoprobes tips and accounts for the presence of heating sources around the iceball. RESULTS: Experimental results of two studies have been obtained: an ex vivo warm gel setup and simulation on five retrospective patient cases of kidney tumors cryoablation with various levels of complexity of the vascular structure and warm saline solution around the tumor tissue. The experiments have been conducted in various conditions of cube size and algorithm implementations. Results show that it is possible to obtain an accurate result within seconds. CONCLUSION: The promising results indicate that our method yields accurate iceball shape predictions in a short time and is suitable for surgical planning.

Complications of Percutaneous Bone Tumor Cryoablation: A 10-year Experience.

Background Percutaneous cryoablation has been shown to be effective in the management of painful bone tumors. However, knowledge of the complication rate and risk factors for complication is currently lacking. Purpose To report the complication rate and associated risk factors for bone tumor cryoablation. Materials and Methods This retrospective study reviewed complications in 239 consecutive patients (131 men and 108 women; median age, 64 years; age range, 6-86 years) who underwent cryoablation of 320 primary or metastatic bone tumors between January 2008 and November 2017. Common Terminology Criteria for Adverse Events was used to categorize complications as major (grade 3-4) or minor (grade 1-2). Multivariable analysis was performed for variables with P values less than .20, including age, tumor location, adjacent critical structures, number of cryoprobes, and Eastern Cooperative Oncology Group performance status (ECOG-PS). Results Among the 320 tumors, the total complication rate was 9.1% (29 of 320; 95% confidence interval [CI]: 6%, 12.2%). The major complication rate was 2.5% (eight of 320; 95% CI: 0.8%, 4.2%), with secondary fracture the most frequent complication (1.2% [four of 320]; mean delay, 71 days); cryoablation site infection, tumor seeding, bleeding, and severe hypotension were each observed in 0.3% (one of 320) of procedures. Minor complications included postprocedural pain (2.2% [seven of 320]), peripheral neuropathy (0.9% [three of 320]), and temporary paresthesia (0.9% [three of 320]). For all complications, associated risk factors included ECOG-PS greater than 2 (odds ratio [OR], 3.1 [95% CI: 3, 7.6]; P = .01), long-bone cryoablation (OR, 17.8 [95% CI: 2.3, 136.3]; P = .01), and use of more than three cryoprobes (OR, 2.5 [95% CI: 1.0, 6.0]; P = .04); for major complications, associated risk factors included age greater than 70 years (OR, 7.1 [95% CI: 1.6, 31.7]; P = .01) and use of more than three cryoprobes (OR, 23.6 [95% CI: 2.8, 199.0]; P = .01). Conclusion Bone tumor cryoablation is safe, with a 2.5% rate of major complications, most commonly secondary fracture (1.2%). Major complications are associated with age greater than 70 years and use of more than three cryoprobes. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Jennings in this issue.

Hydrodissection of the Retrohepatic Space: A Technique to Physically Separate a Liver Tumour from the Inferior Vena Cava and the Ostia of the Hepatic Veins.

OBJECTIVE: To report a technique of percutaneous retrohepatic hydrodissection, highlighting its potential to physically separate liver tumours from the inferior vena cava (IVC) and the ostia of the hepatic veins (HV). MATERIALS AND METHODS: Between December 2017 and April 2018, hydrodissection of the retrohepatic IVC was performed in 5 patients (5 females; mean age 64.5 years) undergoing percutaneous ablation of 5 liver metastases (mean size: 3.6 cm) located adjacent to the IVC. Number of hydrodissection needles, volume of hydrodissection, separation of tumour/liver parenchyma from IVC/HV post-hydrodissection; technical success of ablation; and complications were tabulated. RESULTS: Two to three 22G spinal needles were required per case for adequate dissection. Mean volume to obtain sufficient hydrodissection was 410 ml on average. Physical separation of the IVC and tumour/hepatic parenchyma was successful in all cases, by 9 mm on average (range 5-12 mm). It also leaded to physical separation of the ostia of the right and middle HV in all cases. There was no early or delayed complication, notably no venous thrombosis in the post-operative period. All lesions but one were completely ablated after one session at 3-month follow-up. The patient with residual tumour was successfully retreated. CONCLUSION: Retrohepatic hydrodissection is a feasible technique to separate a tumour from the IVC and/or ostia of the HV. This could potentially limit the heat-sink effect/reduce the risk of thrombosis. Larger follow-up studies are required to assess efficacy on a long-term basis.

Adjunctive Thermoprotection During Percutaneous Thermal Ablation Procedures: Review of Current Techniques.

Although rare, unintended thermal injury to organs surrounding the ablation zone can lead to severe complications. Over the past 15 years, different protective methods have been developed to limit risk of complications, and expand indications to include more challenging lesions in various locations including liver, kidney, lung and bone. The most frequently used techniques include hydrodissection, carbodissection, balloon interposition and probe torqueing. In most cases, tumours can be physically separated from sensitive structures, reducing risk of thermal injury. Endoluminal cooling/warming is an alternative option for complex ablations close to the ureter or major bile ducts. Different techniques may be combined to achieve successful protection in locations with complex anatomy. The purpose of this review is to provide an overview of available protective measures and discuss respective advantages/drawbacks.

Transgraft sac Embolization Combined with Graft Reinforcement for Refractory Mixed-Type Endoleak.

An 80-year-old female underwent EVAR 4 years ago. She presented type II endoleak with sac expansion from 68 to 80 mm during 3-year follow-up after EVAR. Although she underwent translumbar percutaneous sac embolization, the AAA sac continued to enlarge, suggesting mixed-type endoleak including type I, II, and III. Transgraft direct sac angiography revealed endoleak cavity without demonstrable feeding vessel. Transgraft sac embolization using n-butyl cyanoacrylate and graft reinforcement was performed concurrently, without complications. The graft reinforcement consisted of graft extension for eliminating occult type I endoleak, and relining for eliminating occult type III endoleak. Six months after the procedure, CT showed no signs of sac expansion. Transgraft sac embolization combined with graft reinforcement is one of the available options for persistent and refractory mixed-type endoleak.

Percutaneous image-guided ablation of bone metastases: local tumor control in oligometastatic patients.

INTRODUCTION: Percutaneous image-guided cryo- (CA) and radiofrequency- (RFA) ablations have been widely used in the treatment of painful bone metastases (BM). However, paucity of data is available for the performance of these treatments when used with a curative intent. The aim of this study is to investigate the local progression free-survival (LPFS) after radical percutaneous image-guided ablation of BM in oligometastatic patients, and to identify predictive factors associated with local tumor progression. MATERIALS AND METHODS: This is a retrospective review of all patients who underwent percutaneous image-guided CA or RFA of BM with a radical intent between 2007 and 2018. RESULTS: Forty-six patients with a total of forty-nine BM underwent percutaneous image-guided CA (N = 37; 75,5%) or RFA (N = 12; 24,5%). Primary malignancies included thyroid (N = 11, 22.5%), breast (N = 21; 42.9%), lung (N = 8; 16.3%) and other (N = 9; 18,3%) cancers. Additional consolidation was performed after ablation in 20.4% cases (N = 10). Mean follow-up was 34.1 ± 22 months. Local progression at the treated site was observed in 28.5% cases (N = 14); 1- and 2-year LPFS was 76.8% and 71.7%, respectively. Size of BM (>2 cm) predicted local tumor progression (p = .002). CONCLUSIONS: Percutaneous image-guided locoregional therapies used in the radical treatment of BM in oligometastatic patients demonstrate significant rates of LPFS providing the size of BM ≤2 cm.

Percutaneous radiofrequency ablation of painful spinal metastasis: a systematic literature assessment of analgesia and safety.

PURPOSE: Radiofrequency ablation (RFA) is the most common percutaneous technique applied to treat painful spinal metastasis; however, experience in this field is somehow still limited. A systematic literature research was performed to understand the effects of RFA in terms of analgesia and safety. MATERIALS AND METHODS: Inclusion criteria for the studies were as follows: (1) randomised controlled or non-randomised studies with a prospective or retrospective design; (2) population made up of adults with spinal metastasis; (3) spinal metastasis treated with RFA alone or in combination/comparison with other treatments; (4) studies reporting about patients' pain before and at least one time-point following RFA; and (5) English-language studies. RESULTS: Seven hundred and thirty-three articles were screened and 8 (4 prospective, 4 retrospective) matched the inclusion criteria. Study population ranged between 10 and 92 patients across studies. Five out of eight studies reported a highly effective pain management (≥4 points of pain reduction between baseline and the last time-point available); 2/8 studies reported moderate results (≥2 points of pain reduction between baseline and the last time-point available). All studies combined RFA with cement augmentation in the vast majority of patients (40-100%) or metastasis (94-95.8%). Grade I-IIIa neural complications were reported in up to 16% of the cases and were always managed conservatively or with steroids. CONCLUSIONS: RFA, combined with vertebral augmentation in most of the cases, is effective and safe in achieving short- to mid-term (from 1 week to 6 months) analgesia in patients affected by painful spinal metastasis.

Low-power bipolar radiofrequency ablation and vertebral augmentation for the palliative treatment of spinal malignancies.

AIM: To investigate the analgesic properties and the safety of low power bipolar radiofrequency ablation (RFA) performed with internally cooled electrodes and vertebral augmentation for the treatment of painful spinal malignancies. MATERIALS AND METHODS: Consent was waived for retrospective study participation. Review of electronic records identified 11 consecutive patients (6 females; 5 males; mean age 61.3 ± 11.6 years) with one-index painful spinal tumour, who were treated between June 2016 and October 2017 with bipolar RFA and vertebral augmentation. Patients were treated if they presented with focal pain (≥4/10 on a 0-10 visual analogic scale in the 24-h period) corresponding to a metastatic vertebral level on cross sectional imaging. The Wilcoxon test was used to evaluate the significance of the post-operative pain. RESULTS: Lumbar levels were treated in 72.7% cases; metastatic epidural involvement was noted in 81.8% cases; 54.5% patients received associated treatments in addition to RFA, which was coupled to vertebral augmentation in all cases. Two (18.2%) complications were noted. Mean pain score measured at last clinical follow-up available (mean 1.9 ± 1.4 months) was 3.5 ± 2 (versus 7.8 ± 1.1 at baseline; p <0.01). CONCLUSIONS: Low-power bipolar RFA performed with internally cooled electrodes and coupled to vertebral augmentation provides safe and effective early analgesia in patients affected by painful spinal malignancies.

Percutaneous Image-Guided Cryoablation of Challenging Mediastinal Lesions Using Large-Volume Hydrodissection: Technical Considerations and Outcomes.

OBJECTIVE: This study was designed to describe the technique of percutaneous image-guided cryoablation with large-volume hydrodissection for the treatment of challenging mediastinal lesions. METHODS: Between March 2014 and June 2015, three patients (mean age 62.7 years) with four neoplastic anterior mediastinal lesions underwent five cryoablation procedures using large-volume hydrodissection. Procedures were performed under general anaesthesia using CT guidance. Lesion characteristics, hydrodissection and cryoablation data, technical success, complications, and clinical outcomes were assessed using retrospective chart review. RESULTS: Lesions (mean size 2.7 cm; range 2-4.3 cm) were in contact with great vessels (n = 13), trachea (n = 3), and mediastinal nerves (n = 6). Hydrodissection was performed intercostally (n = 4), suprasternally (n = 2), transsternally (n = 1), or via the sternoclavicular joint (n = 1) using 1-3 spinal needles over 13.4 (range 7-26) minutes; 450 ml of dilute contrast was injected (range 300-600 ml) and increased mean lesion-collateral structure distance from 1.9 to 7.7 mm. Vulnerable mediastinal nerves were identified in four of five procedures. Technical success was 100 %, with one immediate complication (recurrent laryngeal nerve injury). Mean follow-up period was 15 months. One lesion demonstrated residual disease on restaging PET-CT and was retreated to achieve complete ablation. At last follow-up, two patients remained disease-free, and one patient developed distant disease after 1 year without local recurrence. CONCLUSIONS: Cryoablation using large-volume hydrodissection is a feasible technique, enabling safe and effective treatment of challenging mediastinal lesions.

Percutaneous MR-Guided Cryoablation of Morton's Neuroma: Rationale and Technical Details After the First 20 Patients.

OBJECTIVES: The purpose of this study is to discuss technical aspects and rationales of magnetic resonance (MR)-guided cryoablation (CA) of Morton's neuroma (MN); preliminary clinical experience is also retrospectively reviewed. METHODS: Procedures were performed under local anaesthesia on an outpatient basis. Lesion size and location, procedural (technical success, procedural time, complications) and clinical outcomes (patient satisfaction according to a four-point scale, residual pain according to a 0-10 visual analogue scale and instances of "stump neuroma") were assessed via chart review and cross-sectional telephone survey after the 20th case. RESULTS: Twenty patients (15 female, 5 male; mean age 50.3 years) were included; 24 MN (mean size 12.7 mm) were treated. Technical success was 100 %. Mean procedural time was 40.9 ± 10.4 min (range 35-60). One minor complication (superficial cellulitis) was reported (4.2 %). Follow-up (mean 19.7 months) was available for 18/24 MN. Patient satisfaction on a per-lesion basis was as follows: "completely satisfied" in 77.7 %, "satisfied with minor reservations" in 16.6 % and "satisfied with major reservations" in 5.7 % of cases. Mean pain score at last follow-up post-CA was 3.0. No instances of "stump neuroma" were reported. CONCLUSIONS: MR-guided CA of MN is a novel therapy which appears technically feasible. Clinical advantages of the procedure are high patient satisfaction, reduced risk of "stump neuroma" syndrome and good patient tolerance on an outpatient basis. Further, prospective studies are needed to confirm these encouraging results.

18F-FDOPA PET/CT-Guided Radiofrequency Ablation of Liver Metastases from Neuroendocrine Tumours: Technical Note on a Preliminary Experience.

AIM: To review our preliminary experience with 6-L-18F-fluorodihydroxyphenylalanine (18F-FDOPA) PET/CT-guided radiofrequency ablation (RFA) of liver metastases from neuroendocrine tumours (NETs). MATERIALS AND METHODS: Three patients (mean age 51.3 years; range 43-56) with gastro-entero pancreatic NET (GEP-NET) liver metastases underwent 18F-FDOPA PET/CT-guided RFA. Patients were referred with oligometastatic hepatic-confined disease (1-6 metastases; <3 cm) on 18F-FDOPA PET/CT; poor lesion visualisation on US, CT, and MR; and ongoing symptoms. Procedures were performed in an interventional PET/CT scanner under general anaesthesia using a split-dose protocol. Lesion characteristics, procedural duration and technical success (accurate probe placement and post-procedural ablation-zone photopaenia), complications, patient and operator dose, and clinical outcomes were evaluated. RESULTS: Thirteen liver metastases (mean size 11.4 mm, range 8-16) were treated in three patients (two presented with "carcinoid syndrome"). Technical success was 100 % with a mean procedural duration of 173.3 min (range 90-210) and no immediate complications. Mean patient dose was 2844 mGy·cm (range 2104-3686). Operator and radiographer doses were acceptable other than the operator's right hand in the first case (149 µSv); this normalised in the second case. There was no local tumour or extra-hepatic disease progression at mid-term follow-up (mean 12.6 months; range 6-20); however, two cases progressed with new liver metastases at different sites. There was 100 % clinical success (n = 2) in resolving carcinoid syndrome symptoms. CONCLUSION: 18F-FDOPA PET/CT-guided RFA appears technically feasible, safe, and effective in patients with GEP-NETs and low-burden hepatic metastases. Further prospective studies are required to elucidate its precise role in tailored multimodality management of GEP-NET liver metastases.