Search PubMed⌕ Search

Biomedical subjects

B Krug

Publications and source records attributed to B Krug.

At least 19 recordsLinked to original sources
PubMed2005

[Value of postmortem computed tomography in comparison to autopsy].

PURPOSE: To assess the diagnostic value of postmortem computed tomography (CT) in comparison to autopsy. MATERIALS AND METHODS: Twenty-seven cadavers were examined by sequential cranial CT and helical CT through the neck, thorax and abdomen and subsequently underwent an autopsy with histomorphologic examination of the pathologic specimens. The findings of CT, autopsy and histology were registered and compared by three radiologists and one specialist for forensic medicine, using a data entry form. RESULTS: In 19 of 27 cases, the findings explaining the cause of death were concordant for CT and autopsy. Intracranial, intraspinal and intracardiac gas accumulations (n = 12) were registered by CT alone. The detection of skull fractures was equal for both methods (n = 3). CT showed diagnostic problems in the assessment of pneumonic infiltrations (n = 16) and pulmonary edema (n = 21). CONCLUSION: CT is a useful and complementary method to autopsy.

Adult↗
PubMed2005

[Digital X-ray mammography: comparison of the image quality achievable with a wet laser imager, a dry infrared laser imager and a dry laser imager using direct thermography].

PURPOSE: To compare the image quality of digital X-ray mammographies obtained with wet imagers with that of standard dry imaging technology. MATERIAL AND METHODS: Beginning 03/08/2003, 200 X-ray mammographies with a digital fullfield mammography system (Lorad Selenia, Lorad/Hologic) were prospectively and consecutively documented with a wet laser imager (Scopix LR 5200, Agfa), a dry infrared laser imager (DryView 8610, Kodak) and a dry imager using the principle of direct thermography (Drystar 4500M, Agfa, N = 166). One X-ray exposure was systematically chosen from each examination and was presented in an anonymous and randomized form to three radiologists who evaluated the films using a structured questionnaire. RESULTS: The visualization of normal anatomic structures was considered being good to excellent for all imagers with the mean assessments 1.0 - 2.4 for the Drystar 4500M, 1.0 - 2.1 for the DryView 8610 and 1.1 - 2.0 for the Scopix LR 5200. The mean assessments were 0.1 - 0.6 points lower in dense than in normal parenchyma, thus, the parenchymal density is the predominant factor for image quality. CONCLUSION: In view of the comparable image quality obtained with the different imagers used in the study, individual decisions to purchase a specific imager will be based on economics rather than on diagnostic points of view.

Computer Peripherals↗
PubMed2005

Propofol attenuates responses of the auditory cortex to acoustic stimulation in a dose-dependent manner: a FMRI study.

BACKGROUND: Functional magnetic resonance imaging (fMRI) using blood-oxygen-level-dependent (BOLD) contrasts is a common method for studying sensory or cognitive brain functions. The aim of the present study was to assess the effect of the intravenous anaesthetic propofol on auditory-induced brain activation using BOLD contrast fMRI. METHODS: In eight neurosurgical patients, musical stimuli were presented binaurally in a block design. Imaging was performed under five conditions: no propofol (or wakefulness) and propofol plasma target concentrations of 0.5, 1.0, 1.5, and 2.0 microg ml(-1). RESULTS: During wakefulness we found activations in the superior temporal gyrus (STG) corresponding to the primary and secondary auditory cortex as well as in regions of higher functions of auditory information processing. The BOLD response decreased with increasing concentrations of propofol but remained partially preserved in areas of basic auditory processing in the STG during propofol 2.0 microg ml(-1). CONCLUSIONS: Our results suggest a dose-dependent impairment of central processing of auditory information after propofol administration. These results are consistent with electrophysiological findings measuring neuronal activity directly, thus suggesting a dose-dependent impairment of central processing of auditory information after propofol administration. However, propofol did not totally blunt primary cortical responses to acoustic stimulation, indicating that patients may process auditory information under general anaesthesia.

Acoustic Stimulation↗
PubMed2004

[Diagnostic value of preoperative contrast-enhanced MR imaging of the breast].

PURPOSE: To evaluate preoperative contrast enhanced MR imaging in clinically, mammographically and/or ultrasonographically established breast cancer. MATERIALS AND METHOD: From September 1998 to August 1999, preoperative contrast-enhanced MR imaging of the breast was performed in 91 patients with lesions highly suggestive of malignancy (BIRADS IV and V) by clinical, mammographic, and/or ultrasonographic criteria. MR imaging findings were postsurgically correlated with other imaging, intraoperative and histopathologic results. RESULTS: Histopathologic analysis revealed 61 (66 %) malignant and 31 (34 %) benign lesions. In 63 (69 %) of the 91 investigated patients, MR mammographies were classified as tumor suspect and in the remaining 28 (31 %) cases as benign. The sensitivity, specificity and accuracy were 90 %, 67 % and 81 % for contrast-enhanced MR imaging. Additional tumor manifestations (multifocal or multicentric disease, contralateral carcinoma) were found by MR imaging alone in 10 patients (11 %). CONCLUSION: Contrast-enhanced MR imaging may reveal unsuspected multifocal, multicentric or contralateral breast carcinoma that changes the surgical therapy if the intention is total tumor removal. The prognostic role of a potentially more radical surgical therapy on the basis of these findings is not clear.

Breast↗
PubMed2004

[Phantom study for the detection of simulated lesions in five different digital and one conventional mammography system].

PURPOSE: Experimental phantom study for the detection of simulated lesions with five different digital and one conventional screen-film mammography system. MATERIALS AND METHODS: Three radiographs were obtained at various configurations of the phantom with one conventional screen-film system (Mammomat 3000 N) (Siemens), five digital systems (high resolution computed radiography system [Fuji/Siemens], one a-Si detector [GE Medical Systems], two a-Se detectors [Siemens; Hologic / Lorad] and one CCD detector [Fischer Imaging]), applying the same exposure parameters. The Wisconsin Mammographic Random Phantom, Model 152 A, was used. Five investigators with different experience in mammography (3 months to more than 4 years) evaluated the 18 randomly selected radiographs. RESULTS: No significant differences were found in the detection rate of simulated breast lesions for conventional screen-film mammography (84.9 %), high resolution computed radiography (86.7 %) and digital mammography with an a-Si detector (89.8 %). Highly significantly better results (p < 0.001) were found with the two a-Se systems (97.3 %) and the CCD system (100 %). CONCLUSION: Conventional screen-film mammography can be replaced by high resolution computed radiography and digital mammography with a-Si-, a-Se- and CCD-detectors. This has to be confirmed in further clinical studies.

Computer Simulation↗
PubMed2004

[MR-coronary angiography: comparison of SSFP and spoiled GRE sequence (bright blood technique) and a TSE sequence (black blood technique) in healthy volunteers].

PURPOSE: Comparison of a free breathing steady-state free precession (SSFP), a spoiled gradient-echo (GRE) and a turbo spin-echo sequence (TSE) for imaging of the coronary arteries (MRCA) in healthy volunteers. MATERIALS AND METHODS: Twenty-two healthy volunteers were imaged with a standard clinical scanner (1.5 T, Intera, Philips), with the right coronary system imaged in 11 and the left coronary system in the other 11 volunteers. Images were obtained with a 3D-SSFP (balanced TFE, TR 6.2 ms, TE 3.1 ms, alpha 65 degrees ), a 3D-GRE (TFE, TR 7.2 ms, TE 2.2 ms, alpha 30 degrees ) and a 2D-TSE (Dual-IR, TR 2RR, TE 25 ms) sequence. The in plane resolution was 0.7 x 0.8 mm for both the SSFP and GRE sequence with an effective slice thickness of 1.5 mm. For the TSE sequence, an in-plane resolution of 0.7 x 0.9 mm and a slice thickness of 3.0 mm were used. All investigations were performed using prospective navigator gating and slice-following technique. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the blood pool to myocardium and blood pool to epicardial fat were calculated. Image quality and measurement artifacts were assessed for all sequences by 5 independent investigators using a 4- and 5-point grading scale. RESULTS: CNR was significantly higher for the GRE sequence compared with the SSFP sequence and TSE sequence (mean 20.8 +/- 4.8 vs. 14.6 +/- 5.0 and 10.1 +/- 3.7 for blood pool to myocardium; mean 27.5 +/- 6.3 vs. 16.4 +/- 5.4 and 18.1 +/- 5.7 for blood pool to fat). The SNR revealed no significant differences between the SSFP and GRE sequences. The SSFP and the TSE sequences showed significantly more artefacts than the spoiled GRE sequence. Image quality was graded slightly higher for the GRE than for the SSFP sequence for the right coronary system, while there was no substantial difference in the left coronary system (median 2.1 +/- 0.6 and 2.5 +/- 0.6 vs. 2.5 +/- 0.8 and 2.6 +/- 0.7 for the right and left coronary system). In comparison, image quality was lower with the TSE sequence (median 2.9 +/- 0.5 for the right coronary system with p < 0.05 vs. GRE sequence and 3.0 +/- 0.3 for the left coronary system). CONCLUSION: For the scan parameters chosen in this study, the GRE-sequence represents the most robust technique for imaging of the coronary arteries. Currently, the TSE sequence is no alternative.

Adult↗
PubMed2004

Computed-tomography-guided percutaneous core needle biopsies of suspected malignant lymphomas: impact of biopsy, lesion, and patient parameters on diagnostic yield.

PURPOSE: To investigate the diagnostic yield of core needle biopsy in patients with malignant lymphoma. MATERIAL AND METHODS: Computed-tomography-guided core needle biopsies in patients with malignant lymphoma performed in the period 1996 to 2001 were evaluated retrospectively. A biopsy was considered as "fully diagnostic" if a histological diagnosis, including the histologic subtype in the event of malignant lymphoma, was achieved and the clinical course and CT follow-up of at least 6 months confirmed the biopsy results. A biopsy was regarded as "partly diagnostic" if histological work-up defined malignant lymphoma but not the histological subtype, and if histological diagnosis bore therapeutic relevance. Diagnostic yield was correlated with features such as size of specimen, location and depth of the target lesion, and experience of the investigator. RESULTS: 45 biopsies were performed in 40 patients. With respect to definite histopathological diagnosis, 31 biopsies (68.9%) were diagnostic and 14 (31.1%) non-diagnostic. In 4 cases (8.8%), biopsies yielded partly diagnostic results, since therapy could be scheduled after biopsy without final sub-classification. Statistical analysis of biopsy parameters revealed that sample sizes were significantly larger in the diagnostic group. CONCLUSION: CT-guided biopsy can be considered as an alternative for lymphoma diagnosis and should be the first interventional procedure. The most important parameter for diagnostic success is the size of the specimen.

Biopsy, Needle↗
PubMed2003

[Quality control of outpatient imaging examinations in North Rhine-Westphalia, part I].

PURPOSE: In the state of North-Rhine Westphalia (NRW), Germany, a survey was conducted on radiologic examinations ordered by general practitioners (GPs). Part I of this study aims to collect characteristic epidemiological data and to assess structural quality. MATERIALS AND METHODS: All GPs in NRW were asked to cooperate. Participating GPs filled out a questionnaire for each patient. The patients recorded the symptoms prompting the imaging examinations. The radiologists or other physicians performing the examinations were asked to provide the images and written reports and to complete a questionnaire. Two university radiologists documented the pertinent test data from the submitted images and written records. Independently of each other, five university radiologists anonymously reviewed the image quality of each examination using structured questionnaires. RESULTS: A total of 920 patients gave their informed consent and participated. Questionnaires from 787 patients, 852 GPs and 611 radiologists or other interpreting physicians as well as the complete survey data from 530 examinations were available. Of 1503 examinations, conventional radiography made up 52 %, sonography 17 %, computed tomography (CT) 13 % and magnetic resonance imaging (MRI) 5 %. Most indications involved the musculoskeletal (37 %) and respiratory systems (24 %). Physicians without board certification in radiology interpreted 1 % of the CT examinations, 26 % of the radiographic examinations and 71 % of the sonographic examinations. Of the 174 self-referrals, 1 % involved CT, 33 % conventional radiography and 66 % sonography. Written reports were available for 95 % of all 469 examinations performed by radiologists and 74 % of all 127 examinations conducted by non-radiologists. Only 44 % of the 23 sonographic studies were self-referrals by the patient's GP. On average, the radiographic techniques were acceptable in terms of diagnostic information and radiation hygiene. Conventional radiographs were better exposed when obtained by radiologists than by non-radiologists (p = 0.038). The delineation of anatomical structures was rated as good to acceptable for MRI, CT and conventional radiography, while the image quality was rated as diagnostically insufficient for sonography (p < 0.0001). The image quality of radiographic and sonographic examinations performed by radiologists was superior in comparison to examinations performed by physicians without board certification in radiology (p < 0.0001). CONCLUSION: Examination technique and imaging quality of MRI, CT and conventional radiography performed on outpatients were in an acceptable diagnostic range, whereas the quality of sonography was inadequate.

Family Practice↗
PubMed2003

[Quality control of outpatient imaging examinations in North Rhine-Westphalia, Part II].

PURPOSE: In the state of North Rhine-Westphalia (NRW), Germany, a survey was conducted on radiologic examinations ordered by general practitioners (GPs). Part II of this study aims to determine the quality of the process and outcome. The reference standard is the assessment of both radiologists and physicians without board certification in radiology working at a university hospital and in outpatient facilities. MATERIALS AND METHODS: AllGPs in NRW were asked to cooperate. Participating GPs filled out a questionnaire for each patient. The patients recorded the symptoms prompting the imaging examinations. The radiologists or other physicians performing the examinations were asked to provide the images and written reports and to complete a questionnaire. A file was created for each of the 394 patients with image documentation of at least one examination. Each file, which included medical history, physical findings, imaging documentation and written report, was sequentially forwarded to a board-certified radiologist and to a physician without board certification in radiology working in a university hospital and in an outpatient facility. All physicians were requested to complete a structured questionnaire for each file. RESULTS: The referral diagnoses were rated as medically plausible in 81%, the indications for imaging found correct in 76%, the examination techniques considered appropriate in 69%, the clinical question answered in 63%, the interpretation judged medically correct in 50% and all incidental findings documented in 49%. In retrospect, 32 % of the examinations were judged superfluous. The sequence of multiple examinations performed on a particular patient was rated as appropriate in 51%. The interpretation revealed specialty-related differences. The plausibility of the referral diagnoses had a significant impact on the appropriateness of subsequent diagnostic investigations. Marked deficits showed sonography, performance by non-radiologists, self-referrals by GPs, gastroenterologic radiology and the ICD-10 coding (suspicion of cardiovascular disease). CONCLUSION: In the "best-case" scenario, the process quality proved to have moderate deficiencies and the outcome quality severe deficiencies. In consequence, GPs and radiologists should be more communicative by sharing information and exchanging opinions. GP self-referrals should be restricted. Sonography and examinations performed by physicians without board certification in radiology should undergo stricter quality controls. A more intensive interdisciplinary collaboration is needed to determine the optimum implementation of diagnostic imaging of gastroenterologic and cardiovascular diseases.

Ambulatory Care↗
PubMed2003

Reducing the radiation dose during excretory urography: flat-panel silicon x-ray detector versus computed radiography.

OBJECTIVE: The purpose of the study was to examine the possibilities for reducing radiation exposure in uroradiology using digital flat-panel silicon X-ray detector radiography. We compared the subjectively determined image quality of abdominal radiographs and urograms obtained on a digital flat-panel detector radiography system with those obtained on a computed radiography system. SUBJECTS AND METHODS. Fifty patients who had a clinical indication for urography underwent unenhanced abdominal imaging that was alternately performed using flat-panel silicon X-ray detector radiography or computed radiography. For patients who required a second radiograph with contrast medium, the examination modality was changed to avoid exposing the patients to excess radiation. The images obtained on flat-panel X-ray detector radiography were obtained at half the radiation dose of the images obtained on computed radiography (800 speed vs 400 speed). The resulting 50 pairs of images were interpreted by four independent observers who rated the detectability of structures of bone and the efferent urinary tract relevant to diagnosis and compared the image quality. RESULTS: At half the radiation dose, digital flat-panel X-ray detector radiography provided equivalent image quality of the liver and spleen, lumbar vertebrae 2 and 5, pelvis, and psoas margin on abdominal radiographs. The image quality obtained with digital flat-panel X-ray detector radiography of the kidneys, the hollow cavities of the upper efferent urinary tract, and the urinary bladder was judged to be statistically better than those obtained with computed radiography. CONCLUSION: With half the exposure dose of computed radiography, the flat-panel X-ray detector produced urograms with an image quality equivalent to or better than computed radiography.

Diagnosis, Computer-Assisted↗
PubMed2002

[Comparison of flat-panel radiography and computed radiography in urography].

PURPOSE: To evaluate the diagnostic value of digital flat-panel radiography in uroradiology the i. v. urograms of patients who had been examined with computed radiography and digital flat-panel radiography were compared regarding image quality. METHODS: 50 patients who underwent clinically indicated i. v. urography were examined with digital flat-panel radiography and computed radiography. In order to avoid unnecessary double exposure to X-rays, patients were examined either by flat-panel or computed radiography before injection of contrast media. Each further clinically indicated exposure after administration of contrast media was done by alternating the other examination technique. The digital images were compared by 4 radiologists regarding image quality for the detection of defined anatomic structures. RESULTS: Digital flat-panel radiography showed an image quality of the liver, spleen and both kidneys that was similar to computed radiography. The urinary tract, lumbar spine, pelvis and psoas muscle were significantly better visible on flat-panel radiography images. CONCLUSIONS: Compared to computed radiography there is no loss of image information by using digital flat-panel radiography in uroradiology. On the contrary, some anatomic structures on abdominal survey images show better image quality. In conclusion, digital flat-panel radiography has the potential to replace computed radiography in uroradiologic examinations.

Contrast Media↗
PubMed2002

[Development of ultrasonography in a radiological university department from 1994 to 2001].

BACKGROUND: In 1994, 5 % of a total of 25 718 examinations and 7 % of all 4630 B-mode sonograms performed in the Radiology Department, University of Cologne was classified as not indicated. In light of these results, the health care policy guidelines for sonographic indications have been amended. PURPOSE: The aim of this study was to establish the current rate of non-indicated sonographic examinations performed in routine diagnostics by radiology departments at university hospitals, to determine the reasons for such over-diagnosis and identify which regulatory mechanisms can be implemented to prevent his. METHOD: We counted the number of 1) B-mode and 2) color-flow Doppler ultrasound imaging procedures carried out in patients who had had no change in symptoms within the previous 4 weeks or who were scheduled without reference to an existing sonogram (double examinations). 3) The reasons for over-diagnosis were analyzed. 4) The 1994 survey was repeated in 2000 with an identical protocol and 5) additionally, a modified survey of the diagnostic questions was conducted. RESULTS: 1) Out of 4,119 patients presenting for the first time to receive a B-mode sonogram, 443 prior sonograms (11 %), 305 CT scans (7 %) and 57 MRI scans (1 %) were documented. 2) Double sonograms were carried out in 6 % of the 1,118 patients presenting for the first time for color-flow Doppler ultrasounds and in 16 % of the 651 patients assigned to receive catheter angiographies with arterial color-flow Doppler. 2) 41 out of 55 (75 %) prior sonograms from non-university settings stated by 94 surgery patients were listed in the medical records. 36 out of 43 (84 %) prior sonograms from the university hospital were repeated in the same patients despite the fact that the medical report with the findings was available. None of the 48 sonograms indicated to confirm a plausible finding yielded any information that was additionally relevant to therapy. 4) In the period April - June, 2000, 12 % of all 15,921 tests and interventions, 26 % of 3,569 B-mode sonograms and 58 % of 1,033 abdominal sonograms performed in adults were classified as having not been indicated. 5) Staging and follow-up were stated as the most common reasons that a sonography was carried out in 46 % of the 1,017 adults who were given B-mode sonograms conducted from Jan - Mar, 2000 and comprised 62 % of the 410 sonograms classified as not or probably not medically indicated. CONCLUSION: The results showed that a multidisciplinary consensus was required to establish the diagnostic value of sonographic procedures. Therefore, this research group drafted a hospital-internal interdisciplinary guideline for "abdominal transcutaneous B-mode sonography in oncological questions".

Diagnostic Imaging↗
PubMed2001

Whole-body positron emission tomography using 18F-fluorodeoxyglucose for initial staging of patients with Hodgkin's disease.

An accurate initial staging of patients with Hodgkin's disease (HD) is important for the evaluation of clinical stage and risk factors, which are crucial for the choice of an appropriate treatment. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is useful for detecting active tumor tissue in patients with lymphoproliferative diseases and may contribute to conventional staging methods in patients with HD. Twenty-two patients who presented with newly diagnosed HD underwent conventional staging methods including computed tomography (CT) as well as FDG PET. Lesions apparent in FDG PET and CT were correlated to each other. Seventy-seven lesions were observed either in PET or CT or in both. In 48 (62%) lesions PET and CT were both positive. In 20 (26%) sites, PET was positive and CT negative. Of 22 patients (18%) 4 were upstaged due to these positive PET findings, and as a result one patient received a different therapeutic regimen. PET failed to detect nine (12%) CT-positive sites in six patients. Statistically, these data are reflected by a sensitivity for PET and CT of 88% and 74%, respectively. Specificity of both imaging modalities was 100%. PET can contribute valuable information as an additional staging examination and led to an upstaging in some patients with primary HD. However, PET should not be used as the only imaging modality as it failed to detect CT-positive, active tumor regions in some cases.

Adult↗
PubMed2001

Age related signal decrease in functional magnetic resonance imaging during motor stimulation in humans.

Right handed healthy volunteers underwent functional magnetic resonance imaging (fMRI) examinations on a 1.5 Tesla MRI-scanner (Gyroscan ACS NT; Philips, Best, NL). Blood oxygen level dependent (BOLD) images were obtained using a three dimensional multi-shot echo planar imaging sequence employing a shifted echo technique (Principles of echo shifting with a train of observations). Finger tapping of the right hand was used as a task for motor stimulation. A total of 86 subjects was included into statistical analysis. Absolute and relative signal differences and cluster sizes of activation for the left motor cortex were obtained. In addition, Z-score, pooled Z-score and cross correlation activation maps were calculated and matched with high resolution anatomic images. A significant decrease with age could be detected for absolute and relative signal intensity differences for the whole group and for the male subgroup. Correlation analysis for the female subgroup also bore negative albeit non-significant correlation coefficients. An age-related decline of BOLD-contrast can be assumed to explain signal decrease. This age-related effect should be considered in clinical fMRI applications.

Adult↗
PubMed2001

Cricopharyngeal muscle hypertrophy associated with florid myositis.

Hypertrophy of the cricopharyngeal muscle is a serious clinical condition that can cause severe dysphagic symptoms, including prolonged deglutition and postdeglutitive aspiration. Although the therapeutical concepts are well established, the pathogenic mechanism of cricopharyngeal hypertrophy remains unclear. We present a patient with a ten-year history of progressive dysphagia. The neurological and MRI findings were normal. However, videocineradiography showed severe hypertrophy of the cricopharyngeal muscle. This condition was first treated by injections of botulinum toxin, which did not alleviate the symptoms. Next, myotomy and muscle biopsy were performed. Histological evaluation disclosed lymphoplasmacellular florid myositis, single-fiber atrophy, and muscle fiber necrosis with phagocytosis. There were no signs of inclusion body myositis or oculopharyngeal muscular dystrophy. Our finding of severe cricopharyngeal muscle hypertrophy associated with myositis has been published previously (n = 34). The study presented here shows cricopharyngeal dysphagia associated with various systemic diseases, including motor neuron disease, general granulomatous disease, dermatomyositis, or inclusion body myositis. Isolated changes of the cricopharyngeal muscle were described in 65% of the cases.

Aged↗