BACKGROUND AND OBJECTIVE:Length of stay is an important factor for managing the limited resources of a hospital. The early, accurate prediction of hospital length of stay leads to optimized disposition of resources, particularly in complex stroke treatment. In the present study, we evaluated different machine learning techniques in their ability to predict the length of stay of patients with stroke of the anterior circulation who were treated with thrombectomy. MATERIALS AND METHODS:This retrospective study evaluated four algorithms (support vector machine, generalized linear model, K-nearest neighbor, and random forest) to predict the length of hospitalization of 113 patients with acute stroke who were treated with thrombectomy. Input variables encompassed baseline data at admission, as well as peri-procedural and imaging data. Tenfold cross-validation was used to estimate accuracy. The accuracy of the algorithms was checked with a validation dataset. In addition to a regression analysis, we performed a binary classification analysis to identify patients who stayed longer than the mean length of stay. RESULTS:The median length of stay was 10.6 days (interquartile range 6-15). The sensitivity of the best performing random forest model was 0.8, the specificity was 0.68, and the area under the curve was 0.73 in the classification analysis. The mean absolute error of the best performing random forest model was 4.6 days in the validation dataset in the regression analysis. CONCLUSION:The length of stay of patients with acute ischemic stroke of the anterior circulation can be predicted with machine learning. Machine learning could aid in optimal resource allocation in clinical routine.

Zusammenfassung Obwohl bei der transarteriellen periartikulären Embolisation (TAPE) noch viele Aspekte erforscht werden müssen, findet sie eine zunehmende Verbreitung und Akzeptanz bei der Behandlung von Gelenkschmerzen. Diese Arbeit stellt den aktuellen Stand vor, benennt mögliche Indikationen, beschreibt die interventionelle Technik und fasst die in der Literatur verfügbaren Ergebnisse zusammen.

In den letzten Jahren erfährt die transarterielle periartikuläre Embolisation (TAPE) eine zunehmende Aufmerksamkeit bei der Behandlung von chronischen Gelenkschmerzen, die z. B. durch degenerative Veränderungen wie der Arthrose aber auch durch entzündliche Veränderungen des Kapsel-Band-Apparates bedingt sein können. Ziel der Arbeit ist es, die Einsatzmöglichkeiten der TAPE bei der Behandlung der therapieresistenten Achillodynie, das prozedurale Vorgehen und die initialen Ergebnisse zu beschreiben. Die TAPE wurde bei 7 Patienten (weiblich: 1, männlich: 6) zur Behandlung der chronischen Achillodynie eingesetzt. Dabei wurden die technische Erfolgsrate und die Komplikationsrate erfasst. Ferner wurde die Veränderungen des subjektiven Schmerzes mittels einer visuellen Analogskala (VAS) und die Belastbarkeit mit dem Foot-and-Ankle-Disability-Index (FADI) analysiert. Alle Prozeduren konnten erfolgreich durchgeführt werden (technische Erfolgsrate: 100

PURPOSE:To evaluate Vessel Tracking software for determining the prostatic arteries feeding the prostate gland during prostatic artery embolization (PAE) using Conebeam-CT (CBCT). MATERIALS AND METHODS:EmboGuide is a software developed to assist interventional radiologists in performing embolization of hypervascular tumors in the liver. In this study, a single-center retrospective image collection of 120 intraprocedural CBCT of 60 patients with benign prostatic hyperplasia treated using PAE between May 2017 and January 2019 was evaluated. All patients received 1 intraprocedural CBCT per side for evaluation of vessel anatomy. The "reference standard" of the vascular anatomy was defined by segmentation of the prostatic gland and marking of the prostatic artery in conjunction with pre-embolization DSA series. The datasets were then anonymized. Three interventional radiologists with experience in PAE from different centers reviewed the images and used the automatic feeder detection to determine the prostatic artery. Finally, two clinical experts compared the feeding vessels indicated in the "reference standard" and those identified by the readers. Objectives of the study were to evaluate the clinical performance of the software based on sensitivity and the agreement between interventional radiologists. RESULTS:Sensitivity was estimated as 0.968 with a 90% confidence interval. Overall agreement was estimated as 0.801 with a 90% confidence interval. On both objectives (Sensitivity and Agreement), specifications were met. CONCLUSIONS:The results of this study suggest that EmboGuide can be used to determine the prostate arteries in PAE. The findings could be used to expand the intended use of EmboGuide to include PAE.

Interventional oncology (IO) employs various techniques to enable minimally invasive, image-guided treatment of tumor diseases with both curative and palliative goals. Additionally, it significantly contributes to managing tumor-related and perioperative complications, offering diverse supportive procedures for patients at all stages of their diseases. The execution of IO procedures places unique demands on the equipment, personnel, and structural organization of radiological clinics, necessitating specific expertise from interventional radiologists.This position paper aims to comprehensively outline the multifaceted aspects of IO and discuss the requisite criteria for hospitals, radiological clinics, and interventional radiologists (IRs). Furthermore, it underscores overarching considerations of quality assurance that clinics and professional societies should prioritize.The requirements for hospitals, radiological clinics, and IRs are varied and demand not only a high level of proficiency in performing IO procedures but also in-depth knowledge of the differential therapy for various tumor diseases. This expertise is essential for effectively serving as clinical partners in the interdisciplinary treatment of oncologic patients. Additionally, a thorough understanding and safe handling of ionizing radiation technologies, along with proficiency in radiation protection methods, which are fundamental aspects of radiological specialist training, is crucial for ensuring the safety of IO procedures for both patients and staff. The Deutsche Gesellschaft für Interventionelle Radiologie und minimal-invasive Therapie (DeGIR) and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE) have long-established dedicated quality management programs, accrediting radiology clinics and certifying IRs. These initiatives aim to uphold the highest standards of care and meet the quality expectations set by politics in healthcare system, particularly in the realm of interventional radiology. · The various procedures in the field of interventional oncology (IO) are complex medical interventions that require not only the most advanced technical equipment but also adequate human resources, particularly specialized expertise in interventional radiology, diagnostic imaging, oncology, and radiation protection.. · This expertise is an integral part of the specialized medical training in radiology and is certified by professional societies such as the German Society for Interventional Radiology (DeGIR) and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).. · Professional societies like DeGIR, CIRSE, and the American Society of Interventional Radiology (SIR) establish the necessary quality assurance framework for comprehensive, high-quality IO therapy through quality assurance (QA) registries, standard operating procedure (SOP) documents, and participation in guideline development.. · Currently, radiology is the only discipline that provides physicians with the theoretical and practical knowledge, skills, and competencies required to perform the demanding procedures in the field of IO through specialized training programs and tailored certification processes.. · Isfort P, Sommer CM, Bruners P et al. Position Paper of the German Society for Interventional Radiology and Minimally Invasive Therapy (DeGIR) and the German Roentgen Society (DRG) on Structural and Professional Requirements in Interventional Oncology. Rofo 2025; 197: 546-556.

Background In recent years, transarterial periarticular embolization (TAPE) has received increasing attention in the treatment of chronic joint pain, which can be caused by degenerative changes such as osteoarthritis but also by inflammatory changes in the capsule-ligament apparatus. Objectives The aim of this study is to describe the method as well as preliminary results of TAPE in the treatment of therapy-resistant achillodynia. Material and methodsTAPE was used in the treatment of seven patients (female: 1, male: 6) with chronic achillodynia. The technical success rate and complication rates were analyzed. Furthermore, the changes in subjective pain were assessed using a visual analogue scale (VAS) and the load-bearing capacity using the Foot and Ankle Disability Index (FADI). Results All procedures were performed successfully (technical success rate: 100%); no complications were observed. In the first postoperative week, pain was reduced from an initial average VAS of 8.2 to 4.2. After 12 months, there was a further reduction to 1.4. At the same time, based on the FADI, the Achilles tendon load capacity increased on average from 45.4 initially to 60.1 after 1 week and to 89.9 after 12 months. Conclusion Our results suggest that TAPE may be a new, promising procedure in the treatment of therapy-resistant, chronic achillodynia. This technically demanding but minimally invasive procedure, performed only under local anesthesia, can significantly reduce pain and restore the patient's ability to bear weight.

Background Various endovascular techniques for the recanalization of large vessel occlusion in patients with acute ischemic stroke have been established. In this series a combined distal and proximal aspiration technique was used as a novel approach. The aim of this study was to investigate, whether this technique achieves reperfusion faster and if embolization in distal territories can be reduced. Results The success of the treatment was dependent on the localization of the clot. Fast reperfusion was achieved in all patients when the clot was located at the level of the middle cerebral artery. Aspiration failed when the vessel occlusion was located at the level of the carotid-T and subsequent rescue treatment was performed. Median groin puncture to reperfusion time was 20 min (range 9–66). No Embolization to new territories (ENT) and no intracerebral hemorrhage were observed. One patient died. In all other patients favorable neurological outcome was observed as measured by a modified Rankin score at discharge (mRS 0, range 0–1). Conclusion Simultaneous proximal and distal aspiration appears to be fast and effective. Furthermore, it reliably prevented ENT in patients with vessel occlusion at the level of the middle cerebral artery in a small cohort.

Abstract Aims Intravenous iron therapy (IVIT) is known to improve functional status in chronic heart failure (CHF) patients. The exact mechanism is not completely understood. We correlated magnetic resonance imaging (MRI) patterns of T2* iron signal in various organs to systemic iron and exercise capacity (EC) in CHF before and after IVIT. Methods and results We prospectively analysed 24 patients with systolic CHF for T2* MRI pattern of the left ventricle (LV), small and large intestines, spleen, liver, skeletal muscle, and brain for iron. In 12 patients with iron deficiency (ID), we restored iron deficit by IVIT using ferric carboxymaltose. The effects after 3 months were analysed by spiroergometry and MRI. Patients with vs. without ID showed lower blood ferritin, haemoglobin (76 ± 63 vs. 196 ± 82 μg/L and 12.3 ± 1.1 vs. 14.2 ± 1.1 g/dL, all P < 0.002), and in trend a lower transferrin saturation (TSAT) (19.1 [13.1; 28.2] vs. 25.1 [21.3; 29.1] %, P = 0.05). Spleen and liver iron was lower as expressed by higher T2* value (71.8 [66.4; 93.1] vs. 36.9 [32.9; 51.7] ms, P < 0.002 and 33.5 ± 5.9 vs. 28.8 ± 3.9 ms, and P < 0.03). There was a strong trend for a lower cardiac septal iron content in ID (40.6 [33.0; 57.3] vs. 33.7 [31.3; 40.2] ms, P = 0.07). After IVIT, ferritin, TSAT, and haemoglobin increased (54 [30; 104] vs. 235 [185; 339] μg/L, 19.1 [13.1; 28.2] vs. 25.0 [21.0; 33.7] %, 12.3 ± 1.1 vs. 13.3 ± 1.3 g/L, all P < 0.04). Peak VO2 improved (18.2 ± 4.2 vs. 20.9 ± 3.8 mL/min/kg−1, P = 0.05). Higher peak VO2 at anaerobic threshold was associated with higher blood ferritin, reflecting higher metabolic exercise capacity after therapy (r = 0.9, P = 0.0009). Increase in EC was associated with haemoglobin increase (r = 0.7, P = 0.034). LV iron increased by 25.4% (48.5 [36.2; 64.8] vs. 36.2 [32.9; 41.9] ms, P < 0.04). Spleen and liver iron increased by 46.4 and 18.2%, respectively (71.8 [66.4; 93.1] vs. 38.5 [22.4; 76.9] ms, P < 0.04 and 33.5 ± 5.9 vs. 27.4 ± 8.6 ms, P < 0.007). Iron in skeletal muscle, brain, intestine, and bone marrow remained unchanged (29.6 [28.6; 31.2] vs. 30.4 [29.7; 30.7] ms, P = 0.7, 81.0 ± 6.3 vs. 82.9 ± 9.9 ms, P = 0.6, 34.3 ± 21.4 vs. 25.3 ± 14.1 ms, P = 0.2, 9.4 [7.5; 21.8] vs. 10.3 [6.7; 15.7] ms, P = 0.5 and 9.8 ± 1.5 vs. 13.7 ± 8.9 ms, P = 0.1). Conclusions CHF patients with ID showed lower spleen, liver, and in trend lower cardiac septal iron. After IVIT, iron signal of the left ventricle as well as spleen and liver increased. Improvement in EC was associated with increase in haemoglobin after IVIT. In ID, liver, spleen, and brain but not heart iron were associated with markers of systemic ID.

Purpose Clinical outcomes vary considerably among individuals with vessel occlusion of the posterior circulation. In the present study we evaluated machine learning algorithms in their ability to discriminate between favourable and unfavourable outcomes in patients with endovascular treatment of acute ischaemic stroke of the posterior circulation. Methods This retrospective study evaluated three algorithms (generalised linear model, K-nearest neighbour and random forest) to predict functional outcomes at dismissal of 30 patients with acute occlusion of the basilar artery who were treated with thrombectomy. Input variables encompassed baseline as well as peri and postprocedural data. Favourable outcome was defined as a modified Rankin scale score of 0–2 and unfavourable outcome was defined as a modified Rankin scale score of 3–6. The performance of the algorithms was assessed with the area under the receiver operating curve and with confusion matrixes. Results Successful reperfusion was achieved in 83%, with 30% of the patients having a favourable outcome. The area under the curve was 0.93 for the random forest model, 0.86 for the K-nearest neighbour model and 0.78 for the generalised linear model. The accuracy was 0.69 for the generalised linear model and 0.84 for the random forest and the K nearest neighbour models. Conclusion Favourable and unfavourable outcomes at dismissal of patients with acute ischaemic stroke of the posterior circulation can be predicted immediately after the follow-up non-enhanced computed tomography using machine learning.

Background Hemorrhoids are a widespread disease. Treatment options range from dietary measures to open surgery. A novel treatment approach is the embolization of the hemorrhoidal arteries. Method A review was performed based on a selective literature search in PubMed representing the current state of research. The keywords "hemorrhoid" and "embolization" and "emborrhoid" were used. In addition, technical details of the hemorrhoidal embolization procedure are explained. Results and Conclusion Embolization of hemorrhoidal arteries is a safe treatment, which allows efficient symptom control even in patients with contraindications for open surgery.

To examine the feasibility of the quantification of abdominal periaortic fat tissue (PaFT) (tissue within − 45 to − 195 HU) in enhanced CT-angiographies compared to unenhanced CT-scans and identify methodological issues affecting its clinical implementation. Using OsirixMD, PaFT volume and mean HU value were retrospectively measured within a 5 mm periaortic ring in paired unenhanced and enhanced abdominal aortic CT-scans. The correlation between PaFT values was examined in a derivation cohort (n = 101) and linear regression analysis produced correction factors to convert values from enhanced into values from unenhanced CTs. The conversion factors were then applied to enhanced CTs in a different validation cohort (n = 47) and agreement of corrected enhanced values with values from unenhanced scans was evaluated. Correlation between PaFT Volume und Mean HU from enhanced and unenhanced scans was very high (r > 0.99 and r = 0.95, respectively, p < 0.0001 for both). The correction factors for PaFT Volume and Mean HU were 1.1057 and 1.0011. Potential confounding factors (CT-kilovoltage, slice thickness, mean intraluminal contrast density, aortic wall calcification, longitudinal variation of intraluminal contrast density, aortic diameter) showed no significant effect in a multivariate regression analysis (p > 0.05). Bland-Altman analysis of corrected enhanced and unenhanced values showed excellent agreement and Passing–Bablok regression confirmed minimal/no residual bias. PaFT can be quantified in enhanced CT-angiographies very reliably. PaFT Volume scores are very consistently slightly underestimated in enhanced scans by about 10%, while the PaFT Mean HU value remains practically constant and offers distinct methodological advantages. However, a number of methodological issues remain to be addressed.

Purpose: To evaluate the detection rate of intracranial aneurysms on reconstructed thin slice non enhanced CT (NECT) scans. Methods: NECT scans from 34 patients with 35 aneurysms and 35 individuals without aneurysms were collected. Thin slice maximum intensity projections of the NECT scans were reconstructed. One observer evaluated the native images twice with a time interval of six month between both passes with respect to the prevalence and location of an aneurysm. The size and location of the aneurysms were evaluated in corresponding CT-Angiography and Time of flight datasets. A logit regression analysis was performed with size and location as dependent variables. 2 × 2 tables were constructed. The sensitivity and false negative rate were calculated for aneurysms with 0–6.9 mm, 7–9.9 mm and 10–20 mm and the under the curve (AUC) was calculated. Results: The overall detection rate of the aneurysms was 63% for the first pass and 66% for the second pass in the reconstructed NECT scans. The detection rate of aneurysms is size dependent. The sensitivity to detect aneurysms with a size of 0–6.9 mm was 0.09 and 0.03, for aneurysms with a size of 7–9.9. mm was 0.8 and 0.7 and for aneurysms with a size of 10–20 mm was 0.92 for both passes. The AUC was 0.77 for the first pass and 0.78 for the second pass. Conclusions: NECT scans can be used to detect a significant proportion of intracranial aneurysms larger than 7 mm if properly displayed and reconstructed. These patients should receive further vascular imaging to prevent future aneurysm related subarachnoid hemorrhage.

Target vessel catheterization remains challenging in patients with complex anatomies. Fenestrated endovascular aneurysm repair (FEVAR) is an established technique to treat aortic aneurysms. In this case report, we treated a juxtarenal aneurysm using FEVAR. Initial attempts to complete the target vessel stenting were unsuccessful because of an unfavorable orifice and tortuosity of the right renal artery. The completion of FEVAR was achieved with a bifemoral approach using a snare system, which aligned the tip of a steerable sheath at the level of the fenestration for the right renal artery to create a stable condition. Control angiography and computed tomography confirmed a successful stenting of the target vessel and the sealing of the fenestration without an endoleak.

Background: To evaluate the feasibility, safety and efficacy of magnetic resonance imaging (MRI)-guided lumbar facet joint radiofrequency denervation (FRD) in patients with chronic low back pain. Methods: The study consisted of two parts. First, a preclinical analysis using an ex vivo animal model was performed to define optimal technical parameters for ablation. Then, 17 patients with chronic lumbar facet joint pain syndrome were prospectively included and underwent MRI-guided FRD in an open 1.0-Tesla MRI. We analyzed technical feasibility and complications as well as clinical outcome in terms of subjective pain assessed on a numerical visual analogue scale (VAS) before and after 1 week/6 months after FRD. Clinical assessment was complemented by measurement of paravertebral muscle volume and fat content before the intervention and at 6-month follow-up. Results: All interventions were technically successful without major complications. Initial VAS scores (median: 8, IQR: 1, range: 6-9, CI: 7.14-8.04) decreased significantly both after one week (median: 4, IQR: 5, range: 0-7, CI: 1.9-4.69, P=0.003) and after 6 months (median: 1, IQR: 6, range: 0-7, CI: 1.064.23, P< 0.001). Mean multifidus muscle volume increased significantly in the patient population (from 366.8 +/- 130.8 cm(3) before to 435.4 +/- 146.7 cm(3) after FRD, P=0.031). Conclusions: This proof of principle study shows MRI-guided FRD in an open 1.0-Tesla MRI system to be a potential therapy option for patients with chronic low back pain.

Ziel Anhand von Fallbeispielen sollen die Anwendungsmöglichkeiten, Technik und initialen Ergebnisse der transarteriellen periartikulären Embolisation (TAPE) dargestellt werden. Material und Methoden Die TAPE wurde bei 3 Patienten mit chronischen Schmerzen an unterschiedlichen Gelenken angewendet. Im ersten Fall lag eine aktivierte Arthrose des Schultergelenks, im zweiten Fall eine Epicondylitis humeri ulnaris („Golfer-Ellenbogen“) und im dritten Fall ein Patellaspitzensyndrom („Jumpers Knee“) vor. Ergebnisse Bei allen 3 Patienten konnte die TAPE technisch erfolgreich durchgeführt werden. Dabei wurden entweder durch einen transradialen oder transfemoralen Zugang die Endäste der entsprechenden Gelenkarterien superselektiv mittels Mikrokatheter sondiert und mit in Kontrastmittel aufgelöstem Imipenem/Cilastatin embolisiert. Postinterventionell kam es bei der Behandlung des Kniegelenks zu einer Hautrötung, die sich innerhalb einer Woche wieder zurückbildete. Weitere Komplikationen traten nicht auf. Bei allen Patienten zeigte sich bereits am ersten postoperativen Tag eine Linderung der Beschwerden, die anhand von klinischen Tests und der subjektiven Einschätzung der Schmerzen auf einer visuellen Analogskala dokumentiert werden konnte. Schlussfolgerung Die initialen Erfahrungen, die in unserer Klinik mit der TAPE gemacht werden konnten, sind ermutigend und zeigen, dass das Verfahren das Potenzial zur Erweiterung der gering invasiven Therapieoptionen bei Patienten mit therapierefraktären chronischen Gelenkschmerzen und Enthesiopathien hat. Kernaussagen

Purpose Evaluation of the efficacy and safety of chemical renal denervation by image-guided periarterial ethanol injection in pigs with emphasis on histopathological characteristics. Materials and Methods Unilateral renal periarterial ethanol injection under general anesthesia was performed in 16 animals with the contralateral kidney serving as the control. All interventions were performed in an open MRI system under real-time multiplanar guidance. In 10 pigs an ethanol-carbostesin contrast agent mixture was injected with amounts of 5 ml (6 animals, group I) and 10ml (4 animals, group II). 6 pigs (group III) were treated with 10ml of an ethanol-polyacrylic (2 %) mixture. Four weeks after treatment, all animals underwent MRI including MRA. After euthanasia, macroscopic and histologic examination of the kidneys, renal arteries and periarterial tissue was performed to assess nerve injury and potential side effects. Furthermore, the norepinephrine concentration (RTNEC) in the renal tissue was determined as a surrogate parameter of efficacy. Results Histologic signs of nerval degeneration with various degrees of severity and circumferential distribution were found in all groups. Injury depths ranged up to 7.6mm. In groups II and III the nerve count was significantly lower on the treated side. Renal artery stenosis was not observed in any pig. In all pigs of group II treatment resulted in neural degeneration with a mean RTNEC reduction of 53% (p < 0.02). In groups I and III significant changes in RTNEC were not observed. Conclusion Image-guided percutaneous periarterial ethanol injection was efficient and safe for renal denervation. The detected variations in histologic outcome underlined the importance of the preclinical optimization of the technique in order to maximize treatment effects in humans. Key Points: ▪ Renal denervation by percutaneous periarterial ethanol injection is an effective and potentially safe procedure. ▪ The percutaneous approach is less prone to anatomical and procedural limitations compared to catheter-based procedures. ▪ The achievable nerve injury depth lies beyond those of current RFA-probes. ▪ Efficacy depends on amount, concentration, viscosity and periarterial distribution of the ethanol-mixture. ▪ Establishing an optimal balance between these parameters is mandatory for a maximum treatment effect at minimum risk for sensitive adjacent structures. Citation Format ▪ Freyhardt P, Haage P, Walter A et al. Renal Sympathetic Denervation by Image-Guided Percutaneous Ethanol Injection – Histopathologic Characteristics, Efficacy and Safety. Fortschr Röntgenstr 2020; DOI 10.1055/a-10852645

Purpose The purpose of this article is to demonstrate the potential indications, procedural technique and initial results of the transarterial periarticular embolization (TAPE). Material and Methods TAPE was performed in three patients with chronic pain in different joints. In the first case the patient suffered from osteoarthritis of the shoulder, in the second case from epicondylitis humeri ulnaris ("golferelbow") and in the third case from patellar tendinitis ("jumpers-knee"). Clinical as well as pain assessment was performed pre and post-interventionally. Results TAPE was performed with technical success in all three patients. For vessel access, either a transradial or trans-femoral access was chosen. The joint supplying vessels were catheterized superselectively with microcatheters and embolized with Imipenem/Cilastatin diluted in contrast medium. After embolization of the knee the patient demonstrated skin redness, which disappeared within one week. No further complications were noted. All patients reported significant pain relief within the first day after intervention. Conclusion TAPE is a novel therapy for the treatment of persistent, chronic joint pain and tendinopathies, supported by publications from institutes outside of Europe. The initial experiences made in our institute are encouraging and suggest that TAPE may have the potential as an adjunct therapy option for patients with therapy-resistant chronic joint and tendinopathy-pain.

PURPOSE:Evaluation of the efficacy and safety of chemical renal denervation by image-guided periarterial ethanol injection in pigs with emphasis on histopathological characteristics. MATERIALS AND METHODS:Unilateral renal periarterial ethanol injection under general anesthesia was performed in 16 animals with the contralateral kidney serving as the control. All interventions were performed in an open MRI system under real-time multiplanar guidance. In 10 pigs an ethanol-carbostesin contrast agent mixture was injected with amounts of 5 ml (6 animals, group I) and 10 ml (4 animals, group II). 6 pigs (group III) were treated with 10 ml of an ethanol-polyacrylic (2 %) mixture. Four weeks after treatment, all animals underwent MRI including MRA. After euthanasia, macroscopic and histologic examination of the kidneys, renal arteries and periarterial tissue was performed to assess nerve injury and potential side effects. Furthermore, the norepinephrine concentration (RTNEC) in the renal tissue was determined as a surrogate parameter of efficacy. RESULTS:Histologic signs of nerval degeneration with various degrees of severity and circumferential distribution were found in all groups. Injury depths ranged up to 7.6 mm. In groups II and III the nerve count was significantly lower on the treated side. Renal artery stenosis was not observed in any pig. In all pigs of group II treatment resulted in neural degeneration with a mean RTNEC reduction of 53 % (p < 0.02). In groups I and III significant changes in RTNEC were not observed. CONCLUSION:Image-guided percutaneous periarterial ethanol injection was efficient and safe for renal denervation. The detected variations in histologic outcome underlined the importance of the preclinical optimization of the technique in order to maximize treatment effects in humans. KEY POINTS:· Renal denervation by percutaneous periarterial ethanol injection is an effective and potentially safe procedure.. · The percutaneous approach is less prone to anatomical and procedural limitations compared to catheter-based procedures.. · The achievable nerve injury depth lies beyond those of current RFA-probes.. · Efficacy depends on amount, concentration, viscosity and periarterial distribution of the ethanol-mixture.. · Establishing an optimal balance between these parameters is mandatory for a maximum treatment effect at minimum risk for sensitive adjacent structures.. CITATION FORMAT:· Freyhardt P, Haage P, Walter A et al. Renal Sympathetic Denervation by Image-Guided Percutaneous Ethanol Injection - Histopathologic Characteristics, Efficacy and Safety. Fortschr Röntgenstr 2020; 192: 549 - 560.

PURPOSE:To evaluate the radiation dose in patients undergoing prostatic artery embolization (PAE) using cone-beam CT and 3-dimensional (3D) guidance software. MATERIALS AND METHODS:In this single-center retrospective study, 100 patients with benign prostatic hyperplasia (mean prostate volume, 83.6 mL ± 44.2; 69.4 ± 9.6 years of age; body mass index, 26.5 ± 4.2) were treated using PAE between October 2016 and April 2018. Informed consent was obtained from all participants included in the study. All patients received at least 1 intraprocedural cone-beam CT per side for evaluation of the vessel anatomy and software rendering of 3D guidance for catheter guidance. Digital subtraction angiography (DSA) was performed in the distal branches only. The total dose area product (DAP), along with the DAP attributed to fluoroscopy, DSA, and cone-beam CT, were assessed. RESULTS:Bilateral embolization was achieved in 83 patients (83%). The average total DAP was 134.4 Gy ⋅ cm2 ± 69.5 (range, 44.7-410.9 Gy ⋅ cm2). Fluoroscopy, DSA, and cone-beam CT accounted for 35.5 Gy ⋅ cm2 ± 21.3 (range, 8.6-148.6 Gy ⋅ cm2) or 26.4% (percentage of total DAP), 58.2 Gy ⋅ cm2 ± 48.3 (range, 10.3-309.3 Gy ⋅ cm2) or 43.3%, and 40.7 Gy ⋅ cm2 ± 14.5 (range, 15.9-86.3 Gy ⋅ cm2) or 30.3%, respectively. Average procedure time was 89.4 ± 27.0 minutes, and the average fluoroscopy time was 30.9 ± 12.2 minutes. CONCLUSIONS:Intraprocedural cone-beam CT in combination with 3D guidance software allows for identification and catheterization of the prostatic artery in PAE. Furthermore, the results of this trial indicate that this study protocol may lead to a low overall radiation dose.