We appreciate the letter from members of the chest radiology workshop of the German Roentgen Society concerning the scan range of CT examinations for diagnosis of pulmonary embolism [Comment on: Diagnostic Reference Levels for Diagnostic and Interventional X-Ray. Procedures in Germany: Update and Handling, October 2019]. This gives us the opportunity to address central aspects of the use of diagnostic reference levels (DRL) on this specific issue once again in somewhat more detail. According to § 83 para. 3 of the German Radiation Protection Law (StrlSchG), each clinical x-ray examination has to be individually justified (“rechtfertigende Indikation”) by a competent physician taking into account relevant aspects, such as anamnesis, symptoms, details of the proposed procedure, the expected dose to patients, the availability of information on previous examinations, social and economic aspects as well as the state-of-the-art of medical science. Subsequently, the examination has to be optimized according to § 83 para. 5 StrlSchG. This means, among others, that the scan length has to be carefully adapted to the purpose of the X-ray examination in order to reduce the radiation exposure of the individual patient as far as reasonable achievable (ALARA principle). In this context, national DRLs established by the Federal Office for Radiation Protection (BfS) have to be considered, where applicable. As stated in the letter to the editor, in only 10–15 % of patients undergoing a CTA for suspected pulmonary embolism, the diagnosis of pulmonary embolism is confirmed. Instead, the CT examination reveals in the majority of these patients pathologic findings other than pulmonary embolism as cause for their symptoms (e. g. pneumonia, pleural disease, malignancy). In the case of patients with equivocal symptoms, with pulmonary embolism being only one of several possible differential diagnoses, full coverage of the lungs by the CT scan may thus be clinically justified. In these cases, however, the justifying indication is not restricted to pulmonary embolism. In contrast, there is, in no event, a justification to extend the length of a CT scan to not miss an incidental finding as argued in the letter to the editor. Regardless of the individual justification for a CT examination, however, all available strategies and technologies for dose reduction have obligatory to be exploited as an indispensable component of the optimization process.

Zusammenfassung Ziel: Analyse der Behandlungsqualität der endovaskulären Versorgung von Aortenaneurysmen anhand der Eingaben in das DeGIR-Qualitätssicherungssystem. Material und Methoden: Die Daten des Jahres 2011 zur Behandlungsqualität der endovaskulären Versorgung von Aortenaneurysmen des freiwilligen DeGIR-Qualitätssicherungssystems wurden retrospektiv ausgewertet. Die Indikationsstellung, der Therapieprozess und die Ergebnisqualität wurden überprüft. Hinsichtlich der Ergebnisparameter wurden insbesondere der Therapieerfolg, die Komplikationsraten und die Strahlenexposition untersucht. Ergebnisse: Von 82 881 Datensätzen des DeGIR-Qualitätssicherungssystems des Jahres 2011 beschreiben 1167 Datensätze die Behandlung eines Aortenaneurysmas. Bei 12,4 % der Fälle handelte es sich um eine Notfallindikation. Die häufigste Indikation zur EVAR-Behandlung stellte mit 85 % das abdominelle Aneurysma dar. Der mediane Aortendurchmesser betrug 56,5 mm, 253 Fälle hatten eine Aortendurchmesser zwischen 50 und 55 mm. Der technische Erfolg der EVAR-Behandlung lag bei 94,6 %. Die Komplikationsrate aller EVAR einschließlich der Notfallindikationen lag bei 4 % mit einer Major-Komplikationsrate von 2,5 %. Elektiv behandelte Patienten wiesen eine Letalität von 0,34 % auf. Bei bereits präinterventionell rupturierten Aneurysmen lag die Letalität bei 12 %. Die Mediane des Flächendosisprodukts und der Durchleuchtungszeit lagen bei 10 676,5 cGy × cm2 und 17,32 min. Schlussfolgerung: Die Datenauswertung des DeGIR-Qualitätssicherungssystems belegt eine sehr hohe technische Erfolgsrate der erfassten endovaskulären Behandlungen von Aortenaneurysmen bei gleichzeitig geringer Komplikationsrate. Um die Datenqualität noch weiter zu verbessern, ist eine Modifikation der Datenerhebung mit Einführung weiterer Pflichtfelder bei der Eingabe notwendig. Kernaussagen: Das freiwillige DeGIR-Qualitätssicherungssystem hat unter interventionell tätigen Ärzten eine hohe Akzeptanz gefunden. Die endovaskuläre Aneurysmabehandlung durch Radiologen besitzt eine hohe technische Erfolgsrate bei gleichzeitig sehr niedriger Komplikationsrate.

BACKGROUNDRecanalisation favourably influences outcome in acute stroke. Improved endovascular approaches seem to have higher recanalisation rates than systemic thrombolysis. Substantial efforts have been undertaken to increase the proportion of patients to whom these therapies can be applied. It is still unclear what rates can be realised in a clinical setting.PATIENTS AND METHODSThis is a retrospective single-centre analysis of patients with acute ischaemic stroke and specific recanalisation therapy primarily admitted to our tertiary care centre from 1/2010 to 3/2012.RESULTS20 % of patients received systemic thrombolysis, 20 % of these additional endovascular strategies. Pathological multimodal CT patterns were more common in patients not fulfilling the inclusion criteria for thrombolysis. Short-term clinical outcomes were similar in on-label and off-label applications.CONCLUSIONStructured clinical pathways including multimodal CT imaging are useful in identifying patients likely to profit from revascularisation therapies. Based upon our data, some realistic aims concerning therapy rates in patients with ischaemic stroke treated in everyday practice may be formulated (20/20 in 2020).

Hintergrund: Aufgrund des besseren Verlaufes nach Rekanalisierung und vielversprechender interventioneller Verfahren werden derzeit strukturelle Bemühungen unternommen, die Rate dieser Therapien beim Schlaganfall zu verbessern. Unklar ist, wie und auf welchem Niveau dies optimierbar ist. Patienten und Methode: Retrospektive unizentrische Analyse aller primär zugewiesener, nach einem strukturierten Behandlungspfad mit multimodaler CT Bildgebung spezifisch rekanalisierend behandelter Schlaganfallpatienten eines tertiären Versorgungszentrums im Zeitraum 1/2010 bis 3/2012. Ergebnisse: 20 % der Patienten wurden lysiert, etwa 20 % hiervon zusätzlich interventionell behandelt. Bei Off-label-Indikation war die Rate spezifischer Perfusionsbefunde signifikant höher als bei On-label-Lysen. Der kurzzeitige klinische Verlauf war hiervon unabhängig. Schlussfolgerung: Ein strukturierter Behandlungspfad erlaubt eine hohe Rate an Lysen und Interventionen. Anhand der dargestellten Daten kann eine erste Zielsetzung für die allgemeine Versorgungsrealität formuliert werden (20/20 in 2020).

Die katheterbasierte, interventionelle Behandlung („endovascular aortic repair“, EVAR) abdomineller Aortenaneurysmen („abdominal aortic aneurysm“, AAA) hat heute einen festen Platz im Therapiespektrum eingenommen. Das Verfahren ist durch eine niedrige periinterventionelle Morbidität und Mortalität gekennzeichnet. Der Multislice-CT-Untersuchung kommt für eine differenzierte Indikationsstellung und Auswahl eines geeigneten Stentgrafts präinterventionell entscheidende Bedeutung zu. Bei unseren eigenen Patienten konnte seit 2010 die akute Konversionquote bei elektiver Versorgung von 2,9 auf 0 % reduziert werden. Im hiesigen GefässCentrum betrug der Anteil endovaskulär behandelter Patienten 39,5 % (102 von 258). Das Verfahren wird routinemäßig bei Patienten eingesetzt, die aufgrund von Begleiterkrankungen ein erhöhtes Narkose- bzw. Operationsrisiko haben und bei Patienten, bei denen durch vorangegangene Operationen, abdominelle Erkrankungen oder Bestrahlungen die lokale Operabilität erschwert ist. Verschlusssysteme erlauben bei einem Teil der Patienten ein vollständig perkutanes Vorgehen. Nach EVAR wird allerdings eine lebenslange Nachsorge empfohlen, da auch im Spätstadium Therapieversager beschrieben wurden. Bei jüngeren Patienten ohne erhöhtes Risiko bietet sich nach wie vor die offene chirurgische Versorgung an. Die Arbeit geht auf Techniken, Ergebnisse und Komplikationen der EVAR ein.

To prove that 1.0 M gadobutrol provides superior contrast enhancement and MRI image characteristics of primary and secondary brain tumours compared with 0.5 M gadoteridol, thereby providing superior diagnostic information.

The catheter-based interventional therapy (endovascular aortic repair EVAR) of abdominal aortic aneurysms (AAA) has gained an established place in the spectrum of therapeutic options. The procedure is characterized by low peri-interventional morbidity and mortality. Multislice computed tomography (CT) has a dominant role in defining the correct indications and in selecting an appropriate stent graft prior to the intervention. The rate of acute conversions could be reduced from 2.9 % to 0 % in our own elective patient population since 2010. In our vascular centre the proportion of patients treated by EVAR was 39.5 % (102 out of 258). The procedure is used routinely in patients who have an increased risk for general anesthesia or open surgery due to concomitant diseases. It is also used in patients with a reduced local operability due to prior surgery, abdominal diseases or radiation therapy. Arterial closure devices allow a completely percutaneous approach in a certain group of patients. However, after EVAR a life-long surveillance is mandatory because delayed therapy failure has been described. In younger patients who do not have a higher risk open surgery is still an option. The paper describes techniques, results und complications of EVAR.

In 1994 the German Society of Interventional Radiology (DeGIR) introduced a voluntary quality mangement program. Out of a total of 82 881 of the year 2011, 36 467 patients, who received interventional recanalisation of pelvic or lower extremity arteries were chosen for an in depth analysis. In 33 104 (90.8 %) cases indication for interventional treatment was determined by at least one further discipline or even a multidisciplinary conference. Most treated patients were classified as Fontaine II or higher. Technical success rate over all procedures and regions was 96.2 % showing a very low failure rate of only 3.8 %. The overall complication rate was 3.2 %, periinterventional morbidity (complication C, D or E according to SIR classification) was 1.37 % and periinterventional mortality was 0.07 % (24 cases). X-ray exposure was recorded as well showing an average fluoroscopy time of 12 minutes and a dose-area product of 5034 cG × cm2. The voluntary quality management system was well accepted by the interventional radiologists. The software allows to compare the individual data of a single institution with the pooled data of all 192 participating radiology departments.

Diagnosis and therapy of vascular diseases are increasingly being performed following a multimodal, interdisciplinary and less invasive approach. The introduction of specialized, organ-related centers is a logical consequence in view of a better treatment quality and a more effective use of resources. The German societies of radiology, vascular surgery and angiology jointly developed a process of certification, which has been successfully applied to more than 100 units in Germany. In this article the terms and results of the process are described and possible effects on the quality and structures of the healthcare system are discussed.

PURPOSE:To test a system using ultrasound computed tomography (USCT) that superimposes ultrasound data acquired in one cross-sectional plane from multiple angles around the breast (Full Angle Spatial Compounding, FASC) and to reconstruct the distribution of the speed of sound in the breast (SoS reconstruction).MATERIALS AND METHODS:We developed a system combining a conventional ultrasound scanner with a PC-controlled mechanical setup integrated in a custom-made examination couch. In a feasibility study, 3 volunteers (age 26 - 74 years) and one patient with breast cancer were studied. Subjects were placed in the prone position on this couch, with the breast hanging in a water tank. The ultrasound probe was moved in several planes around the breast. A curved reflector that followed the movement of the probe behind the breast was used to calculate the SoS within the breast tissue. Echo-data was processed offline by custom-made software to calculate both FASC and SoS images.RESULTS:In FASC images a reduction of artifacts (i. e. shadowing of Cooper's ligaments and irregular edges of inhomogeneous lesions) and speckles as well as clear visualization of the inner architecture of the breast was achieved. SoS images delivered further diagnostic information and helped to compensate for geometric distortions in the computed images. Difficulties in the visualization of lesions near the thoracic wall and/or the axillary are limitations of this technique.CONCLUSION:The first clinical results of USCT imaging have proven its feasibility as an automated and standardized technique for breast imaging.

Article Kalibrierung von Volumendatensätzen aus Spiral-CT-Akquisitionen zur Konturfindung bei individueller Schädelimplantatfertigung was published on January 1, 1998 in the journal Biomedical Engineering / Biomedizinische Technik (volume 43, issue s1).

Objective: Material and Method: Results: Conclusion: Hintergrund: Material und Methode: Ergebnisse: Zusammenfassung:

The quality assurance of treatment measures is legally required but as yet not generally established in practice. For interventional radiology, the introduction of quality assurance for PTA of arteries of the lower limbs is planned for January 1999. It is reasonable to subject at least the most important and/or most frequently performed interventions to quality management. In the present article, the term quality in the management of diseases is defined and the system of total quality management discussed at the levels structure, process, and results. For its application, parameters of quality measurement in the form of standards, criteria, and characteristics values are necessary and must be laid down by a team of experts on the basis of subjective experience and/or results in the literature. Practical quality assurance takes place not only within a clinic but also externally by comparison with other centers. Data collection and evaluation requires high-performance software that will be continuously improved, expanded, and adapted to current needs during regular meetings between the various users.

Objective: Breast cancer is the most common type of cancer in women worldwide. Mammography is considered the “gold standard“ in detecting even small cancers, leading to identification of early-stage breast cancers. Despite this, mammography has substantial disadvantages such as moderate sensitivity ranging from 69–90%, radiation risk and further diminished sensitivity in radiographically dense breasts. Apart from mammography, ultrasound examination is being offered as the most important adjunct to the preoperative diagnostic work-up. However, ultrasound is operator-dependent, has a variable false-positive rate and the examination technique is not standardized. Furthermore, ultrasound shadowing as well as minimal or absent contrast between echolucent breast cancer and echolucent fatty tissue may hamper a clear delineation of the lesion. Due to this, the extent and 3D-geometry of the cancer may be difficult to determine. In order to overcome those limitations we developed a system for Full Angle Spatial Compounding (FASC). Here, ultrasound data are acquired from multiple viewing angles around the breast and superimposed with respect to its correct orientation. Though FASC has already been investigated in the 1980s, recent improvements in ultrasound imaging (e.g. harmonic imaging, beam forming and array technology) encourage a re-assessment. Using our system a standardized image generation is realized and compound images of high quality are computed in a cross-sectional view.

BACKGROUND:Computed tomographic angiography (CTA) has been shown to reliably detect aneurysms pre-operatively. The aim of this study was to compare the ability of post-operative CTA to detect aneurysmal remnants in connection with clip placement compared with digital subtraction angiography (DSA). Furthermore, special attention was paid to identifying factors influencing the image quality of CTA.METHOD:Between January 2005 and January 2006 a total of 76 patients with intracranial aneurysms were treated in our department. Thirty-two patients with a total of 33 clipped aneurysm were included in this study. All patients underwent CTA and DSA after surgery. Two investigators, each blinded to the classifications of the other, assessed image quality and clip placement.FINDINGS:In three patients aneurysmal remnants could be detected with CTA and DSA. One 2-mm aneurysmal remnant was not clearly identified on CTA; two small (<2-mm) aneurysmal remnants were definitely not seen on CTA. A single titanium clip was used for aneurysmal clipping in 26 patients, two clips were needed in six patients and one aneurysm required three clips being used. Overall, use of one titanium clip tended to result in better image quality. In addition, clip-gantry angles between 30 degrees and 60 degrees tended to yield better image quality.CONCLUSION:Post-operatively, CTA can be recommended as a reliable non-invasive diagnostic tool only with optimal image quality and with this criterion up to 66% of the aneurysms can be evaluated. Titanium artefacts, especially in the important zone (<2 mm) around the clip in which small aneurysmal remnants can occur, can render adequate evaluation impossible. CTA image quality depends on the number of titanium clips used, but clip-gantry-angle does not significantly influence the image quality.

Ziele: Zur Aneurysmasuche bei SAB wird als Primärdiagnostik die CTA der intracraniellen Gefäße meist als alleiniges präoperatives Verfahren eingesetzt. Gegenüber der DSA bietet die CTA den Vorteil der fehlenden Invasivität sowie der kürzeren Akquisitionszeit. Inwieweit dieses auch auf die postoperative Kontrolle nach Aneurysmaclipping zu übertragen ist, soll prospektiv gezeigt werden. Methode: In einer prospektiven, verblindeten Studie wurden Patienten zwischen 1/2005 und 8/2006 eingeschlossen. Um den 27. postoperativen Tag wurde eine DSA (Goldstandard) und im Abstand von im Mittel 11 Tagen eine CTA durchgeführt. Diese Untersuchungen wurden verblindet durch ein Team aus 1 Neuroradiologen und 1 Neurochirurgen im Konsensus beurteilt. Bewertet wurden nach Schulnoten (1–5) die Qualität der Untersuchung, die Beurteilbarkeit der Aneurysmen und Therapierelevanz. Zusätzlich: Cliplokalisation und -anzahl; Rest-, Rezidiv- und Zweitaneurysmen sowie Nebendiagnosen. Ergebnis: Insgesamt konnten 33 Patienten zwischen 38 und 71 Jahren (MW 53 Jahren) eingeschlossen werden. Mit 4Männern und 29 Frauen lag die Geschlechterverteilung zu Gunsten der Frauen. Die operierten Aneurysmen waren vor allem lokalisiert im Bereich der MCA (16), ACoA (8) und PcoA (3). Im Vergleich der Qualität der Untersuchungen in Bezug auf die Gefäßbeurteilbarkeit wurde die DSA mit 1,2 (MW) signifikant besser bewertet als die CTA (MW 2,4).

PURPOSE:Evaluation of different parameters of contrast media enhancement for the differentiation between scar tissue and local recurrence of rectal cancer.MATERIALS AND METHODS:We included 83 patients after operation and radiotherapy of rectal cancer. In total, 20 local recurrences were diagnosed. After administration of 75 ml Iopromide (370 mg/ml) and a delay of 65 s, the whole abdomen and pelvis were scanned in a collimation of 4 x 2.5 mm and 12.5 mm table feed per rotation. The suspected tissue was marked by the freehand ROI option in every slice and the minimum, average and maximum densities were calculated. A local recurrence was suspected if maximum density was higher than 90 HU after admission of contrast media. In addition we calculated the maximum difference of density as the difference between maximum and minimum density.RESULTS:The minimum and average densities showed no reliable differences for patients with or without local recurrence (minimum density 4 HU ( +/- 12 HU) vs. 13 HU ( +/- 21 HU), P = 0.23, average density 48 HU ( +/- 10 HU), vs. 48 HU ( +/- 17 HU)), P = 0.52. The patients suffering from local recurrence showed higher maximum densities and a higher maximum difference than the patients without recurrence (maximum density 111 HU ( +/- 13 HU) vs. 81 HU ( +/- 24 HU), P = 0.02, maximum difference 103 HU ( +/- 20 HU) vs. 76 HU ( +/- 31 HU), P = 0.06. These differences were not significant. We calculated a sensitivity of 0.6, a specificity of 0.83, a positive predictive value of 0.52 and an accuracy of 0.77.CONCLUSION:It is not possible to diagnose a recurrent rectal cancer by density values alone.