Semi-automatic artifact quantification in thermal ablation probe and algorithms for the evaluation of metal artifact reduction.

OBJECTIVES: To compare metal artifacts and evaluation of metal artifact reduction algorithms during probe positioning in computed tomography (CT)-guided microwave ablation (MWA), cryoablation (CRYO), and radiofrequency ablation (RFA). MATERIALS AND METHODS: Using CT guidance, individual MWA, CRYO, and RFA ablation probes were placed into the livers of 15 pigs. CT imaging was then performed to determine the probe's position within the test subject's liver. Filtered back projection (B30f) and iterative reconstructions (I30-1) were both used with and without dedicated iterative metal artifact reduction (iMAR) to generate images from the initial data sets. Semi-automatic segmentation-based quantitative evaluation was conducted to estimate artifact percentage within the liver, while qualitative evaluation of metal artifact extent and overall image quality was performed by two observers using a 5-point Likert scale: 1-none, 2-mild, 3-moderate, 4-severe, 5-non-diagnostic. RESULTS: Among MWA, RFA, and CRYO, compared with non-iMAR in B30f reconstruction, the largest extent of artifact volume percentages were observed for CRYO (11.5-17.9%), followed by MWA (4.7-6.6%) and lastly in RFA (5.5-6.2%). iMAR significantly reduces metal artifacts for CRYO and MWA quantitatively (p = 0.0020; p = 0.0036, respectively) and qualitatively (p = 0.0001, p = 0.0005), but not for RFA. No significant reduction in metal artifact percentage was seen after applying iterative reconstructions (p > 0.05). Noise, contrast-to-noise-ratio, or overall image quality did not differ between probe types, irrespective of the application of iterative reconstruction and iMAR. CONCLUSION: A dedicated metal artifact algorithm may decrease metal artifacts and improves image quality significantly for MWA and CRYO probes. Their application alongside with dedicated metal artifact algorithm should be considered during CT-guided positioning.

[What can/should be treated in kidney tumors and when]. / Was kann/soll bei Nierentumoren wann behandelt werden.

CLINICAL/METHODICAL ISSUE: In the treatment of localized renal cell carcinoma, the lack of randomization in controlled trials on thermal ablation is a major limitation. The latter leads to significant study bias and it ultimately remains unclear whether the improved overall survival in favor of partial nephrectomy can actually be attributed to the treatment method. STANDARD RADIOLOGICAL METHODS: For T1a (≤4 cm) renal cell carcinoma without lymph node and distant metastases, excellent technical and clinical results have been described after imaging-guided radiofrequency ablation and cryoablation. METHODICAL INNOVATIONS: Low major complication rates, preservation of renal function and three-dimensional confirmation of negative ablation margins (A0 ablation) are the advantages of computed tomography (CT)-guided thermal ablation. PERFORMANCE: According to the results of controlled (non-randomized) trials on T1a renal cell cancer, the cancer-specific survival rates are comparable between ablative and surgical techniques. ACHIEVEMENTS: It is high time for prospective randomized controlled trials to define the actual value of percutaneous thermal ablation and partial nephrectomy in the treatment of T1a renal cell carcinoma. PRACTICAL RECOMMENDATIONS: Apart from localized renal cell carcinoma, angiomyolipoma and oncocytoma can be treated by thermal ablation. Transarterial embolization extends the radiological spectrum for the treatment of renal tumors, either as complementary embolization (e. g. before thermal ablation of T1a and T1b renal cell carcinoma), prophylactic embolization (e. g. angiomyolipoma >6 cm), preoperative embolization (e. g. before laparoscopic partial nephrectomy) or palliative embolization (e. g. in patients with symptomatic macrohematuria due to renal cell carcinoma).

[National S3 guidelines on hepatocellular carcinoma]. / Nationale S3-Leitlinie hepatozelluläres Karzinom.

CLINICAL/METHODICAL ISSUE: Evidence-based therapeutic and diagnostic algorithm for hepatocellular carcinoma. STANDARD RADIOLOGICAL METHODS: Ultrasound, computed tomography, magnetic resonance imaging, image-guided percutaneous biopsy, percutaneous thermal ablation and transarterial chemoembolization. METHODICAL INNOVATIONS: Diagnostic and therapy of hepatocellular carcinoma according to the official German interdisciplinary guidelines. PERFORMANCE: The formulation of the German S3 guidelines on diagnosis and therapy of hepatocellular carcinoma was performed under special consideration of quality indicators and standardized quality improvement methods. ACHIEVEMENTS: In 2013 the German S3 guidelines on diagnosis and therapy of hepatocellular carcinoma were published and clinically implemented as part of the nationwide guideline program in oncology of the Deutsche Krebsgesellschaft (German Cancer Society). PRACTICAL RECOMMENDATIONS: The German S3 guidelines on diagnosis and therapy of hepatocellular carcinoma have to be considered as the national gold standard with the goal of optimization of patient care.

Chytridiomycosis: a global threat to amphibians.

Chytridiomycosis, which is caused by Batrachochytrium dendrobatidis, is an emerging infectious disease of amphibians. The disease is one of the main causes of the global decline in amphibians. The aetiological agent is ubiquitous, with worldwide distribution, and affects a large number of amphibian species in several biomes. In the last decade, scientific research has substantially increased knowledge of the aetiological agent and the associated infection. However, important epidemiological aspects of the environment-mediated interactions between the aetiological agent and the host are not yet clear. The objective of the present review is to describe chytridiomycosis with regard to the major features of the aetiological agent, the host and the environment.

[Image-guided therapy with closed MRI: an update]. / Image-Guided Therapy am geschlossenen MRT: Ein Update.

STANDARD RADIOLOGICAL METHODS: Standard imaging modalities for percutaneous minimally invasive therapy are ultrasound, fluoroscopy and computed tomography. METHODICAL INNOVATIONS: Magnetic resonance imaging is becoming increasingly more popular for minimally invasive procedures. The advantages are high soft-tissue contrast, the possibility of free selection of multiple imaging slices, multiple tools for intrainterventional monitoring and the absence of ionizing radiation for the patient and the interventional radiologist. ACHIEVEMENTS: Magnetic resonance imaging is a promising imaging modality for minimally invasive procedures. The most common clinical applications are thermoablative procedures for treatment of hepatic, renal and prostatic malignancies.

The Impact of COVID-19 on Interventional Radiology Practice Worldwide: Results from a Global Survey.

BACKGROUND: The COVID-19 pandemic had an unprecedented impact on clinical practice and healthcare professionals. We aimed to assess how interventional radiology services (IR services) were impacted by the pandemic and describe adaptations to services and working patterns across the first two waves. METHODS: An anonymous six-part survey created using an online service was distributed as a single-use web link to 7125 members of the Cardiovascular and Interventional Radiological Society of Europe via email. Out of 450 respondents, 327 who completed the survey at least partially including 278 who completed the full survey were included into the analysis. RESULTS: Interventional radiologists (IRs) reported that the overall workload decreased a lot (18%) or mildly (36%) or remained stable (29%), and research activities were often delayed (30% in most/all projects, 33% in some projects). Extreme concerns about the health of families, patients and general public were reported by 43%, 34% and 40%, respectively, and 29% reported having experienced significant stress (25% quite a bit; 23% somewhat). Compared to the first wave, significant differences were seen regarding changes to working patterns, effect on emergency work, outpatient and day-case services in the second wave. A total of 59% of respondents felt that their organisation was better prepared for a third wave. A total of 19% and 39% reported that the changes implemented would be continued or potentially continued on a long-term basis. CONCLUSION: While the COVID-19 pandemic has negatively affected IR services in terms of workload, research activity and emotional burden, IRs seem to have improved the own perception of adaptation and preparation for further waves of the pandemic.

Evaluation of MR imaging guided steroid injection of the sacroiliac joints for the treatment of children with refractory enthesitis-related arthritis.

OBJECTIVES: To test the hypothesis that MR imaging guided triamcinolone acetonide injection into the sacroiliac joints of children with enthesitis-related arthritis is feasible, accurate and safe; and effectively reduces sacroiliac inflammation and disease progression. METHODS: A retrospective analysis of 14 children (6/14 [43%] female, 8/14 (57%) male; mean age, 13.2 years; range, 6-16 years) who received MR imaging guided sacroiliac joint injections at 0.2 Tesla or 1.5 Tesla for enthesitis-related arthritis and acute sacroilitis refractory to medical therapy was performed. 20 mg triamcinolone acetonide were injected. Assessed were intra-articular drug delivery; image quality, duration, and complications. Success of therapy was defined by change of sacroiliac inflammation. Remission time and erosions were assessed by follow-up MRI (range, 10-22 months). RESULTS: Twenty four procedures resulted in intra-articular injection. Image quality was sufficient. No complications occurred. Procedure time was 40 min. Sedation time was 22 min. Success of therapy was achieved in 11/14 (79%) children. Sacroiliac inflammation decreased significantly (-59%). Median remission time was 13.7 months. No erosions occurred. CONCLUSIONS: MR imaging guided steroid injection of the sacroiliac joints is feasible, accurate, and safe and can effectively reduce sacroiliac inflammatory activity and may therefore aid in the prevention of disease progression.

Inherently Radiopaque Narrow-Size-Calibrated Microspheres: Proof of Principle in a Pig Embolization Model.

PURPOSE: To investigate radiopacity, size and size calibration, morphology, and vascular distribution of inherently radiopaque microspheres in vitro and in a pig embolization model. MATERIALS AND METHODS: We compared three types of microspheres: DCBead™ (size 100-300 µm) and Embozene™ (250 µm) as clinically established microspheres, and the prototype Visible (250 µm) that contains additional radiopaque material. Size and size calibration of microspheres were examined by laser diffraction. Pulmonary artery embolization was performed in 12 pigs, and radiopacity was examined by in vitro micro-computed tomography (CT), in vivo cone-beam CT, and ex vivo micro-CT after killing. Morphology and vascular distribution of microspheres were microscopically examined. RESULTS: In in vitro and ex vivo micro-CT, radiopacity of Visible was higher than that of Embozene™, whereas DCBead™ showed no radiopacity. In in vivo cone-beam CT, radiopacity was observed with Visible but not with Embozene™ and DCBead™. Laser diffraction revealed that 7.0% (Visible), 6.5% (Embozene™), and 22.5% (DCBead™) of microspheres were smaller than 223.5 µm. Visible and Embozene™ microspheres were very often located in bronchiolus-associated arteries, but rarely in subsegmental and capillary arteries, whereas DCBead™ were very often and often detected in bronchiolus-associated arteries and capillary arteries, respectively (and rarely in subsegmental arteries). CONCLUSION: After pulmonary artery embolization, Visible but not Embozene™ or DCBead™ provide in vivo radiopacity in cone-beam CT. In contrast to non-narrow-size-calibrated DCBead™, pulmonary artery embolization with narrow-size-calibrated Visible and Embozene™ result in a predictable arterial distribution without embolization-related hemorrhagic lung infarction.

[MR-Guided pain therapy: principles and clinical applications]. / MR-gesteuerte Schmerztherapie: Prinzipien und klinische Applikationen.

X-ray fluoroscopy and computed tomography are frequently used to perform percutaneous interventions in pain therapy. The development of MR-compatible therapy needles now allows these interventions to be performed under MR imaging guidance. MR-guided interventions may be performed using most clinical MR scanners; however, systems with an open configuration are advantageous. Multiplanar pre- and intra-procedural MR imaging provides the interventionalist with essential information, such as evaluation of anatomy and pathology, as well as the planning of the procedure and monitoring of fluid distribution without the use of contrast agents. With the use of non-ionizing radiation, interventional MR imaging is especially suited for the treatment of children and young adults as well as for serial injection therapy. For spinal MR interventions, passive needle visualization is an easily achievable and reliable method. The resulting needle artifact is influenced by several factors such as the alloy of the needle, the strength of the static magnetic field, the sequence type, the spatial orientation of the therapy needle as well as the echo time and may further be optimized during the intervention by alteration of the last three factors. Fast acquisition techniques and image processing allow for continuous, near real-time MR imaging (so-called MR fluoroscopy) and interactive needle navigations, comparable to X-ray fluoroscopy and CT fluoroscopy. The purpose of this review is to illustrate and discuss general concepts of interventional MR imaging. A spectrum of interventional MR imaging procedures in spinal pain therapy is described and illustrated, including procedures such as lumbar facet joint injections, sacroiliac joint injections, lumbar spinal nerve root infiltrations and drug delivery to the lumbar sympathetic chain.

[Internally cooled bipolar radiofrequency ablation: is a lower power output more effective?]. / Intern gekühlte bipolare Radiofrequenzablation: Ist eine niedrige Leistung effektiver?

PURPOSE: Evaluation of bipolar radiofrequency (RF) ablation using internally cooled electrodes in an ex-vivo experiment. MATERIALS AND METHODS: Bipolar RF ablations (n = 154) were performed in ex-vivo bovine liver. Both electrodes with a total length of the active tip of 4 cm were located on the same shaft of an internally cooled applicator. The power output was systematically varied between 20 and 100 watts (W). The energy application was continuous or modulated depending on the tissue resistance. In relationship to the maximum power output, the volume of coagulation was assessed. RESULTS: In continuous energy application the induced volume of coagulation was increased at lower power outputs up to 33.7 cm (3) (20 watts). Parallel to an increased volume of coagulation, the required duration of energy application was increased up to a maximum of 51.6 minutes. Modulation of the power output as a function of the tissue resistance enabled application of a wide range of power outputs (40 - 75 watts) leading to a comparable extent of coagulation with a maximum of 14.9 cm (3) (10 min.), 16.8 cm (3) (15 min.), and 19.1 cm (3) (20 min.). CONCLUSION: Continuous application of RF energy leads to an inverse relationship between volume of coagulation and power output. Modulation of the power output as a function of the tissue resistance enables application of a wider range of power outputs compared to continuous application of RF energy.

[Interventional MR imaging in musculoskeletal]. / La Résonance Magnétique Interventionnelle en pathologie ostéoarticulaire.

Magnetic resonance (MR) imaging is well established for the diagnosis of musculoskeletal diseases. The excellent tissue contrast and the multiplanar imaging capability have both contributed to the improvement of this technique. The development of fast acquisition techniques, sufficient patient access obtained with open magnet configurations and advances in the technology of MR compatible instruments allow a new approach to interventional radiology. These recently commercially available open-bored high-field magnets allow standard interventions such as biopsies or intra-articular infiltrations. Moreover, new interventions e.g. preoperative marking of soft tissue or bone marrow tumors are now possible with the better tissue contrast of MR imaging.

Cirse Quality Assurance Document and Standards for Classification of Complications: The Cirse Classification System.

Interventional radiology provides a wide variety of vascular, nonvascular, musculoskeletal, and oncologic minimally invasive techniques aimed at therapy or palliation of a broad spectrum of pathologic conditions. Outcome data for these techniques are globally evaluated by hospitals, insurance companies, and government agencies targeting in a high-quality health care policy, including reimbursement strategies. To analyze effectively the outcome of a technique, accurate reporting of complications is necessary. Throughout the literature, numerous classification systems for complications grading and classification have been reported. Until now, there has been no method for uniform reporting of complications both in terms of definition and grading. The purpose of this CIRSE guideline is to provide a classification system of complications based on combining outcome and severity of sequelae. The ultimate challenge will be the adoption of this system by practitioners in different countries and health economies within the European Union and beyond.

Transarterial embolization (TAE) as add-on to percutaneous radiofrequency ablation (RFA) for the treatment of renal tumors: Review of the literature, overview of state-of-the-art embolization materials and further perspective of advanced image-guided tumor ablation.

Percutaneous radiofrequency ablation (RFA) for the treatment of stage I renal cell carcinoma has recently gained significant attention as the now available long-term and controlled data demonstrate that RFA can result in disease-free and cancer-specific survival comparable with partial and/or radical nephrectomy. In the non-controlled single center trials, however, the rates of treatment failure vary. Operator experience and ablation technique may explain some of the different outcomes. In the controlled trials, a major limitation is the lack of adequate randomization. In case reports, original series and overview articles, transarterial embolization (TAE) before percutaneous RFA was promising to increase tumor control and to reduce complications. The purpose of this study was to systematically review the literature on TAE as add-on to percutaneous RFA for renal tumors. Specific data regarding technique, tumor and patient characteristics as well as technical, clinical and oncologic outcomes have been analyzed. Additionally, an overview of state-of-the-art embolization materials and the radiological perspective of advanced image-guided tumor ablation (TA) will be discussed. In conclusion, TAE as add-on to percutaneous RFA is feasible and very effective and safe for the treatment of T1a tumors in difficult locations and T1b tumors. Advanced radiological techniques and technologies such as microwave ablation, innovative embolization materials and software-based solutions are now available, or will be available in the near future, to reduce the limitations of bland RFA. Clinical implementation is extremely important for performing image-guided TA as a highly standardized effective procedure even in the most challenging cases of localized renal tumors.

Magnetic resonance imaging for hepatic radiofrequency ablation.

Image-guided radiofrequency (RF) ablation is a minimally invasive therapy option in the treatment of primary and secondary hepatic malignancies. Magnetic resonance (MR) imaging offers an accurate pre-interventional imaging having important impact on patient selection and planning of the ablation procedure. Peri-interventional imaging is used for targeting, monitoring, and controlling of the ablation procedure. Due to a high soft-tissue contrast offering delineation of tumor tissue and the surrounding anatomy, coupled with multiplanar capabilities, MR imaging is an advantageous targeting technique compared with ultrasonography (US) or computed tomography (CT). MR imaging is sensitive to thermal effects enabling a monitoring of ablation therapy subsequently being supportive to control the ablation procedure. Therefore, MR imaging can fulfil the conditions for overlapping ablations by enabling a precise repositioning of the MR compatible RF applicator if required. Thus, the probability of achieving complete coagulation in larger tumors within a single therapy session is potentially increased. A monitoring of thermal effects is moreover essential in order to prevent unintended tissue damage from critical structures in the surrounding of the target tissue. Post-interventional imaging is performed to assess treatment response after RF ablation and has prognostic impact, as an early detection of treatment failure, e.g. residual tumor tissue, enables immediate therapy. Nevertheless, differential diagnostic difficulties arise from benign periablational enhancement which may cover tumor tissue. Hence, further evaluation and improvement in the assessment of treatment response is essential.

[Radiofrequency ablation of lung tumors]. / Radiofrequenz-Ablation von Lungentumoren.

Radiofrequency (RF) ablation is an effective therapy option in the treatment of primary and secondary liver tumors. Percutaneous RF ablation of primary and secondary pulmonary tumors is a possible new indication. Due to the minimally invasive character of percutaneous RF ablation, application in patients who are not candidates for curative radical resection is possible. Moreover, pulmonary RF ablation is a promising palliative therapy option. In this context, an increasing number of results regarding RF ablation of lung tumors were recently published. The present review summarizes and discusses the possible indications, techniques, results, and complications of pulmonary RF ablation.

Medical Liability and Patient Law in Germany: Main Features with Particular Focus on Treatments in the Field of Interventional Radiology.

UNLABELLED: On February 26th, 2013 the patient law became effective in Germany. Goal of the lawmakers was a most authoritative case law for liability of malpractice and to improve enforcement of the rights of the patients. The following article contains several examples detailing legal situation. By no means should these discourage those persons who treat patients. Rather should they be sensitized to to various aspects of this increasingly important field of law. To identify relevant sources according to judicial standard research was conducted including first- and second selection. Goal was the identification of jurisdiction, literature and other various analyses that all deal with liability of malpractice and patient law within the field of Interventional Radiology--with particular focus on transarterial chemoembolization of the liver and related procedures. In summary, 89 different sources were included and analyzed. The individual who treats a patient is liable for an error in treatment if it causes injury to life, the body or the patient's health. Independent of the error in treatment the individual providing medical care is liable for mistakes made in the context of obtaining informed consent. Prerequisite is the presence of an error made when obtaining informed consent and its causality for the patient's consent for the treatment. Without an effective consent the treatment is considered illegal whether it was free of treatment error or not. The new patient law does not cause material change of the German liablity of malpractice law. KEY POINTS: •On February 26th, 2013 the new patient law came into effect. Materially, there was no fundamental remodeling of the German liability for medical malpractice. •Regarding a physician's liability for medical malpractice two different elements of an offence come into consideration: for one the liability for malpractice and, in turn, liability for errors made during medical consultation in the process of obtaining informed consent. •Forensic practice shows that patients frequently enforce both offences concurrently.

BLM germline and somatic PKMYT1 and AHCY mutations: Genetic variations beyond MYCN and prognosis in neuroblastoma.

Neuroblastoma (NB) is the most common extra cranial solid tumor of childhood and often lethal in childhood. Clinical and biologic characteristics that are independently prognostic of outcome in NB are currently used for risk stratification to optimally the therapy. It includes age at diagnosis, International Neuroblastoma Staging System tumor histopathology and MYCN amplification. However, even in patients with theoretically good prognosis, such as localized tumor and non-amplified MYCN, either disease progress or recurrence may occur. Potential genetic determinants of this unfavorable behavior are not yet fully clarified. The presence of elevated expression of AHCY, PKMYT1, and BLM has accompanied poor prognosis MYCN-amplified neuroblastoma patients. Considering the potential implication of these genes on the clinical management of NB, we hypothesize that the identification of genetic variations may have significant impact during development of the recurrent or progressive disease. Using targeted DNA sequencing, we analyzed the mutation profiles of the genes PKMYT1, AHCY, and BLM in tumor samples of five patients with MYCN amplified and 15 MYCN non-amplified NB. In our study, BLM germline variants were detected in two patients with MYCN-non-amplified neuroblastoma. Our data allow us to hypothesize that, regardless of MYCN status, these mutations partially abolish BLM protein activity by impairing its ATPase and helicase activities. BLM mutations are also clinically relevant because BLM plays an important role in DNA damage repair and the maintenance of genomic integrity. We also found a novel variant in our cohort, PKMYT1 mutation localized in the C-terminal domain with effect unknown on NB. We hypothesize that this variant may affect the catalytic activity of PKMYT1 in NB, specifically when CDK1 is complexed to cyclins. The prognostic value of this mutation must be further investigated. Another mutation identified was a nonsynonymous variant in AHCY. This variant may be related to the slow progression of the disease, even in more aggressive cases. It affects the maintenance of the catalytic capacity of AHCY, leading to the consequent functional effects observed in the NB patients studied. In conclusion, our hypothesis may provide that mutations in BLM, AHCY and PKMYT1 genes found in children with MYCN-amplified or MYCN-non amplified neuroblastomas, may be associated with the prognosis of the disease.

[Magnetic resonance imaging -- guided corticosteroid-infiltration of the sacroiliac joints: pain therapy of sacroiliitis in patients with ankylosing spondylitis]. / Magnetresonanzgesteuerte Kortikosteroid-Infiltration der Sakroiliakalgelenke: Schmerztherapie der Sakroiliitis bei Patienten mit Spondylitis ankylosans.

PURPOSE: To evaluate the efficacy and specific properties of MR imaging-guided corticosteroid infiltration of the sacroiliac (SI) joints in the treatment of therapy-refractory sacroiliitis in patients with ankylosing spondylitis. MATERIALS AND METHODS: In this study, 26 patients were prospectively included. Inclusion criteria were AS with therapy refractory acute sacroiliitis and inflammatory back pain > or = 6 months. The intervention was performed using an open low-field MR-scanner. Inflammatory back pain was assessed on a visual analog scale (VAS). Success of the therapy was defined as an absolute reduction of the VAS score or = 35 % and persisting improvement > or = 2 months. The grade of sacroiliitis was documented using high-field MR imaging. Variables were compared using McNemar test and Wilcoxon test. The mean remission time was calculated using a Kaplan-Meier analysis. A p-value < 0.05 was considered statistically significant. RESULTS: The intervention was technically successfully performed in all patients. Following MR imaging-guided corticosteroid infiltration of the SI joints, the VAS score improved from 8 (5 - 10) points to 4.5 (0 - 8) points (- 44 %) in all patients (n = 26), which was statistically significant (p < 0.001). Of 26 patients, 22 (85 %) fulfilled the predefined criteria for successful therapy. This group had a statistically significant (p < 0.01) improvement of the VAS score from 8 (6 - 10) to 3 (0 - 5) (- 63 %). Improvement was seen after 7 (1 - 30) days. There was a marked reduction of the subchondral bone marrow edema (- 38 %). The mean remission time was 12 (4 - 18) months. CONCLUSION: MR imaging-guided corticosteroid infiltration of the SI joints proved to be an effective therapy of inflammatory back pain in patients with therapy refractory AS. With the ability of multiplanar imaging, precise localization of the bone marrow edema and the lack of ionizing radiation, interventional MR imaging currently represents the superior method for the treatment of the predominantly young patient group presenting with ankylosing spondylitis. Owing to short intervention times, open MR-scanners are ideally suited for MR imaging-guided infiltration of the SI joints.

[Radiofrequency ablation of renal cell carcinomas using MR imaging: initial results]. / Radiofrequenzablation des Nierenzellkarzinoms unter MR-Bildgebung: Erste Ergebnisse.

PURPOSE: First results of a study about the efficacy of magnetic resonance-(MR-)guided radiofrequency ablation of renal cell carcinomas (RCC) are presented. MATERIAL AND METHODS: Eight patients (63 to 82 years old) with RCC up to 3.9 cm in diameter were treated by percutaneous RF ablation under MR-guidance in an open MR scanner at 0.2T field strength. For positioning of the RF-electrode, fluoroscopic rapid gradient echo sequences (acquisition time about 2 sec) were used. The ablation was monitored by intermittent imaging with T1- and T2-weighted spin echo sequences. RESULTS: In each patient, the applicator was successfully positioned within the tumor using MR-guidance. Seven of eight patients were completely treated within one single session; one patient had to be retreated for tumor relapse at 13 months. The mean number of electrode repositionings under MR guidance for complete ablation was 2.0; ablation time ranged between 12 and 28 minutes. Maximum diameter (volume) of induced coagulation necrosis within one session was 3.9 cm (30.2 cm (3)) by using cluster electrodes. With single electrodes, maximum short axis diameter of coagulation without repositioning was 2.4 cm (11.6 cm (3)). All patients are now disease-free after a mean follow up of 13 months (5 to 21 months). No major complications occurred during or after the ablation procedure. CONCLUSION: MR-guided RF ablation in an open interventional 0.2T MR-unit is a safe and effective modality for the treatment of RCC. Fast MR-imaging is a convenient method for exact positioning of MR-compatible RF-electrodes. Near on-line MR-monitoring of ablation procedure with T2-weighted imaging allows for immediate assessment of the coagulation extent.

[Percutaneous radiofrequency ablation of renal tumors: update 2015]. / Perkutane bildgeführte Radiofrequenzablation von Nierentumoren : Update 2015.

BACKGROUND: Stage I renal cell carcinoma is a malignancy with a relatively good prognosis. The incidence of all renal cell carcinomas is approximately 9/100,000 persons. There are nearly 15,000 newly diagnosed patients every year (men twice as often as women). TREND: In the last decade, a trend away from radical open resection towards nephron-sparing approaches has been observed. Currently, partial nephrectomy is the surgical gold standard for the treatment of small renal tumors. However, excellent clinical results are obtained using percutaneous radiofrequency ablation (RFA): low complication rates and preservation of the renal function. RESULTS: Primary and secondary technical success rates are 69-100% and 90-100%, respectively. In large series, major complication rates of RFA of 0-14% are reported. A relevant deterioration of renal function after RFA is very rare. The 5-year local recurrence-free survival rates, metastasis-free survival rates, cancer-specific survival rates, and overall survival rates are 88-93, 95-100, 98-100, and 58.3-85%, respectively. In this context, the lack of appropriate long-term data is often cited as a limitation. CONCLUSION: Different meta-analyses come to the conclusion that in case of adequate tumor and patient selection RFA shows oncologic results comparable with surgical resection. Accepted indications for RFA are T1 renal tumors in patients with advanced age, significant comorbidities, reduced renal function, single kidney, and/or no wish for operation. Predictors for the success include tumor size and location as well as operator experience. To define the real efficacy of RFA in the treatment of renal tumors, randomized controlled clinical long-term studies are indicated.