ChatGPT: Evaluating answers on contrast media related questions and finetuning by providing the model with the ESUR guideline on contrast agents

OBJECTIVE

This study aimed to assess the feasibility of GPT-4 for answering questions related to contrast media with and without the context of the European Society of Urogenital Radiology (ESUR) guideline on contrast agents. The overarching goal was to determine whether contextual enrichment by providing guideline information improves answers of GPT-4 for clinical decision-making in radiology.

METHODS

A set of 64 questions, based on the ESUR guideline on contrast agents mirroring pertinent sections, was developed and posed to GPT-4 both directly and after providing the guideline using a plugin. Responses were graded by experienced radiologists for quality of information and accuracy in pinpointing information from the guideline as well as by radiology residents for utility, using Likert-scales.

RESULTS

GPT-4's performance improved significantly with the guideline. Without the guideline, average quality rating was 3.98, which increased to 4.33 with the guideline (p = 0036). In terms of accuracy, 82.3% of answers matched the information from the guideline. Utility scores also reflected a significant improvement with the guideline, with average scores of 4.1 (without) and 4.4 (with) (p = 0.008) with a Fleiss´ Kappa of 0.44.

CONCLUSION

GPT-4, when contextually enriched with a guideline, demonstrates enhanced capability in providing guideline-backed recommendations. This approach holds promise for real-time clinical decision-support, making guidelines more actionable. However, further refinements are necessary to maximize the potential of large language models (LLMs). Inherent limitations need to be addressed.

Contrast media for hysterosalpingography: systematic search and review providing new guidelines by the Contrast Media Safety Committee of the European Society of Urogenital Radiology

OBJECTIVES

Hysterosalpingography (HSG) is widely used for evaluating the fallopian tubes; however, controversies regarding the use of water- or oil-based iodine-based contrast media (CM) remain. The aim of this work was (1) to discuss reported pregnancy rates related to the CM type used, (2) to validate the used CM in published literature, (3) to discuss possible complications and side effects of CM in HSG, and (4) to develop guidelines on the use of oil-based CM in HSG.

METHODS

A systematic literature search was conducted for original RCT studies or review/meta-analyses on using water-based and oil-based CM in HSG with fertility outcomes and complications. Nine randomized controlled trials (RCTs) and 10 reviews/meta-analyses were analyzed. Grading of the literature was performed based on the Oxford Centre for Evidence-Based Medicine (OCEBM) 2011 classification.

RESULTS

An approximately 10% higher pregnancy rate is reported for oil-based CM. Side effects are rare, but oil-based CM have potentially more side effects on the maternal thyroid function and the peritoneum.

CONCLUSIONS

1. HSG with oil-based CM gives approximately 10% higher pregnancy rates. 2. External validity is limited, as in five of nine RCTs, the CM used is no longer on the market. 3. Oil-based CM have potentially more side effects on the maternal thyroid function and on the peritoneum. 4. Guideline: Maternal thyroid function should be tested before HSG with oil-based CM and monitored for 6 months after.

CLINICAL RELEVANCE STATEMENT

Oil-based CM is associated with an approximately 10% higher chance of pregnancy compared to water-based CM after HSG. Although side effects are rare, higher iodine concentration and slower clearance of oil-based CM may induce maternal thyroid function disturbance and peritoneal inflammation and granuloma formation.

KEY POINTS

• It is unknown which type of contrast medium, oil-based or water-based, is the optimal for HSG. • Oil-based contrast media give a 10% higher chance of pregnancy after HSG, compared to water-based contrast media. • From the safety perspective, oil-based CM can cause thyroid dysfunction and an intra-abdominal inflammatory response in the patient.

Waiting times between examinations with intravascularly administered contrast media: a review of contrast media pharmacokinetics and updated ESUR Contrast Media Safety Committee guidelines

The pharmacokinetics of contrast media (CM) will determine how long safe waiting intervals between successive CT or MRI examinations should be. The Contrast Media Safety Committee has reviewed the data on pharmacokinetics of contrast media to suggest safe waiting intervals between successive contrast-enhanced imaging studies in relation to the renal function of the patient. CLINICAL RELEVANCE STATEMENT: Consider a waiting time between elective contrast-enhanced CT and (coronary) angiography with successive iodine-based contrast media administrations in patients with normal renal function (eGFR > 60 mL/min/1.73 m2) of optimally 12 h (near complete clearance of the previously administered iodine-based contrast media) and minimally 4 h (if clinical indication requires rapid follow-up). KEY POINTS: • Pharmacokinetics of contrast media will guide safe waiting times between successive administrations. • Safe waiting times increase with increasing renal insufficiency. • Iodine-based contrast media influence MRI signal intensities and gadolinium-based contrast agents influence CT attenuation.

Analytical interference of intravascular contrast agents with clinical laboratory tests: a joint guideline by the ESUR Contrast Media Safety Committee and the Preanalytical Phase Working Group of the EFLM Science Committee

The Contrast Media Safety Committee of the European Society of Urogenital Radiology has, together with the Preanalytical Phase Working Group of the EFLM Science Committee, reviewed the literature and updated its recommendations to increase awareness and provide insight into these interferences.

Occupational orthopedic problems and its relation to personal radiation protection in interventional radiology

PURPOSE

Several studies report occupational orthopedic problems among interventional cardiologists. These health problems are usually multifactorial. However, the personal protective equipment used should play a major role. An online survey was conducted to determine the frequency of such health problems among interventional radiologists and to correlate them with the use of personal radiation protective clothing.

MATERIAL AND METHODS

An anonymous online survey that comprised of 17 questions was sent via e-mail to 1427 members of the German Society for Interventional Radiology (DeGIR) in Germany, Austria and Switzerland. The questions were focused on interventional workload, the use of personal radiation protection apparel and orthopedic problems. Given the different scale levels, the associations between the variables were analyzed using different statistical methods. A significance level of p < 0.05 was chosen.

RESULTS

There were 221 survey responders (15.5% response rate). About half of responders (47.7%) suffered from more than five episodes of orthopedic problems during their interventional career. Lumbar spine was involved in 81.7% of these cases, cervical spine in 32.8%, shoulder in 28.5% and knee in 24.7%. Because of orthopedic problems, 16.1% of the responders had to reduce and 2.7% had to stop their interventional practice. The number of affected body regions correlates with the fit of the radiation protection means (p < 0.05, r = 0.135) and the reduction of activity as an interventional radiologist (p < 0.05, r = -0.148).

CONCLUSION

Overall, the survey reveals widespread orthopedic problems at several body regions among interventional radiologists, associated with the fit of radiation protection systems, among other factors. A connection between the orthopaedic complaints and the radiation protection system used could not be established.

Differences in neonatal gastric tubes during insertion into a 3D model in relation to risk of potential perforation

OBJECTIVES

Perforation of esophagus or stomach is a potential complication during and after insertion of a gastric tube in neonates. The aim of this study was to analyze different types of gastric tubes in a three-dimensional (3D) model of neonatal esophagus and stomach regarding potential perforations.

METHODS

A 3D model of esophagus and stomach was created based on computed tomography data of a term neonate. Three types of gastric tubes were inserted into the 3D model, the localization was examined by radioscopy and the behavior, stiffness and manageability of each gastric tube was evaluated.

RESULTS

Insertion of gastric tubes with higher stiffness was easier. The rates of correct localization differed significantly between the gastric tubes with the highest rate of correct localization in the softest tube (48.5%) and the lowest rate in the tube with the highest stiffness (21.2%). Additionally, the softest tube showed the lowest rate of localization of its tip at the stomach wall.

CONCLUSIONS

The study illustrates differences between various types of gastric tubes regarding stiffness, behavior and resiliency. Softer gastric tubes may be beneficial. These differences may be relevant in neonatal care of very immature and very sick infants.

Medical students' general and radiology-specific motivation: Correlations, stability and associations with learning strategies and ability beliefs

PURPOSE

This study investigated general and subject-specific motivational beliefs from the perspectives of self-determination theory (i.e. intrinsic, identified, introjected, and extrinsic motivation) and achievement goal theory (i.e. mastery, performance-approach, and -avoidance goal orientation including the respective classroom goal structures), their interrelations, their stability over time, and their associations with desirable outcomes (i.e. deep-level learning strategies, self-concept of ability). It was hypothesized that motivational beliefs are interrelated but demonstrate a distinct correlational pattern depending on whether they were assessed as general or subject-specific motivation. In addition, motivational beliefs were hypothesized to relate to learning strategies and ability beliefs.

METHODS

Medical students (n = 146) participated in this longitudinal study with measurement points at the beginning and end of a semester. The questionnaire included established motivational scales to assess motivational beliefs and desirable outcomes. Measurement models were tested using confirmatory factor analyses; correlations of scale means were investigated to assess the nomological network of motivational beliefs.

RESULTS

As expected, intrinsic and identified motivation were associated with mastery goal orientation and with desirable outcome variables, such as the use of deep-level learning strategies. General and subject-specific motivation exhibited distinct correlational patterns. Motivation was relatively stable over time. Results did not confirm the factor structure of classroom goal structure.

CONCLUSIONS

The study emphasizes the benefit of a subject-specific conceptualization of motivation and the need for a careful adaptation of theoretical constructs from the secondary school context to make them fruitful for the promotion of medical students' motivation. Medical teachers can use established motivational interventions (e.g. using an individual frame of reference for feedback) to support students' adaptive motivational beliefs (e.g. self-determined motivation, mastery goals). Given the subject specificity of motivation, it seems beneficial to promote adaptive motivation in the respective medical specialty regardless of students' general motivational characteristics.

Assessment of Efficacy and Complications of Endovascular Interventions for Critical Limb Ischemia in Germany: A Nationwide Study

PURPOSE

 Endovascular interventional radiological procedures have become the mainstay for the treatment of critical limb ischemia (CLI) due to arterial stenosis or occlusion. Open surgical or endovascular procedures, such as percutaneous transluminal angioplasty (PTA) or stenting can be used as a treatment strategy. The aim is to evaluate the success and major complication rates of interventional radiology treatments for CLI in Germany in 2021, and to compare these results with internationally published data.

MATERIALS AND METHODS

 Data for PTA and stenting in CLI for 2021 was obtained from the quality management system of the German Society of Interventional Radiology (DeGIR). 16 393 PTA procedures, 701 stenting procedures, and 8110 combined procedures were documented for 2021. Data was analyzed for technical and clinical success rates, as well as major complication rates documented mainly as major bleeding, distal embolization, and aneurysm formation.

RESULTS

 PTA had technical and clinical success rates of 96.3 % and 92.33 %, respectively. Stenting had technical and clinical success rates of 98.7 % and 96.15 %, respectively. PTA and stenting combined had success rates of 98.71 % and 96.91 %, respectively. The major complications were mainly: major bleeding (PTA: 0.40 %; stenting: 1.28 %; PTA and stenting: 0.54 %), distal embolization (PTA: 0.48 %; stenting: 1 %; PTA and stenting: 0.96 %), and aneurysm formation (PTA: 0.19 %; stenting: 0.43 %; PTA and stenting: 0.19 %). All procedures showed high technical and clinical success rates, while the complication rates were low.

CONCLUSION

 Interventional radiologists in Germany perform effective and safe treatment for CLI, achieving outcomes that tend to surpass internationally published data.

KEY POINTS

  · German interventional radiologists provide safe and effective critical limb ischemia treatment.. · Major complications occurred at maximum in 1.28 % of cases.. · Outcomes tend to surpass international data, indicating strong performance..

Retrospective evaluation of interventional radiological treatments for chronic mesenteric ischemia in Germany based on a four-year period of the DeGIR Registry: comparison of outcomes with international quality standards

PURPOSE

 Endovascular treatment has emerged as the gold standard for managing chronic mesenteric ischemia (CMI) resulting from arterial stenosis or occlusion. This study aimed to assess the efficacy and complication rates of continuous interventional radiology treatment for CMI in Germany between 2018 and 2021, comparing these findings with international quality standards.

MATERIALS AND METHODS

 Data for CMI therapy with stenting and percutaneous transluminal angioplasty (PTA) was obtained from the quality management system of the German Interventional Radiological Society (DeGIR). A total of 3752 endovascular procedures for CMI performed from 2018 to 2021 were documented (PTA: n = 675; stenting: n = 3077). Data was analyzed for technical and clinical success rates, as well as major complication rates.

RESULTS

 Overall technical and clinical success rates for PTA and stenting procedures were 92.03 %/85.9 % and 98.76 %/96.62 %, respectively. The most common major complications were: arterial occlusion (PTA: 0.73 %; stenting: 0.63), major bleeding (PTA: 1.05 %; stenting: 0.68 %), aneurysm formation (PTA: 0.29 %; stenting: 0.72 %), stent dislodgment (PTA: 0 %; stenting: 0.06 %), and organ failure (PTA: 0.43 %; stenting: 0.96 %). Technical and clinical success rates were higher, while complication rates were lower than the corresponding threshold recommended by the Society of Interventional Radiology for the percutaneous management of chronic mesenteric ischemia.

CONCLUSION

 Treatment of CMI performed by interventional radiologists in Germany is safe and effective during daily and on-call shifts with results exceeding internationally accepted standards.

KEY POINTS

  · Treatment of CMI by interventional radiologists in Germany is effective and safe.. · The interventions are safe and effective regardless of whether they are performed during on-call shifts or the daily routine.. · The clinical and technical success rates favorably surpass the thresholds presented by SIR.. · Different major complications occurred in under 1.1 % of CMI interventions..

Feasibility of GPT-3 and GPT-4 for in-Depth Patient Education Prior to Interventional Radiological Procedures: A Comparative Analysis

PURPOSE

This study explores the utility of the large language models, GPT-3 and GPT-4, for in-depth patient education prior to interventional radiology procedures. Further, differences in answer accuracy between the models were assessed.

MATERIALS AND METHODS

A total of 133 questions related to three specific interventional radiology procedures (Port implantation, PTA and TACE) covering general information as well as preparation details, risks and complications and post procedural aftercare were compiled. Responses of GPT-3 and GPT-4 were assessed for their accuracy by two board-certified radiologists using a 5-point Likert scale. The performance difference between GPT-3 and GPT-4 was analyzed.

RESULTS

Both GPT-3 and GPT-4 responded with (5) "completely correct" (4) "very good" answers for the majority of questions ((5) 30.8% + (4) 48.1% for GPT-3 and (5) 35.3% + (4) 47.4% for GPT-4). GPT-3 and GPT-4 provided (3) "acceptable" responses 15.8% and 15.0% of the time, respectively. GPT-3 provided (2) "mostly incorrect" responses in 5.3% of instances, while GPT-4 had a lower rate of such occurrences, at just 2.3%. No response was identified as potentially harmful. GPT-4 was found to give significantly more accurate responses than GPT-3 (p = 0.043).

CONCLUSION

GPT-3 and GPT-4 emerge as relatively safe and accurate tools for patient education in interventional radiology. GPT-4 showed a slightly better performance. The feasibility and accuracy of these models suggest their promising role in revolutionizing patient care. Still, users need to be aware of possible limitations.

A New Iterative Metal Artifact Reduction Algorithm for Both Energy-Integrating and Photon-Counting CT Systems

OBJECTIVES

The aim of this study was to introduce and evaluate a new metal artifact reduction framework (iMARv2) that addresses the drawbacks (residual artifacts after correction and user preferences for image quality) associated with the current clinically applied iMAR.

MATERIALS AND METHODS

A new iMARv2 has been introduced, combining the current iMAR with new modular components to remove residual metal artifacts after image correction. The postcorrection image impression is adjustable with user-selectable strength settings. Phantom scans from an energy-integrating and a photon-counting detector CT were used to assess image quality, including a Gammex phantom and anthropomorphic phantoms. In addition, 36 clinical cases (with metallic implants such as dental fillings, hip replacements, and spinal screws) were reconstructed and evaluated in a blinded and randomized reader study.

RESULTS

The Gammex phantom showed lower HU errors compared with the uncorrected image at almost all iMAR and iMARv2 settings evaluated, with only minor differences between iMAR and the different iMARv2 settings. In addition, the anthropomorphic phantoms showed a trend toward lower errors with higher iMARv2 strength settings. On average, the iMARv2 strength 3 performed best of all the clinical reconstructions evaluated, with a significant increase in diagnostic confidence and decrease in artifacts. All hip and dental cases showed a significant increase in diagnostic confidence and decrease in artifact strength, and the improvements from iMARv2 in the dental cases were significant compared with iMAR. There were no significant improvements in the spine.

CONCLUSIONS

This work has introduced and evaluated a new method for metal artifact reduction and demonstrated its utility in routine clinical datasets. The greatest improvements were seen in dental fillings, where iMARv2 significantly improved image quality compared with conventional iMAR.

Analytical interference of intravascular contrast agents with clinical laboratory tests: a joint guideline by the ESUR Contrast Media Safety Committee and the Preanalytical Phase Working Group of the EFLM Science Committee

The Contrast Media Safety Committee of the European Society of Urogenital Radiology has, together with the Preanalytical Phase Working Group of the EFLM Science Committee, reviewed the literature and updated its recommendations to increase awareness and provide insight into these interferences. CLINICAL RELEVANCE STATEMENT: Contrast Media may interfere with clinical laboratory tests. Awareness of potential interference may prevent unwanted misdiagnosis. KEY POINTS: • Contrast Media may interfere with clinical laboratory tests; therefore awareness of potential interference may prevent unwanted misdiagnosis. • Clinical Laboratory tests should be performed prior to radiological imaging with contrast media or alternatively, blood or urine collection should be delayed, depending on kidney function.

Feasibility of the chick chorioallantoic membrane model for preclinical studies on tumor radiofrequency ablation

BACKGROUND

We evaluated the feasibility of a chick chorioallantoic membrane (CAM) tumor model for preclinical research on tumor radiofrequency ablation (RFA).

METHODS

Fertilized chicken eggs were incubated and divided into five cohorts: RFA for 30 s (n = 5), RFA for 60 s (n = 5), RFA for 120 s (n = 4), sham (n = 8), and controls (n = 6). Xenografting using pancreatic neuroendocrine tumor cells of the BON-1 cell line was performed on embryonic day (ED) 8. The RFA was performed on ED 12. Survival, stereomicroscopic observations, and histological observations using hematoxylin-eosin (H&E) and Ki67 staining were evaluated.

RESULTS

The survival rates in the 30-s, 60-s, and 120-s, sham and control cohort were 60%, 60%, 0%, 100%, and 50%, respectively. Signs of bleeding and heat damage were common findings in the evaluation of stereomicroscopic observations. Histological examination could be performed in all but one embryo. Heat damage, bleeding, thrombosis, and leukocyte infiltration and hyperemia were regular findings in H&E-stained cuts. A complete absence of Ki67 staining was recorded in 33.3% and 50% of embryos in the 30-s and 60-s cohorts that survived until ED 14, respectively.

CONCLUSIONS

The CAM model is a feasible and suiting research model for tumor RFA with many advantages over other animal models. It offers the opportunity to conduct in vivo research under standardized conditions. Further studies are needed to optimize this model for tumor ablations in order to explore promising but unrefined strategies like the combination of RFA and immunotherapy.

RELEVANCE STATEMENT

The chick chorioallantoic membrane model allows in vivo research on tumor radiofrequency ablation under standardized conditions that may enable enhanced understanding on combined therapies while ensuring animal welfare in concordance with the "Three Rs."

KEY POINTS

• The chorioallantoic membrane model is feasible and suiting for tumor radiofrequency ablation. • Radiofrequency ablation regularly achieved reduction but not eradication of Ki67 staining. • Histological evaluation showed findings comparable to changes in humans after RFA. • The chorioallantoic membrane model can enable studies on combined therapies after optimization.

Safety and efficacy of interventional treatment of acute limb ischemia in Germany 2021

PURPOSE

Interventional procedures have become a mainstay in the therapy of acute limb ischemia caused by embolism or arterial thrombosis. Treatment options include pharmacological thrombolysis (PT) and mechanical thrombectomy (MT). The aim of this study was to evaluate success and major complication rates of interventional radiological treatments of arterial embolism and thrombosis in Germany in 2021 and to compare their results with accepted international quality standards.

MATERIALS AND METHODS

Data for PT and MT for 2021 was obtained from the quality management system of the German interventional radiological society (DeGIR). 2431 PT and 1582 MT procedures were documented for 2021, with 459 combinations of PT and MT. Data was analysed for technical and clinical success rates, as well as major complication rates such as intracranial bleeding, major bleeding, distal embolization, aneurysm formation, organ-failure and cardiac-decompensation.

RESULTS

PT alone had technical and clinical success rate of 90.21% and 81.08%, respectively. MT alone had technical and clinical success rates of 97.41% and 95.39%, respectively. MT&PT had technical and clinical success rates of 91.07% and 84.75%, respectively. Major complications were: distal embolization (PT:2.02%; MT:1.74%; PT&MT:2.61%), major bleeding (PT:0.94%; MT:1.14%; PT&MT:0.87%), aneurysm formation (PT:0.33%;MT: 1.14%;PT&MT: 0%), intracranial bleeding (PT:0.16%;MT:0%;PT&MT:0.22%), cardiac-decompensation (PT:0.21%;MT: 0.06%;PT&MT:0%) and organ-failure (PT:0%;MT:0.06%;PT&MT:0.22%). Technical and clinical success rates were higher, while complication rates were lower than the corresponding threshold recommended by the Society of Interventional Radiology for percutaneous management of acute lower-extremity ischemia.

CONCLUSION

Treatment of arterial embolism and thrombosis performed by interventional radiologists in Germany is effective and safe with outcomes exceeding internationally accepted standards.

A nonlinear scaling-based normalized metal artifact reduction to reduce low-frequency artifacts in energy-integrating and photon-counting CT

BACKGROUND

Metal within the scan plane can cause severe artifacts when reconstructing X-ray computed tomography (CT) scans. Both in clinical use and recent research, normalized metal artifact reduction (NMAR) has established as the reference method for correcting metal artifacts, but NMAR introduces inconsistencies within the sinogram, which can cause additional low-frequency artifacts after image reconstruction.

PURPOSE

This paper introduces an extension to NMAR by applying a nonlinear scaling function (NLS-NMAR) to reduce low-frequency artifacts, which get introduced by the reconstruction of interpolation-edge-related sinogram inconsistencies in the normalized sinogram domain.

METHODS

After linear interpolation of the metal trace, an NLS function is applied in the prior-normalized sinogram domain to reduce the impact of the interpolation edges during filtered backprojection. After sinogram denormalization and image reconstruction, the low frequencies of the NLS image are combined with different high frequencies to restore anatomic details. An anthropomorphic dental phantom with removable metal inserts was utilized on two different CT systems to quantitatively assess the artifact reduction performance in terms of HU deviations and the root-mean-square-error within relevant regions of interest. Clinical dental examples were assessed to qualitatively demonstrate the problem of the interpolation-related blooming as well as to demonstrate the performance of the NLS function to reduce respective artifacts. To quantitatively prove HU consistency, HU values were assessed in central ROIs in the clinical cases. In addition, single clinical cases of a hip replacement and pedicle screws in the spine are shown to demonstrate the method's results in other body regions.

RESULTS

The NLS-NMAR can minimize the effect of interpolation-related sinogram inconsistencies and thus reduce resulting hyperdense blooming artifacts. In the phantom results, the reconstructions with the NLS-NMAR-corrected low frequencies demonstrate the lowest error. In the qualitative assessment of the clinical data, the NLS-NMAR shows a tremendous enhancement in image quality, also performing best within all assessed images series.

CONCLUSION

The NLS-NMAR provides a small yet effective extension to conventional NMAR by reducing low-frequency hyperdense metal trace-interpolation-related artifacts in computed tomography.

pTEVAR of an aorto-esophageal fistula in esophageal cancer: Case report and review of the literature

An aorto-esophageal fistula (AEF) is a rare and life-threatening situation, associated with aneurysms, foreign bodies, infiltrating tumors, and radiotherapy. The ideal management is unclear. Open surgery of AEF has a high mortality and morbidity. Thoracic endovascular aortic repair (TEVAR) of an AEF is an effective and safe emergency treatment for these patients. We describe a case of AEF due to esophageal cancer successfully treated the first time by total percutaneous TEVAR (pTEVAR). A 70-year-old male patient presented with massive hematemesis at the emergency department. The patient had a known history of esophageal cancer previously treated by radiochemotherapy which was completed 3 days before. Emergency upper gastrointestinal endoscopy failed to stop the bleeding. Subsequent contrast-enhanced computed tomography revealed an aorto-esophageal fistula and emergency pTEVAR was performed. The bleeding stopped directly after stent graft placement and the patient was discharged after 10 days later. He died 3 months after pTEVAR from cancer progression. pTEVAR is an effective and safe treatment option for AEF. It can be applied as a first-line treatment and offers the potential to improve survival in the emergency setting.

How to Xenograft Cancer Cells on the Chorioallantoic Membrane of a Fertilized Hen's Egg and Its Visualization by PET/CT and MRI

The chorioallantoic membrane (CAM) of fertilized hen's eggs represents a unique and alternative model for cancer research. The CAM model provides an optimal platform for xenografting cancer cell lines and studying essential key factors. Tumor size and growth as well as angiogenesis can be investigated to evaluate the response of therapies and strategies against cancer. Preclinical imaging represented by magnetic resonance imaging and positron emission tomography/computed tomography can generate detailed anatomical and functional information and reveal excellent metabolic sensitivity. In the following, a guideline is introduced in order to find a simplified entrance to the CAM model in combination with modern preclinical imaging techniques. Finally, the presented procedures are additionally completed by histological studies in the form of hematoxylin and eosin as well as immunohistochemical staining.

Comparison of the radiation protection effect of different radiation protection aprons made of different materials

OBJECTIVE

The objective of this study is to examine the performance of new generation protection aprons as alternative to conventional lead aprons regarding their radiation protection effectiveness.

METHOD AND MATERIALS

Radiation protection aprons made of lead-containing and lead-free materials from a total of seven companies were compared. Furthermore, different lead equivalent values of 0.25, 0.35 and 0.5 mm were compared. For quantitative assessment, radiation attenuation was determined with increasing voltage in steps of 20 kV from 70 kV up to 130 kV.

RESULTS

New generation aprons and conventional protection lead aprons showed a similar shielding performance at lower tube voltages below 90 kVp. When tube voltage was increased above 90 kVp, significant (p < 0.05) differences between the three apron types were observed, with conventional lead material as best shielding performer over lead composite and lead-free aprons.

CONCLUSION

We observed a similar radiation protection performance between conventional lead aprons and new generation aprons at low intensity radiation workplaces, with lead aprons being dominant for all energies. Only new generation aprons of 0.5 mm thickness would adequately replace 0.25 and 0.35 mm conventional lead aprons. For healthy radiation protection, the possibility of using weight-reduced X-ray aprons is very limited.

Focal Therapy for Renal Cancer: Comparative Trends in the USA and Germany from 2006 to 2020 and Analysis of the German Health Care Landscape

INTRODUCTION

The aim of the study was to investigate trends of FT for in-patient treatment of renal RCC in the USA and Germany.

METHODS

We analyzed the SEER database for the USA and the nationwide German hospital billing database each from 2006 to 2019 for a RCC diagnosis in combination with FT, radical nephrectomy, and partial nephrectomy. FT was defined as radiofrequency ablation (RFA) or cryotherapy. Linear regression analysis was performed to detect changes over time.

RESULTS

For the USA, we included 7,318 FT cases. The share of FT increased from 2.4% in 2006 to 6.4% in 2019 (p < 0.001). For Germany, we identified 2,920 FT cases. The share of FT increased from 0.7% in 2006 to 2.0% in 2019 (p < 0.001). The number of RFAs in the USA steadily increased by 227% from a total of 93 in 2006 to 304 in 2019 while the number of cryotherapies in the USA steadily increased by 289% from a total of 127 in 2006 to 494 in 2019 (p < 0.001). The number of RFAs in Germany increased by 344% from a total of 59 in 2006 to 262 in 2019 (p < 0.001) while the number of cryotherapies steadily increased by 43% from a total of 54 in 2006 to 77 in 2019 (p < 0.001). In Germany, RFA is significantly more performed than cryotherapy while in the USA cryotherapy is more frequently applied.

CONCLUSION

We observed a constant increase of FT in the USA and Germany for RCC in-patient treatment with a higher share in the USA.

Non-linearly scaled (NLS) prior image-controlled frequency split for high-frequency metal artifact reduction in Computed Tomography

PURPOSE

This paper introduces a new approach for the dedicated reduction of high-frequency metal artifacts, which applies a non-linear scaling transfer function (NLS) on the high-frequency projection domain to reduce artifacts, while preserving edge information and anatomic detail by incorporating prior image information.

METHODS

A non-linear scaling function is applied to suppress high-frequency streak artifacts, but to restrict the correction to metal projections only, scaling is performed in the sinogram domain. Anatomic information should be preserved and is excluded from scaling by incorporating a prior image from tissue-classification. The corrected high-frequency sinogram is reconstructed and combined with the low-frequency component of an NMAR image. Scans of different anthropomorphic phantoms were acquired (unilateral hip, bilateral hip, dental implants, and embolization coil). Multiple ROIs were drawn around the metal implants and HU deviations were analyzed. Clinical datasets including single image slices of dental fillings, a bilateral hip implant, spinal fixation screws, and an aneurysm coil were reconstructed and assessed.

RESULTS

The prior image-controlled non-linear scaling function can remove streak artifacts while preserving anatomic detail within the bone and soft tissue. The qualitative analysis of clinical cases showed a tremendous enhancement within dental fillings and neuro coils, and a significant enhancement within spinal screws or hip implants. The phantom scan measurements support this observation. In all phantom setups, the NLS-corrected result showed lowest HU derivation and the best visualization of the data.

CONCLUSIONS

The prior image-controlled NLS provides a method to reduce high-frequency streaks in metal-corrupted CT data. This article is protected by copyright. All rights reserved.

Physical strain while wearing personal radiation protection systems in interventional radiology

Objectives

Multiple studies show orthopedic health problems for medical staff due to wearing radiation protection aprons. The aim of this study was to evaluate the weight pressure on the shoulder as a marker of physical strain caused by different radiation-protection devices.

Methods

For the weight pressure measurement, a pressure sensor (OMD-30-SE-100N, OptoForce, Budapest, Hungary) placed on the left and right shoulder was used. Wearing different radiation protection systems the force measurement system was used to quantify the weight pressure. Measurements were acquired in still standing position and during various movements.

Results

A mean significant decreasing weight pressure on the shoulder between 74% and 84% (p<0.001) was measured, when the free-hanging radiation protection system was used in comparison to one-piece and two-piece radiation protection aprons and coats. Using two-piece radiation protection aprons, the weight pressure was significantly lower than that of one-piece radiation protection coats. If a belt was used for the one-piece radiation protection coat, the weight pressure on the shoulder was reduced by 32.5% (p = 0.003). For a two-piece radiation protection apron and a one-piece radiation protection coat (with and without belt) a significant different weight pressure distribution between the right and left shoulder could be measured.

Conclusions

The free-hanging radiation protection system showed a significant lower weight pressure in comparison to the other radiation protection devices. Apart from this, use of a two-piece radiation protection apron or addition of a belt to a radiation protection coat proved to be further effective options to reduce weight pressure.

Work and Training Conditions of German Residents and Young Radiologists in Interventional Radiology - A Nationwide Survey

INTRODUCTION

 With the increasing need for minimally invasive procedures based on lower complication rates, higher patient acceptance, and technical developments, there is a growing focus on the sound interventional training of young radiologists. This survey aimed to analyze the current situation in interventional radiology (IR) training in Germany to detect shortcomings and identify areas for improvement.

MATERIALS AND METHODS

 From November 1-30, 2020, an online questionnaire was distributed to representative radiological associations and societies with the request to forward it to radiology residents and radiologists < 40 years. The 44 questions covered six distinct areas from personal working conditions to the characterization of the IR department, training conditions, role of women in IR, and attendance at congresses/external training.

RESULTS

 A total of 330 participants completed the questionnaire. 77 % of participants expressed a high interest in IR, and 47 % could even imagine subspecializing in interventional radiology. Most institutions provided the necessary learning conditions and infrastructure. The rate of overall satisfaction with IR training conditions was 45 % (vs. a dissatisfaction rate of 39 %). However, females showed a lower satisfaction rate with their training environment than male participants (28 % vs. 51 %; P = 0.06). Positive correlations with work satisfaction were found for the presence and duration of the IR rotation, the number of partly independently/mentored performed interventions, and structured feedback. Moreover, the need for a structured training curriculum was expressed by 67 % of participants.

CONCLUSION

 Radiological residents and young radiologists expressed a high interest in interventional radiology, and they rate the infrastructure of German hospitals regarding IR as sufficient. However, they expressed the need for consistent IR rotations and better-structured resident and postgraduate education (curricula & interviews).

KEY POINTS

Interest in interventional radiology among radiological residents and young radiologists in Germany is high, but satisfaction with interventional radiology training leaves room for improvement. The most frequently mentioned aspects that can improve IR training were · organized rotations of at least 6 months. · structured curriculums with face-to-face feedback. · structured guidance by senior interventionists during procedures.

CITATION FORMAT

· Sieren M, Katoh M, Mahnken AH et al. Work and Training Conditions of German Residents and Young Radiologists in Interventional Radiology - A Nationwide Survey. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1853-8549.

[Chronic type B aortic dissection-what to do?]

BACKGROUND

Chronic type B aortic dissection requires optimal medical therapy. However, secondary complications like organ or extremity malperfusion or development of aneurysmal dilatation require interventional therapy.

OBJECTIVES

Presentation of different endovascular treatment options for complications of chronic type B aortic dissection.

MATERIALS AND METHODS

Analysis of current literature with regard to indications, techniques, results, and differential indications of interventional techniques for the treatment of chronic type B aortic dissection complications.

RESULTS

Endovascular implantation of an aortic stent graft is interventional standard therapy for treatment of aneurysmal dilatation of the aorta following type B dissection. Technical problems are the proximal and distal landing zones and the treatment of persistent flow in the false lumen.

CONCLUSION

Endovascular treatment of chronic complicated type B aortic dissection is increasingly used compared to open surgical treatment because not only are more complex stent grafts (fenestrated and branched devices) available but also because of newly developed techniques for effective occlusion of flow in the false lumen (e.g., candy plug).

Intravenous contrast medium extravasation: systematic review and updated ESUR Contrast Media Safety Committee Guidelines

NEED FOR A REVIEW

Guidelines for management and prevention of contrast media extravasation have not been updated recently. In view of emerging research and changing working practices, this review aims to inform update on the current guidelines.

AREAS COVERED

In this paper, we review the literature pertaining to the pathophysiology, diagnosis, risk factors and treatments of contrast media extravasation. A suggested protocol and guidelines are recommended based upon the available literature.

KEY POINTS

• Risk of extravasation is dependent on scanning technique and patient risk factors. • Diagnosis is mostly clinical, and outcomes are mostly favourable. • Referral to surgery should be based on clinical severity rather than extravasated volume.

[Interdisciplinary management of extracranial vascular anomalies]

BACKGROUND

A multitude of vascular anomalies exist and can lead to severe complications. Treatment can be complex.

OBJECTIVE

This overview aims to provide important information for the management of vascular anomalies.

MATERIALS AND METHODS

In addition to current literature, experiences from the interdisciplinary Vascular Anomalies Center in Marburg were included in this review.

RESULTS

Hemangiomas at critical sites, arteriovenous malformations, and vascular anomalies of uncertain etiology require particular attention.

CONCLUSION

Self-help and support groups, specialized interdisciplinary centers, scientific medical societies, and networks can provide help for the treatment of vascular anomalies.

Efficacy and Safety of Combined Embolization and Radiofrequency Ablation in Stage 1 Renal Cell Carcinomas

PURPOSE

 To retrospectively evaluate outcomes of a combined interventional approach to stage 1 (cT1cN0cM0) renal cell carcinomas (RCCs) by transarterial embolization (TAE) followed by percutaneous CT-guided radiofrequency ablation (RFA) in patients ineligible for surgery.

MATERIALS AND METHODS

 13 patients (9 male, 4 female, 69.6 ± 16.6 y/o) with 14 RCCs (largest diameter: 40.4 ± 6.7 mm, cT1a: 4, cT1b: 10) were treated by RFA a median of one day after TAE in a single center. Indications for minimally invasive interventional therapy were bilateral RCCs (n = 4), RCCs in a single kidney after nephrectomy (n = 3), increased surgical risk due to comorbidities (n = 4), and rejection of surgical therapy (n = 2). Technical success, effectiveness, safety, ablative margin, cancer-specific survival, overall survival, and tumor characteristics were analyzed.

RESULTS

 All RCCs were successfully ablated after embolization with a minimum ablative margin of 1.2 mm. The median follow-up was 27 (1-83) months. There was no residual or recurrent tumor in the ablation zone. No patient developed metastasis. Two minor and two major complications occurred. Four patients with severe comorbidities died during follow-up due to causes unrelated to therapy. The 1-year and 5-year overall survival was 74.1 % each. Cancer-specific survival was 100 % after 1 and 5 years. There was no significant decline in mean eGFR directly after therapy (p = 0.226). However, the mean eGFR declined from 62.2 ± 22.0 to 50.0 ± 27.8 ml/min during follow-up (p < 0.05).

CONCLUSION

 The combination of TAE and RFA provides an effective minimally invasive therapy to stage 1 RCCs in patients ineligible for surgery. The outcomes compare favorably with data from surgery.

KEY POINTS

  · Interventional treatment by TAE and ablation is a safe and effective alternative to surgery in stage 1 RCCs.. · Focal therapy of RCCs preserves renal function.. · A small ablative margin appears to be sufficient in the ablation of RCCs..

CITATION FORMAT

· Wessendorf J, König AM, Heers H et al. Efficacy and Safety of Combined Embolization and Radiofrequency Ablation in Stage 1 Renal Cell Carcinomas. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1770-4724.

Nationwide Provision of Radiologically-guided Interventional Measures for the Supportive Treatment of Tumor Diseases in Germany - An Analysis of the DeGIR Registry Data

PURPOSE

 In addition to direct oncologic therapy, interventional radiology plays an important supportive role in oncologic therapy primarily guided by other disciplines. These supporting measures include diagnostic punctures, drainages, biliary interventions, central venous access including port implantations, osteoplasties, pain therapies etc.). This study investigated the extent to which these radiologically guided supportive measures are available in Germany.

MATERIAL AND METHODS

 All interventional procedures documented in the DeGIR-registry (excluding transhepatic portosystemic shunts) of the years 2018 and 2019 were recorded (DeGIR-module C). A breakdown of the documented interventions was performed based on federal states as well as 40 individual regions (administrative districts and former administrative districts).

RESULTS

 A total of 136,328 procedures were recorded at 216 centers in DeGIR Module C in 2018 and 2019. On average, 389 cases were documented per hospital in 2018 and 394 cases in 2019; the increase per hospital from 2019 is not statistically significant but is relevant in the aggregate when new participating centers are included, with an overall increase of 10 % (6,554 more cases than the previous year). Normalized to one million inhabitants, an average of 781 procedures took place across Germany in 2018 and 860 in 2019. Districts with no registered procedures are not found for Module C.Indications for Module C interventions were mostly interdisciplinary in 2018 and 2019. In this context, the quality of outcome was very high; for the procedures drain placement, marking and biopsy the technical success was 99 %, while the complication rate was lower than 1 %.

CONCLUSION

 The structural analysis of this work concludes that in Germany there is good nationwide availability of radiologically guided supportive measures in oncological therapy. Accordingly, the training situation for prospective interventional radiologists is good, as the distribution to centers with high experience is excellent. In addition, the overall outcome quality of radiology-guided interventions is very high.

KEY POINTS

· In Germany, there is good nationwide coverage of radiologically guided supportive interventions in oncological therapy.. · The training situation for prospective interventional radiologists is good, as the distribution to centers with high experience is excellent.. · The overall outcome quality of radiology-guided interventions is very high..

CITATION FORMAT

· Nadjiri J, Schachtner B, Bücker A et al. Nationwide Provision of Radiologically-guided Interventional Measures for the Supportive Treatment of Tumor Diseases in Germany - An Analysis of the DeGIR Registry Data. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1735-3615.

Availability of Interventional Oncology in Germany in the Years 2018 and 2019 - Results from a Nationwide Database (DeGIR Registry Data)

OBJECTIVE

 Over the past few decades, radiology has established itself in tumor therapy through interventional oncology including innovative and efficient procedures for minimalinvasive treatment of various tumor entities besides the "classic" therapeutic options such as surgery, chemotherapy and radiotherapy.Aim of this study was to evaluate the extent to which interventional oncology can provide nationwide care using the data from the register of the German Society for Interventional Radiology and Minimally Invasive Therapy (DeGIR registry), which records radiological interventions as part of quality assurance.

METHODS

 The numbers of interventions of participating clinics, which were recorded as part of module D (oncological procedures including TACE or other tumor-specific embolization, ablation, percutaneous tumor therapy) and identified by the DeGIR registry between 2018 and 2019, were analyzed retrospectively. The collected intervention data were evaluated regarding federal states and 40 smaller regions (administrative districts and former administrative districts).

RESULTS

 In 2018, 11 653 oncological interventions in 187 clinics were recorded by the DeGIR registry. In 2019, the number of participating clinics rose to 216 and the number of oncological interventions increased by 6 % to 12 323. The average number of oncological interventions per clinic decreased slightly from 62.5 (2018) to 57.1 (2019). The DeGIR requirement for being certified as a training center was met by 116 clinics in 2018 including 31 clinics with more than 100 interventions and 129 clinics in 2019 including 36 with more than 100 interventions. Oncological interventions have been performed in each of the 40 regions. An average of 599 interventions per region (standard deviation of 414) was recorded in the period between 2018 and 2019.

CONCLUSION

 Based on the distribution of the documented oncological interventions at federal state level as well as the district level, the supply of interventional tumor therapy depends on the geographical location. Therefore, the demand of oncological interventions might not be sufficiently covered in some regions.

KEY POINTS

· Interventional-oncological tumor therapies are performed throughout Germany. · Looking at the notable geographical differences, the need for interventional oncological procedures does not seem to be sufficiently met.. · In order to improve the comprehensive provision of oncological interventions, the training of interventional radiologists should be promoted further..

CITATION FORMAT

· Radosa CG, Nadjiri J, Mahnken AH et al. Availability of Interventional Oncology in Germany in the Years 2018 and 2019 - Results from a Nationwide Database (DeGIR Registry Data). Fortschr Röntgenstr 2022; DOI: 10.1055/a-1729-0951.

Establishment of a new valid animal model for the evaluation of hyperthermic intraperitoneal chemotherapy (HIPEC) in pediatric rhabdomyosarcoma

BACKGROUND

Cytoreductive surgery in combination with hyperthermic intraperitoneal chemotherapy has been established as a novel treatment approach for peritoneal sarcomatosis. Despite promising clinical reports, there is still a lack of knowledge regarding optimal drug usage and local effects. Therefore, we intended to establish a murine animal model for further evaluation.

PROCEDURE

Alveolar rhabdomyosarcoma cells were xenotransplanted into NOD/LtSz-scid IL2Rγnullmice (n = 100). The mice received a continuous intraperitoneal lavage with isotonic saline solution as control or with cisplatin (30 or 60 mg/m² ) as treatment group for 60 minutes at 37°C or 42°C (6 subgroups, each n = 16). Tumor spread was documented by an adapted peritoneal cancer index and MRI (n = 4). Tumor and tissue samples, harvested at the end of the perfusion, were evaluated regarding morphology, proliferation, and apoptosis (H&E-, Ki-67-, cleaved caspase 3-staining, TUNEL assay).

RESULTS

Extensive peritoneal sarcomatosis in over 91% of the cases was observed. HIPEC was feasible without acute side effects. Ki-67 staining revealed concentration- or temperature-dependent effects of cisplatin-based HIPEC on the tumors. Although cleaved caspase-3 showed only sporadic apoptotic effects. TUNEL assay detected concentration- or temperature-dependent apoptotic effects at the outer tumor surface. MRI scans confirmed the observed tumor dissemination.

CONCLUSION

This is the first animal model for evaluation of HIPEC in pediatric RMS in mice. Cisplatin-based HIPEC had early effects on the proliferation whereas circumscribed apoptotic effects could be detected at the tumor surface. This model allows further insights on the possible efficiency of HIPEC in RMS. Further studies using other drug combinations and treatment will follow.

Digital Variance Angiography in Selective Lower Limb Interventions

PURPOSE

To evaluate the potential benefits of digital variance angiography (DVA) in selective lower limb angiography and to compare the performance of 2 DVA algorithms (conventional DVA1 and the recently developed DVA2) to that of digital subtraction angiography (DSA).

MATERIALS AND METHODS

From November 2019 to May 2020, 112 iodinated contrast media (ICM) and 40 carbon dioxide (CO₂) angiograms were collected from 15 and 13 peripheral artery disease patients, respectively. The DVA files were retrospectively generated from the same unsubtracted source file as DSA. The objectively calculated contrast-to-noise ratio (CNR) and the subjective visual image quality of DSA, DVA1, and DVA2 images were statistically compared using the Wilcoxon signed-rank test. The images were evaluated by 6 radiologists (R.P.T., S.V., A.M.K., S.S.A., O.E., and J.S.) from 2 centers using a 5-grade Likert scale.

RESULTS

Both DVA algorithms produced similar increase (at least 2-fold) in CNR values (P < .001) and significantly higher image quality scores than DSA, independent of the contrast agent used. The overall scores with ICM were 3.61 ± 0.05 for DSA, 4.30 ± 0.04 for DVA1, and 4.33 ± 0.04 for DVA2 (each P < .001 vs DSA). The scores for CO₂ were 3.10 ± 0.14 for DSA, 3.63 ± 0.13 for DVA1 (P < .001 vs DSA), and 3.38 ± 0.13 for DVA2 (P < .05 vs DSA).

CONCLUSIONS

DVA provides higher CNR and significantly better image quality in selective lower limb interventions irrespective of the contrast agent used. Between DVA algorithms, DVA1 is preferred because of its identical or better image quality than DVA2. DVA can potentially help the interventional decision process and its quality reserve might allow dose management (radiation/ICM reduction) in the future.

Repeat Percutaneous Radiofrequency Ablation of T1 Renal Cell Carcinomas is Safe in Patients with Von Hippel-Lindau Disease

Purpose

Patients with Von Hippel-Lindau disease often develop multifocal, metachronous renal cell carcinomas which require therapy. The purpose of this retrospective single-center study is to evaluate the outcomes of radiofrequency ablation (RFA) in the treatment of renal cell carcinomas in patients with Von Hippel-Lindau disease.

Materials and Methods

9 patients (4 male, 5 female, 47.9 ± 10.7 y/o) with Von Hippel-Lindau disease underwent 18 CT-guided percutaneous RFA procedures for the treatment 21 renal cell carcinomas (largest diameter: 32.9 ± 8.6 mm, cT1a: 16, cT1b: 5). Seven patients were previously treated either by partial or radical nephrectomy. Technical success, effectiveness, safety, progression-free survival, overall survival and tumor characteristics were analyzed.

Results

All RFA procedures were technically successful without major complications. There were 5 minor complications. No residual or recurrent tumor was seen in the ablation zone during a follow-up of 34.0 ± 18.1 months (0–58 months). No patient required dialysis during follow-up. One patient died after 63 months after the first treatment due to complications from a cerebellar hemangioblastoma. No endpoint was reached for overall or progression-free survival.

Conclusions

The results from this limited case series suggest that RFA of RCCs in patients with VHL is a safe and effective therapy, which can preserve sufficient renal function even after renal surgery.

DeGIR Quality Report 2019: Report on the treatment quality of minimally invasive methods - Interventional therapy (EVAR) of abdominal aortic aneurysms

PURPOSE

To analyze the quality of endovascular aortic aneurysm repair using the data of the DeGIR quality management system. Comparison of data between 2011 and 2019.

MATERIALS AND METHODS

A retrospective analysis of all data registered in the DeGIR quality management system of the year 2019 was performed regarding the treatment quality for endovascular aortic aneurysm repair. Registration of data was voluntary. As quality parameters indication, treatment process data and quality of results were examined. The latter was judged by treatment success, complication rates and radiation exposure.

RESULTS

Out of 189 590 data sets overall 1639 cases of EVAR were registered; compared to 2011 this was an increase of 472 cases. 5.9 % of these cases encompassed emergency treatments. The most frequent indication was an abdominal aneurysm with 72 % of cases. In 54 % of cases, the aortic diameter ranged 50-70 mm. The rates for technical success, over all complications and major complications were 92.8 %, 6.7 % and 6.0 % respectively for all EVAR including emergency indications. In general, EVAR yielded a mortality rate of 1.2 % while emergency procedures had a mortality rate of 7.3 %. Median dose area product and fluoroscopy time were 10 503 cGy × cm2 and 20 minutes respectively at a mean procedure time of 114 minutes.

CONCLUSION

Data analysis of the DeGIR quality management system persistently showed a very high technical success rate for endovascular aortic aneurysm repair performed by interventional radiologists accompanied by a low complication rate.

KEY POINTS

· The voluntary DeGIR quality assurance-system has reached high acceptance among interventional radiologists.. · The database has nearly 200 000 submissions on record for 2019.. · EVAR by interventional radiologists has shown very high technical success as well as a low complication rate..

CITATION FORMAT

· Frenzel F, Bücker A, Paprottka P et al. DeGIR Quality Report 2019: Report on the treatment quality of minimally invasive methods - Interventional therapy (EVAR) of abdominal aortic aneurysms. Fortschr Röntgenstr 2022; 194: 49 - 61.

Availability of interventional-radiological revascularization procedures in Germany - an analysis of the DeGIR Registry Data 2018/19

PURPOSE

 Peripheral artery disease (PAD) is a common condition with high socio-economic relevance. Therefore, qualified nationwide provision of interventional treatments of PAD is important for maintaining a high quality medical service in Germany.

MATERIALS AND METHODS

 All data on revascularization procedures from the quality management system of the German interventional radiological society (DeGIR) for the years 2018 and 2019 were retrospectively analysed. Number and distribution of DeGIR certified endovascular specialists and treatment centres was mapped. Documented procedures were broken down to the level of administrative districts. Absolute number of revascularization procedures and normalized number per one million inhabitants were computed.

RESULTS

 In 2019 there were 57 732 revascularization procedures from 228 participating centres performed by DeGIR certified interventional radiologists. A median of 62 recanalization procedures were documented per centre. 36 centres were considered to be high volume centres, with more than 500 procedures each. On a regional level in the years 2018 and 2019 combined a median (range) of 2324 (323-12 518) revascularization procedures per administrative district were performed by DeGIR certified interventional radiologist.

CONCLUSION

 There is a comprehensive nationwide high quality interventional-radiology service for the provision of revascularization procedures available in Germany.

KEY POINTS

  · In Germany there is a nationwide comprehensive infratsructure for the interventional-radiological treatment of PAD. · The volume of interventional-radiological treatments for PAD is growing. · There is a sufficient number of training and treatment centres for the delivery of interventional radiology procedures.

CITATION FORMAT

· Mahnken AH, Nadjiri J, Schachtner B et al. Availability of interventional-radiological revascularization procedures in Germany - an analysis of the DeGIR Registry Data 2018/19. Fortschr Röntgenstr 2021; DOI: 10.1055/a-1535-2774.

CIRSE Clinical Practice Manual

Background

Interventional radiology (IR) has come a long way to a nowadays UEMS-CESMA endorsed clinical specialty. Over the last decades IR became an essential part of modern medicine, delivering minimally invasive patient-focused care.

Purpose

To provide principles for delivering high quality of care in IR.

Methods

Systematic description of clinical skills, principles of practice, organizational standards and infrastructure needed for the provision of professional IR services.

Results

There are IR procedures for almost all body parts and organs, covering a broad range of medical conditions. In many cases IR procedures are the mainstay of therapy, e.g. in the treatment of hepatocellular carcinoma. In parallel the specialty moved from the delivery of a procedure towards taking care for a patient’s condition with the interventional radiologists taking ultimate responsibility for the patient’s outcomes.

Conclusions

The evolution from a technical specialty to a clinical specialty goes along with changing demands on how clinical care in IR is provided. The CIRSE Clinical Practice Manual provides interventional radiologist with a starting point for developing his or her IR practice as a clinician.

Optimized 64-channel array configurations for accelerated simultaneous multislice acquisitions in 3T cardiac MRI

PURPOSE

Three 64-channel cardiac coils with different detector array configurations were designed and constructed to evaluate acceleration capabilities in simultaneous multislice (SMS) imaging for 3T cardiac MRI.

METHODS

Three 64-channel coil array configurations obtained from a simulation-guided design approach were constructed and systematically evaluated regarding their encoding capabilities for accelerated SMS cardiac acquisitions at 3T. Array configuration A_Uni-sized consists of uniformly distributed equally sized loops in an overlapped arrangement, B_Gapped uses a gapped array design with symmetrically distributed equally sized loops, and C_Dense has non-uniform loop density and size, where smaller elements were centered over the heart and larger elements were placed surrounding the target region. To isolate the anatomic variation from differences in the coil configurations, all three array coils were built with identical semi-adjustable housing segments. The arrays' performance was compared using bench-level measurements and imaging performance tests, including signal-to-noise ratio (SNR) maps, array element noise correlation, and SMS acceleration capabilities. Additionally, all cardiac array coils were evaluated on a healthy volunteer.

RESULTS

The array configuration C_Dense with the non-uniformly distributed loop density showed the best overall cardiac imaging performance in both SNR and SMS encoding power, when compared to the other constructed arrays. The diffusion weighted cardiac acquisitions on a healthy volunteer support the favorable accelerated SNR performance of this array configuration.

CONCLUSION

Our results indicate that optimized highly parallel cardiac arrays, such as the 64-channel coil with a non-uniform loop size and density improve highly accelerated SMS cardiac MRI in comparison to symmetrically distributed loop array designs.

The Effect of Obstructive Sleep Apnea and Continuous Positive Airway Pressure Therapy on Skeletal Muscle Lipid Content in Obese and Nonobese Men

Obstructive sleep apnea (OSA), independently of obesity (OBS), predisposes to insulin resistance (IR) for largely unknown reasons. Because OSA-related intermittent hypoxia triggers lipolysis, overnight increases in circulating free fatty acids (FFAs) including palmitic acid (PA) may lead to ectopic intramuscular lipid accumulation potentially contributing to IR. Using 3-T-¹H-magnetic resonance spectroscopy, we therefore compared intramyocellular and extramyocellular lipid (IMCL and EMCL) in the vastus lateralis muscle at approximately 7 am between 26 male patients with moderate-to-severe OSA (17 obese, 9 nonobese) and 23 healthy male controls (12 obese, 11 nonobese). Fiber type composition was evaluated by muscle biopsies. Moreover, we measured fasted FFAs including PA, glycated hemoglobin A_1c, thigh subcutaneous fat volume (ScFAT, 1.5-T magnetic resonance tomography), and maximal oxygen uptake (VO₂max). Fourteen patients were reassessed after continuous positive airway pressure (CPAP) therapy. Total FFAs and PA were significantly (by 178% and 166%) higher in OSA patients vs controls and correlated with the apnea-hypopnea index (AHI) (r ≥ 0.45, P < .01). Moreover, IMCL and EMCL were 55% (P < .05) and 40% (P < .05) higher in OSA patients, that is, 114% and 103% in nonobese, 24.4% and 8.4% in obese participants (with higher control levels). Overall, PA, FFAs (minus PA), and ScFAT significantly contributed to IMCL (multiple r = 0.568, P = .002). CPAP significantly decreased EMCL (–26%) and, by trend only, IMCL, total FFAs, and PA. Muscle fiber composition was unaffected by OSA or CPAP. Increases in IMCL and EMCL are detectable at approximately 7 am in OSA patients and are partly attributable to overnight FFA excesses and high ScFAT or body mass index. CPAP decreases FFAs and IMCL by trend but significantly reduces EMCL.

Feasibility and safety of automated CO2 angiography in peripheral arterial interventions

Carbon dioxide (CO2) gas is an established alternative to iodine contrast during angiography in patients with risk of postcontrast acute kidney injury and in those with history of iodine contrast allergy. Different CO2 delivery systems during angiography are reported in literature, with automated delivery system being the latest. The aim of this study is to evaluate the safety, efficacy, and learning curve of an automated CO2 injection system with controlled pressures in peripheral arterial interventions and also to study the patients' tolerance to the system.From January 2018 to October 2019 peripheral arterial interventions were performed in 40 patients (median age-78 years, interquartile range: 69-84 years) using an automated CO2 injection system with customized protocols, with conventional iodine contrast agent used only as a bailout option. The pain and tolerance during the CO2 angiography were evaluated with a visual analog scale at the end of each procedure. The amount of CO2, iodine contrast used, and radiation dose area product for the interventions were also systematically recorded for all procedures. These values were statistically compared in 2 groups, viz first 20 patients where a learning curve was expected vs the rest 20 patients.All procedures were successfully completed without complications. All patients tolerated the CO2 angiography with a median total pain score of 3 (interquartile range: 3-4), with no statistical difference between the groups (P = .529). The 2 groups were statistically comparable in terms of comorbidities and the type of procedures performed (P = .807). The amount of iodine contrast agent used (24.60 ± 6.44 ml vs 32.70 ± 8.70 ml, P = .006) and the radiation dose area product associated were significantly lower in the second group (2160.74 ± 1181.52 μGym2 vs 1531.62 ± 536.47 μGym2, P = .043).Automated CO2 angiography is technically feasible and safe for peripheral arterial interventions and is well tolerated by the patients. With the interventionalist becoming familiar with the technique, better diagnostic accuracy could be obtained using lower volumes of conventional iodine contrast agents and reduction of the radiation dose involved.

Prenatal radiation exposure in diagnostic and interventional radiology

BACKGROUND

 The exposure of a pregnant woman to X-rays is an event that can cause uncertainty for all concerned. This review provides guidance on how to assess such a situation and how to determine the dose to the unborn child. In general, the use of X-rays in pregnant women in radiology should be avoided. If possible, alternatives should be used, or examinations postponed to a time after the pregnancy. This review gives a summary of the procedure for determining the radiation exposure of a pregnant woman.

METHOD

 Based on the previous report of 2002 and the literature on prenatal radiation exposure published thereafter, the DGMP/DRG report on the procedure for the assessment of prenatal radiation exposure was adapted to the current state of science and technology.

RESULTS

 Typically, only relatively low radiation exposures of less than 20 mSv occur for the unborn child in X-ray diagnostics in the vast majority of cases. At these dose level the additional risk of damage to the embryo or fetus caused by the radiation is low and therefore only a rough conservative estimate using tabulated values are made. Only in a few types of examination (CT and interventional radiology) higher doses values might occur in the uterus. Instead of dose estimates (step 1 in the two-step model) in these cases the calculation of dose (step 2) are required and further action by the physician may be necessary.

CONCLUSIONS

 During the assessment, it is useful to initially use simple conservative estimation procedures to quickly determine whether a case falls into this large group less than 20 mSv, where there is a very low risk to the unborn child. If this is the case, the pregnant woman should be informed immediately by the doctor who performed the examination/treatment. This avoids a psychological burden on the patient. The DGMP/DRG report suggests a relatively simple, clearly structured procedure with advantages for all parties involved (physician, medical physics experts, MTRA and patient).

KEY POINTS

  · The DGMP/DRG report on prenatal radiation exposure describes the procedure for calculating radiation exposures and the associated risks for the unborn child.. · Using the two-step model, only a simple assessment based on the first step is necessary for most prenatal radiation exposures.. · With the given tables it is possible to estimate individual risks for the unborn child taking into account the radiation exposure.. · Only in the rare case that the first estimate results in a uterine dose larger 20 mSv a more accurate calculation is necessary..

CITATION FORMAT

· Fiebich M, Block A, Borowski M et al. Prenatal radiation exposure in diagnostic and interventional radiology. Fortschr Röntgenstr 2021; 193: 778 - 786.

Scatter radiation reduction with a radiation-absorbing pad in interventional radiology examinations

PURPOSE

Radiation-absorbing pads are an additional possibility to reduce scattered radiation at its source. The goal of this study is to investigate the efficacy of a new reusable radiation-absorbing pad at its origin in an experimental setup.

MATERIAL AND METHODS

All measurements were carried out using a clinical angiography system with a standardized fluoroscopy protocol, different C-arm angulations and an anthropomorphic torso phantom as a scattering body. An ionization chamber was used to measure the radiation exposure at five different heights of a simulated operator during a simulated transfemoral angiography intervention. Measurements were carried out with and without radiation-absorbing pads with lead equivalents of 0.25 and 0.5 mm placed onto the scattering body. For all measurements a mobile acrylic shield and an under-table lead curtain was used.

RESULTS

At all operator heights from 100 to 165 cm a significant radiation dose reduction of up to 80.6 % (p < 0.01) using the radiation-absorbing pad was measured, when compared to no radiation-absorbing pad. At the height of 165 cm the radiation-absorbing pad with a lead equivalence of 0.5 mm showed a significant radiation dose reduction (51.4 %, p < 0.01) in comparison to a lead equivalence of 0.25 mm.

CONCLUSION

The addition of a radiation-absorbing pad to the standard protection means results in a significant dose reduction for the operator, particularly for upper body parts.

Comparison of different resuscitation methods with regard to injury patterns in cardiac arrest survivors based on computer tomography

PURPOSE

To ensure that patients survive cardiac arrest, cardiopulmonary resuscitation (CPR) is needed. However, the procedure itself can lead to severe injuries. This study aims to examine both possibilities of resuscitation - mechanical or manual - with regard to their risk of injury. To this end, we compare the injuries patterns in both groups of patients after successful resuscitation based on computer tomography (CT).

METHODS

This single-centre retrospective study included 32 patients (female: 21.87 %, male: 78.12 %, Mean age: 60.22 ± 13.93 years) with cardiac arrest followed by successful mechanical CPR, who underwent an early whole-body CT. A control group of 32 patients (female: 21.87 %, male: 78.12 %, mean age: 60.75 ± 13.34 years) that had been resuscitated successfully with manual CPR was matched according to gender and age for a better statistical comparison. Patients with cardiac arrest due to trauma were excluded from the study population.

RESULTS

Mechanically resuscitated patients showed significantly more CPR-related injuries than those who were resuscitated manually (100 % vs. 84.37 %; p = 0.02). In particular, dislocated rib fractures (40.47 vs. 23.80 mean rank, p < 0.01), sternal fractures (74.19 % vs. 25 %; p < 0,01), bleeding complications (29.03 % vs. 3.12 %; p = 0.01), pneumothorax (38.71 % vs. 9.37 %; p = 0.01), mediastinal haematomas (58.01 % vs. 25 %, p = 0.01) and liver lacerations (29.03 % vs. 0 %, p = 0.04) were observed significantly more in patients after mechanical CPR compared to those with manual resuscitation.

CONCLUSIONS

The guideline-based use of mechanical CPR results in a significant increase of internal and musculoskeletal injuries compared to manual CPR.

Position Paper of the German Society for Interventional Radiology (DeGIR) on Prostatic Artery Embolization

BACKGROUND

 In recent years prostate artery embolization (PAE) evolved into a clinically established minimally invasive endovascular treatment option for lower urinary tract symptoms caused by benign prostate syndrome (BPS).

METHODS

 In this interdisciplinary position paper, initiated by the steering group for research of the German Society for Interventional Radiology (IR), the method of PAE is presented and discussed in the context of current evidence.

RESULTS

 PAE is a safe IR procedure for the treatment of BPS. In terms of symptom relief, measured with the IPSS (International Prostate Symptom Score), the PAE has comparable effect, similar to the historic gold standard, transurethral resection (TUR) of the prostate. With regard to reducing subvesical obstruction PAE is inferior to TUR, but does not limit subsequent surgery. Based on current evidence, PAE is recommended by the British National Institute for Health and Care Excellence as an alternative therapy. The feasibility under local anaesthesia and the preservation of sexual function are important arguments for patients in favour of interventional therapy. Patient selection and therapy concepts require close interdisciplinary collaboration between urologists and radiologists.

CONCLUSION

 Effectiveness and safety of PAE for the treatment of BPS are proven. Further randomized trials should focus on long term outcome and help to identify most suitable indications for PAE.

KEY POINTS

  · PAE, an endovascular procedure, is a patient-friendly, minimally invasive, alternative therapy option of the BPS. · PAE can reduce the symptoms of the lower urinary tract (LUTS), comparable to transurethral resection (TUR). The deobstructive and volume-reducing potential of the PAE is inferior to that of the TUR. · The main advantages of PAE are use of local anesthesia (no general anesthesia required), short patient recovery and maintenance of sexual function, including antegrade ejaculation.. · Based on current evidence PAE should be considered after conservative drug therapy and before TUR.. · The role of PAE in the context of other minimally invasive procedures (MIST) requires further evaluation with an open minded approach towards PAE.. · PAE is carried out by interventional radiologists, usually on a referral basis from urologists, and requires close interdisciplinary cooperation..

CITATION FORMAT

· Kovacs A, Bücker A, Grimm M et al. Position Paper of the German Society for Interventional Radiology (DeGIR) on Prostatic Artery Embolization. Fortschr Röntgenstr 2020; 192: 835 - 846.

CIRSE Standards of Practice on Analgesia and Sedation for Interventional Radiology in Adults

This CIRSE Standards of Practice document provides best practices for the safe administration of procedural sedation and analgesia for interventional radiology procedures in adults. The document is aimed at health professionals involved in the provision of sedation and analgesia during interventional radiology procedures. The document has been developed by a writing group consisting of physicians with internationally recognised expertise in interventional radiology, and analgesia and sedation.

Toward automatic C-arm positioning for standard projections in orthopedic surgery

Purpose

Guidance and quality control in orthopedic surgery increasingly rely on intra-operative fluoroscopy using a mobile C-arm. The accurate acquisition of standardized and anatomy-specific projections is essential in this process. The corresponding iterative positioning of the C-arm is error prone and involves repeated manual acquisitions or even continuous fluoroscopy. To reduce time and radiation exposure for patients and clinical staff and to avoid errors in fracture reduction or implant placement, we aim at guiding—and in the long-run automating—this procedure.

Methods

In contrast to the state of the art, we tackle this inherently ill-posed problem without requiring patient-individual prior information like preoperative computed tomography (CT) scans, without the need of registration and without requiring additional technical equipment besides the projection images themselves. We propose learning the necessary anatomical hints for efficient C-arm positioning from in silico simulations, leveraging masses of 3D CTs. Specifically, we propose a convolutional neural network regression model that predicts 5 degrees of freedom pose updates directly from a first X-ray image. The method is generalizable to different anatomical regions and standard projections.

Results

Quantitative and qualitative validation was performed for two clinical applications involving two highly dissimilar anatomies, namely the lumbar spine and the proximal femur. Starting from one initial projection, the mean absolute pose error to the desired standard pose is iteratively reduced across different anatomy-specific standard projections. Acquisitions of both hip joints on 4 cadavers allowed for an evaluation on clinical data, demonstrating that the approach generalizes without retraining.

Conclusion

Overall, the results suggest the feasibility of an efficient deep learning-based automated positioning procedure, which is trained on simulations. Our proposed 2-stage approach for C-arm positioning significantly improves accuracy on synthetic images. In addition, we demonstrated that learning based on simulations translates to acceptable performance on real X-rays.

Safety of Prophylactic Gastrostomy Tube Placement and Gastrostomy Tube Usage in Patients Treated by Radio(chemo)therapy for Head and Neck Cancer

BACKGROUND

A gastrostomy feeding tube is one method for long-term feeding support in patients undergoing radio(chemo)therapy for head and neck cancer (HNC). The aim of this study was to analyze the safety of prophylactic gastrostomy tube placement and usage in HNSCC patients.

PATIENTS AND METHODS

HNC patients undergoing percutaneous endoscopic gastrostomy (PEG) or radiological percutaneous gastrostomy (RPG) tube placement prior to radio(chemo)therapy from 2010-2014 were retrospectively reviewed regarding procedural and long-term gastrostomy tube-related complications, usage of PEG/RPG, weight profile, pretreatment and posttreatment body mass index.

RESULTS

A total of 212 patients underwent prophylactic feeding tube placement (71% RPG, 27% PEG and 2% surgical jejunostomy). A total of 173 patients utilized their gastrostomy tubes for either total or supplemental nutrition support. Despite this, 157 patients (74%) lost weight during therapy (mean weight loss=8 kg). The rate of severe tube-related complications (peritonitis/incorrect placement) was low and similar in both groups (PEG 2.7% vs. RPG 3.4%).

CONCLUSION

Although a very high proportion of patients used their PEG/RPG during radio(chemo)therapy there was a high mean weight loss. Serious complications of tube placement were rare.

Update Regarding Imaging of Neuroendocrine Neoplasms

BACKGROUND

 Neuroendocrine neoplasms (NEN) are a heterogeneous group of tumors characterized by the expression of typical proteins. A wide range of morphological and functional imaging methods is required in order to adequately assess the course of the disease and to optimally treat the patient. The spectrum of indications ranges from the detection of small primary tumors to the documentation of the metastasis pattern and the assessment of the suitability for certain invasive or noninvasive therapy methods. The exact recording and quantification of findings is indispensable.

METHODS

 This article is based on a comprehensive literature search on the different aspects of neuroendocrine neoplasm imaging.

RESULTS

 This article is intended to provide an overview of the available imaging procedures with their respective advantages and disadvantages for diagnostics and their value for the follow-up of neuroendocrine neoplasms. Recommendations for examination protocols, typical image findings, and an outlook regarding future developments are presented.

KEY POINTS

  · Neuroendocrine neoplasms are relatively rare and represent a complex and multiform disease group. Even in metastatic disease, long-term progression-free survival is not uncommon.. · Diagnostics in neuroendocrine neoplasms use a wide range of complementary morphological and functional imaging methods.. · Adequate selection of the imaging method, examination planning and preparation of the patient are essential for exact staging and reliable follow-up..

CITATION FORMAT

· Figiel JH, Viniol SG, Görlach J et al. Update Regarding Imaging of Neuroendocrine Neoplasms. Fortschr Röntgenstr 2020; 192: 171 - 182.

Protective Efficacy of Different Ocular Radiation Protection Devices: A Phantom Study

PURPOSE

The aim of this study was to investigate the efficacy of different designs and types of ocular radiation protection devices depending on simulated varied body heights in a phantom-simulated thoracic intervention.

MATERIALS AND METHODS

A clinical angiography system with a standardized fluoroscopy protocol with an anthropomorphic chest phantom as a scattering object and optically stimulated luminescence dosimeters for measuring radiation dose were used. The dosimeters were placed at the position of eyes of an anthropomorphic head phantom simulating the examiner. The head phantom was placed on a height-adjustable stand simulating the height of the examiner from 160 to 200 cm with 10 cm increments. The dose values were then measured with no radiation protection, a weightless-like radiation protection garment, radiation protection glasses and visors.

RESULTS

The average dose reduction using radiation protection devices varied between 57.7 and 83.4% (p < 0.05) in comparison with no radiation protection. Some radiation protection glasses and visors showed a significant dose reduction for the eye lenses when the height of the examiner increased. The right eye was partially less protected, especially if the distances between the simulated examiner's head and the scatter object were small.

CONCLUSION

All the investigated protection devices showed a significant reduction in radiation exposure to the simulated examiner. For some devices, the radiation dose increased with decreasing distance to the scattering object, especially for the right eye lens.

Early whole-body CT for treatment guidance in patients with return of spontaneous circulation after cardiac arrest

PURPOSE

Non-traumatic cardiac arrest (CA) and return of spontaneous circulation (ROSC) after cardiopulmonary resuscitation (CPR) are often associated with multiple pathologies. Expecting a high prevalence of important findings, a whole-body CT (WBCT) could be of relevance for therapy. The aim of this study is to investigate the feasibility and diagnostic yield of an early WBCT in this setting.

METHODS

This single-center retrospective study included 100 consecutive patients (27 female; 73 male; mean age 68.5± 12.57 years) with non-traumatic, in- and out-of-hospital CA and ROSC following CPR, who underwent a contrast-enhanced WBCT within 6 h after ROSC over 12 months. CT findings were determined corresponding to anatomical region.

RESULTS

Early WBCT was successfully carried out in 100% of the patients with CA and ROSC after CPR. Acute pathologies were found not only in the chest but also in the head (15%) and the abdomen (6%). Early global brain edema (n = 12), acute stroke (n = 3), pulmonary embolism (n = 10), pneumothorax (26%), acute abdominal pathologies (n = 6), iatrogenic bleeding (4%), and CPR-related injuries (93%) were detected by CT right from the beginning of the post-cardiac arrest care.

CONCLUSIONS

An early WBCT is feasible and provides added diagnostic value for patients with ROSC after non-traumatic CA.