PubMed Health⌕ Search

Biomedical subjects

R D Müller

Publications and source records attributed to R D Müller.

At least 37 records · Page 2Linked to original sources
PubMed1996

Frequency-filtered image post-processing of digital luminescence radiographs in pulmonary nodule imaging.

AIM: The aim of the study was to optimize unsharp masking image post-processing of digital luminescence radiographs (DLR) for the representation of pulmonary nodules, and to compare DLR to screen-film radiography at two dose levels. PATIENTS AND METHODS: A total of 284 CT-validated pulmonary nodules were evaluated. One hundred and forty-nine nodules were exposed with a 200-speed screen-film combination (SFC) and 135 nodules with a 400-speed SFC, with correspondingly exposed storage phosphor images. The kernal size in digital post-processing using 'unsharp masking' was varied between S 10 (2.83 mm) and S 70 (19.80 mm). A total of 11928 individual assessments were obtained from six independent observers and evaluated in multifactorial variance analyses. RESULTS: The large filter kernels of S 40 and S 70 were on a par with the 200-speed SFC (P > 0.05). As the exposure dose was reduced, the quality of the digital image vis-à-vis the 400-speed SFC improved significantly (P < 0.05). Smaller filter kernels (S 10; S 20) producing edge-enhancement processing were significantly inferior to the analog image technique in both dose ranges (P < 0.05). CONCLUSIONS: At speed class 200, low-frequency emphasizing digital image post-processing with large filter kernels are significantly superior to high-frequency emphasizing filtrations for the recognition of pulmonary nodules. In the lower dose range DLR with large filter kernel unsharp masking processing showed significantly improved image quality compared to 400 speed SFC for the detection of pulmonary nodules.

Adolescent↗
PubMed1996

Effects of varying filter kernel sizes on the image quality of interstitial lung diseases.

PURPOSE: The aim of the study was to optimize the postprocessing of digital luminescence radiographs of interstitial infiltrates of the lung. MATERIAL AND METHODS: Ninety-seven patients with established diseases of the lung parenchyma were examined: 514 pathological details were investigated, using a 200-speed screen-film system and a storage phosphor plate. In digital postprocessing, the size of the filter kernel (S) varied between S 5 and S 70. Based upon 32896 individual evaluations, the image quality was evaluated in multifactorial variance analyses. RESULTS: The digital standards were significantly inferior to the tested screen-film system. The large filter kernel S 70 and the small filter kernels S 5 and S 10, as well as an algorithm for edge enhancement, showed selective advantages in the depiction of nodular or small linear structures. For micronodular and linear structures, kernel sizes of S 20 and S 40 produced equally good results (p > 0.05). CONCLUSION: Whenever optimized postprocessing is involved, storage phosphor radiography is equal to a modern screen-film system and can be substituted for the latter without any loss of image quality; this is especially valid for the imaging of interstitial infiltrates of the lung.

Female↗
PubMed1996

ROC-analysis of detection performance by analogue and digital plain film systems in chest radiography.

PURPOSE: To compare the performances of 4 imaging systems in the diagnostic radiology of the chest: an asymmetric screen-film combination (a-SFC); a conventional screen-film combination of speed class 200 (SFC); a screen-film combination of speed class 200 with an aluminium lung filter; and digital luminescence radiographs (DLR). MATERIAL AND METHODS: Object detectability studies were carried out using an anthropomorphic chest phantom. The images were obtained under standard exposure conditions at 125 kVp. The detection performance of the various systems was evaluated by receiver operating characteristic (ROC) analysis on the basis of a total of 12,240 observations. RESULTS: In the overall evaluation the a-SFC and the SFC plus lung filter received equally high ratings of 0.878+/-0.018 and 0.860+/-0.21, respectively (p>0.05). There was no significant difference between the 200-speed SFC and the storage phosphor radiographs. In the mediastinum all the tested systems were clearly superior to the 200-speed SFC (p<0.05) while in the lung fields the 200-speed SFC received a high rating of 0.866+/-0.026. The a-SFC had slight advantages over the SFC plus lung filter and the 2 digital imaging modes (p>0.05). CONCLUSION: The a-SFC and the digital luminescence radiographs provide a significant gain in diagnostic information in the mediastinum without diminishing detail detectability in the lung fields and without additional radiation exposure.

Filtration↗
PubMed1996

[Use of digital luminescence radiography in voiding cystourethrography].

PURPOSE: Optimization of image quality by use of digital luminescence radiography (DLR) in voiding cystoureterography (VCU) instead of a conventional screen film system. PATIENTS AND METHODS: 53 patients with a suspected vesicouretral reflux were examined with a VCU in analogous and digital technique. The X-rays were taken in a sitting position while simultaneously measuring the bladder pressure. An intraindividual comparison was omitted for X-ray saving reasons. In the follow-up 3 patients were examined with the other system. Two radiologists and two urologists compared 60 VCU of 53 patients--30 VCU in conventional screen film and 30 in DLR technique presented in standard and edge-enhanced images--with regard to image quality according to 3-step score (A--good image quality, B--sufficient image quality, C--insufficient image quality). RESULTS: The 59 conventional films were scored 72 times with an A, 76 times with a B, and 72 times with a C, whereas the DLR films were scored 116 times with an A, 72 times with a B, and only 8 times with a C. Hereby the edge-enhanced images were the most useful for distinguishing the bladder shadow from the soft tissue of the thigh and for detecting reflux. Furthermore, the exposure dose when applying DLR could be decreased to 75% in grown-ups and to 57% in children without any significant loss of information. CONCLUSION: The DLR is highly superior to the conventional film screen system because of its relatively high tolerance towards wrong exposures, especially with respect of the sitting position during MCU. With the DLR we obtained 96% and with the conventional system only 63% films usable for diagnosis.

Adolescent↗
PubMed1996

[CT-guided punctures in the area of the spine. The "fluorotechnique" as localization method].

The increased anatomical resolution of the Computed Tomography allows the localized excision of tissue malformation even less than 5 mm in diameter. Within difficult areas of the body, e.g. the spine, it is possible to reach intra- as well as extraosseous lesions with high accuracy. Results and technique of puncture are reported in 31 patients with unclear diagnosis or therapy (Neurolysis). In 24 cases diagnosis was established or therapy was successful, in 2 cases the result was false negative. In 5 cases the tissue was non diagnostic. According to the low number of complications (n = 1) a repeated study would have been possible.

Adolescent↗
PubMed1996

[Value of percutaneous catheter cholangiography in postoperative biliodigestive and bilio-biliary anastomoses].

AIM OF STUDY: To examine the relative importance of percutaneous catheter cholangiography in postoperative diagnostics after biliary reconstruction. METHODS: 55 patients (33 males, 22 females) were subjected to 101 catheter cholangiographies. 30-50 ml of a water-soluble, iodic contrast medium were administered via an infusion system. Initial examinations were performed between the 3rd and 7th day following operation, while follow-up examinations were executed between the 8th and 145th day after surgery. The position of the catheter, the function of the anastomosis, the filling of the biliary ducts and the discharge of the contrast medium were assessed. RESULTS: 45 examinations were inconspicuous. Drainage obstruction of the contrast medium was observed in 24 cases. Filling defects were observed in 8 examinations. A dislocation of the catheter was encountered in 5 cholangiographies while 19 examinations displayed a bile leak. CONCLUSION: Percutaneous catheter cholangiographies can be used to detect postoperative complications following biliary reconstruction in an easy, reliable, and cost-effective manner that also does not put too much strain on the patient. Indications for the implementation of catheter cholangiographies are the occurrence of abdominal complaints, the clinical appearance of a peritonitis, or an increase of the serum bilirubin value. Routine examinations are recommended in conditions following liver transplantations. In addition to this, a cholangiography should be carried out prior to the removal of the catheter.

Adult↗
PubMed1995

[ROC analysis in post-processing of image data in digital thoracic radiography].

PURPOSE: To examine the extent to which digital luminescence radiography (DLR) can be used for the imaging of pulmonary nodules and interstitial lung disease in chest radiography without any loss of image quality. Additionally: to examine whether post-processing of image data can optimise the recognizability of varied image details. MATERIALS AND METHODS: Detail perceptibility studies were performed on an anthropomorphic thorax phantom with simulated nodules and small linear and reticular details. Under standard conditions, digital luminescence radiographs were obtained in 7 different image modes, and these were compared with a 200-speed screen-film system. The detection of these systems was evaluated in an ROC analysis on the basis of 19,200 individual observations. RESULTS: Edge enhancement or application of high-frequency-enhancing small filter kernels (S 5) slightly improves the detection of linear structures; however, the illustration of nodular details is markedly reduced. Larger filter kernels (S 20, S 40) make a definitive detection possible--not only of circular, but also of linear details. CONCLUSIONS: Storage phosphor radiographs are equal to the tested analog screen-film-system. The optimization of post-processing can be helpful in the prevention of routine multiple documentations.

Adult↗
PubMed1995

[The use of an asymmetric film-screen combination for the imaging of round pulmonary foci].

PURPOSE: To examine the diagnostic advantages of an asymmetric film-screen system (a-FSS) compared to a conventional 200-speed FSS with and without anatomical lung filter. METHODS: Standard radiographs were obtained from an anthropomorphic chest phantom with simulated pulmonary nodules. The existence or non-existence of nodules was assessed in 7344 individual observations. The results were evaluated using ROC analysis. RESULTS: In an overall evaluation the a-FSS with an ROC area of 0.873 +/- 0.018 was not significantly superior (p > 0.05) to the lung filter but significantly superior (p < 0.05) to the 200-speed FSS. In the mediastinum the a-FSS and the lung filter were significantly superior (p < 0.05) to the 200-speed FSS. In the lung areas the 200-speed FSS and the a-FSS attained equivalent results (p > 0.05), whereas the lung filter was rated significantly lower (p < 0.05). CONCLUSIONS: Asymmetric FSS improves chest diagnostics, because it yields significantly more diagnostic information in the mediastinum using equivalent x-ray exposure without reducing the image quality in the lung areas in respect of simulated pulmonary nodules.

Evaluation Studies as Topic↗
PubMed1995

[ROC analysis of image quality in digital luminescence radiography in comparison with current film-screen systems in mammography].

AIM: To compare in mammography the image quality of digital luminescence radiography (DLR) to that of usual film screen mammography and xeromammography. MATERIALS AND METHODS: Three single emulsion film-screen combinations, one double coated high resolution film and xeroradiography, were tested for this purpose. In our phantom study the detectability of microcalcifications, fibrils and low contrast details were first of all studied separately. Image processing techniques were, for example, contrast variation by grey scale level windowing, "unsharp mask" filtering and regulatable edge enhancement. Phantom images were made and then the image quality was evaluated by observer performance study using a receiver operating characteristic (ROC analysis). RESULTS: Best results in respect of detection of microcalcifications and fibrils were found in xeroradiography, luminescent image plate and double-coated film-screen combination. These systems showed more favourable ROC curves than the single emulsion film-screen combinations. CONCLUSIONS: Our results indicate that image quality of digital images in the field of image processing is equal to that of conventional mammographic techniques and partially superior to detection of low contrast details.

Breast Neoplasms↗
PubMed1993

[Primary diagnosis of osseous carpal area injuries--a comparison of conventional examination methods with digital luminescence radiography].

Despite recent progress in improving diagnostic methods carpal bone lesions are still a major problem of primary diagnosis. Diagnostic imaging with digital luminescence radiography (DLR) allows the reliable presentation of traumatologically relevant carpal structures. In this study on 39 patients with suspected carpal bone injuries individually worked over DLR images were superior to "standard" DLR and conventional X-ray film/screen images. Though "standard" DLR images were inferior to film images edge-enhanced DLR images showed definite advantages in the demonstration of soft tissues. Fractures undetectable in conventional X-rays could not be recognized by digital imaging. In our experience bone-scanning remains the most reliable method for definite exclusion of carpal bone fractures after standard and digital X-ray methods are exhausted.

Adolescent↗
PubMed1993

[Are high-intensifying film-screen combinations suitable for the detection of fine interstitial lung changes? The results of a ROC study with an anthropomorphic thorax phantom].

Exposures of an anthropomorphic thorax phantom in posteroanterior projection were made using a focus-film distance of 200 cm and 125 kV with film-screen combinations in class 200 (Curix RP 1L/MR 200) and class 400 (Curix ST-L/Regular). Pathomorphological structures of the lung parenchyma of fine nodular, linear and reticular types were simulated by suitable materials. A ROC analysis including a t-test showed no significant difference in the evaluation of these structural details (p > 0.05). In order to describe image quality for the two film-screen systems, density curves, sigma D-curves and modulation transfer function (MTF) were determined. The only demonstrable difference was reduced MTF of 10-15% for the higher intensification film-screen combination with a resulting poorer resolution of 3.7 l/mm (for the 400 system) compared with 4.3 l/mm for the 200 system.

Evaluation Studies as Topic↗
PubMed1992

[Irradiation field controls by digital luminescence radiography].

Since portal images taken with conventional X-ray films suffer from poor contrast and unsharpness due to the high energy of the radiation beam, scattered radiation, patient motion, and the large dimensions of the radiation source, comparison of portal images with simulation images is often difficult and time consuming. Therefore many efforts have been made to improve such images. The use of storage phosphors and electronic image post-processing provides a remarkable improvement of image quality with better delineation of anatomical landmarks in high contrast areas such as head, neck, and mediastinum, as well as in low contrast regions, i.e. abdomen and pelvis.

Adolescent↗
PubMed1991

[Digital luminescence radiography (DLR) for skeletal diagnosis in traumatology].

170 patients who had suffered trauma to bones or soft tissues were examined by a digital and a conventional film/screen technique. In addition to "standard" and edge-enhanced images, post-processing was carried out and compared with conventional radiographs. Four radiologists and two surgeons evaluated the compacta, spongiosa, soft tissues, fractures and osteo-synthetic materials as shown on the two systems. The "standard" digital images are inferior to film images, but edge-enhanced images showed definite advantages for demonstrating soft tissues. Evaluation of osteo-synthetic material is limited by the creation of artifacts. Recognition of detail can be significantly improved by using post-processing with optimized parameters.

Adolescent↗
PubMed1991

[Roentgen diagnosis of pulmonary complications following allogeneic bone marrow transplantation--application of and experience with digital luminescence radiography].

Pulmonary complications exercise a decisive influence on the prognosis of leukaemia patients after bone marrow transplantation. Very early diagnosis is a mandatory prerequisite to successful therapeutic intervention. Of great importance besides the clinical findings and bronchoalveolar lavage is the analysis of the x-ray morphology of pneumonic infiltrates to narrow down the differential diagnostic spectrum. Since the patients are at high risk of infection, they are under isolated care, so that x-ray examinations can only be performed by means of projection radiography using mobile units. Due to these difficulties in performing relevant radiography the required optimal and constant image quality cannot be achieved by means of conventional x-ray film, so that very early detection of pulmonary complications is not always possible. The use of digital luminescence radiography (DLR) with luminescent storage foils enables a highly constant and hence comparable image quality thanks to increased image dynamics, a larger area of the examined object, and histogram evaluation of the image data for determining the optimal parameters for assessment. In addition, details can be better identified to supply answers to specific questions, because the image can be reprocessed to select relevant image parameters by monitoring. Pulmonary complications in 86 patients were analysed retrospectively. These patients had received an allogeneic bone marrow transplant for acute myeloic leukaemia, after they had been treated with high-dose radio-/chemotherapy. The x-ray morphology, clinical and sometimes autopsy findings were correlated with the occurrence of pulmonary complications subsequent to bone marrow transplant.

Adolescent↗
PubMed1991

Carotid body tumor: appearance on color-flow Doppler sonography.

Color doppler sonography permits differentiation of vascular malformations in the neck from solid and cystic tumors. This case report of a 67-yearly-old woman demonstrates the hypervascularized nature of a carotid body tumor displacing the internal carotid artery and fed by branches of the external carotid artery.

Aged↗