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Biomedical subjects

R Otto

Publications and source records attributed to R Otto.

At least 19 recordsLinked to original sources
PubMed2006

Photodetachment of cold OH- in a multipole ion trap.

The absolute photodetachment cross section of OH- anions at a rotational and translational temperature of 170 K is determined by measuring the detachment-induced decay rate of the anions in a multipole radio-frequency ion trap. In comparison with previous results, the obtained cross section shows the importance of the initial rotational-state distribution. Using a tomography scan of the photodetachment laser through the trapped ion cloud, the derived cross section is model-independent and thus features a small systematic uncertainty. The tomography also yields the column density of the OH- anions in the 22-pole ion trap in good agreement with the expected trapping potential of a large field free region bound by steep potential walls.

Journal Article↗
PubMed2006

Quantitative high resolution transmission electron microscopy of nanostructured semiconductors.

Peak-finding procedures and the geometric phase method of quantitative high resolution electron microscopy (qHRTEM) were applied to determine the local strain and the chemical composition of nanostructured semiconductor materials. The growth of the structures investigated was induced by minimization of strain energy. The analysis of strain distribution is necessary for the understanding of the self-organized formation of nanostructures. The possibilities and limitations of the methods are discussed in detail by analysing HRTEM images of (Si,Ge) islands and of a double layer of stacked quantum dots of (In,Ga)As and Ga(Sb,As).

Journal Article↗
PubMed2005

Dose optimization of contrast-enhanced carotid MR angiography.

The purpose of this work was to compare the diagnostic performance of a single-contrast or a double-contrast dose of carotid contrast-enhanced MR angiography (MRA). One-hundred nineteen patients (mean age 65+/-14.4 years) underwent carotid contrast-enhanced MRA with a standardized protocol (repetition time/echo 3.73 ms/1.38 ms, flip-angle 25 degrees, acquisition-time 19 s, voxel size 1.2 x 1.2 x 0.9 mm3) on a 1.5-T scanner (Sonata, Siemens-Medical-Systems) using a neck phased-array coil. Contrast agent was administered intravenously at a rate of 3.0 ml/s, either as a single dose (n=57; 0.1 mmol/kg body weight) or as a double dose (n=62; 0.2 mmol/kg body weight) of meglumine gadoterate (0.5 M/l), followed by 30 ml saline. Qualitative image analysis was performed on maximum intensity projections using a five-point scale. Signal intensities were measured at three different vascular levels on both sides to assess the contrast-to-noise ratios (CNRs). Image quality was rated as good or excellent in all cases. A double dose did not influence the efficacy of carotid enhancement (CNR single dose 69.12+/-19.8; CNR double dose 70.01+/-20.7; p = 0.81) compared with a single dose. In both dose groups the mean CNRs were inversely related to bodyweight, despite adjusted contrast volumes (p=0.0005). Double-dose contrast-enhanced carotid MRA is not superior to single-dose MRA, as overall diagnostic performance and quantitative contrast enhancement are equal. Being more cost-efficient, a single-dose administration of contrast agent is recommended for MRA of the carotid arteries.

Adult↗
PubMed2005

[Referrer satisfaction as a quality criterion: developing an questionnaire for measuring the quality of services provided by a radiology department].

PURPOSE: To develop a questionnaire for measuring referring physician satisfaction and to conduct a pilot study in which this questionnaire is given to all physicians referring patients to the authors' radiology department. MATERIALS AND METHODS: After qualitative pre-testing and adjustment of the prototype questionnaire, data were collected using the finalized standardized questionnaire comprising 29 indicators rated on a 4-point ordinal scale mailed with a personalized cover letter to the total referring physician population of a radiology department (n = 727). The replies, rated 1 - 4, were entered into a data entry mask for statistical analysis. RESULTS: The response rate was 33.8 %. The indicators with the highest satisfaction rating were the range of examinations offered ("very satisfied": 79.3 % mean 3.79), the quality of the technical equipment used for MRI and CT (79.3 %, 3.79) and mammography (82.5 %, 3.82), and the quality of the images yielded by these procedures (74.5 %, 3.73 and 82.2 %, 3.83). Dissatisfaction was relatively high with the indicators "time to receipt of the written report" (28.3 % "not very satisfied" or "not at all satisfied", mean 2.97), "time to receipt of the X-ray images" (18.2 %, 3.07) and "availability of previous findings" (20.9 %, 3.05); satisfaction was higher among external referring physicians (p < 0.05). Physicians rated the importance of these three indicators as relatively high ("very important": 62.4 %, 54.3 % and 49.6 %). Other indicators showing a similar level of dissatisfaction were "car parking availability" (24.1 %, 3.01), "patient waiting time" (27.4 %, 2.87) and "patient environment" (21.2 %, 2.99), although these factors were rated as less important ("very important": 33.0 %, 33.7 % and 40.4 %). CONCLUSION: This questionnaire constitutes a standardized validated instrument for assessing referring physician satisfaction with a radiology department. The data from this pilot study highlight areas for potential improvement. Deployment of such a questionnaire in different radiology departments could serve to establish best practice benchmarks.

Consumer Behavior↗
PubMed2005

[Referrer satisfaction as a quality criterion: developing an questionnaire for measuring the quality of services provided by a radiology department].

PURPOSE: To develop a questionnaire for measuring referring physician satisfaction and to conduct a pilot study in which this questionnaire is given to all physicians referring patients to the authors' radiology department. MATERIALS AND METHODS: After qualitative pre-testing and adjustment of the prototype questionnaire, data were collected using the finalized standardized questionnaire comprising 29 indicators rated on a 4-point ordinal scale mailed with a personalized cover letter to the total referring physician population of a radiology department (n = 727). The replies, rated 1 - 4, were entered into a data entry mask for statistical analysis. RESULTS: The response rate was 33.8 %. The indicators with the highest satisfaction rating were the range of examinations offered ("very satisfied": 79.3 % mean 3.79), the quality of the technical equipment used for MRI and CT (79.3 %, 3.79) and mammography (82.5 %, 3.82), and the quality of the images yielded by these procedures (74.5 %, 3.73 and 82.2 %, 3.83). Dissatisfaction was relatively high with the indicators "time to receipt of the written report" (28.3 % "not very satisfied" or "not at all satisfied", mean 2.97), "time to receipt of the X-ray images" (18.2 %, 3.07) and "availability of previous findings" (20.9 %, 3.05); satisfaction was higher among external referring physicians (p < 0.05). Physicians rated the importance of these three indicators as relatively high ("very important": 62.4 %, 54.3 % and 49.6 %). Other indicators showing a similar level of dissatisfaction were "car parking availability" (24.1 %, 3.01), "patient waiting time" (27.4 %, 2.87) and "patient environment" (21.2 %, 2.99), although these factors were rated as less important ("very important": 33.0 %, 33.7 % and 40.4 %). CONCLUSION: This questionnaire constitutes a standardized validated instrument for assessing referring physician satisfaction with a radiology department. The data from this pilot study highlight areas for potential improvement. Deployment of such a questionnaire in different radiology departments could serve to establish best practice benchmarks.

Consumer Behavior↗
PubMed2004

[Ovarian torsion in childhood].

A six year old afebrile girl was referred to the emergency department with abdominal pain in the right lower region. A retrouterine partially cystic lesion with an inhomogene echogenity was demonstrated by transabdominal ultrasound. Pelvic MR showed an enlarged right-sided ovary and a thickened vascular pedicle as well as few adjacent free fluid. Diagnosis of ovarian torsion was confirmed intraoperatively. Conservative ovary-sparing treatment was not possible, so right-sided adnexectomy followed. Histopathologically a haemorrhagic infarction of the ovary and the tube was seen. No signs of malignancy and no tumor could be detected.

Abdomen, Acute↗
PubMed2002

A new design of a polysomnography-based multi-center treatment study for the restless legs syndrome.

Periodic limb movements (PLM) cause sleep disorders and daytime symptoms and are frequently associated with restless legs syndrome (RLS). Treatment of RLS with increased PLM during sleep (PLMS) has been evaluated in studies limited in size, methodology and study length. This long-term, placebo-controlled, multi-center, study with polysomnography (PSG) recordings has been designed in order to assess efficacy and safety parameters of pergolide treatment in RLS. This novel approach for a study was created to assure consistently high quality of sleep recording and analysis. Using defined criteria, 21 sleep centers were approved for the study after a pilot phase. Seventeen centers with 16 different PSG systems randomized 100 patients. Digital sleep recordings from 4 visits (baseline, 6 weeks, 6 months, 1 year) were submitted to one central evaluation center following previously defined standardized operating procedures. Visual scoring of all recordings was performed by one independent scorer. Reliability of scoring was evaluated for 20 randomly selected baseline recordings. The mean epoch by epoch agreement for sleep stages was 88% (range 81-96%), mean arousal re-scoring differed by 0.5 (range: -16 to 20), and mean PLM index re-scoring differed by 0.1 (range: -1.5 to 2.1). Using one scorer with a demonstrated high reliability in PSG scoring for all sleep recordings was very effective in terms of study cost, study duration, and data quality.

Dopamine Agonists↗
PubMed2001

Interventional ultrasound.

Modern cross-sectional imaging methods of computed tomography, sonography and lately MRI have contributed greatly to non-invasive studies of different parenchymal organs and permit the evaluation of pathological changes in different areas of the body. Although these techniques have reached a very high level of refinement, it is often not possible to define whether a focal lesion is benign or malignant. Ultrasound-guided fine-needle aspiration biopsy (FNA) or core-needle biopsy (including high-speed- and vacuum-assisted techniques) are essential to find out the character of the disease in these cases. Experience of more than 10,000 interventions of different organs are presented. Technique, results, problems, as well as risks are discussed. Moreover, it is shown how the results of percutaneous biopsies often change the treatment of a patient. This is especially of interest in those suffering from lymphomas, pancreatic carcinomas, and breast cancers, as well as relapsing tumors.

Biopsy, Needle↗
PubMed2001

[Vacuum needle biopsy of the breast with digital stereotaxic control--initial experiences with the Mammotome in Baden].

The purpose of our study was to evaluate a stereotactic, percutaneous, vacuum-assisted breast biopsy system. The Mammotome (Biopsies) was used to perform breast biopsies in 35 of 37 patients using only one small incision. In two patients a biopsy was not possible: one lesion could not be positioned into the limited field of the digital CCD-camera. One lesion was not enough dense to be seen on digital images. Biopsies were performed because of suspicious microcalcifications (34) or nodules (3). Histology revealed 32 benign and 3 malignant lesions. We encountered 4 syncopes. Because the biopsies are performed in the sitting position, they were the cause we had to break up 2 biopsies. Relevant hematomas occurred in 4 cases. Vacuum assisted core biopsy has proven to be a safe and accurate technique for obtaining a histologic diagnosis in most patients who have screening-detected lesions; it is done at a lower cost with lower resultant morbidity to the patient compared with traditional surgical excisional biopsy. A certain learning phase must be granted.

Biopsy, Needle↗
PubMed2000

Telepathology: design of a modular system.

Although telepathology systems have been developed for more than a decade, they are still not a widespread tool for routine diagnostic applications. Lacking interoperability, software that is not satisfying user needs as well as high costs have been identified as reasons. In this paper we would like to demonstrate that with a clear separation of the tasks required for a telepathology application, telepathology systems can be built in a modular way, where many modules can be implemented using standard software components. With such a modular design, systems can be easily adapted to changing user needs and new technological developments and it is easier to integrate modular systems into existing environments.

Computer Systems↗
PubMed2000

A phase I study of Onyx-015, an E1B attenuated adenovirus, administered intratumorally to patients with recurrent head and neck cancer.

An E1B 55 kDa gene-deleted adenovirus, Onyx-015, which reportedly selectively replicates in and lyses p53-deficient cells, was administered by a single intratumoral injection to a total of 22 patients with recurrent head and neck cancer. The objectives of this Phase I study were to determine the safety, feasibility, and efficacy of this therapy and determine any correlation to p53 status. Six cohorts were investigated with a dose escalation from 10(7)-10(11) plaque-forming units. Toxicity was assessed using NCIC criteria. Tumor response was assessed by clinical and radiological measurement. Blood samples were taken to detect adenovirus DNA and neutralizing antibody to adenovirus. Tumor biopsies were taken to detect adenovirus by in situ hybridization. Treatment was well tolerated, with the main toxicity being grade 1/2 flu-like symptoms. Dose-limiting toxicity was not reached at the highest dose of 10(11) plaque-forming units. Twenty-one of the 22 patients treated showed an increase in neutralizing antibody to adenovirus. In situ hybridization showed viral replication in 4 of 22 patients treated, all of whom had mutant p53 tumors. Using conventional response criteria, no objective responses were observed. However, magnetic resonance imaging scans were suggestive of tumor necrosis at the site of viral injection in five patients, three of whom were classified using nonconventional criteria as partial responders, and two of whom were classified using nonconventional criteria as minor responders. Of these five cases, four had mutant p53 tumors. The response duration for the three partial responders was 4, 8, and 12 weeks. An additional eight patients had stable disease in the injected tumors lasting from 4-8 weeks. These preliminary results show that intratumoral administration of Onyx-015 is feasible, well tolerated, and associated with biological activity. Further investigation of Onyx-015, particularly with a more frequent injection protocol and in combination with systemic chemotherapy, is warranted.

Adenovirus E1B Proteins↗
PubMed1999

[Contrast media-enhanced duplex ultrasonography of liver tumors].

The differentiation of focal liver processes is a daily clinical problem. A new option in addition to magnetic resonance tomography has been created with the development of new stable sonographic contrast agents. In this paper, Levovist was studied as a sonographic contrast agent in the detection of specific tumour perfusion patterns. All focal liver processes were proven by cytology or histology. In 19 of 22 cases there was a pathological diagnosis. In 5 of 7 haemangiomas a feeding vessel was visualised. In 3 focal nodular hyperplasias intense intratumoural enhancement was visible shortly after injection. In 2 cases of hepatocellular carcinomas tumoural neovascularisations were visualised which were not seen before the injection of Levovist. The new sonographic contrast agents provide better differentiation of specific perfusion patterns of liver tumours than normal duplex sonography.

Adult↗