Registered image subtraction for CT-, MR- and coronary angiography.

Conventional post-processing of digital subtraction angiography (DSA) by 3D spiral CT, 3D MRI and 2D DSA is often hampered by extended artefacts due to patient movements during examination. In this paper an image registration procedure prior to the digital subtraction is introduced allowing an enhanced visualization of the contrast agent. The object displacement is detected by analysis of image deformations in small local regions. The motion pattern is used to compute a new synthetic mask of maximum congruence with the contrast medium image. This new mask image is then used in the subsequent subtraction. The algorithm works fully automatically and does not need any interactive placement of landmarks. Results obtained from subtraction of uncorrected and corrected sequences were compared with each other. The registration procedure provided good results in the suppression of subtraction artefacts and in the enhancement of vascular structures. Results are presented from subtraction of 2D and 3D data from CTA, MR mammography and coronary angiography.

[The correction for motion and visualization of subtraction angiographic data from the spiral CT]. / Bewegungskorrektur und Visualisierung subtraktions-angiographischer Daten vom Spiral-CT.

Conventional image subtraction of CT sequences is hampered by extended motion artifacts. In this paper a motion correction procedure for the subtraction of images from two time-separate CT investigations is introduced. Native images are obtained in the first CT sequence, and a contrast medium examination is imaged in the second. The aim of image subtraction is sole presentation of the contrast medium. In contrast to conventional digital subtraction angiography (DSA), CT angiography rules out the possibility of direct image subtraction due to occurrence of extended motion artifacts in the time-shifted images. Such shortcomings can now be corrected by means of a new registration method developed for determination of local displacement vectors between the two images. This motion pattern is used to compute a new synthetic mask of maximum congruence with the contrast medium image. The resulting three-dimensional data record is presented by means of a special-purpose hardware enabling fast rotations and cut planes. New diagnostic possibilities can be achieved such as the creation of views that are not obtainable with conventional modalities and the assessment of calcified vessels.

CT angiography of the pelvic arteries.

UNLABELLED: A comparison was performed between CT angiography and digital subtraction angiography (DSA) on 55 patients with atherosclerotic obstructions of the pelvic arteries. Two post-processing algorithms were employed, maximum intensity projection (MIP) and 3D technique. RESULTS: (a) MIP: conformity with DSA: 20/23 occlusions and 24/36 stenoses; underestimation: three occlusions, seven stenoses; overestimation: five stenoses. (b) 3D display: conformity with DSA: 19/23 occlusions and 16/36 stenoses; underestimation: four occlusions, 17 stenoses; overestimation: three stenoses. The MIP technique proved to be the only method to display the localisation of vascular calcifications with their exact topographical relationship to the stenoses and occlusions. MIP also proved to be valuable in controlling the position of intravascular stents. Complementary to DSA, the MIP method therefore seems to be a clinically valuable technique for calcified and non-calcified stenoses, and for displaying intravascular stents. Its use in interventional procedures could therefore become increasingly important.

[CT angiography and arterial DSA in the evaluation of occlusive processes in pelvic arteries. Initial results]. / CT-Angiographie und arterielle DSA zur Bewertung von Verschlussprozessen der Beckenarterien. Erste Ergebnisse.

UNLABELLED: 32 patients with iliac artery stenosis and occlusion were studied by means of CT angiography. The results were compared with the results of intraarterial digital subtraction angiography (DSA). Postprocessing was performed with Maximum Intensity Projection (MIP) and 3-D-display. RESULTS: 1. MIP: 27/37 stenoses/occlusions were correctly assessed, underestimation of 5 stenoses/occlusions (4 stenoses, one occlusion), overestimation of 5 stenoses. 2. 3-D-Display: 22/37 stenoses/occlusions were correctly assessed, underestimation of 9/37 (8 stenoses, one occlusion), two false negative results (one stenosis, one occlusion), overestimation of 4/37 stenoses. The MIP technique proved to be the only method to display the localisation of vascular calcifications with their exact topographical relationship to the stenoses and occlusions. MIP also proved to be valuable in controlling the position of intravascular stents. Complementary to DSA, the MIP method therefore seems to be a clinically valuable technique for calcified and noncalcified stenoses.

[Three-dimensional imaging of the pelvic veins using magnetic resonance angiography]. / Dreidimensionale Darstellung der Beckenvenen mit Magnetresonanz-Angiographie.

The veins in the pelvis and lower limbs have been demonstrated by means of magnetic resonance angiography (MRA) in 11 normals and in 20 patients, using a "time-of-flight" technique (TOF). Using normals, changes in the measurement parameters were used in order to optimise the examination protocol; consequently, the internal and external iliac veins and the superior and inferior gluteal veins could be identified in all cases and the internal pudendal veins in 6 out of 11 cases. This examination protocol was then used in patients with clinical suspicion of lower limb or pelvic vein thrombosis. Comparison of the MRA findings with those of phlebography (7 cases), duplex sonography (6 cases) and colour Doppler examinations (11 cases) showed that MRA was better for diagnosing thrombosis of the internal iliac veins (10 cases) than the other methods. In two patients thromboses of the common iliac veins and the inferior vena cava were demonstrated which were missed by colour Doppler examination. On the basis of our present experiences, MRA, using a two-dimensional TOF technique, appears to be a reliable non-invasive technique for demonstrating the veins of the pelvis and thigh.

Binding of Lactobacillus reuteri to fibronectin immobilized on glass beads.

Human fibronectin was immobilized on glass beads. The beads were used to evaluate binding of Lactobacillus reuteri to fibronectin. Organisms bound to the glass beads were detected using fluorescence microscopy after treatment with acridine orange. This binding was confirmed and quantified with the use of [3H]-labelled organisms. Three strains of Lactobacillus reuteri, three strains of Lactobacillus acidophilus and one strain of Lactobacillus fermentum were tested for binding capacity. L. reuteri strain 1063 exhibited a strong binding to the immobilized fibronectin, and L. acidophilus 1754 showed a slight binding. The binding of L. reuteri to the fibronectin was mediated by a protein as judged by the absence of binding after treatment of the bacteria with proteolytic enzymes. Treatment of the bacteria with urea, SDS and heat (80 degrees C) also reduced binding. Treatment of the bacterial cells prior to the assay with fibronectin interfered with binding. Albumin did not show this interaction.

Isolation, identification, and characterization of a feather-degrading bacterium.

A feather-degrading culture was enriched with isolates from a poultry waste digestor and adapted to grow with feathers as its primary source of carbon, sulfur, and energy. Subsequently, a feather-hydrolytic, endospore-forming, motile, rod-shaped bacterium was isolated from the feather-degrading culture. The organism was Gram stain variable and catalase positive and demonstrated facultative growth at thermophilic temperatures. The optimum rate of growth in nutrient broth occurred at 45 to 50 degrees C and at pH 7.5. Electron microscopy of the isolate showed internal crystals. The microorganism was identified as Bacillus licheniformis PWD-1. Growth on hammer-milled-feather medium of various substrate concentrations was determined by plate colony count. Maximum growth (approximately 10 cells per ml) at 50 degrees C occurred 5 days postinoculation on 1% feather substrate. Feather hydrolysis was evidenced as free amino acids produced in the medium. The most efficient conditions for feather fermentation occurred during the incubation of 1 part feathers to 2 parts B. licheniformis PWD-1 culture (10 cells per ml) for 6 days at 50 degrees C. These data indicate a potential biotechnique for degradation and utilization of feather keratin.

Fatal pneumonia with terminal emaciation in nude mice caused by pneumonia virus of mice.

Athymic nude mice used as sentinel animals in a mouse holding room died of pneumonia 17 to 32 weeks after being placed in the room. Lesions in the pulmonary parenchyma consisted of monocytic exudate, epithelial cell necrosis, hemorrhage, fibrin deposition and interstitial fibrosis. Septal edema, septal cell necrosis and septal capillary stasis were common, but there was limited sloughing of bronchial lining epithelium. Indirect fluorescence microscopy (IFA) of lung sections using pneumonia virus of mice (PVM) antibody was positive. The pneumonia and IFA results were reproduced in euthymic mice inoculated experimentally with lung suspension from naturally infected mice or with tissue culture fluid from cultures infected with American Type Culture Collection PVM. The lungs of a naturally infected nude mouse were studied by transmission electron microscopy. Virus growth was found on Type II alveolar epithelium and on poorly differentiated replacement alveolar epithelium. Virus particles appeared as long exophytic filaments containing one to six linearly arranged nucleocapsids. Inclusion bodies and intracellular virus structures were not observed.