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Biomedical subjects

C Manke

Publications and source records attributed to C Manke.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Therapy of iliac artery lesions with a new premounted balloon-expandable stent ("Flexible Iliac Bridge Stent")].

PURPOSE: Evaluation of the handling, technical success rate and six month patency rate of a new, premounted balloon-expandable stent in iliac artery lesions. MATERIALS AND METHODS: In a prospective study 26 stenoses and 3 occlusions of the iliac arteries were primary treated in 24 patients (Fontaine IIa-III, mean age 60.4 year) with the "Flexible Iliac Bridge Stent" (Medtronic AVE, Düsseldorf). Five patients had bilateral stenoses. The ankle-brachial index (ABI) in rest and after exercise was determined before the intervention as well as 1-3 days, 1 and 6 months after the Intervention. The handling and visibility of the stent was scored on a three grade scale by the operators. Follow-up angiography including intraarterial pressure measurement was performed in 17 out of 24 patients (21 out of 29 lesions) after 6 months. RESULTS: All 29 lesions were treated with technical success by implantation of 36 stents. The mean degree of the stenoses before intervention was 72.7 +/- 13.8% (+/- 1 standard deviation) and less than 5% in all cases postinterventionally. The mean pressure gradient before and after stent placement was 21 +/- 13.1 mm Hg and 0.8 +/- 2.3 mm Hg, respectively. The Fontaine stage improved by at least one in all patients. The mean ABI at rest improved from 0.63 +/- 0.15 to 0.89 +/- 0.16, and after exercise from 0.46 +/- 0.17 to 0.8 +/- 0.2, respectively. At 6 months 2 lesions out of 21 (9.5%) showed a restenosis of 55% and 70% with an intraarterial pressure gradient of 16 mm Hg and 27 mm Hg, respectively. After 6 months the mean ABI at rest decreased to 0.83 +/- 0.13, and to 0.72 +/- 0.14 after exercise. Handling and visibility was scored as good by all operators. CONCLUSION: Endoluminal therapy of iliac artery lesions with the used stent is safe and effective. The six month patency rate is comparable to the published data of other stents.

Adult↗
PubMed2000

[Contrast media-enhanced MR angiography of the lower extremity arteries using a dedicated peripheral vascular coil system. First clinical results].

PURPOSE: To evaluate contrast enhanced magnetic resonance angiography (ceMRA) of the pelvic and peripheral arteries with a dedicated peripheral vascular coil system and automated table-feed technique in patients with arterial occlusive disease. METHODS: Three-dimensional gadolinium-enhanced MR angiography in a two-step automatic table feed technique was performed in 45 patients using a 1.5 Tesla imager (Magnetom Symphony, Siemens). The pelvic arteries were imaged with a single injection of contrast material. The upper and the lower leg were imaged with a second injection of contrast material in an automated table feed technique using a dedicated vascular coil system. In 20 patients ceMRA was compared with digital subtraction angiography (DSA) as the standard of reference and in 25 patients ceMRA was performed solely. RESULTS: Sensitivity and specificity for grading significant stenoses > or = 50% and occlusions (in parenthesis) were in the pelvic arteries 94.7%, 96.8%, (100%, 100%), in the arteries of the upper leg 92.3%, 93.3% (87.5%, 100%) and in the arteries of the lower leg 96.5%, 95.8%, (95.2%, 96.8%), respectively. Depiction of the runoff vessels of the lower leg was excellent in ceMRA. CeMRA was of diagnostic quality in all the patients. CONCLUSION: Contrast-enhanced MRA using a dedicated peripheral vascular coil system increases the diagnostic quality of the lower leg. The runoff vessels can be evaluated. Thus, ceMRA in the presented technique is a diagnostic alternative to arterial angiography.

Adult↗
PubMed2000

Morphology and hemodynamics in dissection of the descending aorta. Assessment with MR imaging.

PURPOSE: To obtain morphologic and functional information in patients with dissection of the descending aorta using contrast-enhanced MR angiography (MRA) and MR blood flow quantification of the true and false lumina. MATERIAL AND METHODS: Fourteen patients were studied prospectively using a 1.5 T unit. MRA was performed with a 3D FISP sequence (TR/TE/flip angle 4.7/1.9 ms/30 degrees) after injection of 0.2 mmol Gd-DTPA per kg b.w. Flow quantification with phase velocity mapping was done at the level of the diaphragm using a 2D FLASH technique (TR/TE/flip angle 28/6.5 ms/30 degrees) with an average temporal resolution of 23 frames per cardiac cycle (34 ms). A spectral broadening index was applied to quantify the amount of flow irregularity within both channels of the aorta. Extension of the dissection and involvement of the major branch vessels were analyzed. RESULTS: The mean flow volume per minute was 1,982 ml (SD 1,083 ml) in the true and 1,052 ml (SD 763 ml) in the false lumen. Average peak-velocities were 98 cm/s (SD 33 cm/s) in the true channel and 47 cm/s (SD 26 cm/s) in the false channel. Ten patients had bidirectional flow in the false lumen with a reflux volume ranging between 6.8% and 98%. Only 1 patient presented with bidirectional flow in the true lumen (reflux volume 15%). A significantly higher degree of flow irregularity was found in the false lumen compared with the true channel. CONCLUSION: Different hemodynamic patterns were found in aortic dissection. Their prognostic value and the impact on therapy, specifically percutaneous interventional procedures, have to be further studied.

Adult↗
PubMed2000

Magnetic resonance monitoring of stent deployment: in vitro evaluation of different stent designs and stent delivery systems.

RATIONALE AND OBJECTIVES: To evaluate MR imaging features of commercially available stents before, during, and after in vitro deployment as a step toward MR-guided stent deployment. METHODS: Fourteen stents were deployed in a phantom under MR monitoring at 1.5 T by using a gradient-echo sequence. Device visibility was rated on a four-point scale (excellent, fair, poor, not visible). RESULTS: The Memotherm stent and the rolling membrane (RM) Wallstent showed excellent stent visibility and at least fair scores for artifact-induced narrowing of the stent lumen. Three stents (Palmaz, AVE, Easy Wallstent) showed excellent visibility of the stent but no visible lumen. Five stents (Strecker, Accuflex, Hemobahn, Passager, Sinus) displayed fair visibility. The delivery catheters of four stent systems (Smart, Vascucoil, Symphony, ZA) displayed severe black hole artifacts. CONCLUSIONS: The imaging features of several stent systems might be suitable for MR-guided intervention. The Memotherm and the Wallstent RM combine good visibility of the stent and the lumen.

Blood Vessel Prosthesis↗
PubMed2000

Chest radiography with a large-area detector based on cesium-iodide/amorphous-silicon technology: image quality and dose requirement in comparison with an asymmetric screen-film system.

The purpose of this study was to evaluate a large-area, flat-panel X-ray detector, which uses cesium-iodide (CsI) and amorphous silicon (a-Si). Conventional images were compared with digital images acquired with equal dose (2.5 microGy) and with 50% dose reduction. Fifteen consecutive patients were studied prospectively using an asymmetric screen-film system (detector dose, 2.5 microGy). Digital images were taken from the same patients in a posteroanterior view with detector doses of 2.5 and 1.25 microGy, respectively. The CsI/a-Si active-matrix imager had a panel-size of 43 x 43 cm, a matrix of 3 x 3k, and a pixel-pitch of 143 microm. Hard copies were presented in a random order to eight independent observers, who rated image quality according to six subjective quality criteria. Statistical significance of differences was evaluated with Student's t test for paired samples (confidence level, 95%). Digital radiographs with 2.5 and 1.25 microGy were superior to conventional images regarding all quality criteria. Statistically significant differences were observed for five of six criteria at a detector dose of 2.5 microGy and for only one quality feature at 1.25 microGy. Flat-panel digital imagers based on CsI/a-Si technique have the potential to replace conventional systems and might allow a reduction of radiation dose by 50% without loss of image quality.

Adult↗
PubMed2000

Stent appearance at contrast-enhanced MR angiography: in vitro examination with 14 stents.

PURPOSE: To evaluate signal intensity changes influencing assessment of stent patency at contrast material-enhanced magnetic resonance (MR) angiography. MATERIALS AND METHODS: By using an in vitro model, 14 stents-nine nitinol, one tantalum, two stainless steel, and two cobalt alloy-were investigated regarding their appearance at MR imaging. A vascular phantom consisting of tubes filled with 2.00 mmol/L gadopentetate dimeglumine in saline solution was studied in different orientations within the magnetic field. Imaging was performed with a fast three-dimensional gradient-echo sequence (4. 70/1.89 [repetition time msec/echo time msec]). Relative signal intensity reduction within the stents and the degree of artificial narrowing of the stent lumen were calculated. RESULTS: The stent lumen was visible within 13 stents. A total signal void inside the stent lumen appeared in only one cobalt alloy stent. Artificial narrowing of the diameter was less than 33% in 10 of 14 stents. The tantalum stent and four nitinol stents seemed best suited for contrast-enhanced MR angiography. A bandlike artifact occurred at the ends of the stents when positioned along the readout direction. CONCLUSION: To differentiate between artifacts and stenoses, knowledge of the degree of signal intensity reduction and artificial lumen narrowing within vascular stents is essential. Stent geometry, relative orientation to the magnetic field, and alloy composition influence signal intensity alteration within the stent lumen.

Contrast Media↗
PubMed2000

Time-resolved contrast-enhanced MR angiography of renal artery stenosis: diagnostic accuracy and interobserver variability.

OBJECTIVE: The purpose of this study was to evaluate diagnostic accuracy and interobserver variability of time-resolved three-dimensional gadolinium-enhanced MR angiography in the detection of renal artery stenosis in comparison with intraarterial digital subtraction angiography as the standard of reference. SUBJECTS AND METHODS: Forty consecutive patients (age range, 25-81 years; mean, 62.9 +/- 11.9 years) with suspected renal artery stenosis underwent intraarterial digital subtraction angiography and gadolinium-enhanced MR angiography, performed on a 1.5-T system with fast low-angle shot three-dimensional imaging (3.8/1.49 [TR/TE], 25 degrees flip angle, 10-sec acquisition time, and 1.5-mm partition thickness). Three time-resolved phases were obtained in a single breath-hold. Digital subtraction angiography and gadolinium-enhanced MR angiography were evaluated by four observers who studied 80 main renal arteries and 19 accessory vessels to evaluate the degree of stenosis. A stenosis reducing the intraarterial diameter by more than 50% was regarded as hemodynamically significant. Interobserver variability was calculated. RESULTS: Only one gadolinium-enhanced MR angiography study was not of diagnostic quality, as a result of failure of the power injector. All main branches were of diagnostic quality in 38 (97.4%) of the remaining 39 gadolinium-enhanced MR angiography studies. Seventeen (89.5%) of 19 accessory renal arteries were depicted with gadolinium-enhanced MR angiography. The overall sensitivity for significant stenoses was 92.9%. The overall specificity was 83.4%, and the overall accuracy was 85.9%. Interobserver variability of gadolinium-enhanced MR angiography exceeded that of digital subtraction angiography. CONCLUSION: Time-resolved three-dimensional gadolinium-enhanced MR angiography is a useful noninvasive method of screening suspected renal artery stenosis because of its easy application, short examination time, and high sensitivity despite of its higher interobserver variability.

Adult↗
PubMed1999

[Contrast medium-enhanced MR angiography of the pelvic and leg vessels with an automated table-feed technique].

PURPOSE: To evaluate contrast enhanced magnetic resonance angiography (ceMRA) with an automated table-feed technique in patients with arterio-occlusive disease for imaging of the pelvic and peripheral arteries. METHODS: Twenty-two patients underwent three-dimensional gadolinium-enhanced MR angiography in a three-step automatic table-feed technique on a Magnetom Symphony operating at 1.5 Tesla. Maximum intensity projection images (MIP) were generated from the subtracted and original studies. Image quality and venous contrast were evaluated by two groups of observers. 304 vessels (17 patients) were compared with DSA as the standard of reference. RESULTS: All examinations were performed without any technical problems. Diagnostic quality of the MIP of subtracted data sets was superior to that of the unsubtracted images. Venous overlay was 61% in the lower leg. In a total of 599 observations, a sensitivity of 96% (95%, 82%) and a specificity of 87% (88%, 99%) were high compared to DSA in the detection of significant stenoses > or = 50% (> or = 75%, occlusions). Interobserver correlation was good (linear correlation 0.9). CONCLUSION: Stepping-table digital subtraction contrast enhanced MRA is a promising technique in the diagnosis of peripheral arterio-occlusive disease.

Aged↗
PubMed1999

[Transfemoral pelvic vein angiography with CO2: experiences with pressure- and volume-controlled injections].

PURPOSE: To evaluate the efficacy of CO2 in aortobifemoral DSA with a pressure- and volume-controlled injector. MATERIALS AND METHODS: In an intraindividual prospective study, 42 patients with arterial occlusive disease underwent stepwise aortobifemoral DSA with CO2 and with iopromid 300. RESULTS: With Co2, diagnostic images were obtained in 74% of the iliac, 98% of the femoral, 89% of the popliteal arteries, but in only 36% of the arteries of the lower leg. 73% of the stenoses were correctly identified. With therapeutic relevance 8% of the stenoses were overestimated. The length of 1 of 53 occlusions was overestimated and 3 occlusions were simulated. No stenoses or occlusion was missed. There were no severe side-effects. The injector proved to be safe and easy to handle. Fragmentation of the CO2 bolus could be compensated by postprocessing with a minimum opacification summation mode. CONCLUSIONS: With the equipment used, CO2 was a safe alternative to iodinated CM in routine stepwise aortobifemoral DSA of the iliac, femoral, and popliteal arteries. Because of the risk of overestimation, occlusions and high grade stenoses should be verified with selective injections or iodinated CM before PTA or operations.

Adult↗
PubMed1999

[Ischemic complications in aortic dissection--percutaneous treatment with balloon fenestration and stent implantation].

PURPOSE: To describe principles and results of percutaneous treatment of ischemic complications of aortic dissection. MATERIALS AND METHODS: In five cases (four patients) aortic dissection was clinically complicated by renal (n = 4), iliofemoral (n = 2) or mesenterial ischemia (n = 1). After evaluation by means of computed tomography, angiography, and manometry, treatment consisted of balloon fenestration of the intimal flap, stent placement or both. RESULTS: Eleven of 25 vascular beds were classified as ischemic. Treatment consisted of 11 balloon fenestration procedures in 3 patients, in one case supported by stent placement across the dissection membrane. Stents were placed in five renal arteries, one stent was placed in the true lumen of the aorta. One iliac artery was treated with balloon dilatation. One renal artery dissection became symptomatic after balloon fenestration and was treated successfully by stent placement. In all cases ischemia was resolved by endovascular treatment. All patients had persistent relief of symptoms. Mean follow-up time is 5.8 months. CONCLUSION: Ischemic complications of aortic dissection can be effectively and safely treated with stent placement and balloon fenestration.

Adult↗
PubMed1998

Ischiogluteal bursitis mimicking soft-tissue metastasis from a renal cell carcinoma.

We report a case of ischiogluteal bursitis mimicking a soft-tissue metastasis from a renal cell carcinoma. A 66-year-old woman suffered from pain over the left buttock 6 months after she was operated on for renal cell carcinoma of the left kidney. CT of the abdomen and pelvis revealed a tumor-like lesion adjacent to the left os ischii, which was suspected to be a soft-tissue metastasis. Percutaneous biopsy revealed no evidence of malignancy, but the histopathological diagnosis of chronic bursitis.

Aged↗
PubMed1998

[Radiologic implantation of central venous portal systems in the forearm].

PURPOSE: To assess the safety and effectiveness of fluoroscopic guided brachial implanted central-venous miniport systems. PATIENTS AND METHODS: In 32 oncological patients a central-venous miniport system (Vital-Port, CPC-Cook) was implanted in the forearm. The group included 15 women and 17 men (range 33-78, mean 56 years). RESULTS: Technical success was 100%, in 6 patients vasospasm produced difficulties in catheter placement. In a total of 2878 patients days (range 3-445, mean 90 days) 5 complications occurred (15.6%, 1.7 on 1,000 catheterdays): In one patient (3.13%, 0.35/ 1000 d) the system was changed due to leakage of the catheter near the chamber. Four patients had minor complications: in one case excision of a suture line granuloma was necessary, one haematoma at the site of the chamber was treated with dressing, one patient had a wound dehiscence and one occluded catheter returned to patency by flushing the system with contrast material. Venous thrombosis, phlebitis, catheter dislocation, paravasation or system-related infection did not occur. CONCLUSION: Fluoroscopic guided peripheral central-venous port implantation is a safe and easy procedure with a high success rate and a low complication rate which can be performed in an outpatient setting.

Adult↗
PubMed1998

[Percutaneous abscess drainage in Crohn disease].

PURPOSE: To evaluate the success of percutaneous, CT-guided abscess drainage (PAD) in patients with Crohn's disease. METHODS: Within the last 5 years 8 patients with Crohn's disease were treated by PAD for intra-abdominal abscesses. A fistula was determined to be the cause in 4 patients. The abscesses arose spontaneously in 7 patients while one patient had a postoperative abscess. We used single lumen 10 F- and double lumen 12 F- and 14 F-catheters for drainage (duration of drainage 8-20 days). RESULTS: In all cases the abscess was successfully drained by PAD. However, an operation-free interval of at least three months was achieved in only two patients. A healing of the fistula was not attained in any of the 4 patients with a proven fistula. No enterocutaneous fistulas arose within the course of PAD. CONCLUSIONS: PAD is also useful for patients with Crohn's disease since it improves the starting situation for the necessary operative interventions. In most cases (especially with enterogenic fistulas), however, a long-lasting therapeutic result cannot be expected.

Abdominal Abscess↗
PubMed1998

Clinical application of a flat-panel X-ray detector based on amorphous silicon technology: image quality and potential for radiation dose reduction in skeletal radiography.

OBJECTIVE: The purpose of this study was to compare images obtained with a self-scanning, flat-panel X-ray detector based on amorphous silicon technology with conventional screen-film radiographs and to evaluate the possibility of radiation dose reduction in skeletal radiography. SUBJECTS AND METHODS: One hundred twenty patients were examined prospectively using a conventional screen-film system (speed, 400; detector dose, 2.5 microGy) and a prototype digital amorphous silicon detector (simulated speed, 400 and 800, n = 120; simulated speed, 1600, n = 40). The resulting 400 images were evaluated independently by six radiologists using a subjective five-point preference scale that rated overexposure, underexposure, contrast resolution, spatial resolution, and soft-tissue presentation. Image quality was ranked on a scale from 0 to 10 according to subjective criteria. Statistical significance of differences was determined using Student's t test and confidence intervals (95% confidence level). RESULTS: Comparison of conventional radiographs with digital images revealed a statistically significant preference for the digital system for soft-tissue presentation (speed 400 and 800) and visualization of osteoarthrotic changes (speed 400). A small but statistically significant preference for conventional images was found with respect to contrast and spatial resolution when digital speed was 800 or 1600; and the visibility of arthrosis at digital speed 1600, osteolysis at digital speed 800 and 1600, and fractures at digital speed 1600. CONCLUSION: The amorphous silicon-based system with a simulated speed of 400 provided images equivalent to screen-film radiographs. For clinical tasks such as routine follow-up studies, assessment of instability, or orthopedic measurements, a radiation dose reduction of up to 75% may be possible.

Aged↗
PubMed1997

[Computer tomography-guided gastrostomy, jejunostomy and gastrojejunostomy. A reliable non-surgical method also for contraindications and failure of percutaneous endoscopic gastrostomy].

OBJECTIVE: To analyse retrospectively the results of CT (computed tomography)-guided gastrostomy or gastroenterostomy where an endoscopic procedure was not possible or had failed. PATIENTS AND METHODS: Between August 1993 and March 1997, CT-guided gastrostomy (n = 50) or gastroenterostomy (n = 8) was performed in 58 patients (mean age 56 +/- 6 years; 51 males, 7 females). An endoscopic or fluoroscopic method had been contraindicated in 52 and had failed in 6 patients. RESULTS: Technical success was achieved in all patients. Three patients needed intravenous sedation. There were no procedure related complications requiring treatment. Three patients had a mild infection at the site of the skin puncture. CONCLUSION: CT-guided gastrostomy or gastroenterostomy is a safe and simple procedure which provides a minimally invasive alternative also in patients with contraindications to the established percutaneous method.

Adult↗
PubMed1997

Flat-panel x-ray detector using amorphous silicon technology. Reduced radiation dose for the detection of foreign bodies.

RATIONALE AND OBJECTIVES: The authors evaluate a new flat-panel x-ray detector (FD) with respect to foreign body detection and reduction of radiation dose compared with screen-film radiography. METHODS: Flat-panel x-ray detector is based on amorphous silicon technology and uses a 1 k x 1 k photo-detector matrix with a pixel size of 143 x 143 microns and 12-bit digital output. A thallium-dotted cesium iodide scintillation layer converts x-rays into light. An ex vivo experimental model was used to determine the detectability of foreign bodies. Foreign bodies with varying sizes were examined: glass with and without addition of lead, bone, aluminium, iron, copper, gravel fragments, and graphite. Four hundred observation fields were examined using conventional radiography (speed, 400; system dose: 2.5 microGy) as well as FD with a simulated speed of 400, 800, 1200, and 1600, corresponding to a detector dose of 2.5 microGy, 1.25 microGy, 0.87 microGy, and 0.625 microGy, respectively. Four independent radiologists performed receiver operating characteristic analysis of 8000 observations. RESULTS: Flat-panel x-ray detector with a simulated speed of 400 was significantly superior (P = 0.012) to screen-film radiography (speed, 400). At a simulated speed of 800 and 1200 FD yielded results equivalent to screen-film radiography. Flat-panel x-ray detector was significantly inferior to screen-film radiography at a simulated speed of 1600 (P = 0.012). CONCLUSIONS: Flat-panel x-ray detector technology allows significant reduction in radiation dose compared with screen-film radiography without loss of diagnostic accuracy.

Foreign Bodies↗
PubMed1995

Identification of the valine 408 to methionine mutation in the LDL receptor in a Greek patient with homozygous familial hypercholesterolemia.

We have identified the cytosine to thymine change in the codon for amino acid 408 which causes valine to be replaced by methionine in exon 9 of the LDL receptor gene in a 12-year-old Greek boy living in Germany, with homozygous familial hypercholesterolemia, by using polymerase chain reaction-amplified genomic DNA and subsequent restriction digestion. Homozygosity was confirmed by direct DNA sequencing. The mutation was present in both his parents, and his brother, grandmother, uncle and cousin. Six restriction fragment length polymorphisms of the LDL receptor gene were used to determine the haplotype of the defective allele. The haplotype was different from the one reported earlier in African Afrikaners and from Holland. We conclude that the mutation in the Greek boy probably occurred as an independent mutation. Because the parents are from different areas in Greece, this mutation may be common in Greeks.

Base Sequence↗