[ROC analysis in post-processing of image data in digital thoracic radiography]. / ROC-Analyse zur Bildnachverarbeitung digitaler Thoraxaufnahmen.

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.

[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]. / Sind hochverstärkende Film-Folien-Kombinationen zur Detektion feiner interstitieller Lungenveränderungen geeignet? Ergebnisse einer ROC-Studie am anthropomorphen Thoraxphantom.

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.

[Digital luminescence radiography (DLR) for skeletal diagnosis in traumatology]. / Digitale Lumineszenzradiographie (DLR) zur Skelettdiagnostik in der Traumatologie.

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.

[The use of an asymmetric film-screen combination for the imaging of round pulmonary foci]. / Einsatz einer asymmetrischen Film-Folien-Kombination zur Abbildung pulmonaler Rundherde.

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.

[Determining rotational errors of the femur by axial computerized tomography in comparison with clinical and conventional radiologic determination]. / Rotationsfehlerbestimmung am Femur durch axiale Computertomographie im Vergleich zu klinischer und konventioneller radiologischer Bestimmung.

58 patients, suspicious to have a rotation deformity of the femur, were treated between 1981 and 1988 at our hospital. To compare the value of diagnostic methods in measuring the degree of malrotation we estimated this degree using clinical tests and calculated the anteversion of the femoral neck, taking radiographs in the technique of Dunn and Rippstein and a modified method of computed tomography. Surprisingly only in twelve cases the direction of malrotation, not to consider the degree, with all three methods was corresponding. Clinical evaluation only in cases with extreme deformity produces clear results. Maintaining the exact position of the patient, necessary to get reproducible results using conventional X-ray technique, was impossible in most cases of elderly patients with postraumatic joint-stiffness and malalignment. Determination of femoral neck anterversion by means of CT is a quick, reproducible method to calculate the degree of rotation deformation, insensitive to the position of the patient's extremities as far as there is no motion during the time of scan.

[Radiological determination of femoral rotation deformity--computerized tomography, optimized measurement accuracy and exposure dosage]. / Radiologische Rotationsfehlerbestimmung am Femur--Computertomographie, optimierte Messgenauigkeit und Expositionsdosis.

58 Patients, suspicious to have rotation deformity of the femur, were examined. To compare the value of diagnostic methods in measuring the degree of malrotation we estimated this degree using clinical examination and calculated the anteversion of the femoral neck, taking radiographs in the technique of Dunn and Rippstein, and a modified method of computed tomography. Only in twelve cases the direction of malrotation was corresponding in all three methods, although considerable variations in quantitative results were noted. Maintaining the exact position of the patient, necessary to get reproducible results using conventional X-ray technique, was impossible in most cases of patients with posttraumatic joint-stiffness and malalignment. Determination of femoral neck anteversion using this modified method of CT is a quick, reproducible technique to calculate the degree of malrotation, insensitive to the position of the patient. By means of this CT method it was possible to approach the highest accuracy in precise preoperative planing. Furthermore the radiation exposure could be reduced in a range of 20%-40%.

[Minimally invasive treatment of abscesses by CT-controlled drainage with a basket catheter system]. / Minimal invasive Behandlung von Abszessen durch CT-gesteuerte Drainage mit einem Korbkatheter-System.

PURPOSE: To examine whether the percutaneous drainage of abscess formations by a new basket catheter system is usefull. MATERIAL AND METHODS: 58 patients with abscesses in different locations and origins have been treated by an interventional radiologic procedure. On the whole 77 basket-catheters were placed under CT-guidance into abscess formations of different size and localization. 36 patients developed an abscess after surgery, two patients achieved abscess drainage after embolisation of a tumor. In 20 patients the abscess was a complication of a septic infectious disease. RESULTS: Open surgery was avoided in 41/58 patients of these patients 9/41 received only percutaneous drainage and 32/41 patients suffering from illness were given antibiotic medication according to the resistogram in combination with percutaneous drainage. 17/58 patients required secondary surgery but with a lower risk because of the smaller abscess volume and the better clinical constitution after percutaneous drainage. CONCLUSIONS: A minimally invasive management of abscesses using a basket-catheter system is successful even in localisations deep inside the body and hard to reach. An irreversible catheter occlusion followed by the implantation of a new catheter system could be avoided in all patients.

Unsharp masking of low-dosed digital luminescence radiographs: results of a receiver operating characteristics analysis.

The extent to which the diagnostic performance of low-dosed storage phosphors can be improved by suitable image postprocessing was investigated. Storage phosphor radiographs and conventional 200- and 400-speed screen-film combinations of an anthropomorphic chest phantom with simulated nodules and linear structures were compared. The detection of test bodies was determined in a ROC analysis based on 16200 individual observations. The two analog screen-film systems did not differ significantly. As far as the storage phosphor radiographs are concerned, a higher diagnostic performance was achieved with a large filter kernel (S 40) whereas small filter kernels and edge-enhanced imaging modes reduced the detection of detail. The image quality of low-dosed storage phosphors is thus similar to high-amplification screen-film combinations if large filter kernels are used in postprocessing of the image.

[Primary diagnosis of osseous carpal area injuries--a comparison of conventional examination methods with digital luminescence radiography]. / Die primäre Diagnostik knöcherner Handwurzelverletzungen--ein Vergleich konventioneller Untersuchungsmethoden mit der digitalen Lumineszenzradiographie (DLR).

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.

Detection of radiographic findings in lung fibrosis using storage phosphor plates.

The aim of this work was to examine the influence of the filter kernel size on the detectability of differing radiological findings in interstitial lung disease. In 97 patients with confirmed pulmonary fibrosis chest radiographs were obtained with a filmscreen system of speed class 200 and with correspondingly exposed storage phosphorous plates. The size of the filter kernel used for the image postprocessing varied between sigma 5 and sigma 70. The detectability of interstitial lung changes was evaluated independently by eight readers on the basis of a defined rating system. The results were analysed using multifactorial analysis of variance with Scheffé test at a significance level of p = 0.05. Small kernel sizes (S 5, S 10) combined with high edge enhancement were only of benefit in the imaging of septal lines, but reduced the detectability of nodular and reticular structures. Good detail detectability of both micronodules and septal lines was obtained with a medium kernel size of sigma 40. Storage phosphor radiography utilizing the appropriate choice of postprocessing parameters provides equivalent image quality for evaluating interstitial lung changes compared with a modern filmscreen technique.

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.

[Value of lung filter, asymmetric film-screen technique and digital storage screen radiography in diagnosis of coin lesion]. / Zur Wertigkeit von Lungenfilter, asymmetrischer Film-Folien-Technik under digitaler Speicherfolienradiographie in der Rundherddiagnostik.

AIM: To evaluate the image quality of an asymmetric film-screen combination (a-FSC), a conventional screen-film combination (FSC) at speed class 200, a lung filter, and digital luminescence radiograms in detecting pulmonary nodules. METHODS: Detail perception studies were carried out with an anthropomorphic phantom. The image systems were exposed under standardised conditions with 125 kVp. The systems' perception efficiency was evaluated on the basis of 12.240 single observations with ROC analysis. RESULTS: In the overall evaluation the a-FSC and the filter achieved equally high assessments of 0.878 +/- 0.018 and 0.860 +/- 0.21 respectively (p > 0.05). The 200 speed FSC and the storage phosphor screen radiograms did not differ significantly. In the mediastinum all the tested systems were clearly superior to the 200 speed FSC (p < 0.05). In the lung fields on the other hand the 200 speed system was given a higher assessment of 0.866 +/- 0.026. The a-FSC had slight advantages over the lung filter and the digital imagining modes (p > 0.05). CONCLUSIONS: The a-FSC and digital luminescence radiograms provide significantly more diagnostic information in the mediastinum, together with high detail detectability in the lung fields and without requiring additional dosage.

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.