Effects of contour propagation and background corrections in different MRI flow software packages.

BACKGROUND: Velocity-encoded magnetic resonance imaging (VENC-MRI) is a commonly used technique in cardiac examinations. This technique utilizes the phase shift properties of protons moving along a magnetic field gradient. VENC-MRI offers a unique way of measuring the severity of valve regurgitation by directly quantifying the regurgitation flow volume. PURPOSE: To compare flow analysis results of different software programs and to assess the effect of background correction in sample patient cases. MATERIAL AND METHODS: A phantom was built out of Polymethyl methacrylate (PMMA) which provides tubes of different diameters. These tubes can be connected to an external water circuit to generate a water flow inside the tubes. Expected absolute flow quantities inside the tubes were determined from preset tube- and flow-parameters. Different flow conditions were measured with a VENC-MRI sequence and the images evaluated using different software packages. In a second step six randomly selected patients showing different degrees of aortic insufficiency were evaluated in clinical terms. RESULTS: The contour propagation algorithms used in the software packages performed differently even on static phantom geometry. In terms of clinical evaluation the software packages performed similarly. Enabling background correction or leaving out manual correction of propagated contours changed results for severity of aortic insufficiency. CONCLUSION: Turning on background correction and manual correction of propagated contours in MRI flow volume measurements is strongly recommended.

The effects of prometryne on subchronically treated mice evaluated by SCGE assay.

Prometryne is a methylthio-s-triazine herbicide used to control annual broadleaf and grass weeds in many cultivated plants. Significant traces are documented in environment, mainly water, soil and plants used for human and domestic animal nutrition. Data on the toxic effects of prometryne and other methylthio-s-triazine have scorcely been published. The goal of this study was to investigate if prometryne, applied orally, could induce DNA damage in mouse leukocytes, in subchronical in vivo experimental design. Three different doses of prometryne were applied per os repeatedly every 48 hours. After the 7th dose (day 14) and the 14th dose (day 28) blood leucocytes were analyzed by alkaline Single Cell Gel Electrophoresis (Comet) assay. The results of three different comet parameters showed general increase in Olive tail moment, tail length and tail intensity values in treated groups of animals. The increase in measured values was almost proportional to the dose received and the time of exposure. We conclude that prometryne or its metabolic residues have the potential to induce processes that cause genotoxic effects on leukocytes on mice in in vivo repeated exposure.

Using receiver operating characteristic methodology to evaluate the diagnostic quality of radiography on paper prints versus film.

OBJECTIVE: The aim of this study was to compare the diagnostic quality of paper prints with film copies in a sample of observers who were trying to detect small coin lesions on radiographs of a phantom. MATERIALS AND METHODS: The phantom consisted of 60 high-contrast and 60 low-contrast test objects, half of which had holes in them. Diameter and depth of the holes varied from 0.5 mm to 2 mm. Fifteen radiographs were obtained from different areas of the test objects. Film copies and paper prints were made using high-quality printers. Five observers independently evaluated 1,800 high-contrast and 1,800 low-contrast images. Data were evaluated using the well-established receiver operating characteristic methodology. RESULTS: The mean area under the curve rated 0.863 for paper prints (0.859 for high contrast and 0.860 for low contrast) and 0.926 for laser films (0.937 for high contrast and 0.913 for low contrast). The difference between the two imaging techniques was statistically significant for both high- and low-contrast lesions (p < 0.05). CONCLUSION: Detection of small coin lesions on radiographs of a phantom was significantly less sensitive on paper prints than on film. We found paper prints less acceptable for the diagnosis of small-sized lesions.

Intravertebral vacuum phenomenon following fractures: CT study on frequency and etiology.

PURPOSE: The purpose of this work was to determine the frequency and etiology of the intravertebral vacuum phenomenon (IVP). METHOD: CT examinations of 96 vertebral fractures were evaluated for IVP. Bone mineral density (BMD) was determined in nonfractured vertebrae. For calibration purposes, densities of a standard phantom measured in 30 patients who underwent quantitative CT examinations in the same time period were used and precision was calculated. RESULTS: Eleven of 96 fractures (11.5%) showed IVP. IVP was present in 4 of 20 fractures at T12 (20%), in 4 of 23 at L1 (17.4%), and 1 IVP was found at L2-4 each. Mean +/- SD age of patients with IVP was 68.3 +/- 10.5 years and without 47.8 +/- 19.4 years (p < 0.001). Mean +/- SD density of nonaffected vertebra was 45.9 +/- 17.0 mg of hydroxyapatite/ml for patients with IVP and 139.5 +/- 62.6 mg/ml for those without IVP (p < 0.0005). An average precision of 1.2% was calculated for the density measurements over the investigated time. CONCLUSION: Following vertebral fractures, IVP on CT scans is more common than presumed and increases with age. There exists a significant inverse correlation between the BMD and the frequency of IVP.

[Thermoanalytical studies on gypsum- and phosphate-bonded casting investments]. / Thermoanalytische Untersuchungen an gips- und phosphat-gebundenen Einbettmassen

The two test series were carried out with the dilatometer TMA 500 (of Haereus company). The measurements for thermic expansion are easily reproducible, not so for setting expansion. The recorded setting expansion values are identical with the manufacturers' data given for Luster Cast, Aurovest, and Deguvest HFG, among the thermic expansion values only those for Luster Cast are in line with the data given; the values given for Bayer DC are most different from those we found.