Can contrast enhanced MRI predict the response of Graves' ophthalmopathy to orbital radiotherapy?

The purpose of this study was to try to determine by means of contrast-enhanced MRI, a subset of patients with Graves' ophthalmopathy who will not respond to orbital radiotherapy. 54 patients with Graves' ophthalmopathy were treated with orbital radiotherapy (10 x 2 Gy) and symptom relief was recorded. MRI examinations prior to radiotherapy were retrospectively evaluated for enlargement, contrast enhancement and fibrotic changes in extraocular muscles and surrounding soft tissue. Imaging data were correlated with clinical features and response. Symptom relief was observed in 61% of patients but this could not be predicted by any of the MRI signs investigated. However, there is a trend for a better treatment reponse in patients who show contrast enhancement of extraocular muscles prior to orbital radiotherapy (p=0.08). MRI could not adequately predict the efficacy of orbital radiotherapy in this group of patients. Clinical assessment of disease activity is still the most reliable method.

[Computer-assisted visualization of digital mammography images]. / Computergestützte Visualisierung digitaler Mammogramme.

PURPOSE: In a clinical study, the feasibility of using a mammography workstation for the display and interpretation of digital mammography images was evaluated and the results were compared with the corresponding laser film hard copies. MATERIALS AND METHODS: Digital phosphorous plate radiographs of the entire breast were obtained in 30 patients using a direct magnification mammography system. The images were displayed for interpretation on the computer monitor of a dedicated mammography workstation and also presented as laser film hard copies on a film view box for comparison. The images were evaluated with respect to the image handling, the image quality and the visualization of relevant structures by 3 readers. RESULTS: Handling and contrast of the monitor displayed images were found to be superior compared with the film hard copies. Image noise was found in some cases but did not compromise the interpretation of the monitor images. The visualization of relevant structures was equal with both modalities. Altogether, image interpretation with the mammography workstation was considered to be easy, quick and confident. CONCLUSIONS: Computer-assisted visualization and interpretation of digital mammography images using a dedicated workstation can be performed with sufficiently high diagnostic accuracy.

Storage phosphor direct magnification mammography in comparison with conventional screen-film mammography--a phantom study.

Contact mammography with current photostimulable storage phosphors is hampered by its low spatial resolution. Detail visualization can be improved by geometric magnification radiography which enlarges small details to exceed inherent image noise. This study compares storage phosphor mammography using a dedicated direct magnification system with state-of-the-art conventional screen-film mammography. Storage phosphor direct magnification survey views (1.7x) and spot views (4x) were obtained with a prototype mammography unit providing focal spot sizes of 120-40 microns. Conventional technique screen-film survey views (1.1x) and spot views (1.8x) served as comparison. A contrast detail study and a receiver operating characteristic (ROC) analysis using an anthropomorphic breast phantom with superimposed microcalcifications was performed. Contrast detail resolution in the digital and conventional survey views were equivalent. For the spot views, contrast detail resolution was significantly higher with the digital technique (p < 0.001). ROC analysis of 400 observations demonstrated a significantly higher performance (p < 0.001) with digital images versus conventional screen-film mammograms. The area under the ROC curve (Az) in the digital survey views was 0.76 +/- 0.07 versus 0.59 +/- 0.02 in the conventional technique. In digital spot views, Az was 0.82 +/- 0.07 as compared with 0.66 +/- 0.04 in the conventional spot views. These results suggest that storage phosphor digital mammography in conjunction with direct geometric magnification technique may be superior to conventional screen-film mammography in the detection of microcalcifications.

Magnification survey and spot view mammography with a new microfocus X-ray unit: detail resolution and radiation exposure.

The aim of our study was to evaluate a mammography unit capable of magnification of up to fourfold at an equivalent or lower dose than with current systems. A prototype mammography tube with an electron-beam-focusing technology resulting in a focal spot size of 40-120 micro m was combined with a highly intensifying screen-film system. To evaluate contrast-detail resolution, phantom radiographs were performed with the prototype magnification mammography system using a magnification factor of 1.7 for survey views and a magnification factor of 4.0 for spot views. They were compared with unmagnified survey views and magnification spot views (magnification factor 1.9) of a state-of-the-art mammography system. The radiation exposure was measured and mean glandular doses were calculated. The contrast-detail resolution with both prototype (m = 1.7) and conventional (m = 1.1) survey views was equivalent while the entrance dose and the mean glandular dose were approximately 50 % lower with the prototype. For spot views, the contrast-detail resolution was substantially higher for the prototype than for conventional magnification while the dose was equivalent. Dose reduction and improved detail resolution are possible with this new technology.

[A new specimen radiography device with a maximum 20-fold magnification for breast diagnosis]. / Ein neues Präparatradiographiegerät mit maximal 20facher Vergrösserung für die Mammadiagnostik.

PURPOSE: A radiography system specially developed for specimen radiography and allowing maximal 20-fold magnification is presented. The efficiency of the system was tested and compared with that of conventional magnification mammography systems. METHODS: 23 surgical and 90 core biopsies of the breast were examined for detection of microcalcifications. As criteria the number of identifiable calcifications, their shape and configuration as well as tissue contrast were chosen. RESULTS: The new technique detected about 400% more microcalcifications, 200% more core and 50% more surgical biopsies containing calcifications. Thus, in a few cases, additional core biopsies were unnecessary. Moreover, this new system yielded additional information for the pathologist and surgeon concerning the exact localisation of suspicious lesions that facilitated working up specimens, or indicated additional surgical removal in special cases. CONCLUSIONS: By identification of malignant lesions not detectable with conventional magnification radiography systems, as well as a more exact localisation of suspicious lesions, false negative results may be reduced.

[Digital magnification mammography in computed radiography. Initial clinical results]. / Digitale Vergrösserungsmammographie in Speicherfolientechnik. Erste klinische Ergebnisse.

INTRODUCTION: The combination of direct magnification mammography and computed radiography provides an improvement in spatial resolution of storage phosphor-based digital systems. A clinical study comparing conventional and digital direct magnification mammograms was performed. METHODS: 100 survey mammograms in 1.5-or 1.7-fold magnification and 50 4-fold spot magnification views were obtained with a prototype direct magnification mammography system and a storage phosphor-based digital system. An intraindividual comparison of these with previous conventional radiograms of the same patients was carried out. RESULTS: The diagnostic value of digital survey mammograms using the direct magnification technique is comparable to that of conventional radiograms of the breast, especially with regard to the identification of microcalcifications and lesions and the clinical consequences. Spot magnification views performed with this combination of techniques allowed improvement in the evaluation of microcalcifications. In 15% of cases, diagnostic procedures were adjusted accordingly. CONCLUSION: The combination of the direct magnification technique with digital storage phosphor radiography systems allows the performance of digital mammography by improving the overall spatial resolution. The diagnostic value of digital direct magnification survey mammograms was comparable to that of conventional mammograms. Digital 4-fold spot magnification views improved visualisation of the morphologic aspects of microcalcifications.

[Direct radiographic magnification mammography with a new microfocus tube. Experimental studies of resolution and radiation exposure]. / Direktradiographische Vergrösserungsmammographie mit einer neuen Mikrofokusröhre. Experimentelle Untersuchungen zum Auflösungsvermögen und zur Strahlenexposition.

A recently developed X-ray unit for mammography using microfocal (spot size 0.12-0.05 mm) direct magnification radiography will soon be introduced into clinical practice. Unit arrangement and tube construction have been demonstrated. Mean surface dose was measured using PMMA-phantoms. A dose reduction of up to 50% was obtained in 1.7-fold magnification mammography (full sized views) compared with conventional techniques. The image quality was almost equivalent. However, in comparison with 1.7-fold magnification mammography, a comparable dose range for 4-fold magnifications with the microfocus system was measured with a substantial gain in spatial resolution. These findings satisfy the demands of a modern mammographic unit.

[Digital storage phosphor mammography in a magnification technic: experimental studies for spatial resolution and for detection of microcalcifications]. / Digitale Speicherfolienmammographie in Vergrösserungstechnik: experimentelle Untersuchungen zur Ortsauflösung und zur Erkennbarkeit von Mikrokalk.

PURPOSE: Since the routine use of storage phosphor systems for mammography has been limited by its inadequate spatial resolution of 5 linepairs/mm, a combination of a magnification mammography technique with storage phosphor plates was investigated to detect microcalcifications. MATERIAL AND METHODS: A new mammography system with a microfocus tube using an anode of 0.05-0.12 mm allowed to obtain survey views of the breast with 1.7x magnification (m), and spot views with 4x magnification. The digital image receptor comprised a high resolution storage phosphor plate. To determine spatial resolution, contrast transfer curves were obtained, and the detection of microcalcifications was investigated by ROC (receiver operating characteristic) analysis. RESULTS: Spatial resolution for digital survey views (m = 1.7) was 8 linepairs/mm and for spot views (m = 4) was 18 linepairs/mm. ROC analysis demonstrated a significantly higher performance of the digital magnification technique compared to the conventional screen-film mammography technique. CONCLUSIONS: The limitations of digital mammography with respect to spatial resolution can be overcome by using a high magnification technique.

[Digital image magnification mammography with the storage-screen technique. Standardized and findings-oriented image processing parameters]. / Digitale Vergrösserungsmammographie mit Speicher-Folien-Technik. Standardisierte und befundorientierte Bildverarbeitungsparameter.

Present day mammography has not been able to make use of the advantages of digital luminescence radiography because of the limited spatial resolution. The recent development of electromagnetic focusing x-ray tube with effective focal spot sizes from 0.04 to 0.12 mm allows radiographic direct magnification with less geometric blur. It is now possible to combine direct magnification mammography with digital luminescence radiography. By combining high quality storage phosphor screens with an HQ-workstation a spatial resolution of 8 lp/mm is possible for 1.7-fold magnification. For 4-fold spot magnification views spatial resolution can be theoretically increased to approx. 20 lp/mm. One important advantage of digital radiography is the possibility of image-post-processing. This article presents two sets of standard parameters and three sets of image dependent parameters for better imaging of specific lesions, such as microcalcifications. The introduction of the the storage phosphor screen technique in mammography is one step in the development of direct digital radiography. Further interesting perspectives for the future include post-processing programs for detecting suspicious lesions which are already being clinical tested.

In vitro effects of aprosulate sodium, a novel anticoagulant, on platelet activation: possible mechanism for antiplatelet action.

Aprosulate sodium, a bis-lactobionic acid amide derivative, is a novel synthetic polyanion with potent anticoagulant activities. In the present study, the effects of aprosulate on platelet aggregation were investigated in a plasma-free system. Aprosulate inhibited thrombin (0.03-0.3 U/ml)-induced aggregation in rat washed platelets in a concentration-dependent manner, with an IC50 value of 0.38 microgram/ml. In contrast, aprosulate, at up to 10 micrograms/ml, did not affect collagen (1 microgram/ml)- or ADP (3 microM)-induced aggregation. In fura 2-loaded platelets, aprosulate (1-10 micrograms/ml) inhibited intracellular Ca2+ mobilization induced by thrombin, but not that by ADP. Protamine, a highly basic protein, abolished aprosulate-mediated inhibition of thrombin-induced platelet aggregation, suggesting that the observed inhibition is primarily due to the negative charge contained on the aprosulate molecule. In human platelets, aprosulate inhibited thrombin-induced aggregation, but failed to inhibit platelet aggregation induced by SFLLRN, a synthetic tethered ligand of a thrombin receptor. Antiplatelet profiles of aprosulate were largely similar to those of heparin, although heparin inhibited both thrombin- and collagen-induced aggregation. These in vitro studies indicate that aprosulate is capable of inhibiting thrombin-induced platelet activation and that this effect is independent of its anticoagulant activity. These results suggest that the polyanionic feature of aprosulate plays an essential role in promoting its antiplatelet activities, and that a plausible mechanism to explain the observed inhibition conferred by this agent, would be one which involves blocking the platelet-thrombin interaction.

[An anatomically adapted variation of the tube current in CT. Studies on radiation dosage reduction and image quality]. / Anatomisch adaptierte Variation des Röhrenstroms bei der CT. Untersuchungen zur Strahlendosisreduktion und Bildqualität.

PURPOSE: To assess the impact of a method for anatomically adapted tube current variation. The resulting CT image quality was evaluated quantitatively and qualitatively. METHODS: CT scans of 100 patients were performed with a constant tube current (Group 1) and another 100 patients with an anatomically adapted tube current (Group 2). The CT tube current was varied during a 360 degrees tube rotation reflecting the measured density values extracted from two perpendicular scout views. The standard deviation of densities of defined regions was measured. The image quality was ranked (1 = non-diagnostic-5 = excellent) by three radiologists. RESULTS: The effective tube current could be reduced by an average of 8.9% (0-20.4%). The mean tube current reduction depended on the body region: pelvis (13.2%), abdomen (8.4%) and thorax (3.3%). The image quality was not significantly reduced in Group 2. CONCLUSION: The method for anatomically adapted tube current variation leads especially in the pelvis to a significant mAs reduction without considerable loss of image quality.

[A bimetal anode with tungsten or rhodium? Comparative studies on image quality and dosage requirement in mammography]. / Bimetallanode mit Wolfram oder Rhodium? Vergleichende Untersuchungen zur Bildqualität und zum Dosisbedarf in der Mammographie.

PURPOSE: The impact of different anode materials (tungsten and rhodium) on spatial resolution, image contrast and radiation exposure was studied. MATERIALS AND METHODS: Two mammographic systems providing bimetal x-ray tubes (Mo/W and Mo/Rh) were compared by imaging a breast radiography phantom with additional acrylic plates from 3 to 8 cm thickness. Spatial resolution was evaluated using a line bar pattern. Image contrast was assessed by measuring the ratio of optical densities in a acrylic step-wedge. The entrance dose was measured with a low energy ionisation chamber. RESULTS: The spatial resolution was about 13 lp/mm regardless of the beam quality. The image contrast depended substantially on the thickness. A similar image contrast was found with Mo/Mo, Mo/Rh and Rh/Rh for simulated breast thicknesses of 4 to 6 cm and with Rh/Rh and W/Rh for 7 cm. In comparison to Mo/Mo the dose reduction was significant for Mo/Rh (35%), Rh/Rh (50%) and W/Rh (60%). CONCLUSIONS: Bimetal x-ray tubes provide optimal conditions for screen film mammography of both normal and dense breasts, allowing good contrast and dose reduction by using the adequate anode/filter-combination.

The effect of dose fractionation on radiation injury in the rat stomach.

Localized 300 kV X-irradiation of the rat stomach with single and fractionated (two and five fractions given daily and in 4 weeks) doses was performed. In the second and third week after irradiation acute radiation gastritis developed which resulted in a dose-dependent drop in body weight. The alpha/beta value for a 10% drop in body weight was calculated to be 9.6 Gy (95% confidence interval 2.1-25.9 Gy). Between 4 and 40 weeks after irradiation subchronic radiation damage was observed which presented itself as atonic dilatation of the stomach. For this effect, the alpha/beta value is 4.8 Gy (graphical estimation) and 5.3 Gy (95% confidence interval 0.4-13.1 Gy; direct Poisson model). In the five-fraction (5F) experiment a significant increase in tolerance amounting to 0.8 Gy/day for the acute effect and 0.4 Gy/day for the subchronic effect was observed when intervals were increased from 1 day to 1 week. In a separate experiment animals were pre-irradiated with subtoxic and toxic radiation doses. One hundred days later acute tolerance to a second irradiation was completely restored. However, no recovery of subchronic damage was observed.

[Development of methods for measuring the emptying time of solid and liquid test meals in rat stomachs]. / Entwicklung von Methoden zur Messung der Entleerung fester und flüssiger Testmahlzeiten aus dem Rattenmagen.

Different methods for experimental measuring the gastric emptying time in the rat have been developed. For the invasive method of measuring the stomach emptying time of a solid test meal containing Amberlite pellets too many animals are necessary. On the other hand, for the non-invasive examination of the emptying of a radioactively marked liquid test meal by scintigraphy the resolution of the gamma-camera is too low. However we were able to develop a non-invasive fluoroscopic method for the simultaneous measurement of the gastric emptying of a solid (10 radiodense markers) and a liquid (0.5 ml diluted contrast medium) test meal. Using this method it was possible to examine the influence of stomach motility stimulating drugs, such as the parasympathomimeticum carbachol and the dopamine antagonist metoclopramide.

[Acute and chronic disorders in gastric emptying after the x-ray irradiation of the rat stomach and their therapeutic modification]. / Akute und chronische Störungen in der Magenentleerung nach Röntgenbestrahlung des Rattenmagens und deren therapeutische Beeinflussbarkeit.

After localized 300 kV X-irradiation of the rat stomach the stomach emptying time of a liquid and a solid test meal was examined with a non-invasive radiological method. In the acute period one to three weeks after irradiation with single doses between 10.7 and 21.3 Gy we observed a faster emptying of the liquid and a delayed emptying of the solid test meal. The faster emptying of the liquid test meal was treated successfully with atropine. In the chronic period we observed a delayed emptying of the liquid and of the solid test meal. These emptying disorders were treated partially successfully with the parasympathomimeticum carbachol and they were treated completely successfully with the dopamine antagonist metoclopramide.

Influence of X-irradiation on the motor activity of rat urinary bladder in vitro and in vivo.

Preparations of rat detrusor vesicae urinariae exposed to 50 kV X-irradiation with 10 to 200 Gy (single dose) at dose-rates of 30 and 60 Gy/min reacted immediately with a dose and dose-rate dependent reversible or persistent increase (up to ten hours) of the basal tone and an increase or a decrease of the acetylcholine contractile response. The motor activity was recorded isotonically. For measurements of time changes following treatment in vivo the bladder was locally irradiated from lateral position with single 300 kV X-ray doses of 10, 25 and 50 Gy. The motor reaction of isolated detrusor preparations to acetylcholine had a threshold concentration in control animals of 2.3 X 10(-10) mol/l (n = 33); the sensitivity to acetylcholine was diminished as early as one to two hours after local irradiation with 50 Gy as reflected in a ten times higher threshold concentration, which decreased further with time past treatment up to 40 days. The inhibitory effect after 25 Gy was weaker. The contractile response of acetylcholine at different concentrations (10(-10) to 10(-5) mol/l) was also diminished after irradiation (50 Gy). It is suggested that the pathophysiological reactions of the radiogenic bladder are based on multifactorial mechanisms and X-ray induced tonic contraction as well as inhibition of the acetylcholine contractile response could be essential factors for the clinically observed hypertonia of the irradiated bladder ("radiogene Harnblase") and its functional volume decrease as well as of the diminished pressure during micturition.

[Effects of tetrachlorodecaoxide (TCDO) in chronic radiation lesions of the rat colon]. / Die Wirkung von Tetrachlordecaoxid (TCDO) auf den chronischen Strahlen-schaden am Rattenkolon.

The influence of tetrachlorodecaoxide (TCDO) on the chronic radiation damage after local irradiation of the rat colon was examined when given at different times and at different doses. A tetrachlorodecaoxide treatment before the acute period resulted in an extension of the latency period. When tetrachlorodecaoxide was given by the highest dose of 0.8 ml WF 10 at the onset of the chronic phase we observed an increase in the survival rate. Endoscopically and histologically we did find demonstrable signs of an improved healing of the mucosa.

Effect of X-irradiation on the stomach of the rat.

A model for localized 300 kV X-irradiation of the rat stomach was developed. After irradiation with single doses, three distinct gastric disorders were observed which occurred at different latency times. Acute death 2-3 weeks after irradiation was caused by an erosive and ulcerative gastritis and occurred in all animals given 28.5 Gy without diet, in 17% of the animals given 28.5 Gy plus diet, and in 13% of the animals given 23 Gy. Subacute to chronic fatal disorders 4 weeks to 7 months after irradiation were seen as stomach dilatation and gastroparesis, associated with the replacement of the normal gastric mucosa by a hyperkeratinized multilayered squamous epithelium. These disorders occurred in 40-100% of the animals after doses between 16 Gy and 28.5 Gy (+diet). An ED 50 value of 19.2 Gy (16.5-21.2 Gy, 95% confidence interval) was calculated for this gastroparesis. Late gastric obstruction exceeding 7 months after irradiation was seen in the rats because of profound changes in the gastric wall in 13-18% of the animals after doses between 23 Gy and 14 Gy. In animals surviving these three periods, an atrophic mucosa and intestinal metaplasia developed. From functional and morphohistological studies, it can be concluded that there are differences in the pathogenesis of the fatal radiation damage for each of these periods after irradiation.

[Endoscopic control of the course and its histological correlation in chronic radiation injury of the rat rectum]. / Die endoskopische Verlaufskontrolle und deren histologische Korrelation des chronischen Strahlenschadens am Enddarm der Ratte.

On the basis of endoscopic investigations, the reaction to X-radiation of the hindgut of the rat could be divided into four phases. Their courses after different radiation doses as well as after dietary influence are described. This enabled us-besides the acute (diarrhoea) and chronic (diarrhoea followed by intestinal occlusion) phases shown by clinical examination - to demonstrate the early vascular reaction (first week after irradiation) as well as the asymptomatic interval between the acute and chronic phases. The interval phase was found to be of importance for prognosis and therapy, because all animals who died later on of intestinal occlusion developed already during this phase circular ulcerations which could be demonstrated by endoscopy.