Training of a deep learning based digital subtraction angiography method using synthetic data.

BACKGROUND: Digital subtraction angiography (DSA) is a fluoroscopy method primarily used for the diagnosis of cardiovascular diseases (CVDs). Deep learning-based DSA (DDSA) is developed to extract DSA-like images directly from fluoroscopic images, which helps in saving dose while improving image quality. It can also be applied where C-arm or patient motion is present and conventional DSA cannot be applied. However, due to the lack of clinical training data and unavoidable artifacts in DSA targets, current DDSA models still cannot satisfactorily display specific structures, nor can they predict noise-free images. PURPOSE: In this study, we propose a strategy for producing abundant synthetic DSA image pairs in which synthetic DSA targets are free of typical artifacts and noise commonly found in conventional DSA targets for DDSA model training. METHODS: More than 7,000 forward-projected computed tomography (CT) images and more than 25,000 synthetic vascular projection images were employed to create contrast-enhanced fluoroscopic images and corresponding DSA images, which were utilized as DSA image pairs for training of the DDSA networks. The CT projection images and vascular projection images were generated from eight whole-body CT scans and 1,584 3D vascular skeletons, respectively. All vessel skeletons were generated with stochastic Lindenmayer systems. We trained DDSA models on this synthetic dataset and compared them to the trainings on a clinical DSA dataset, which contains nearly 4,000 fluoroscopic x-ray images obtained from different models of C-arms. RESULTS: We evaluated DDSA models on clinical fluoroscopic data of different anatomies, including the leg, abdomen, and heart. The results on leg data showed for different methods that training on synthetic data performed similarly and sometimes outperformed training on clinical data. The results on abdomen and cardiac data demonstrated that models trained on synthetic data were able to extract clearer DSA-like images than conventional DSA and models trained on clinical data. The models trained on synthetic data consistently outperformed their clinical data counterparts, achieving higher scores in the quantitative evaluation of peak signal-to-noise ratio (PSNR) and structural similarity index measure (SSIM) metrics for DDSA images, as well as accuracy, precision, and Dice scores for segmentation of the DDSA images. CONCLUSIONS: We proposed an approach to train DDSA networks with synthetic DSA image pairs and extract DSA-like images from contrast-enhanced x-ray images directly. This is a potential tool to aid in diagnosis.

Effectiveness of Radiation Protection Caps for Lowering dose to the Brain and the Eye Lenses.

PURPOSE: This work was designed to study the effectiveness of radiation protection caps in lowering the dose to the brain and the eye lens during fluoroscopically guided interventions. MATERIALS AND METHODS: Two types of radiation protection caps were examined with regards to their capacity to lower the radiation dose. One cap is equipped with lateral flaps, the other one is not. These caps were fitted to the head of an anthropomorphic Alderson-Rando (A.-R.) phantom. The phantom was positioned aside an angiographic table simulating the position of the first operator during a peripheral arterial intervention. One of the brain slices and both eyes of the A.-R. phantom were equipped with thermoluminescence dosimeters (TLDs). RESULTS: The analysis of the data showed that the cap without lateral flaps reduced the dose to the brain by 11,5-27,5 percent depending on the position within the brain. The cap with lateral protection flaps achieved a shielding effect between 44,7 and 78,9 percent. When evaluating the dose to the eye, we did see an increase of dose reduction from 63,3 to 66,5 percent in the left eye and from 45,8 to 46,8 percent in the right eye for the cap without lateral protection. When wearing the cap with lateral protection we observed an increase of dose reduction from 63,4 to 67,2 percent in the left eye and from 45,8 to 50,0 percent in the right eye. CONCLUSION: Radiation protection caps can be an effective tool to reduce the dose to the brain and the eyes.

Predictive Value of VIBE using Subtraction to Evaluate Idiopathic Facial Palsy after Starting Therapy.

PURPOSE: To determine the predictive value of 3-dimensional spoiled gradient-echo volumetric interpolated breath-hold examination (VIBE) using subtraction to evaluate the short-term effect of therapy for facial palsy. MATERIALS AND METHODS: We included 97 patients with idiopathic facial palsy (52 male, 45 female; aged 50.7 ±â€Š19.4 years) who underwent MR imaging with a contrast agent after starting therapy. The mean interval between onset and therapy was 1.55 ±â€Š1.69 days, between therapy and MR imaging was 3.19 ±â€Š2.78 days, and between MR imaging and assessment of the therapeutic effect was 3.50 ±â€Š0.71 days. The degree of therapeutic effect was determined using a 4-grade scale based on the House-Brackmann scale for grading facial nerve function. Two radiologists reviewed VIBE with pre- and postcontrast subtraction using the 4-point scale. We evaluated the diagnostic performance and compared the degree of therapeutic effect and enhancement of facial nerves that were divided into 5 segments bilaterally. RESULTS: We identified 98 facial palsy initially and significant enhancement in 55 facial nerves after the start of therapy and residual palsy in 87. Sensitivity for all facial palsy was 62.0 %, specificity was 90.9 %, positive predictive value was 98.2 %, negative predictive value was 23.3 %, and accuracy was 65.3 %. Eleven patients recovered completely, 1 showed significant enhancement, and the remaining 10 did not show significant enhancement of the facial nerve. CONCLUSION: VIBE has a potential to predict the prognostic outcome and assess facial palsy after the start of therapy. KEY POINTS: · Three-dimensional spoiled gradient-echo volumetric interpolated breath-hold examination (VIBE) using subtraction can be useful to predict residual facial palsy after initial therapy.. · Strong enhancement of the facial nerve on VIBE using subtraction was associated with residual facial palsy after the start of therapy.. · Patients with a favorable prognosis did not show strong enhancement.. CITATION FORMAT: · Tomita H, Detmar K, Nakajima Y et al. Predictive Value of VIBE using Subtraction to Evaluate Idiopathic Facial Palsy after Starting Therapy. Fortschr Röntgenstr 2020; 192: 1183 - 1189.

The new radiation protection framework since 2019 - Implementation in Germany and comparison of some aspects in seven European countries. / Das neue Strahlenschutzrecht ab 2019 ­ Umsetzung in Deutschland und Vergleich einzelner Aspekte in 7 europäischen Ländern.

PURPOSE: The implementation of EU Directive 2013/59 EURATOM (EU-BSS) of 2014 led to a reorganization of radiation protection legislation in Germany in the form of a new radiation protection law Strahlenschutzgesetz (StrlSchG) of 2017 and a new radiation protection ordinance Strahlenschutzverordnung (StrlSchV) of 2018. For application of ionizing radiation in medicine these changes affect radiology, nuclear medicine and radiotherapy. A comparison between the old and the new legal system analyses changes that are relevant for diagnostic and interventional radiology. For the important new regulation of unintended exposures, a comparison is made with the implementation of Art. 63 EU-BSS in 7 European countries. MATERIAL AND METHODS: The provisions of the Röntgenverordnung (RöV) and the old Strahlenschutzverordnung (StrlSchV alt), which were valid until 2018, are compared with the new legislation of StrlSchG and StrlSchV for changes in radiation protection for patients, the population and occupational radiation protection of staff members. The occupational dose limit of the eye lens was reduced. The reduction by a factor of 7.5 results in new requirements for radiation protection equipment. New requirements in teleradiology are compared with the previous regulation, as well as the necessary involvement of medical physics experts (MPE) in high dose procedures, such as CT and fluoroscopic interventions. The regulation for unintended exposures of the German StrlSchV are analyzed in terms of their reporting criteria. RESULTS: The principles of medical radiation protection in Germany have not changed as a result of the new radiation protection legislation from 2019 onwards. However, there are a number of changes and new requirements that must be considered and implemented. Important points are e. g. new regulations on teleradiology, early detection of diseases in asymptomatic individuals and reporting of unintended exposure of patients. As all new regulations are no longer found in only one single regulation, both knowledge of the StrlSchG and the StrlSchV are necessary. KEY POINTS: · The EU Directive 2013/59 EURATOM (EU-BSS) was transposed into the new German radiation protection law 2018. · The basic regulations of the RöV and old StrlSchV remain unchanged. · Newly added regulations must be known and implemented in practice. · Many regulations of the EU-BSS are so vaguely formulated that they allow a wide scope for national implementation. CITATION FORMAT: · Loose R, Wucherer M, Walz M et al. The new radiation protection framework since 2019 - Implementation in Germany and comparison of some aspects in seven European countries. Fortschr Röntgenstr 2020; 192: 1036 - 1045.

Transhepatic forceps biopsy after PTCD for histological assessment of bile duct stenoses or occlusions.

PURPOSE: The goal of this study was to evaluate the experience of 11 years of wire-guided forceps biopsy via PTCD in patients with obstructive jaundice. MATERIALS AND METHODS: In a retrospective approach, 56 biopsies in 51 patients were analyzed (22 female, 29 male). Data was collected from 2006 to 2016. Mean age was 71 years (range: 34 - 86 years). Data was extracted from dig. Patients' records (KIS, PACS, RIS) to be analyzed in Microsoft Excel. RESULTS: All 56 procedures were technically successful. Stenosis in anastomoses were benign due to scarring in 7 patients and in 9 due to papillitis or others. In 4 patients, results in anastomosis were malignant. In 19 patients without anastomosis, CCC was the diagnosis, thereof 10 klatskin, 9 stenosis in other locations, followed by gastric, pancreatic, and colon carcinoma in 5, 3, and 2 patients. Three patients had a CUP (multimetering in case of more than 1 related category). Overall results were 35 mal. and 16 benign, 76.8 % of all proc. had a correct histopathologic result, and 23.2 % were false negative. Sensitivity was 65.8 %, which results in negative predictive value of 58.1 %. There was no false positive and so specificity was 100 %, as was the positive predictive value. False negative results (no malignancy but clinically and imaging suspect) were corrected by rerunning the procedure, by CT-guided biopsy or by 1 PET-CT. In 1 case the surg. sample brought the result. Minor complications occurred in 8 patients: shivering in 1 case, distinct but hemodynamically not relevant hemobilia in 5 cases, 2 portovenal bleedings. All bleedings were short-term and self-limiting. CONCLUSION: Despite good feasibility, low peri- and post-interv. risk and high validity the forceps biopsy via PTCD is not widely used. For experienced interventionalists, it is an effective method for obtaining histology.

Stent Implantation for Superior Vena Cava Syndrome of Malignant Cause.

Purpose The purpose of this paper is the retrospective analysis of endovascular therapy for the treatment of superior vena cava syndrome (SVCS) of malignant cause. This study focuses on the effectiveness of the therapy regarding the duration of remission, symptom control and practicability. Materials and Methods From January 2003 to November 2012, therapeutic implantation of one or more stents was performed in 141 patients suffering from SVCS. The medical history was retrospectively researched using digitalized patient files. If those were incomplete, secondary research was conducted using the cancer registry of the General Hospital Nuremberg, the cancer registry of the tumor center at Friedrich-Alexander-University Erlangen-Nuremberg (FAU) or information given by physicians in private practice. This data was collected using Microsoft Office Excel® and statistically analyzed using IBM SPSS Statistics 22®. Results 168 stents were implanted in 141 patients (median age: 64.6 years; range: 36 - 84), 86 being male and 55 being female. In 121 patients, SVCS was caused by lung cancer (85.8 %), in 9 patients by mediastinal metastasis of an extrathoracic carcinoma (6.4 %), in 3 patients by mesothelioma of the pleura (2.1 %) and in 1 patient by Hodgkin's disease (0.7 %). There was no histological diagnosis in 7 cases (4.9 %). The primary intervention was successful in 138 patients (97.9 %). Immediate thrombosis in the stent occurred in the remaining 3 cases. Recurrence of SVCS was observed in 22 patients (15.6 %), including 5 early and 17 late occlusions. Stent dislocation or breakage was not observed. As expected, the survival after implantation was poor. The median survival was 101 days, and the median occlusion-free survival was 80 days. Conclusion The symptomatic therapy of SVCS with endovascular stents is effective and safe. Despite effective symptom control and a low rate of recurrence, the patients' prognosis is poor. Key Points: · Patients with SVCS of malignant cause have a poor prognosis.. · Lung cancer is the most common cause for SVCS.. · Endovascular therapy is safe and effective.. Citation Format · Büstgens FA, Loose R, Ficker JH et al. Stent Implantation for Superior Vena Cava Syndrome of Malignant Cause. Fortschr Röntgenstr 2017; 189: 423 - 430.

How complicated is complicated diverticulitis?--phlegmonous diverticulitis revisited.

PURPOSE: The purpose of this study is to elucidate the accuracy of a clinical classification system for acute diverticulitis with special regard to "phlegmonous diverticulitis". METHODS: A consecutive patient series (n = 318; General Hospital Nuremberg, 1/2004-12/2006) was classified preoperatively (imaging with 4/16-slice spiral CT scanner) according to the Hansen and Stock (H&S) classification which is commonly used in Germany and evaluated based on histopathology. RESULTS: Pre-treatment classification grouped 30 patients (9.4%) as uncomplicated diverticulitis (type I according to H&S), for whom treatment was merely conservative. One hundred twelve patients (35.2%) were classified as phlegmonous diverticulitis (type IIA), 84 (26.4%) as "covered perforations" (type IIB) and 27 (8.5%) as "free perforations" (type IIC), and 54 (17.0%) as chronically recurrent diverticulitis (type III, 17.0%). The remaining 11 patients (3.5%) were not staged preoperatively. Accuracy of staging of complicated diverticulitis differed significantly between type IIC (100.0%), type IIB (91.0%), and type IIA (36.1%). The latter group was frequently understaged as it concealed a substantial number of patients (n = 44; 53.0%) with IIB disease. Neither laboratory tests (CRP/WBC) nor clinical parameters allowed distinction of correctly and falsely staged patients with type IIA disease. CONCLUSIONS: Patients with phlegmonous diverticulitis (type IIA) represent the most challenging group among patients with acute diverticulitis as they are frequently understaged and conceal cases with covered perforations (type IIB). This may support the view to subsume phlegmonous diverticulitis (type IIA) under complicated diverticulitis.

Endovascular stent--graft repair of a symptomatic superior mesenteric artery aneurysm.

BACKGROUND: Aneurysms of the visceral branches of the abdominal aorta are uncommon and potential life-threatening entities. Although hepatic and splenic artery aneurysms have the highest prevalence among splanchnic aneurysms, superior mesenteric artery aneurysms are even more uncommon. For ruptured visceral arteries aneurysms, a mortality rate of between 20% and 100% has been reported. Besides rupture, the aneurysms can also erode into adjacent visceral organs, which results in severe hemorrhage. Emergency surgery of visceral artery aneurysms is related with significant mortality. In recent years, endovascular therapies have been successfully established in the elective setting. Therefore, we adopted the endovascular stent-graft insertion technique for dealing with an acute symptomatic aneurysm of the superior mesenteric artery. METHOD: We report the case of a 79-year-old male patient with a symptomatic aneurysm of the proximal superior mesenteric artery. Using an endovascular approach, the aneurysm was excluded with an endoluminal stent--graft. RESULT: The endoluminal stent--graft repair resulted in total exclusion of the aneurysm. Patency of the superior mesenteric artery continued and no ischemic complications occurred. Pain and other symptoms disappeared and the patient recovered entirely. CONCLUSIONS: Endovascular management of symptomatic superior mesenteric artery aneurysm is feasible and may display excellent results in selected cases. Therefore, endoluminal stent--graft repair should be considered as an alternative to traditional surgical treatment. However, in each patient, the individual anatomy of the mesenteric circulation and the location of the aneurysm play a major role in determining whether endovascular management is possible or surgical repair should be preferred.

Enhancing transjugular intrahepatic portosystemic shunt puncture by using three-dimensional path planning based on the back projection of two two-dimensional portographs.

The purpose of this study was to prevent transjugular intrahepatic portosystemic shunt (TIPS) puncture failure by using three-dimensional (3D) path planning. This study was approved by the institutional review board; informed consent was obtained for the TIPS procedure. In four patients, a 3D path was planned from two two-dimensional (2D) CO2 portograms obtained at projections of 0 degrees and right anterior oblique 30 degrees . This path was overlaid onto the live fluoroscopy to guide the puncture image. In three of four patients, the target vessel was entered in the first attempt. In one patient with portal vein (PV) stenosis, the PV was entered with the third pass. This method has high potential to improve safety of the procedure and to reduce intervention time.