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M Zähringer

Publications and source records attributed to M Zähringer.

At least 19 recordsLinked to original sources
PubMed2006

[Ultrasound guided implantation of chest port systems via the lateral subclavian vein].

PURPOSE: Retrospective analysis of the success and complication rates of chest port implantation via the lateral subclavian vein. MATERIALS AND METHODS: Between January 2003 and June 2004, the lateral subclavian vein in 271 patients (186 women, 85 men, mean age 53.2 years) was punctured guided by ultrasound. This access was used to insert a port system, and the catheter tip was placed at the cavoatrial junction. The port reservoir was implanted in a subcutaneous infraclavicular pocket and fixed to the fascia of the pectoralis muscle. Indications for port implantation were chemotherapy (n = 239), total parenteral nutrition (n = 2) and intravenous medication (n = 30). The patient follow-up was mainly performed either by the oncology division of the department of gynecology or by the department of internal medicine. RESULTS: A chest port catheter system was successfully implanted in all patients. The catheter remained in place for a mean duration of 269.4 days (SD 192.3 days). No complications occurred during implantation. In the post-interventional period, 6 catheter dysfunctions were found (thrombotic 0.09 per 1000 catheter days; mechanic 0.05 per 1000 catheter days). While one local infection occurred in the early post-interventional period, 3 local and 15 systemic infections were independent of the port catheter placement (0.39 per 1000 catheter days). The rate of port catheter ex-plantation due to dysfunction or infection was 0.07 per 1000 catheter days. CONCLUSION: Ultrasound-guided puncture of the lateral subclavian vein is a safe procedure for the insertion of central venous port catheter systems and had a very low complication rate in our study. For further evaluation of our port placement technique, prospective studies compared to placement through the internal jugular vein are necessary.

Catheterization, Central Venous↗
PubMed2005

[Digital X-ray mammography: comparison of the image quality achievable with a wet laser imager, a dry infrared laser imager and a dry laser imager using direct thermography].

PURPOSE: To compare the image quality of digital X-ray mammographies obtained with wet imagers with that of standard dry imaging technology. MATERIAL AND METHODS: Beginning 03/08/2003, 200 X-ray mammographies with a digital fullfield mammography system (Lorad Selenia, Lorad/Hologic) were prospectively and consecutively documented with a wet laser imager (Scopix LR 5200, Agfa), a dry infrared laser imager (DryView 8610, Kodak) and a dry imager using the principle of direct thermography (Drystar 4500M, Agfa, N = 166). One X-ray exposure was systematically chosen from each examination and was presented in an anonymous and randomized form to three radiologists who evaluated the films using a structured questionnaire. RESULTS: The visualization of normal anatomic structures was considered being good to excellent for all imagers with the mean assessments 1.0 - 2.4 for the Drystar 4500M, 1.0 - 2.1 for the DryView 8610 and 1.1 - 2.0 for the Scopix LR 5200. The mean assessments were 0.1 - 0.6 points lower in dense than in normal parenchyma, thus, the parenchymal density is the predominant factor for image quality. CONCLUSION: In view of the comparable image quality obtained with the different imagers used in the study, individual decisions to purchase a specific imager will be based on economics rather than on diagnostic points of view.

Computer Peripherals↗
PubMed2004

Radiosurgery for cerebral arteriovenous malformations in hereditary hemorrhagic telangiectasia.

The authors evaluated the efficacy of radiosurgery (RS) for cerebral arteriovenous malformations in hereditary hemorrhagic telangiectasia (HHT AVMs). Two patients with seven HHT AVMs were treated by linear accelerator-RS. Complete obliteration was achieved 18 to 24 months post-treatment without side effects. Because HHT AVMs are small and multiple, RS is superior to microsurgery because it is noninvasive and all AVMs can be treated in one session regardless of their location.

Adult↗
PubMed2004

[MR-coronary angiography: comparison of SSFP and spoiled GRE sequence (bright blood technique) and a TSE sequence (black blood technique) in healthy volunteers].

PURPOSE: Comparison of a free breathing steady-state free precession (SSFP), a spoiled gradient-echo (GRE) and a turbo spin-echo sequence (TSE) for imaging of the coronary arteries (MRCA) in healthy volunteers. MATERIALS AND METHODS: Twenty-two healthy volunteers were imaged with a standard clinical scanner (1.5 T, Intera, Philips), with the right coronary system imaged in 11 and the left coronary system in the other 11 volunteers. Images were obtained with a 3D-SSFP (balanced TFE, TR 6.2 ms, TE 3.1 ms, alpha 65 degrees ), a 3D-GRE (TFE, TR 7.2 ms, TE 2.2 ms, alpha 30 degrees ) and a 2D-TSE (Dual-IR, TR 2RR, TE 25 ms) sequence. The in plane resolution was 0.7 x 0.8 mm for both the SSFP and GRE sequence with an effective slice thickness of 1.5 mm. For the TSE sequence, an in-plane resolution of 0.7 x 0.9 mm and a slice thickness of 3.0 mm were used. All investigations were performed using prospective navigator gating and slice-following technique. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the blood pool to myocardium and blood pool to epicardial fat were calculated. Image quality and measurement artifacts were assessed for all sequences by 5 independent investigators using a 4- and 5-point grading scale. RESULTS: CNR was significantly higher for the GRE sequence compared with the SSFP sequence and TSE sequence (mean 20.8 +/- 4.8 vs. 14.6 +/- 5.0 and 10.1 +/- 3.7 for blood pool to myocardium; mean 27.5 +/- 6.3 vs. 16.4 +/- 5.4 and 18.1 +/- 5.7 for blood pool to fat). The SNR revealed no significant differences between the SSFP and GRE sequences. The SSFP and the TSE sequences showed significantly more artefacts than the spoiled GRE sequence. Image quality was graded slightly higher for the GRE than for the SSFP sequence for the right coronary system, while there was no substantial difference in the left coronary system (median 2.1 +/- 0.6 and 2.5 +/- 0.6 vs. 2.5 +/- 0.8 and 2.6 +/- 0.7 for the right and left coronary system). In comparison, image quality was lower with the TSE sequence (median 2.9 +/- 0.5 for the right coronary system with p < 0.05 vs. GRE sequence and 3.0 +/- 0.3 for the left coronary system). CONCLUSION: For the scan parameters chosen in this study, the GRE-sequence represents the most robust technique for imaging of the coronary arteries. Currently, the TSE sequence is no alternative.

Adult↗
PubMed2004

Computed-tomography-guided percutaneous core needle biopsies of suspected malignant lymphomas: impact of biopsy, lesion, and patient parameters on diagnostic yield.

PURPOSE: To investigate the diagnostic yield of core needle biopsy in patients with malignant lymphoma. MATERIAL AND METHODS: Computed-tomography-guided core needle biopsies in patients with malignant lymphoma performed in the period 1996 to 2001 were evaluated retrospectively. A biopsy was considered as "fully diagnostic" if a histological diagnosis, including the histologic subtype in the event of malignant lymphoma, was achieved and the clinical course and CT follow-up of at least 6 months confirmed the biopsy results. A biopsy was regarded as "partly diagnostic" if histological work-up defined malignant lymphoma but not the histological subtype, and if histological diagnosis bore therapeutic relevance. Diagnostic yield was correlated with features such as size of specimen, location and depth of the target lesion, and experience of the investigator. RESULTS: 45 biopsies were performed in 40 patients. With respect to definite histopathological diagnosis, 31 biopsies (68.9%) were diagnostic and 14 (31.1%) non-diagnostic. In 4 cases (8.8%), biopsies yielded partly diagnostic results, since therapy could be scheduled after biopsy without final sub-classification. Statistical analysis of biopsy parameters revealed that sample sizes were significantly larger in the diagnostic group. CONCLUSION: CT-guided biopsy can be considered as an alternative for lymphoma diagnosis and should be the first interventional procedure. The most important parameter for diagnostic success is the size of the specimen.

Biopsy, Needle↗
PubMed2003

[Quality control of outpatient imaging examinations in North Rhine-Westphalia, part I].

PURPOSE: In the state of North-Rhine Westphalia (NRW), Germany, a survey was conducted on radiologic examinations ordered by general practitioners (GPs). Part I of this study aims to collect characteristic epidemiological data and to assess structural quality. MATERIALS AND METHODS: All GPs in NRW were asked to cooperate. Participating GPs filled out a questionnaire for each patient. The patients recorded the symptoms prompting the imaging examinations. The radiologists or other physicians performing the examinations were asked to provide the images and written reports and to complete a questionnaire. Two university radiologists documented the pertinent test data from the submitted images and written records. Independently of each other, five university radiologists anonymously reviewed the image quality of each examination using structured questionnaires. RESULTS: A total of 920 patients gave their informed consent and participated. Questionnaires from 787 patients, 852 GPs and 611 radiologists or other interpreting physicians as well as the complete survey data from 530 examinations were available. Of 1503 examinations, conventional radiography made up 52 %, sonography 17 %, computed tomography (CT) 13 % and magnetic resonance imaging (MRI) 5 %. Most indications involved the musculoskeletal (37 %) and respiratory systems (24 %). Physicians without board certification in radiology interpreted 1 % of the CT examinations, 26 % of the radiographic examinations and 71 % of the sonographic examinations. Of the 174 self-referrals, 1 % involved CT, 33 % conventional radiography and 66 % sonography. Written reports were available for 95 % of all 469 examinations performed by radiologists and 74 % of all 127 examinations conducted by non-radiologists. Only 44 % of the 23 sonographic studies were self-referrals by the patient's GP. On average, the radiographic techniques were acceptable in terms of diagnostic information and radiation hygiene. Conventional radiographs were better exposed when obtained by radiologists than by non-radiologists (p = 0.038). The delineation of anatomical structures was rated as good to acceptable for MRI, CT and conventional radiography, while the image quality was rated as diagnostically insufficient for sonography (p < 0.0001). The image quality of radiographic and sonographic examinations performed by radiologists was superior in comparison to examinations performed by physicians without board certification in radiology (p < 0.0001). CONCLUSION: Examination technique and imaging quality of MRI, CT and conventional radiography performed on outpatients were in an acceptable diagnostic range, whereas the quality of sonography was inadequate.

Family Practice↗
PubMed2003

[Internal carotid artery dissection at the carotid canal after blunt trauma: case report of endovascular repair and literature review].

Symptomatic dissecting aneurysms of the extracranial internal carotid artery after blunt trauma are not frequent. Medical treatment of these lesions can be ineffective and surgical options present high morbidity. We describe a case successfully treated with endovascular therapy, using a self-expanding stent. The advantages of the endovascular treatment are outlined, the literature on carotid artery injuries by blunt trauma and management strategies are reviewed.

Adult↗
PubMed2003

[Quality control of outpatient imaging examinations in North Rhine-Westphalia, Part II].

PURPOSE: In the state of North Rhine-Westphalia (NRW), Germany, a survey was conducted on radiologic examinations ordered by general practitioners (GPs). Part II of this study aims to determine the quality of the process and outcome. The reference standard is the assessment of both radiologists and physicians without board certification in radiology working at a university hospital and in outpatient facilities. MATERIALS AND METHODS: AllGPs in NRW were asked to cooperate. Participating GPs filled out a questionnaire for each patient. The patients recorded the symptoms prompting the imaging examinations. The radiologists or other physicians performing the examinations were asked to provide the images and written reports and to complete a questionnaire. A file was created for each of the 394 patients with image documentation of at least one examination. Each file, which included medical history, physical findings, imaging documentation and written report, was sequentially forwarded to a board-certified radiologist and to a physician without board certification in radiology working in a university hospital and in an outpatient facility. All physicians were requested to complete a structured questionnaire for each file. RESULTS: The referral diagnoses were rated as medically plausible in 81%, the indications for imaging found correct in 76%, the examination techniques considered appropriate in 69%, the clinical question answered in 63%, the interpretation judged medically correct in 50% and all incidental findings documented in 49%. In retrospect, 32 % of the examinations were judged superfluous. The sequence of multiple examinations performed on a particular patient was rated as appropriate in 51%. The interpretation revealed specialty-related differences. The plausibility of the referral diagnoses had a significant impact on the appropriateness of subsequent diagnostic investigations. Marked deficits showed sonography, performance by non-radiologists, self-referrals by GPs, gastroenterologic radiology and the ICD-10 coding (suspicion of cardiovascular disease). CONCLUSION: In the "best-case" scenario, the process quality proved to have moderate deficiencies and the outcome quality severe deficiencies. In consequence, GPs and radiologists should be more communicative by sharing information and exchanging opinions. GP self-referrals should be restricted. Sonography and examinations performed by physicians without board certification in radiology should undergo stricter quality controls. A more intensive interdisciplinary collaboration is needed to determine the optimum implementation of diagnostic imaging of gastroenterologic and cardiovascular diseases.

Ambulatory Care↗
PubMed2003

Reducing the radiation dose during excretory urography: flat-panel silicon x-ray detector versus computed radiography.

OBJECTIVE: The purpose of the study was to examine the possibilities for reducing radiation exposure in uroradiology using digital flat-panel silicon X-ray detector radiography. We compared the subjectively determined image quality of abdominal radiographs and urograms obtained on a digital flat-panel detector radiography system with those obtained on a computed radiography system. SUBJECTS AND METHODS. Fifty patients who had a clinical indication for urography underwent unenhanced abdominal imaging that was alternately performed using flat-panel silicon X-ray detector radiography or computed radiography. For patients who required a second radiograph with contrast medium, the examination modality was changed to avoid exposing the patients to excess radiation. The images obtained on flat-panel X-ray detector radiography were obtained at half the radiation dose of the images obtained on computed radiography (800 speed vs 400 speed). The resulting 50 pairs of images were interpreted by four independent observers who rated the detectability of structures of bone and the efferent urinary tract relevant to diagnosis and compared the image quality. RESULTS: At half the radiation dose, digital flat-panel X-ray detector radiography provided equivalent image quality of the liver and spleen, lumbar vertebrae 2 and 5, pelvis, and psoas margin on abdominal radiographs. The image quality obtained with digital flat-panel X-ray detector radiography of the kidneys, the hollow cavities of the upper efferent urinary tract, and the urinary bladder was judged to be statistically better than those obtained with computed radiography. CONCLUSION: With half the exposure dose of computed radiography, the flat-panel X-ray detector produced urograms with an image quality equivalent to or better than computed radiography.

Diagnosis, Computer-Assisted↗
PubMed2003

Current indication for endovascular treatment of thoracic aneurysms.

The morbidity and mortality for open treatment of thoracic aortic aneurysms have declined over the years, but it is still a major clinical problem. The reason for the mortality is in almost 50% of the cases cardiac failure. Endoluminal treatment of abdominal aortic aneurysm is widely distributed and with promising results, although not as free from complications as expected 10 years ago. This technique has also been adopted for the thoracic aortic aneurysm as the trauma is much less than in open surgery. In our own personal series no specific workup for coronary heart disease has been made and the mortality of stentgrafting of the thoracic aorta was 2.4%. A survey of the world literature, including elective and acute dissections and aneurysms revealed 642 patients treated with stentgraft with a mortality of 6.2%, although no cardiologic work up had been performed. These numbers compete well with those of open surgery, but a systematic prospective comparison would be needed in order to state the real mortality in both groups.

Adult↗
PubMed2002

Does celiac trunk stenosis correlate with anastomotic leakage of esophagogastrostomy after esophagectomy?

The formation of a gastric tube for esophageal replacement requires partial devascularization of the stomach and induces microcirculatory changes in the anastomotic region of the gastric fundus. The additional influence of celiac trunk stenosis on anastomotic healing has not been investigated. In total, 23 patients with an esophageal carcinoma underwent transthoracic esophagectomy. Reconstruction was performed by a gastric tube (x22) with cervical or thoracic esophagogastrostomy or colon interposition (x1). All patients had a selective mesenterico-celiacography preoperatively via puncture of the right femoral artery. Preoperative cardiovascular and pulmonary risk factors were assessed. Angiographic findings were correlated to postoperative anastomotic leakage of esophagogastrostomy (x22). In seven out of 23 patients (30.4%), a stenosis of the celiac trunk could be demonstrated (x3 stenosis of 50%, x4 stenosis > 80%). Except for one patient with an additional stenosis of the superior mesenteric artery of > 80%, none of the patients with celiac trunk stenosis developed a postoperative anastomotic leakage of the esophagogastrostomy. Coronary artery disease was the only preoperative risk factor to predict a stenosis of the celiac trunk. Isolated stenosis of the celiac trunk does not seem to impair circulation of the gastric tube.

Adult↗
PubMed2002

[Endovascular gamma-irradiation for prevention or restenosis after angioplasty of femoropopliteal de-novo-stenoses-long-term results of a feasibility study].

OBJECTIVES: To evaluate the performance and efficacy of endovascular irradiation after percutaneous transluminal angioplasty (PTA) of de-novo femoropopliteal stenoses in a pilot study. METHODS: 6 patients received non-centered endovascular irradiation (12 Gray at surface of the vessel wall) immediately after angioplasty of de-novo femoropopliteal stenosis, 1 patient was given centered endovascular irradiation using 192-iridium (12 Gray at surface of the vessel wall) Centered irradiation was considered for two other patients. Duplex sonographies and interviews were performed the day before and after PTA and after 1, 3, 6, 9, 12, 18, 24 months up to 4 years. Intraarterial angiography was performed in symptomatic patients. RESULTS: Non-centered endovascular irradiation was possible in all patients without problems or complications. Centered irradiation was not possible in two patients with the cross-over approach. One thromboembolic complication occurred during centered irradiation. Both restenosis and new stenosis at the edge of irradiated distance occurred in 1/7 patients. No other side effects were observed during follow-up. CONCLUSIONS: In our pilot study endovascular irradiation after angioplasty of de-novo femoropopliteal stenosis was possible with low rates of complications and restenosis and taking vessel anatomy into account.

Adult↗
PubMed2002

[Comparison of flat-panel radiography and computed radiography in urography].

PURPOSE: To evaluate the diagnostic value of digital flat-panel radiography in uroradiology the i. v. urograms of patients who had been examined with computed radiography and digital flat-panel radiography were compared regarding image quality. METHODS: 50 patients who underwent clinically indicated i. v. urography were examined with digital flat-panel radiography and computed radiography. In order to avoid unnecessary double exposure to X-rays, patients were examined either by flat-panel or computed radiography before injection of contrast media. Each further clinically indicated exposure after administration of contrast media was done by alternating the other examination technique. The digital images were compared by 4 radiologists regarding image quality for the detection of defined anatomic structures. RESULTS: Digital flat-panel radiography showed an image quality of the liver, spleen and both kidneys that was similar to computed radiography. The urinary tract, lumbar spine, pelvis and psoas muscle were significantly better visible on flat-panel radiography images. CONCLUSIONS: Compared to computed radiography there is no loss of image information by using digital flat-panel radiography in uroradiology. On the contrary, some anatomic structures on abdominal survey images show better image quality. In conclusion, digital flat-panel radiography has the potential to replace computed radiography in uroradiologic examinations.

Contrast Media↗
PubMed2002

[Development of ultrasonography in a radiological university department from 1994 to 2001].

BACKGROUND: In 1994, 5 % of a total of 25 718 examinations and 7 % of all 4630 B-mode sonograms performed in the Radiology Department, University of Cologne was classified as not indicated. In light of these results, the health care policy guidelines for sonographic indications have been amended. PURPOSE: The aim of this study was to establish the current rate of non-indicated sonographic examinations performed in routine diagnostics by radiology departments at university hospitals, to determine the reasons for such over-diagnosis and identify which regulatory mechanisms can be implemented to prevent his. METHOD: We counted the number of 1) B-mode and 2) color-flow Doppler ultrasound imaging procedures carried out in patients who had had no change in symptoms within the previous 4 weeks or who were scheduled without reference to an existing sonogram (double examinations). 3) The reasons for over-diagnosis were analyzed. 4) The 1994 survey was repeated in 2000 with an identical protocol and 5) additionally, a modified survey of the diagnostic questions was conducted. RESULTS: 1) Out of 4,119 patients presenting for the first time to receive a B-mode sonogram, 443 prior sonograms (11 %), 305 CT scans (7 %) and 57 MRI scans (1 %) were documented. 2) Double sonograms were carried out in 6 % of the 1,118 patients presenting for the first time for color-flow Doppler ultrasounds and in 16 % of the 651 patients assigned to receive catheter angiographies with arterial color-flow Doppler. 2) 41 out of 55 (75 %) prior sonograms from non-university settings stated by 94 surgery patients were listed in the medical records. 36 out of 43 (84 %) prior sonograms from the university hospital were repeated in the same patients despite the fact that the medical report with the findings was available. None of the 48 sonograms indicated to confirm a plausible finding yielded any information that was additionally relevant to therapy. 4) In the period April - June, 2000, 12 % of all 15,921 tests and interventions, 26 % of 3,569 B-mode sonograms and 58 % of 1,033 abdominal sonograms performed in adults were classified as having not been indicated. 5) Staging and follow-up were stated as the most common reasons that a sonography was carried out in 46 % of the 1,017 adults who were given B-mode sonograms conducted from Jan - Mar, 2000 and comprised 62 % of the 410 sonograms classified as not or probably not medically indicated. CONCLUSION: The results showed that a multidisciplinary consensus was required to establish the diagnostic value of sonographic procedures. Therefore, this research group drafted a hospital-internal interdisciplinary guideline for "abdominal transcutaneous B-mode sonography in oncological questions".

Diagnostic Imaging↗
PubMed2002

[Intravascular ultrasound thrombolysis for recanalization of peripheral arteries: evaluation of an in vitro model and results of a pilot-study].

OBJECTIVES: To evaluate the effectiveness of ultrasound thrombolysis in vitro in comparison with thrombectomy, and in vivo as a pilot-study for the treatment of thrombotic occlusions of peripheral arteries. METHODS: Under standardized conditions, one-day-old and five-day-old thrombi of whole blood, thrombin-induced thrombi and old organized thrombi of human blood were treated with ultrasound thrombolysis and Amplatz thrombectomy device (ATD). Four patients with arterial occlusive disease of Fontaine stage IIb-III underwent intraarterial ultrasound-thrombolysis, applied to long segmental occlusions of the superficial femoral or iliac artery ranging in duration from three days to one year. RESULTS: The weight of the thrombi after ultrasound thrombolysis was 1.5 g +/- 0.53 (ATD: 0 g) compared to 3.65 g +/- 0.34 without treatment, with more weight reduction in five-day-old thrombi than in one-day-old thrombi. In vivo, partial recanalization was achieved in a three-day-old femoral occlusion. There was no effect in the other three patients. Urokinase thrombolysis with subsequent PTA and stenting resulted in complete recanalization in three patients. CONCLUSIONS: Ultrasound thrombolysis in vitro was significantly less effective than ATD. The results of ultrasound thrombolysis were influenced by the age of the thrombus and its in vitro formation. Intravascular ultrasound thrombolysis alone was insufficient to treat occluded peripheral arteries in vivo.

Aged↗
PubMed2002

[Stent prostheses in abdominal aortic aneurysm--pre-interventional exclusion of aneurysms of the internal iliac artery].

The technical success of endoluminal grafting in AAAs depends on the complete apposition of the fixation points of the stent graft with the proximal and distal aneurysm neck. Approximately 20% of patients presenting with AAAs have concomitant iliac artery aneurysms. To achieve a complete apposition at the distal landing zone without endoleak, intentional occlusion of the internal iliac artery is needed. To evaluate the inherent complications, our results of ELG were compared to those of the bibliography.

Aged↗
PubMed2001

Image quality of digital chest X-rays: wet versus dry laser printers.

The aim of this study was to compare the image quality of digital chest x-rays (Thoravision) obtained with 2 "wet" laser imagers of different matrix sizes and a "dry" system. Fifty chest x-rays in 2 planes were printed out in normal (100%) and reduced (61%) format using 3 different systems: 2 "wet" laser imagers (Agfa Matrix LR 3300, 4256 x 5174 pixels, 315 dpi; Agfa Scopix LR 5200, 8512 x 10348 pixels, 630 dpi), and one "dry" system (Agfa Drystar 3000,4352 x 5295 pixels, 330 dpi). All tests yielded normal findings. Anonymous images were evaluated by 4 independent reviewers on record forms rating the detectability of predefined anatomic structures. When the image quality of diagnosis-relevant, anatomic structures was evaluated on digital chest x-rays reproduced in normal and reduced format, the wet laser imagers did not show significant advantages over the dry system, Agfa Drystar 3000. The Agfa Drystar 3000 system is a feasible alternative for reproducing digital images, particularly for decentralized archives.

Adult↗