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Biomedical subjects

S Feuerbach

Publications and source records attributed to S Feuerbach.

At least 37 records · Page 2Linked to original sources
PubMed2004

[In vitro examination of the visibility of 11 stent catheters with real-time MR imaging].

PURPOSE: To evaluate artifacts of unexpended stents and to determine their exact position for MR-guided percutaneous transluminal angioplasty using real-time sequences. MATERIALS AND METHODS: By using an in vitro model, 11 unexpended stents - 9 nitinol, 1 stainless steel, and 1 cobalt alloy - were investigated by MR. Each stent was studied in a vessel-phantom filled with saline solution. Imaging was performed using five different real-time sequences: fast low angle shot (Flash 2D), fast imaging with steady precession (true FISP, FISP, interactive true FISP) and segmented echo planar imaging (seg. EPI). Artifacts of the introducer system and the stent were calculated by four blinded radiologists (scale: 1 - artifacts, making an excellent contribution to visualization; 2 - artifacts, making mainly a contribution to visualization; 3 - artifacts, making no contribution to visualization). Furthermore, an evaluation of the visibility of the tip of the stent-catheter and the proximal and distal end of the stent was performed using a four-point scale (very good visibility to invisible). RESULTS: The artifacts of the introducer system and stent were rated best for Omnilink (1.3 +/- 0.47), Wallstent (1.6 +/- 0.5), Jostent (1.65 +/- 0.5) and Luminexx (1.65 +/- 0.5). The differences between Omnilink and Jostent as well as Omnilink and Luminexx were significant. A very good to good visibility of the catheter tip was observed with a mean of 1.7 +/- 0.66 for Omnilink followed by the Jostent (1.95 +/- 0.69), by the Wallstent(R) (2.1 +/- 0.72) and by Luminexx (2.5 +/- 1.14). Differences between Omnilink and Luminexx were significant. The visibility of the proximal and distal end of the stent was evaluated as very good to good in 4 stent catheters (Omnilink, Wallstent, Jostent, Luminexx). However, the differences between Omnilink and Jostent as well as between Omnilink and Luminexx, and between Wallstent and Luminexx were significant. For all evaluation criteria, the segmented EPI and the interactive true FISP were rated to be most suitable for visualization. There were no significant differences in the evaluation of these two sequences. CONCLUSION: Omnilink stent, Jostent, Wallstent, and Luminexx stent are suitable for MR-angioplasty due to their good visibility in MR. Segmented EPI- and a newly developed interactive true FISP-sequence enable an effective visualization of these stent-catheters.

Alloys↗
PubMed2004

[Influence of sequence type on the extent of the susceptibility artifact in MRI--a shoulder specimen study after suture anchor repair].

PURPOSE: To compare the extent of susceptibility artifacts after metallic suture anchor implantation by analyzing 14 different MRI sequences. MATERIALS AND METHODS: A metallic suture anchor was implanted in the central area of three glenoid porcine specimens. The specimens were imaged with a 1.5 T scanner using a protocol of 14 standard sequences including gradient echo, spin echo and turbo spin echo sequences with and without fat-saturation. Artifact size was measured for each specimen and sequence. The resulting mean artifact areas were determined for each type of sequence and the mean values of the three specimens compared. RESULTS: Gradient echo-sequences produced significantly larger artifact areas than the spin echo and turbo spin echo sequences, whereby the artifacts of the 3D-gradient echo sequences were smaller than the artifacts of the 2D-gradient echo sequences. A turbo spin echo sequence with a high readout band width and a short effective echo time showed the best results. For the conventional spin echo sequence, a reduction in the echo time did not significantly decrease the artifact size. Spectral fat-saturation did not affect the area of the susceptibility artifact compared to the non-saturated sequence. CONCLUSION: Gradient echo sequences should not be used after metallic suture anchor repair. Turbo spin echo sequences showed a decrease in the artifact size compared to conventional spin echo sequences and should be performed with a short effective echo time and a high band width. Spectral fat- saturation did not increase the artifact size significantly.

Animals↗
PubMed2004

Clinical and angiographic outcome after interventional treatment of the iliac arteries with a new carbofilm coated stent: preliminary results.

PURPOSE: To evaluate the handling, the procedural success rate and the six-month outcome of a new Carbofilm coated balloon-expandable stent in iliac artery lesions. MATERIALS AND METHODS: In a prospective study, 46 stenoses and 2 occlusions of the iliac arteries were primarily stented in 30 patients with the Isthmus CarboStent (Sorin Biomedica Cardio S.p. A., Saluggia, Italy). The ankle-brachial index (ABI) at rest was determined before intervention and at the six-month follow-up visit. Iliac angiography, including intraarterial pressure measurement, was performed before intervention, post-procedurally and at the follow-up visit. RESULTS: All lesions were treated with procedural success. The mean degree of all stenoses was 73.9 % +/- 14.6 before and 2.4 % +/- 8.2 after intervention. The mean pressure gradient was 15.6 mm Hg +/- 10.1 before and 2.5 mm Hg +/- 2.7 after treatment. No or only a mild restenosis developed in 27 patients. The mean ABI increased from 0.64 +/- 0.21 to 0.86 +/- 0.33 and the mean pressure gradient was 2.7 mm Hg +/- 5.4 at the six-month visit. The six-month patency rate was 97.9 %. Three patients showed acute stent thrombosis due to an insufficient postprocedural antiplatelet regimen. DISCUSSION: The Isthmus CarboStent is a safe and easy to handle balloon-expandable stent for interventional therapy of iliac artery lesions. The six-month patency rate is good. Despite its Carbofilm coating, postprocedural antiplatelet therapy is necessary.

Administration, Oral↗
PubMed2004

High-resolution contrast-enhanced magnetic resonance angiography of the carotid arteries using fluoroscopic monitoring of contrast arrival: diagnostic accuracy and interobserver variability.

PURPOSE: To evaluate the diagnostic accuracy of high-resolution contrast-enhanced magnetic resonance angiography (CE-MRA) of the supra-aortic arteries using the CareBolus technique. Digital subtraction angiography was the standard of reference. MATERIAL AND METHODS: Fifty consecutive patients with suspected internal carotid artery stenosis underwent CE-MRA and digital subtraction angiography. CE-MRA was performed on a 1.5-T superconducting scanner with the CareBolus technique. CareBolus combines a nearly real-time 2D-FLASH (fast low angle shot) sequence for fluoroscopic triggering and a high-resolution 3D-FLASH with elliptical centric view order for the angiographic pulse sequence (6.0/2.16 ms [TR/TE], 30 degrees flip angle, 30.98 s acquisition time, 0.88 mm effective (interpolated) partition thickness and a 160 x 512 matrix). Intra-arterial digital subtraction angiography and CE-MRA studies were evaluated independently by four blinded readers. Internal carotid artery stenoses were graded according to the NASCET criteria. RESULTS: CE-MRA had an accuracy of 92.53%, a sensitivity of 95.64%, and a specificity of 90.39% for the identification of carotid artery stenoses > or = 70% (grade 3). Image quality for suppression of stationary tissue and venous contrast was good, but was reduced in five cases due to patient motion. CONCLUSION: The CareBolus technique is a useful non-invasive method for high-resolution imaging of the supra-aortic vessels because of its easy application and high sensitivity and specificity. Limitations can occur in non-compliant patients due to motion artifacts during the measurement time.

Adult↗
PubMed2004

Degenerative diseases of the lumbar spine. Comparison of the multiecho data image combination sequence with magnetization transfer saturation pulse versus lumbar myelography/postmyelographic computed tomography.

PURPOSE: To compare a T2* weighted 2D spoiled gradient echo multiecho sequence (MEDIC) with magnetization transfer saturation pulse versus lumbar myelography and postmyelographic computed tomography (pCT). MATERIAL AND METHODS: 84 disk levels in 27 patients were examined. The vertebral bodies, intervertebral disks, neural foramina, cauda equina, ligamentum flavum, and narrowing of the spinal canal were investigated using an evaluation scale. In addition, the pCT and the MEDIC sequence were evaluated for assessing the narrowing of the neural foramina in a phantom study using a cadaver preparation of the lumbar spine. RESULTS: A total of 28 disk herniations, 11 cases of osteophytes narrowing the spinal canal or the neural foramina, and 7 spinal canal stenoses were detected. The pCT was significantly better in visualizing the cauda equina. The MEDIC sequence was significantly superior in visualizing the extension of the ligamentum flavum. No statistical differences between either image modality were found concerning assessment of the narrowing of the neural foramina and the spinal canal, nor regarding evaluation of the vertebral disk and the vertebral body. Measurements of the phantom study showed that the MEDIC sequence did not overestimate narrowing of the neural foramina. CONCLUSIONS: The T2* MEDIC sequence has proved to be as accurate as pCT in evaluating osteophytes and narrowing of the neural foramina. In doubtful standard magnetic resonance imaging findings, this means that an additional axial T2* MEDIC sequence may be of value in reaching the same accuracy as pCT.

Adult↗
PubMed2003

[Evaluation of radiological teaching programs in the Internet].

PURPOSE: Evaluation of web based training programs, which can be contacted from the homepages of radiological departments of German universities. MATERIAL AND METHOD: From June 2000 to January 2002 the 75 web based training programs of 57 providers,which can be contacted from the web pages of the radiological departments of German universities were evaluated in a prospective study. A medical student experienced in using the world wide web examined each training program three times in an interval of six months using the following criteria: availability of the web sites, target group, kind of training program, contents and structure and the technical solution. RESULTS: 51 of the 57 the homepages were fully available at each visit. 64 of the 75 web based training programs which could be connected from these sites were available at all three visits.One program was only partially available at one spot check. 8 of the 75 programs were designed for physicians and medically trained personal, 23 were made for medical students and 44 addressed both target groups (partially more than once mentioned). The number of the presented cases ranged between one single and 3700. In 31 of 75 training programs links to other teaching files were found. A complete presentation of cases was presented by 48 of the 75 web sites.5 of the 75 web sites offered physiological images for comparison. In 20 training programs the pathological changes were optically marked in the x-ray images. A logical and didactical structure was found in 24 teaching files, 14 gave the possibility to check the learning results. No provider made use of the possibility to pass credits to the students or physicians account with regard to official training programs. Multimedia techniques were used in 15 training programs.43 sites used data reduced preview images (thumbnails). The latest update of the site is mentioned in 55 of the 75 web sites. 19 of 57 providers had either no possibility of contact or did not answer to an e-mail. CONCLUSION: From the homepages of the departments of diagnostic radiology of German universities 75 teaching files can be contacted. There is a great variety in quantity and quality. Most sites offer collections of cases. A web based training program which is comparable in quality to a CD-ROM teaching program could not be found. No program used the possibility to give credits to the users with regard to official training programs.

Computer-Assisted Instruction↗
PubMed2003

[Evaluation of a hemostatic device with percutaneous collagen application (VasoSeal) compared to a mechanical compression system (Compressar) after transfemoral catheterization of patients suffering from arterial occlusive disease].

PURPOSE: Comparison of the efficacy of VasoSeal and a mechanical compression system (Compressar) for percutaneous hemostasis after femoral arterial catheterization of patients with arterial occlusive disease. MATERIALS AND METHODS: 60 patients underwent either diagnostic angiography or interventional procedures. The level of anticoagulation, blood pressure, and activation clotting time were recorded, and the time to hemostasis after sheath removal was measured. VasoSeal application was considered "successful" if the compression time was less than two minutes. On the subsequent day as well as 4 months later, color coded Doppler ultrasound was performed to register treatment success and potential (late) complications. RESULTS: 57 patients qualified for inclusion in this study. In 21 of the 26 patients who underwent the procedure with the VasoSeal, immediate hemostasis was achieved within 1.75 minutes. In all 31 patients who had the Compressar applied, hemostasis was successful with a mean compression time of 17.4 minutes. Thus, VasoSeal significantly reduced hemostasis time irrespective of anticoagulation status, but it had a much higher incidence of minor local complications (bleeding, hematoma) compared to the control group (34.6 % vs. 5.8 %). The technical success was lower with VasoSeal than with Compressar (81 % vs. 100 %). Both groups had no severe or late complications. CONCLUSION: According to our results, VasoSeal does not provide a suitable alternative compared to the effective, safe and cheap application of Compressar as a hemostatic device.

Adult↗
PubMed2003

[Indirect MR-arthrography of the shoulder-value in the detection of SLAP-lesions].

PURPOSE: A prospective study to assess the value of indirect magnetic resonance-arthrography (MR-Arthro) in the detection of lesions of the superior labrum (SLAP-lesions). MATERIALS AND METHODS: Unenhanced magnetic resonance imaging (MRI) and indirect MR-Arthro of the shoulder were performed in 35 patients (9 females and 26 males) with a history of acute or chronic shoulder disorder. The images of unenhanced MRI and indirect MR-Arthro were analyzed independently from each other for the occurrence of SLAP-lesions and the findings correlated with the arthroscopic results. For arthroscopy, MRI and MR-Arthro, the SLAP-lesions were categorized based on the classification system of Snyder. RESULTS: SLAP-lesions were diagnosed by arthroscopy in 22 of 35 patients (63 %). 9 of the 22 lesions (41 %) were classified as type 1, 9 (41 %) as type 2, three (13.5 %) as type 3 and one (4.5 %) as type 4. Using unenhanced MRI sensitivity, specificity and accuracy in the detection of SLAP-lesions were calculated to be 73 %, 85 % and 77 %. Indirect MR-Arthro showed a sensitivity of 91 %, a specificity of 85 % and an accuracy of 89 %. Unenhanced MRI revealed correlation to the arthroscopic classification in 9 of 22 cases (41 %) and indirect MR-Arthro in 18 of 22 cases (82 %). CONCLUSION: Indirect MR-Arthro is a non-invasive method which offers excellent sensitivity in the diagnosis of SLAP-lesions. It provides important preoperative informations with regard to the exact location and extent of a tear.

Adult↗
PubMed2003

Alterations of cerebral metabolism in patients with diabetes mellitus studied by proton magnetic resonance spectroscopy.

To evaluate possible pathophysiologic links between cerebral changes in diabetic patients detected by proton magnetic resonance spectroscopy and clinical as well as laboratory parameters. The brains of 30 patients with diabetes mellitus and 30 healthy volunteers were examined using a STEAM sequence (TR 1500 ms, TE 20 ms). We measured in occipital gray matter and parietal white matter in a 1.5-Tesla magnet. Laboratory parameters were acquired before and after the examination. In diabetic patients a significant elevation of the myo-inositol/creatine ratio in gray and white matter was present (p = 0.006). Choline/creatine ratio in gray matter was elevated compared to normal controls (p = 0.002). No correlation with laboratory parameters was detected. Myo-inositol was even more elevated in patients with polyneuropathy (p = 0.024). No correlation with age or sex was detected. The changes found in diabetes are similar to those found in patients with Alzheimer's disease, dialysis, and after renal transplant, suggesting a similar etiology. Elevated myo-inositol may not only indicate osmolar changes in glial cells but also glial cell alteration due to amyloid or amylin deposition with formation of neurofibrillary tangles, especially as these changes are found in all of these diseases and no correlation to osmolar deterioration exists.

Adult↗
PubMed2003

Diffusion-weighted echo-planar MRI of the brain with calculated ADCs: a useful tool in the differential diagnosis of tumor necrosis from abscess?

BACKGROUND AND PURPOSE: It was the aim of this study to evaluate whether brain abscesses could be distinguished reliably from necrotic brain tumors using diffusion-weighted imaging (DWI) with calculated apparent diffusion coefficients (ADCs). METHODS: The authors studied 27 lesions in 26 patients (21 tumors and metastases, 5 pyogenic brain abscesses, and 1 cerebral toxoplasmosis). DWI was obtained with a single-shot echo-planar imaging spin-echo sequence. ADCs were calculated for all images. RESULTS: ADCs (x 10(-3) mm2/s) measured in the necrotic parts of the tumors ranged from 2.94 (glioblastoma) to 1.51 (astrocytoma III). In the inflammatory lesions, ADCs ranged between 0.91 and 3.07 (cerebral toxoplasmosis and pyogenic abscess). The contrast-enhanced parts of the lesions showed ADC values from 0.77 (pyogenic abscess) up to 1.68 (glioblastoma). CONCLUSIONS: DWI with calculated ADC values does not allow the reliable differentiation of enhanced central necrotic intracranial lesions.

Astrocytoma↗
PubMed2002

Tentorial and dural calcification with tertiary hyperparathyroidism: a rare entity in chronic renal failure.

A case of rare calcification of the tentorium cerebelli, the thoracal dura mater of the spine, and the sclera in an adult male patient with tertiary hyperparathyroidism is presented. The often reported feature in the skull is that of a combination of osteopenia and osteosclerosis giving a granular bone texture. Extensive dura calcification with this condition has very rarely been reported. It is the aim of this paper to document the latter in a patient with chronic renal failure and tertiary hyperparathyroidism.

Adenoma↗
PubMed2002

[Evaluation of the Internet presence of diagnostic radiology units at German universities].

PURPOSE: Analyzing the availability and the contents of the internet homepages of the radiological departments of German universities. MATERIAL AND METHOD: In June and July 2001 the internet homepages of 36 radiological departments of German universities were evaluated in a study. A medical student experienced in using the world wide web examined the websites concerning the following criteria: research, teaching, informations for patients, clinical topics and general information. Additionally an evaluation of the technical standard of the presentation was performed. RESULTS: 31 of the 36 radiological departments presented a homepage in the world wide web. The subject research was presented by 29 institutes. Also 29 departments provided information concerning teaching in their presentations. In 24 cases informations especially for patients were given. In all topics there is a huge variety of the quality and quantity of the provided information throughout the different institutions. 21 homepages available without restriction during the study period; 3 were nearly completely under construction. Multimedia techniques were only used in 2 homepages. The structural hierarchy of the webpages was in the average only two or three levels. Only 6 providers presented an additional version of their homepage in english. CONCLUSION: In the moment the possibility of internet-presentation is sub-optimal used by the responsible persons of the radiological institutions. The main emphasis is on research and teaching. There is nearly no use of multimedial elements in the presentations. Only a minority of the homepages can be read by international viewers because of the lack of an english version of the pages.

Germany↗
PubMed2002

[Thoracic computed tomography in intensive care patients - evaluation of clinical usefulness].

PURPOSE: Computed tomography of intensive care patients requires transportation of the patient to the radiology department. This study analyses, whether this consumption of resources is justified by therapeutical and diagnostic consequences derived from helical computertomography of the chest. METHODS: 558 CT studies of the chest were compared with current bedside chest radiographs. The additional information of CT scans and their consequences were evaluated retrospectively. RESULTS: 388 (69.5 %) of these computed tomographies provided additional information compared with projection radiographs. 374 therapeutical procedures resulted from 266 (68.6 %) out of these 388 CT examinations. These therapeutical interventions were significantly more invasive than those 144 procedures derived from 170 (30.5 %) CT studies which did not show any additional findings compared with bedside chest radiographs. CONCLUSION: In more than two thirds (69.5 %) additional diagnoses were found with computertomography. Nearly one half of the CT studies resulted in additional findings and therapeutical consequences. Invasive therapeutical consequences were based on CT studies significantly more frequently than on bedside chest radiographs.

Adolescent↗
PubMed2002

[Cost analysis of radiological interventional procedures and reimbursement within a clinic].

PURPOSE: Analysis of costs for vascular radiological interventions on a per patient basis and comparison with reimbursement based on GOA (Gebührenordnung für Arzte) and DKG-NT (Deutsche Krankenhausgesellschaft-Nebenkostentarif). MATERIAL AND METHODS: The ten procedures most frequently performed within 12 months were evaluated. Personnel costs were derived from precice costs per hour and estimated procedure time for each intervention. Costs for medical devices were included. Reimbursement based on GOA was calculated using the official conversion factor of 0.114 DM for each specific relative value unit and a multiplication factor of 1.0. The corresponding conversion factor for DKG-NT, determined by the DKG, was 0.168 DM. RESULTS: A total of 832 interventional procedures were included. Marked differences between calculated costs and reimbursement rates were found. Regarding the ten most frequently performed procedures, there was a deficit of 1.06 million DM according GOA data (factor 1.0) and 0.787 million DM according DKG-NT. The percentage of reimbursement was only 34.2 (GOA; factor 1.0) and 51.3 (DKG-NT), respectively. CONCLUSION: Reimbursement of radiological interventional procedures based on GOA and DKG-NT data is of limited value for economic controlling purposes within a hospital.

Angioplasty, Balloon↗
PubMed2002

[Contrast-enhanced MR angiography in the routine work-up of the lower extremity arteries].

PURPOSE: Prospective evaluation of the effectiveness of contrast-enhanced moving-table magnetic resonance angiography (CE-MRA) as the sole routine tool for the diagnosis of peripheral arterial occlusive disease and determination whether it can replace catheter arteriography. SUBJECTS AND METHODS: In a time period of 23 weeks, 100 consecutive patients were evaluated. A total of 112 contrast-enhanced moving-table MR angiograms were performed at 1.5 Tesla. A dedicated vascular coil system was used. It was evaluated in which cases MR angiography was sufficient to determine the treatment plan and in which cases limited quality required additional examinations. RESULTS: In 93.75 % (105/112) of all examinations, the treatment plan was determined by MRA as the sole diagnostic tool. Twenty-two patients underwent surgery or percutaneous angioplasty based on MRA findings. Additional examinations due to impaired quality were performed in seven (6.25 %) cases: two MR angiographies of the pelvic arteries, one MR angiography of the calf, and four selective arteriographies because of venous overlay at the calf. CONCLUSION: Contrast-enhanced MR angiography can take the place of catheter angiography in the routine work-up of patients with peripheral arterial occlusive disease. Further assessment might be necessary in five to ten percent of the cases when the diagnostic quality is inadequate, mostly due to venous overlay in the lower leg.

Adult↗