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Biomedical subjects

M Strotzer

Publications and source records attributed to M Strotzer.

At least 73 records · Page 4Linked to original sources
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

[Chronic, pseudocystically altered splenic hematoma as the cause of left-sided chest pain: successful therapy using alcohol instillations].

HISTORY AND CLINICAL FINDINGS: A 26-year-old man was admitted urgently because of breathing-related pain in the left thorax. This pain had started 3 months before, but had at first improved spontaneously. He had lost 13 kg during those weeks and had no recollection of any injury. Physical examination was unremarkable except for slight pain on upper-abdominal pressure and a palpably enlarged spleen. INVESTIGATIONS: All laboratory tests were normal, including the Quick value (100%), partial thromboplastin time (38 sec) and hemoglobin (14.2 g/dl). Chest radiogram showed a high left diaphragm. Abdominal sonography revealed a 12 x 10 cm moderately echogenic tumour in the spleen, extending from the splenic hilus to the upper splenic pole. Contrast-enhanced computed tomography demonstrated a hypodense tumour from which 300 ml of old blood were removed by needle puncture. Biopsy of the wall of the haematoma revealed pseudocystic transformation. TREATMENT AND COURSE: The pseudocyst again filled with blood in a few days. A drain was inserted and remained for 32 days. Six installations of alcohol achieved complete obliteration of the cystic haematoma, which did not recur. CONCLUSION: Splenic haematoma should be considered in the differential diagnosis of pain in the lower left thorax, even in the absence of a history of injury. Sonographically such a haematoma my imitate a solid tumor. Obliteration of the cavity by alcohol installation can be a successful alternative to surgical treatment.

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

[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

Dedicated head-neck coil in MR angiography of the supra-aortic arteries from the aortic arch to the circle of Willis.

PURPOSE: To evaluate the usefulness of a dedicated head-neck coil in preoperative imaging of the supra-aortic arteries. MATERIAL AND METHODS: Forty consecutive patients with suspected carotid artery stenosis underwent MR angiography (MRA). Using a dedicated head-neck coil, we made a complete evaluation of the supra-aortic arteries and graded the internal carotid artery (ICA) stenoses. MRA was performed at 1.5 T with: coronal 3D FISP from the aortic arch to the circle of Willis; transverse 2D FLASH and 3D TONE of the carotid bifurcation; transverse 3D TONE of the carotid siphon and the circle of Willis; and transverse 3D FISP of the aortic arch. I.a. digital subtraction angiography (DSA) was used as the reference. ICA stenoses of 70% and more at DSA (NASCET methodology) were regarded as severe. RESULTS: Severe ICA stenoses were detected with high sensitivity and specificity: 93% and 92% respectively for coronal 3D FISP; 90% and 85% respectively for transverse 2D FLASH; and 97% and 94% respectively for transverse 3D TONE. The carotid siphon and the intracranial ICA were best depicted by 3D TONE. None of the applied sequences gave a satisfactory visualization of the aortic arch or of the origins of the vertebral arteries. CONCLUSION: With the head-neck coil, the supra-aortic arteries (including the intracranial vessels) were visualized without the need to reposition the patient, but depiction of the aortic arch was not acceptable. The quantification of ICA stenoses was reliable.

Aged↗
PubMed1998

Air oesophagogram: a frequent, but not a specific sign of oesophageal involvement in connective tissue diseases.

OBJECTIVE: This study investigates the role of the air oesophagogram in conventional chest X-rays for the diagnosis of oesophageal dysmotility in patients with connective tissue diseases. METHODS: Fifty-one patients with connective tissue diseases were studied by oesophageal manometry and lateral and posterior-anterior chest X-rays. The presence or absence of oesophageal air on chest X-rays were evaluated separately in the upper, middle and distal segment of the oesophagus. Forty-seven chest X-rays of patients without connective tissue diseases, who had undergone manometry for the evaluation of oesophagus-related symptoms and who had normal oesophageal function, were analysed as a control. RESULTS: A total of 23/51 patients with connective tissue diseases showed oesophageal dysfunction in manometry; 16/51 patients (31%) had air in two or more oesophageal segments on the lateral chest X-ray. There was a significant association of manometrically proven oesophageal dysmotility and air in two or three oesophageal segments (P < 0.05; sensitivity 48%, specificity 82%). However, the prevalence of an air oesophagogram showed no significant difference between patients with connective tissue diseases and the control group (10/47; 21%). CONCLUSION: The radiological sign of an air oesophagogram is neither sensitive nor specific enough to omit oesophageal motility studies in patients with connective tissue diseases.

Air↗
PubMed1998

Amorphous silicon, flat-panel, x-ray detector versus screen-film radiography: effect of dose reduction on the detectability of cortical bone defects and fractures.

RATIONALE AND OBJECTIVES: The purpose of this phantom study was to assess the diagnostic performance of a self-scanning, solid-state amorphous silicon (a-Si) detector in skeletal radiography using different exposure parameters. METHODS: A flat-panel detector (15 cm x 15 cm), based on a-Si technology with 143 microm x 143 microm pixel size, 1k x 1k matrix, and 12 bit digital output was used. State-of-the-art screen-film radiography (SFR; speed 400, detector dose 2.5 microGy) was compared with a-Si images taken at doses that were equivalent to a speed of 400, 800, 1,250, and 1,600, respectively. A total of 232 segments of long tubular deer-bones (femur, tibia, humerus, radius) had 110 artificial fractures and 112 cortical defects simulating osteolytic lesions. Receiver operating characteristic analysis was performed for 9,280 observations made by four independent observers. Two-tailed Student's paired t test was used for statistical analysis (95% confidence level). RESULTS: Receiver operating characteristic analysis yielded equivalent results of the a-Si and SFR system. Even at the lowest dose there were no statistically significant differences between both imaging modalities with respect to the detectability of fractures and cortical defects. CONCLUSIONS: The results of this study indicate that a-Si detector technology holds promise in terms of dose reduction in skeletal radiography without loss of diagnostic accuracy.

Animals↗
PubMed1998

Detection of simulated chest lesions with normal and reduced radiation dose: comparison of conventional screen-film radiography and a flat-panel x-ray detector based on amorphous silicon.

RATIONALE AND OBJECTIVES: The authors compared a solid-state amorphous silicon (a-Si) detector and screen-film radiography (SFR) with regard to the detection of simulated pulmonary lesions. Evaluation of the impact of a dose reduction of 50% with this digital flat-panel detector was of special interest. METHODS: A self-scanning flat-panel detector, based on a-Si technology with 143 x 143 microm pixel size, 1 k x 1 k matrix and 12-bit digital output was used. An asymmetric state-of-the-art screen-film system was compared with a-Si images taken at the same dose as SFR-images and at a dose reduced by 50%. An anthropomorphic chest phantom was superimposed by templates containing nodules, linear structures, reticular, and micronodular opacities in a random distribution. Receiver operating characteristic analysis was performed for 23,040 observations made by four independent observers. Student's t test (95% confidence-level) was used for statistical analysis. RESULTS: Receiver operating characteristic analysis showed that a-Si images taken at the same dose as SFR-images were significantly superior to SFR with respect to the detectability of lines (P = 0.01) and micronodular opacities (P < 0.01). For the other objects and the a-Si images taken at a reduced dose, it yielded no statistically significant differences between both imaging modalities. CONCLUSIONS: The results of this phantom study indicate that a-Si detector technology holds promise in terms of dose reduction in chest radiography without loss of diagnostic accuracy compared with SFR.

Humans↗
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

MR angiography of the supra-aortic arteries using a dedicated head and neck coil: image quality and assessment of stenoses.

Our purpose was to evaluate a dedicated head and neck coil for demonstration of supra-aortic arteries with optimised magnetic resonance angiography techniques. We performed 47 examinations with a 1.5-T system. We used coronal 3D fast imaging with steady precession (FISP), axial 3D tilted optimised nonsaturating excitation (TONE) and 2D fast low-angle shot (FLASH) for the carotid bifurcation, axial 3D TONE with or without magnetisation transfer (MT) for intracranial arteries, and axial 3D FISP or TONE for the aortic arch. Evaluation included visual assessment of image quality and grading of stenoses near the carotid bifurcation; digital subtraction angiography was used as the reference method. Axial 3D TONE gave superior image quality at the carotid bifurcation, MT-TONE intracranially, and 3D FISP for the aortic arch vessels. Nevertheless, sensitivity and specificity for detection of significant stenoses were similar with coronal 3D FISP (96.3%, 94.0%), axial 3D TONE (92.6%, 92.5%) and axial 2D FLASH (96.3%, 86.6%). Image quality at the aortic arch needs further improvement.

Aged↗
PubMed1997

Diagnosis of liver metastases from colorectal adenocarcinoma. Comparison of spiral-CTAP combined with intravenous contrast-enhanced spiral-CT and SPIO-enhanced MR combined with plain MR imaging.

PURPOSE: The purpose of this study was to determine whether MR with and without SPIO (AMI-25) could replace spiral-CTAP in the staging of colorectal adenocarcinoma. MATERIAL AND METHODS: Thirty-five patients were studied prospectively by means of i.v. contrast-enhanced spiral-CT, spiral-CTAP, and MR of the liver. MR imaging was performed before and after infusion of AMI-25. Diagnoses were compared to intraoperative findings (n = 35) which included intraoperative ultrasound (n = 21), and follow-up CT (n = 18). RESULTS AND CONCLUSION: Fifteen patients were found to have a total number of 53 liver metastases and 43 benign lesions were detected. Evaluation was performed in four different ways: 1) i.v. contrast-enhanced spiral-CT; 2) i.v. contrast-enhanced spiral-CT + spiral-CTAP; 3) plain MR; 4) plain MR + SPIO-enhanced MR. I.v. contrast-enhanced spiral-CT, spiral-CTAP and SPIO-enhanced MR identified patients with liver metastases with equal sensitivity. However, owing to its significantly higher sensitivity, based on a lesion-by-lesion analysis, spiral-CTAP cannot be replaced by SPIO-enhanced MR in patients who are to undergo liver resection. A limitation in spiral-CTAP is its relatively low specificity.

Adenocarcinoma↗
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↗
PubMed1996

Fluid therapy with Ringer's solution versus Haemaccel following coronary artery bypass surgery.

BACKGROUND: Crystalloid and colloid infusion can be used in volume therapy following heart surgery. In this prospective, randomised study we compared Ringer's solution (group R) to Haemaccel (group H) following coronary artery bypass grafting. METHODS: A stringent protocol for adjusting the infusion rate was used. Haemodynamic parameters and pulmonary function were evaluated as well as chest tube drainage. The double-indicator dilution method was used to measure total blood volume index (TBVI), intrathoracic blood volume index (ITB-VI) and extravascular lung water index (EVLWI). RESULTS: Haemodynamic stability was achieved in both groups throughout the study period, as judged from mean arterial pressure, central venous pressure, pulmonary capillary wedge pressure, and cardiac index. However, the total volume infused was significantly higher in group R. TBVI and ITBV were higher in group H, although only significant at 8 h for TBVI. Pulmonary function was similar in both groups. There was no significant difference in EVLWI, pulmonary shunt fraction, and time on mechanical ventilation. Likewise, chest tube drainage was not significantly different in both groups. CONCLUSION: We conclude that volume therapy with Haemaccel following heart surgery requires less volume and achieves better filling of the circulation compared to Ringer's solution.

Aged↗
PubMed1995

[Accuracy of artificial neural networks in radiological differential diagnosis of solitary bone lesions].

PURPOSE: To evaluate the usefulness of artificial neural networks (ANN) for differential diagnosis of bone tumours and tumour-like lesions. MATERIAL AND TECHNIQUE: Different ANN were designed to distinguish between 23 types of bone lesions and to classify these lesions as benign or malignant on the basis of 28 items of clinical and radiographic information. Training of the feed-forward networks with a back-propagation algorithm was performed using either 46 hypothetical examples or 115 real cases. The data base for testing the different ANN included 115 clinical cases (5 cases for each possible diagnosis), which were different from the examples used for training. The decision performance of the ANN was evaluated by means of ROC analysis. Results were compared to the performance of an experienced radiologist. RESULTS: The radiologist was significantly superior in finding the correct diagnosis (69/115 vs. 41/115; p < 0.001) and the area under his ROC curve (referring to the discrimination between benign and malignant lesions) was slightly larger than that of two different ANN (0.973 vs. 0.945 and 0.973 vs. 0.962 resp.; differences not significant). CONCLUSION: ANN may be potentially useful to distinguish between malignant and benign lesions, but their performance in differentiating between 23 diagnoses must be improved significantly.

Algorithms↗