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W Döhring

Publications and source records attributed to W Döhring.

At least 19 recordsLinked to original sources
PubMed2005

[Comparison of four digital and one conventional radiographic image systems for the chest in a patient study with subsequent system optimization].

PURPOSE: Using a patient study to prove the clinical relevance of a comparison of five different radiographic systems for the chest conducted with an anthropomorphic chest phantom. Depending on the results, it was tested whether the performance of a modern digital system with a transparent imaging plate can be improved by changing the post-processing of the image. METHOD: Chest radiographs of patients were taken with a CsI/aSi-flat panel detector (FDR), transparent imaging plate (tDLR), selenium drum detector (DSR), conventional storage phosphor plate (DLR) and asymmetrical screen-film-system (aFFS), and compared using image criteria scoring (ICS) and visual grading analysis (VGA) for anatomical structures (modified criterions of the EUR 16 260 EN guidelines). After optimizing the post processing, the images of the tDLR-system were evaluated once more in a phantom ROC study and patient VGA study. RESULTS: The flat panel detector-system proved to meet best the anatomical image quality criteria, followed by DSR, tDLR, aFFS and DLR. The modified post processing of the tDLR-images resulted in a significantly better detection of simulated pathological lung-structures, but improved the perceptibility of anatomical structures only slightly. CONCLUSIONS: The results of the patient VGA study and the phantom ROC study are similar and considered valid. The new digital imaging systems with flat panel detector and transparent imaging plate provide the best image quality of the tested radiographic devices for chest imaging, assuming that all system components are attuned and optimized for the type of structure to be detected. Image processing is of primary importance for system optimization.

Humans↗
PubMed2003

[Chest radiography: ROC phantom study of four different digital systems and one conventional radiographic system].

PURPOSE: To compare the diagnostic quality of five different radiographic systems used in chest radiography for visualization of differently configured, clinically relevant pathologic pulmonary structures. MATERIALS AND METHODS: Four digital detector systems using as detection unit a CsI/aSi-based flat panel detector, a transparent imaging plate, a selenium detector and a conventional storage phosphor plate were analyzed for this study, as well as an asymmetrical film-screen system. The analyzed imaging material consisted of radiographs of an anthropomorphic chest-phantom with superimposed simulated pulmonary structures. The images were evaluated for different pathologic structures by a newly developed multiple structure ROC (ms-ROC). RESULTS: The performance of each system was found to have a strong structure-related variability. The flat panel detector system had the best overall performance. The theoretical advantage of the 4k-matrix of the transparent imaging plate over the 3k-matrix of the flat panel detector was only confirmed for reticular structures. CONCLUSIONS: In addition to comparing the image quality of the different systems, this study shows that the performance of a radiographic system depends on the structure to be analyzed. The modified ROC (ms-ROC) provides valid results with less effort.

Humans↗
PubMed2002

[First clinical experience with a full-size, flat-panel detector for imaging the peripheral skeleton - Part II: Post-processing with a newly developed adaptive autowindow algorithm].

PURPOSE: of the second part of the investigation was the evaluation of a newly developed adaptive autowindow algorithm in comparison to the system processing radiographs of the wrist and ankle to further optimize the image quality with softcopy reading. MATERIAL AND METHODS: All 120 radiographs of the wrist and all 100 radiographs of the ankle used in the 1st part of this paper were processed with the adaptive autowindow algorithm. The evaluation was again performed by 5 radiologists with softcopy reading. For the data analysis a variation of the Visual Grading Analysis (VGA) was used. RESULTS: Up to 19 % of the wrist radiographs and 2 % of the ankle radiographs processed with the system software had to be processed manually afterwards to get acceptable results. By the application of the adaptive autowindow algorithm a manual post-processing was no longer necessary. Highly significant (p less-than-or-equal 0.001) differences for all criteria to be evaluated were found for the wrist radiographs and in the case of the ankle radiographs for the bone contrast, the contrast in soft-tissue regions, the fine details in the bone and the artifacts, the adaptive autowindow algorithm performed always better than the system software. CONCLUSION: Using half of the exposition dose on a flat-panel detector, an optimized post-processing leads to comparable or better results compared to the conventional film-screen-system concerning the image quality.

Algorithms↗
PubMed2002

[Optimized image processing with modified preprocessing of image data sets of a transparent imaging plate by way of the lateral view of the cervical spine].

PURPOSE: To improve the diagnostic quality of lateral radiographs of the cervical spine by pre-processing the image data sets produced by a transparent imaging plate with both-side reading and to evaluate any possible impact on minimizing the number of additional radiographs and supplementary investigations. MATERIAL AND METHODS: One hundred lateral digital radiographs of the cervical spine were processed with two different methods: processing of each data set using the system-imminent parameters and using the manual mode. The difference between the two types of processing is the level of the latitude value. Hard copies of the processed images were judged by five radiologists and three neurosurgeons. The evaluation applied the image criteria score (ICS) without conventional reference images. RESULTS: In 99 % of the lateral radiographs of the cervical spine, all vertebral bodies could be completed delineated using the manual mode, but only 76 % oft the images processed by the system-imminent parameters showed all vertebral bodies. Thus, the manual mode enabled the evaluation of up to two additional more caudal vertebral bodies. The manual mode processing was significantly better concerning object size and processing artifacts. This optimized image processing and the resultant minimization of supplementary investigations was calculated to correspond to a theoretical dose reduction of about 50 %. CONCLUSION: The introduction of optimized organ programs for the upper and lower cervical spine based on the 12-bit data of the images should improve the evaluation of the lateral radiograph of the cervical spine without reducing the latitude value.

Cervical Vertebrae↗
PubMed2001

Classification of severe head injury based on magnetic resonance imaging.

OBJECT: In 1991 a new pioneering classification of severe head injuries had been proposed, based on CT findings. Unfortunately CT cannot visualise all lesions. Especially brain stem lesions may escape CT in spite of modern equipment, but may be demonstrated by MRI. The high incidence of CT negative but MRI positive posttraumatic brain stem lesions has already been demonstrated in a limited number of cases. A statistically significant evaluation is still missing. Therefore we have investigated a series of 102 comatose patients, in whom a statistical evaluation of MRI findings and their correlation with mortality and outcome of survivors was possible. PATIENTS AND METHODS: MRI was obtained within 8 days after servere head injury in 102 patients with a minimum of 24 hours of coma. The location of the lesions. identified by a neuroradiologist who was unaware of the clinical findings, was correlated with mortality, outcome of surviors and duration of coma. The correlation was analysed statistically. Follow-up ranged from 3 months to 3 years with a mean of 22 months. Four groups of lesions gave significant correlations: Grade I lesions were lesions of the hemispheres only; Grade II lesions were unilateral lesions of the brain stem at any level with or without supratentorial lesions; Grade III lesions were bilateral lesions of the mesencephalon with or without supratentorial lesions. Grade IV lesions were bilateral lesion of the pons with or without any of the foregoing lesions of lesser grades. RESULTS: Mortality increased from 14% in grade I lesions to 100% in grade IV lesions. The Glasgow outcome score differed significantly for each grade. The mean duration of coma increased from 3 days in grade I patients to 13 days in grade III. The correlations between the lesions grade I to IV with mortality, outcome of survivors and duration of coma were highly significant. CONCLUSION: The statistically significant correlations between the 4 groups of severe head injury patients, as identified by MRI, with mortality and outcome of survivors justify a new classification based on early MRI findings.

Adolescent↗
PubMed2001

[First clinical experience with a full-size, flat-panel detector for imaging the peripheral skeletal system].

PURPOSE: This investigation was intended to show that exposures of the peripheral skeleton system can be done with half of the dose used for conventional screen-film systems with a full-size CsI/a-Si flat panel detector. MATERIAL AN METHODS: 120 exposures of the wrist and 100 exposures of the ankle have been made on a full-size flat panel detector system (43 x 43 cm). The patient dose has been reduced by a factor of two compared to conventional images. Five radiologists evaluated every image as a softcopy and a hardcopy image. For the evaluation, a variation of the Visual Grading Analysis (VGA) without reference images was used. For the determination of the patient entrance dose, measurement of a phantom were performed. RESULTS: A dose reduction of about 50 % is possible with the same or even better image quality in routine diagnostics. Only 3 % of the ankle and approx. 21 % of the wrist exposures required a postprocessing. Exposures with implants did not show any artifacts and some of the those achieved better evaluation results compared with exposures without implants. CONCLUSION: A halving of the patient dose is possible with acceptable results for the image quality. The effect of an improved image processing remains to be evaluated. The patient entrance dose is suitable for an evaluation of a radiographic detector and especially for a dose-referred comparison of digital X-ray units.

Ankle Joint↗
PubMed2000

Digital selenium radiography: detection of subtle pulmonary lesions on images acquired with and without an additional antiscatter grid.

OBJECTIVE: the objective of this ROC-study was to evaluate the diagnostic efficacy of images acquired with a grid in digital selenium radiography compared to that on images obtained with the integrated air gap only. MATERIALS AND METHODS: seven types of simulated lesions were superimposed onto an anthropomorphic chest phantom. Selenium radiography images were obtained either with or without an additional antiscatter grid. For images acquired with a grid either a similar or increased exposure level was used. Both normal and obese patients were simulated. RESULTS: When a grid was used with an equivalent detector dose and a higher exposure, diagnostic performance was significantly improved as compared to images obtained with only the air gap. ROC curve areas for mediastinal nodules and catheters were substantially higher for images acquired with a grid and the same exposure level compared to images obtained without a grid. However, detection of linear, net-shaped and reticulonodular structures in peripheral lung regions was significantly worse when a grid was used with an equivalent exposure level. Concerning the interpretation of images obtained from the normal and obese phantom models, no substantial differences were observed. CONCLUSION: a marked improvement in diagnostic performance could be achieved by means of the use of an additional antiscatter grid and an equivalent detector dose. However, when the same exposure was used, images acquired with the grid allowed a better detection of mediastinal structures although a worse performance was evident in radiolucent lung regions. Therefore, the routine use of a grid without increased exposure is not recommended.

Humans↗
PubMed1998

[Qualitative evaluation of brain structure in CT in panic disorders].

This CT study was designed to assess brain morphology in panic disorder with and without agoraphobia. Twenty-one patients and 21 normal control subjects matched for age and sex were investigated. Frontal and parieto-occipital cortex, temporal cortex, lateral ventricles and 3rd ventricle were evaluated by qualitative assessment on a 3-point scale (normal, questionable, abnormal). Patients showed significant bilateral enlargement of cortical cerebrospinal fluid (CSF) spaces (p < 0.01). The rating "abnormal" was given to none (0%) of the normal controls, but to 7 (33.3%) of the patients. Explorative analysis showed that these abnormalities were predominantly located in prefrontal regions. No qualitative differences were seen in the temporal cortex, lateral ventricles or third ventricle. These findings support the hypothesis that alterations in brain morphology are involved in the etiology of panic disorder. The lack of a correlation between CSF enlargement and duration of illness suggests that frontal CSF enlargement is a neurobiological vulnerability marker in panic disorder.

Adult↗
PubMed1998

[Quantitative assessment of brain morphology with CT in agoraphobia].

This CT study was designed to assess brain morphology in agoraphobia. 21 patients and 21 normal control subjects matched in age and sex were investigated. Frontal and parietooccipital cortex, temporal cortex, lateral ventricles and third ventricle were evaluated by qualitative assessment on a 3-point scale (normal, questionable, abnormal). Patients showed significant bilateral enlargement of prefrontal cortical cerebrospinal fluid (CSF) spaces (p < .05). The rating "abnormal" was given to none (0%) of the normal controls, but to 6 (28.6%) of the patients in the left hemisphere, and to 4 patients (19%) in the right hemisphere, respectively. No qualitative differences were seen in the temporal cortex, lateral ventricles and third ventricle. These findings support the hypothesis that alterations in brain morphology are involved in the etiology of agoraphobia. The lack of a correlation between CSF enlargement and duration of illness suggests that prefrontal CSF enlargement is a neurobiological vulnerability marker in agoraphobia.

Adult↗
PubMed1998

Subtle pulmonary abnormalities: detection on monitors with varying spatial resolutions and maximum luminance levels compared with detection on storage phosphor radiographic hard copies.

PURPOSE: The purpose of this receiver operating characteristic study was to compare diagnostic efficacy with images displayed on monitors of varying spatial resolutions and maximum luminance levels to that with storage phosphor radiographic hard copies. MATERIALS AND METHODS: Seven types of simulated lesions were superimposed onto an anthropomorphic chest phantom. Images were viewed by five radiologists on a 2,560 x 2,048 pixel monitor (maximum luminance, 75 foot-lamberts), on two 1,024 x 1,024 monitors with maximum luminance levels of 25 foot-lamberts and 75 foot-lamberts, respectively, as well as on hard copies. Monitor images were viewed both without and with systematic magnification. RESULTS: Overall visualization of the lesions was best on hard copies, but visualization on the 2,560 x 2,048 monitor was not found to be substantially different. Lines, reticular opacifications, and catheters were found to be particularly poorly visualized with the 1,024 x 1,024 monitor. These results could be statistically significantly improved only with a systematic magnification; however, this involved a considerable increase in viewing time. Observer performance was markedly inferior with the 1,024 x 1,024 monitor with the lower luminance. CONCLUSION: Diagnostic performance with a 1,024 x 1,024 monitor is statistically significantly inferior to that with hard copies. A statistically significant improvement can be achieved with a high-resolution 2,560 x 2,048 monitor with a maximum luminance of 75 foot-lamberts.

Angiography, Digital Subtraction↗
PubMed1998

Hippocampal malformation as a cause of familial febrile convulsions and subsequent hippocampal sclerosis.

OBJECTIVE: One hypothesis proposes that a pre-existing alteration of medial temporal lobe structures contributes to febrile convulsions and subsequent hippocampal sclerosis (HS) in patients with temporal lobe epilepsy (TLE) and antecedent febrile convulsions. It is possible that such a structural alteration does not always lead to convulsions and may also be present in clinically unaffected relatives. METHODS: We tested this hypothesis by MRI investigation of 23 members of two families, of whom 13 had experienced febrile convulsions and 10 had not. One member of each family with febrile convulsions subsequently developed TLE. We compared the right/left ratios of hippocampal volumes (RHV) with 23 age- and sex-matched controls. Additionally, two independent raters assessed hippocampal signal intensity and pattern in T2- and fluid-attenuated inversion recovery images. RESULTS: Both TLE patients showed left HS. All subjects with febrile convulsions who did not develop epilepsy and six clinically unaffected relatives also showed asymmetric RHV (>3 standard deviation) but a normal hippocampal signal intensity. In all of these subjects, the left hippocampus was smaller. Visual inspection of these smaller hippocampi revealed blurred internal pattern or flat hippocampal bodies or both in one family and smaller hippocampal heads in the other. The pattern of HS in TLE patients showed a structural correlation with the abnormalities seen in their relatives. One subject with febrile convulsions had additional subcortical heterotopias. CONCLUSION: These findings suggest a subtle, pre-existing hippocampal malformation that may facilitate febrile convulsions and contribute to the development of subsequent HS.

Adolescent↗
PubMed1998

Early magnetic resonance imaging of brainstem lesions after severe head injury.

OBJECT: The availability of magnetic resonance (MR) imaging data obtained in comatose patients after head injury is scarce, because MR imaging is somewhat cumbersome to perform in patients requiring ventilation and because, in the first hours after injury, its relevance is clearly inferior to computerized tomography (CT) scanning. The authors assessed the value of MR imaging in the early postinjury period. METHODS: In this prospective study MR imaging was performed in 61 consecutive patients within 7 days after they suffered a severe head injury. An initial CT scan had already been obtained. To understand the clinical significance of the lesions whose morphological appearance was identified with MR imaging, brainstem function was assessed by registration of somatosensory and auditory evoked potentials. Brainstem lesions were visualized in 39 patients (64%). Bilateral pontine lesions proved to be 100% fatal and nonbrainstem lesions carried a mortality rate of 9%. In singular cases circumstances allowed for a clear clinical distinction between primary and secondary brainstem lesions. On MR imaging all lesions were hyper- and hypointense after intervals longer than 2 days. Within shorter intervals (< 2 days) after the injury, primary lesions appeared isointense on MR imaging. In one secondary brainstem lesion there were no traces of blood. CONCLUSIONS: Because mean intracranial pressure (ICP) levels in patients without brainstem lesions were similar to those in patients with brainstem lesions, the authors conclude that it was not mainly increased ICP that accounted for the high mortality rates in patients with brainstem lesions. The authors also conclude that brainstem lesions are more frequently found in severe head injury than previously reported in studies based on neuropathological or CT scanning data. Early MR imaging after head injury has a higher predictive value than CT scanning.

Adult↗
PubMed1997

Frontal CSF enlargement in panic disorder: a qualitative CT-scan study.

Brain morphology was assessed qualitatively in CT scans of 21 patients with panic disorder and 21 normal control subjects. Patients showed significant bilateral enlargement of frontal cerebrospinal fluid (CSF) spaces. These findings suggest that alterations in brain morphology are involved in the etiology of panic disorder.

Adult↗
PubMed1997

[Ultrasound diagnosis of soft tissue changes in dialysis-associated amyloidosis].

AIM: To develop criteria for the detection of long term dialysis-associated soft tissue changes due to amyloid deposits in various joints. METHOD: Ultrasonographic examination of the shoulder (15 patients), hip (5 patients), knee (6 patients) and elbow (2 patients) using a 7.5 or 5 MHz scanner. A total of 28 joints were examined. RESULTS: Soft tissue changes in long term dialysis were found to be associated with an increased thickness of the supraspinatus tendon and/or biceps tendon as well as joint effusions with echogenic zones. Moreover, increased thickness of the joint capsule and echogenic proliferation of the synovia were observed. CONCLUSION: Ultrasound is an inexpensive and suitable method in the diagnosis and follow-up of soft tissue changes in patients on long term dialysis.

Adult↗
PubMed1993

[Percutaneous drainage of abscesses, biliomas, seromas and hematomas following liver surgery. Experiences with 46 patients].

Fifty-two fluid collections following hepatic surgery were diagnosed in 46 patients, mostly by sonography. These were treated percutaneously. In 7 patients ultrasound-guided puncture was used, in 36 patients catheter drainage was employed and in three drainage was instituted by a catheter in a pre-existing fistula. One patient with a bile leak in the hilar region had to undergo surgery. One patient died of multi organ failure following liver transplantation and another patient with advanced tumour died 78 days after the drainage procedure. The other patients recovered following conservative treatment (93.5%).

Abscess↗
PubMed1992

[Arthritic changes in small and large joints in digital and conventional x-ray images].

In order to evaluate the suitability of digital radiography for the diagnosis of skeletal abnormalities, inflammatory joint changes were used to test this technique. Early erosive changes, fine irregularities and marginal lamellar abnormalities demand a high degree of resolution from the imaging method. 6 observers studied images of the hand of 67 and of the foot of 19 patients. Joint changes were staged according to the scheme proposed by Larsen; in this study the early stages predominated. With similar techniques there were no significant differences between the digital and conventional techniques. Images of 39 large joints (knee, shoulder, elbow, ankle) were compared only subjectively since even minor differences in projection were able to obscure some erosions. However, in this case also both techniques appear to be of similar value.

Adult↗