Moving-table MR angiography of the peripheral runoff vessels: comparison of body coil and dedicated phased array coil systems

OBJECTIVE: The aim of our study was to compare the signal-to-noise ratio and the diagnostic accuracy of moving-table MR angiography of the peripheral arteries with body coil and dedicated phased array coil systems. SUBJECTS AND METHODS: Forty patients were examined with digital subtraction angiography and moving-table MR angiography with a 1.5-T MR imaging system either with a body coil (n = 20) or with a dedicated phased array coil (n = 20). The timing of contrast material was performed with real-time MR fluoroscopy. RESULTS: For the iliac artery, upper leg, and lower leg, the mean values for signal-to-noise ratios were 56, 51, and 17, respectively, for the body coil, and 54, 74, and 64, respectively, for the dedicated phased array coil. For the body coil, sensitivity and specificity in identifying stenosis greater than 50% and occlusions were 100% and 96%, respectively, for the iliac arteries, and 100% and 96%, respectively, for the upper leg. For the dedicated phased array coil, sensitivity and specificity for stenosis greater than 50% and occlusions were 100% and 96%, respectively, for the iliac arteries, and 100% and 98%, respectively, for the upper leg. Sensitivity and specificity were inferior for the body coil (88% and 85%) compared with the dedicated phased array coil (100% and 96%) in the lower leg. A significant difference of the mean values of contrast-to-noise ratio was found before and after subtraction for the dedicated phased array coil and body-coil techniques (Student's t test, p < 0.01). CONCLUSION: In comparison with the body coil, the dedicated peripheral phased array surface coil system improves signal-to-noise ratio for the upper and lower leg and diagnostic accuracy in the lower leg.     

Peripheral vessels: MR angiography with dedicated phased-array coil with large-field-of-view adapter feasibility study

At magnetic resonance (MR) angiography with conventional phased-array coils, visualization of the vascular tree from the infrarenal aorta to the pedal arch is not possible in most patients. For this purpose, the authors developed a dedicated adapter with a large field of view that allows coverage of a body length of approximately 1,380 mm. Among five patients with peripheral arteriosclerotic disease, four underwent both conventional angiography and MR angiography. One hundred fourteen vascular segments from the infrarenal aorta to the feet were evaluated. Agreement between findings at conventional angiography and those at MR angiography was 94.7% (108 of 114) for all segments (96.1% [25 of 26] in the abdomen or pelvis, 97.5% [39 of 40] in the thigh, and 91.7% [44 of 48] in the calf or foot).     

Fully automated floating table MR angiography of pelvic and leg arteries: initial clinical results]

The aim of this study was to obtain first clinical experiences with magnetic resonance angiography (MRA) with digital subtraction (MR-DSA) using an automatic floating table for visualization peripheral arteriosclerotic occlusive disease (paod). We examined 10 patients on a 1.5 T MR unit applying a fast MRA technique (3D FLASH) with intravenous application of positive contrast agent. MR-DSA examinations were compared with the gold standard intraarterial (i.a.) DSA. MR-DSA proved to be useful for routine application which could be performed sufficiently in all patients. MR-DSA and i.a. DSA showed comparable results for imaging of the pelvic and upper leg arteries. Looking at the thighs image quality of MR-DSA did not match the image quality of i.a. DSA in every case. This was due to venous overlap and in comparison to i.a. DSA reduced signal-to-noise ratios. However, clinical findings, obtained with MR-DSA, were sufficient for adequate therapy planning. Our preliminary results reveal the potential of this new technique to become a realistic, robust, and non-invasive alternative to i.a. DSA in the diagnosis of paod.     

Nuclear magnetic resonance tomography with surface coils--initial experiences in orbital diagnosis

The use of surface coils in magnetic resonance imaging of the orbit leads to an increase in spatial resolution. With the first 14 patients in whom we used the method we obtained detailed images of the orbital topography, especially in cases with tumors and foreign bodies, but the method proved to be little use in finding minimal tissue changes of the muscles or of the optic nerve. The use of oblique views without moving the patients, enables the optic nerve to be imaged in one slice. Edge artefacts caused by "chemical shift" and motion artefacts caused by motion of the bulbs still diminish detail accuracy and contrast differentiation range. Since no side effects have been described so far, magnetic resonance imaging with a surface coil is a highly suitable complementary procedure in the diagnosis of orbital disease.     

Elektronenmikroskopische Untersuchungen am Kanarienpockenvirus

Zusammenfassung Infiziert man Kanarienvögel mit Kanarienpockenvirus, so kann man im Brustmuskelödem elektronenmikroskopisch Rund- und Ovalformen, welche z. T. Innenkörper enthalten, abbilden. Sie sind in einer sonst homogenen Substanz (Inseln) Anzeichen einer Differenzierung. Die Formen werden an durchstrahlten und bedampften Aufnahmen beschrieben. Sie haben Ähnlichkeit mit den vonMorgan, Gaylord undMelnick in Dünnschnitten abgebildeten Körpern. Bei Anwendung des Spreitungsverfahrens treten Oval- und Rundformen (Scheiben) auf, die noch keine zweifelsfreie Innenkörperbildung zeigen, für die aber eine Beziehung zu den El. K. vermutet wird. Es wurde versucht, das Kanarienpockenvirus mit verschiedenen Fermenten abzubauen. Mit Desoxyribonuclease-Pepsin-HCl ergaben sich Befunde, wie sie bei Pocken, Geflügelpocken und Molluscum contagiosum beschrieben worden sind.Der Deutschen Forschungsgemeinschaft danken wir für personelle und sächliche Beihilfen. Die med.-techn. Assistentinnen Frl.Johanna Haass und Frl.B. Schüler waren ständige Mitarbeiterinnen im elektronenmikroskopischen Laboratorium.Vorgetragen am 30. März 1955 auf der 6. Tagung der Deutschen Gesellschaft für Elektronenmikroskopie in Münster (Westf.).     

Quality control of astrocyte-directed Cre transgenic mice: the benefits of a direct link between loss of gene expression and reporter activation

Cre recombinase activity for cell-type restricted deletion of floxed target genes (i.e., flanked by Cre recognition loxP-sites) is often measured by separate matings with recombination-activated reporter gene mice. Using a floxed Gja1 (Cx43) allele, we demonstrate the benefits of a direct link between reporter gene expression and target gene deletion to overcome critical limitations of the Cre/loxP system. The widely used human glial fibrillary acidic protein (hGFAP)-Cre transgene exhibits variable recombination activity and requires postexperimental validation. Such quality control is essential to correlate the extent of Cre-mediated Gja1 ablation with phenotypical alterations and to maintain the activity status of hGFAP-Cre in transgenic mouse colonies. We present several strategies to control for the fidelity of hGFAP-Cre mediated recombination. (c) 2008 Wiley-Liss, Inc.     

A new holder and surface MRI coil for the examination of the newborn infant hip

A special holder was developed for examination of the infant hip joint using MRI. This holder allows the infant hip joint to be examined both in a neutral position and in various defined functional positions. A special integrated surface coil, also developed for this purpose, provides the high spatial resolution required for assessment of the fine joint structures. Thirty infants were examined and the new device has proved useful in advanced hip dysplasia, therapy-resistant subluxation and luxation, and for operative therapy planning (reconstruction of the acetabular roof, redirectional osteotomies). Interpretation errors due to misprojection can be eliminated to a large extent since the holder allows standardized and reproducible positioning.     

High-resolution functional magnetic resonance imaging of cortical activation during tactile exploration

Cortical activation during tactile exploration of macrogeometric objects was investigated in six healthy individuals with the use of magnetic resonance imaging (MRI) sensitized to changes in cerebral blood oxygenation. Dynamic measurement of task-related signal alterations were performed at 2.0 T using a rapid gradient-echo MRI sequence (TR/TE=63/30 ms, flip angle 10°, measuring time 6 s) at high spatial resolution (0.8 × 1.6 mm²). Four contiguous sections (thickness 4 mm) parallel to the bicommissural plane covered the hand area of the primary sensorimotor cortex (M1, S1), the supplementary motor area (SMA), premotor areas (PMA), and superior parts of the parietal cortex (PC). Task-related activation was determined by correlating signal intensity time courses with the stimulus protocol on a pixel-by-pixel basis. In contrast to predominantly contralateral M1 activation, effects in the hand area of S1 were not restricted to the contralateral side but were equally present in the posterior section of ispilateral S1. Furthermore, bilateral responses were encountered in SMA and PC, while observations within PMA remained inconsistent. These findings in single subjects readily demonstrate a highly resolved and interindividually reproducible pattern of cortical activation in relation to exploratory finger movements and associated intergration of somatosensory information. © 1995 Wiley-Liss, Inc.     

Gadofluorine m uptake in stem cells as a new magnetic resonance imaging tracking method: an in vitro and in vivo study

OBJECTIVES: Cell tracking using ultrasmall iron particles is well established in magnetic resonance imaging (MRI). However, in experimental models, intrinsic iron signals derived from erythrocytes mask the labeled cells. Therefore, we evaluated Gadofluorine M with other gadolinium chelates for a T1-weighted positive enhancement for cell tracking in vitro. In addition, Gadofluorine M was tested in vivo. MATERIAL AND METHODS: Gadofluorine M and other gadolinium chelates were used to label stem cells with and without uptake-mediating agents in vitro and in vivo using a 1.5 T MRI. In addition, histology and molecular modeling was investigated. RESULTS: Gadofluorine M revealed comparable properties to an uptake mediating agent in molecular modeling. Without an uptake-mediating agent Gadofluorine M-labeled cells were detected as a T1-weighted positive contrast in vitro and in vivo. Histology confirmed a 100% success rate for intracellular labeling. CONCLUSION: This study describes a novel contrast agent with the capability of intracellular accumulation without an uptake mediator providing a T1-positive MRI signal at 1.5 T and may be suitable for cell tracking in animal models with intraparenchymal hemorrhages such as stroke or malignant tumors.