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S Obenauer

Publications and source records attributed to S Obenauer.

36 records · Page 2Linked to original sources
PubMed2002

Average glandular dose with amorphous silicon full-field digital mammography - Clinical results.

PURPOSE: Determination of average glandular dose with a full-field digital mammography system using a flat-panel X-ray detector based on amorphous silicon technology for a large group of patients. MATERIAL AND METHODS: The patient group includes women who were examined in a 4-month period with the digital mammographic system Senographe 2000D. The number of women was 591 and the number of exposures was 1116; only cranio-caudal projections were considered. Various quantities, including entrance surface air kerma, tube loading, and compressed breast thickness, were determined during actual mammography. Average glandular dose was determined using conversion factors g for standard breast composition. RESULTS: The mean average glandular dose was 1.51 mGy (0.66 - 4.05 mGy) for a single view. The mean compressed breast thickness was 55.7 mm. The mean age of patients was 55 years (34 - 81 years). CONCLUSION: The results demonstrate that full-field digital mammography with a flat-panel detector based on amorphous silicon needs about 25 % less dose in comparison with conventional screen-film mammography.

Adult↗
PubMed2001

[Value and significance of digital full-field mammography within the scope of mammography screening].

To evaluate the digital technique for screening mammography various experimental studies and clinical examinations were performed by using direct full-field digital mammography (FFDM). The findings concerning the detectability and characterization of microcalcifications and soft tissue masses as well as the radiation exposure were compared to the state-of-the-art conventional screen-film mammography (SFM). The results of these studies revealed a high performance of the digital images, which are at least equivalent to the conventional images, whereas digital spot views were significantly superior to conventional ones particularly in the detection of microcalcifications. This was especially true, when the potential of post-processing was used. In addition, the sensitivity of FFDM should be increased, if computer-aided-diagnosis (CAD) is available. Furthermore, the patient radiation dose can be significantly reduced. Additional advantages are quick and easy handling, efficient data transfer and digital archiving. Thus, FFDM will become an important tool in screening mammography.

Breast Neoplasms↗
PubMed2001

[Stereotactic vacuum core biopsy of clustered microcalcifications classified as B1-RADS 3].

PURPOSE: Evaluation of stereotactic vacuum core biopsy of clustered microcalcifications categorized as BI-RADS 3. MATERIAL AND METHODS: 86 patients with microcalcifications BI-RADS 3 (probably benign, < 3% malignant) underwent a stereotactic vacuum core biopsy (Mammotome, Fa. Ethicon Endo-Surgery Breast Care) using a digital stereotactic unit (Mammotest, Fa. Fischer Imaging). The removal of the calcifications was judged by two radiologists in consensus and classified as complete (100%), major (55-99%) or incomplete (< 50%). RESULTS: 4/86 patients could not be evaluated by vacuum core biopsy due to the localization of the microcalcifications close to the skin or lack of detection. In 40/82 cases a complete, in 38/82 a major, and in 4/82 a incomplete removal was achieved. Histology revealed 67 cases of fibrocystic changes, 4 papillomas, 4 fibroadenomas, 4 cases of atypical ductal hyperplasia (ADH), and 3 ductal carcinomas in situ (DCIS), one of these with a minimal-invasive tumor component. Patient with ADH were advised to undergo surgical biopsy. Histology revealed complete removal. 7 patients had complications or side-effects. CONCLUSIONS: Percutaneous vacuum core biopsy is a reliable minimal-invasive diagnostic method to come to the final diagnosis in patients with clustered microcalcifications categorized BI-RADS 3. However, if malignancy is proven (about 4% of our cases) an open biopsy is necessary.

Adult↗
PubMed2001

Rupture of an abdominal aortic aneurysm due to aortic wallstent dislocation masquerading as renal colic.

Placement of an aortic wallstent for treatment of an abdominal aortic aneurysm (AAA) is a frequent therapeutic measure. Whereas AAA is known to mimic renal colic, aortic wallstent dislocation is a novel diagnostic problem. Herein, we report the first case of a patient with a dislocated aortic wallstent and subsequent aneurysm rupture and discuss appropriate diagnostic measures.

Aged↗
PubMed2000

Persistent hypocalcemia with elevated parathyroid hormone levels after long-term primary hyperparathyroidism: report of a case.

We report herein the case of a 48-year-old man with long-term persistent primary hyperparathyroidism (pHPT) despite undergoing a parathyroidectomy in 1976, followed by a reoperation in 1978, for whom resection of a parathyroid adenoma in the upper mediastinum was eventually performed. His postoperative course was complicated by recurrent hypocalcemia refractory to oral calcium substitution and significantly elevated levels of parathyroid hormone (PTH). The radiological findings are presented, and we discuss the possible reasons for the coincidence of severe hypocalcemia with increased PTH levels in association with pHPT.

Adenoma↗
PubMed2000

[Full-field digital mammography: a phantom study for detection of microcalcification].

OBJECTIVES: The study compares direct full-field digital mammography (FFDM) to the state-of-the-art conventional screen-film mammography (SFM) concerning the detectability of simulated microcalcifications. MATERIALS AND METHODS: The investigations were performed with a FFDM system (Senographe 2000D, GEMS) and a SFM system (Senographe DMR, GEMS, Fuji UM MA film with Fuji UM MAMMO FINE screen). An anthropomorphic breast phantom with superimposed microcalcifications (50-200 microns) was used to evaluate the detectability of microcalcifications with a confidence level ranging from 1 to 5. Contact mammograms and magnification spot views (m = 1.8) of the FFDM and SFM systems were compared. A receiver operating characteristic (ROC) analysis was performed by three well-experienced readers. RESULTS: The ROC analysis revealed a higher performance of the digital images compared to the conventional screen-film mammograms. The area under the ROC-curve (Az) in the digital contact mammograms was 0.68 versus 0.63 in the conventional technique. The results were not significantly different. In digital spot views, Az was 0.79 versus 0.70 in the conventional spot views. CONCLUSIONS: The results suggest that FFDM is at least equivalent or--as far as spot views are concerned--may be superior to conventional SFM in the detection of microcalcifications.

Breast Diseases↗
PubMed2000

[The radial scar in contrast media-enhanced MR mammography].

INTRODUCTION: In patients with the mammographic findings of a radial scar, contrast enhanced (CE) MR mammography was evaluated in a retrospective study. MATERIAL AND METHODS: In 24 women with radial opacities and black star configurations, CE MR mammography was performed. Examinations were done on a 1.5 T system using bilateral superficial coil (2D technique, T1-weighted FLASH-sequence, TR 336 ms, TE 5 ms, FA 90 degrees). Findings in mammography and MR mammography were compared with the histological results. RESULTS: 15 radial scars (including 4 with additional ADH) and 9 carcinomas (6 in coexistence with a radial scar) presenting with a diameter of 3 mm to 13 mm were evaluated. There was no evidence of malignancy in MRI in 12 of 15 radial scars. In MR mammography 6 of the carcinomas fulfilled the criteria for malignant tumors. There were 3 borderline cases (scored 3 points) corresponding histologically to 1 radial scar, and to 2 carcinomas. Within the results found in MRI there were 2 false positives and 1 false negative. CONCLUSION: CE MR mammography is superior to other imaging modalities in the differentiation between radial scars and carcinomas. However, lesions suggestive of radial scars have to be removed surgically.

Adult↗
PubMed2000

[Radiation exposure in full-field digital mammography with a flat-panel x-ray detector based on amorphous silicon in comparison with conventional screen-film mammography].

PURPOSE: Comparison of radiation exposure between a digital amorphous silicon and a screen-film based mammography system. Evaluation of a possible potential of full-field digital mammography in order to decrease the radiation dose. METHODS: The average glandular dose for phantom thicknesses from 30 to 60 mm was calculated from experimentally determined entrance surface air kerma for a digital and a conventional mammography system. The effect of reducing the detector dose and of changing the radiation quality on radiation exposure and on image quality were investigated. RESULTS: By using the delivered settings of the automatic exposure control (AEC) devices, both mammographic systems needed nearly the same doses. Regulations and guidelines on radiation doses were complied. With the digital system, a reduction of radiation exposure of up to 40% by using a higher radiation quality and decreasing slightly the detector dose without loss of diagnostic image quality, might be possible. CONCLUSION: The potential of full-field digital mammography for radiation dose reduction, as shown in the present phantom study, needs however, a careful examination under clinical conditions.

Female↗
PubMed2000

[Full-field digital mammography: dose-dependent detectability of breast lesions and microcalcinosis].

OBJECTIVES: The study compares contrast-detail and microcalcification detectability of a full-field digital mammography (FFDM) to a state-of-the-art conventional screen-film mammography (SFM) by using different doses in the digital system. MATERIALS AND METHODS: The investigations were performed with an FFDM (Senographe 2000 D, GEMS) and an SFM system (Senographe DMR, GEMS) using a contrast-detail mammography phantom (CDMAM) and an anthropomorphic breast phantom with superimposed microcalcifications. The digital detector was exposed with standard dose of SFM and with a dose reduction of up to 75%. Contrast-detail curves and correct observation ratio (COR) were performed for the CDMAM phantom. ROC analysis with a confidence level ranging from 1 to 5 was done with the results of the anthropomorphic phantom. RESULTS: Digital mammography with the same dose revealed at least an equivalent or even higher detectability rate than conventional mammography, COR could be increased at about 10-25%. The ROC analysis yielded better results for the FFDM system. The same lesion detectability in digital mammography as in the conventional method was reached at a dose reduction of about 25%, concerning spot views even at higher reduction. Dose reduction in the anthropomorphic phantom resulted in a linear loss of detectability. The same detectability as in conventional mammography was reached, however, by a dose reduction of about 50%. CONCLUSION: The results suggest that FFDM is at least equivalent to or--as far as spot views are concerned--superior to conventional SFM concerning the detectability of simulated lesions. Thus, a potential of dose reduction is suggested.

Breast Diseases↗
PubMed1999

[The diagnosis of acute aortic diseases with multiplanar-detector CT using the spiral technic].

UNLABELLED: Acute diseases of the central arteries require an immediate investigation. An efficient, fast and reliable diagnosis is necessary because of the high mortality, if the patient remains untreated. These requirements are perfectly fulfilled by the new CT-techniques. METHODS: Suspected aortic diseases were examined with a new multi-slice helical CT. The thoracic or the abdominal aorta as well as the entire vascular tree from the supra-aortic branches to the inguinal arteries were investigated with different CT protocols. The slice-thickness and the scan mode were changed while the total examination time was kept constant for the first two groups. In the third group a monophasic examination was compared to a biphasic one. RESULTS: In the diagnosis of acute aortic diseases multi-slice helical CT proved to be a fast and reliable method with all scan protocols. The objective measurements of contrast homogeneity and image quality were comparable in the first two groups. The monophasic contrast medium injection protocol was superior to the biphasic administration mode. CONCLUSIONS: Multi-slice helical CT appears to be a very effective approach for the diagnosis of acute aortic diseases and seems to be the new gold standard.

Acute Disease↗
PubMed1999

Unusual chondrosarcoma of the larynx: CT findings.

A case of a large low-grade mixed clear-cell and conventional chondrosarcoma of the larynx is reported involving the paraglottic space, the cricoid and thyroid cartilage and characterized by an unusual long clinical course over 22 years, although multiple recurrences occurred without developing metastases. Computed tomography suggests diagnosis by detecting calcifications and adequately demonstrates the extension of the tumor. Innersurface and surface-rendering images document the airway stenosis in all directions. The unusual feature of this case consists in the peculiar histopathological differentiation of the observed chondrosarcoma showing a large clear-cell component.

Chondrosarcoma↗
PubMed1999

[Slice sensitivity profile and image pixel noise of multi-slice spiral CT in comparison with single slice spiral CT].

PURPOSE: Presentation and evaluation of slice sensitivity profile and pixel noise of multi-slice CT in comparison to single-slice CT. METHODS: Slice sensitivity profiles and pixel noise of a multi-slice CT equipped with a 2D matrix detector array and of a single-slice CT were evaluated in phantom studies. RESULTS: For the single-slice CT the width of the slice sensitivity profiles increased with increasing pitch. In spite of a much higher table speed the slice sensitivity profiles of multi-slice CT were narrower and did not increase with higher pitch. Noise in single-slice CT was independent of pitch. For multi-slice CT noise increased with higher pitch and for the higher pitch decreased slightly with higher detector row collimation. CONCLUSIONS: Multi-slice CT provides superior z-resolution and higher volume coverage speed. These qualities fulfill one of the prerequisites for improvement of 3D postprocessing.

Artifacts↗
PubMed1999

[The evaluation of experimentally induced injuries to the upper cervical spine with a digital x-ray technic, computed tomography and magnetic resonance tomography].

PURPOSE: To compare digital X-ray, CT, and MRI in the evaluation of ligamentous and osseous lesions in upper cervical spine specimens after artificial craniocervical injury with the findings of macroscopic preparation. MATERIALS AND METHODS: A rotation trauma of defined severity was applied to 19 human corpses. After dissection of the neck specimens, digital X-ray (DIMA Soft P41, Feinfocus), conventional and helical CT (CTi, High Speed, GE, collimation 1 mm; pitch 1.0), and MRI were performed from the skull base to C3. The findings were correlated with the macroscopic results of preparation. MR (Magnetom Vision, Siemens) imaging was obtained with a 1.5 T system using 2D- and 3D-sequences. RESULTS: Preparation revealed 6 fractures of the vertebral bodies, 5 fractures of the dens axis, 1 fracture of the arcus anterior of the atlas, 4 osseous flakes at the occipital condylus, and 6 lesions of the alar ligaments. Digital radiography showed all fractures and 4 osseous flakes at the occipital condylus. With conventional and helical CT, all fractures and all ruptured alar ligaments could be detected. 2D MRI depicted 9 of the fractures and 3D MRI showed fractures. With 2D MRI, 2 of the 4 osseous flakes at the condylus could be detected and with 3D MRI one occipital condylus fracture could be depicted. Ligamentous injuries were visualized by 2D MRI in 2 of 6 cases and by 3D MRI in one case. CONCLUSIONS: In post-mortem studies, CT was superior to MRI in the visualization of osseous and ligamentous injuries after trauma of the upper cervical spine. However, these results are not transferable to patients with rotation injury in general.

Aged↗
PubMed1999

[The optimization of MR cholangiopancreatography].

PURPOSE: To improve the image quality of magnetic resonance cholangiopancreatography (MRCP) by modification of examination conditions. MATERIALS AND METHODS: MRCP of 72 patients was performed with a 1.5 T system (Magnetom Vision, Siemens, 25 mT/m) using two breath-hold techniques, half-fourier acquisition with multislice T2-WI HASTE in MIP technique, and single shot T2-WI turbo-spin-echo (RARE) with different slice thicknesses. The effects of n-butylscopolamine were assessed. Furthermore, oral contrast agents [barium sulfate, Fe(II)-gluconate, Fe(II,III)-oxide] in various concentrations were used. The slice thickness was varied for the RARE sequence (3-7 cm). RESULTS: N-butylscopolamine had no influence on image quality. Improvements could be attained by variation of the slice thickness. A significant reduction of disturbing background noise was obtained by oral application of iron gluconate, or iron oxide-containing contrast media. Similar improvements were achieved with barium sulfate. CONCLUSIONS: Variation of slice thickness allows an improvement of MRCP quality. Oral contrast media improve the image quality of MRCP. The expense of contrast media may be a determinant of choice.

Administration, Oral↗
PubMed1998

[Case report of a large lipomatous soft tissue tumor].

A case of diffuse infiltrating lipomatosis is reported. This entity represents a particular type of lipoma. It can be distinguished from other fatty tumors by its localisation, extent, therapeutic procedure, and prognosis. Magnetic resonance imaging (MRI) enables the differentiation from lipomatosis pelvis and malignant tumors as well. Histopathological examination, however, is necessary to exclude liposarcoma. Further growth or recurrence of diffuse infiltrating lipomatosis can be detected by MRI follow-up examinations.

Buttocks↗
PubMedDate not supplied

MRI in the evaluation of müllerian duct anomalies.

OBJECTIVE: Müllerian duct anomalies (MDAs) result from nondevelopment or nonfusion of the müllerian ducts and occur in 1-5% of women. Accurate diagnosis of the various subtypes is of great importance as MDAs are frequently associated with a broad variety of clinical symptoms. Recently, evidence arose that MRI might play a major role in diagnosis of MDAs. We present four cases of diverse subtypes of MDAs and the corresponding MRI findings. MATERIALS AND METHODS: Patients (n = 4) with clinical suspicion of MDAs were examined with MRI. Coronal and transaxial T1- and T2-weighted images were acquired. Diagnosis was made and patients were grouped according to the American Fertility Society's classification. Patients underwent laparoscopy or laparotomy in order to confirm the diagnosis. RESULTS: MRI revealed MDAs in all patients. In detail, one patient was diagnosed with hypoplastic uterus, one with unicornuate uterus with a noncommunicating rudimentary horn, one with bicornuate uterus bicollis with a double vagina and one with septate uterus. MRI diagnosis was correct in all cases, as confirmed by subsequent surgical intervention. CONCLUSION: MRI is a valuable tool in diagnosis of MDA subtypes. Its use will help to spare patients mutilating surgery and to prevent pregnancy-associated complications.

Adult↗
PubMedDate not supplied

Neurosarcoidosis: findings in MRI.

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology. Neurologic manifestations occur usually as a part of the spectrum of the systemic disease. The aim of this retrospective study was to evaluate the role of magnetic resonance imaging (MRI) in the diagnosis of patients with neurosarcoidosis (NS). Seven patients with sarcoidosis could be included into the study. All patients had neurological symptoms and were evaluated with MRI revealing a wide spectrum of findings: periventricular and white matter lesions, multiple or solitary supra- and infratentorial brain lesions, leptomeningeal enhancement, involvement of brain nerves and intramedullar lesions. These findings are not specific for sarcoidosis and must be considered with the clinical course of the patient in arriving at the correct diagnosis.

Adolescent↗