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The feasibility and diagnostic value of real-time magnetic resonance imaging (RT-MRI) for the diagnosis of acute pulmonary embolism (PE) was evaluated by comparing RT-MRI and magnetic resonance angiography (MRA). In 39 consecutive patients with suspected PE real-time true fast imaging with steady-state precession (TrueFisp) was prospectively compared with contrast-enhanced MRA on a 1.5-T MR scanner. The TrueFisp sequence used allowed acquisition of T2-weighted images at 0.4 s per image so that the pulmonary vasculature could be visualized in three orientations in <3 min without the need for breath holding or contrast media application. Results of additional scintigraphic pulmonary perfusion examinations were available from 17 patients. All 39 primary RT examinations (100%) and 30 of 39 MRA examinations (77%) were of diagnostic quality. The reasons underlying failure to achieve diagnostic quality for MRA were breathing artifacts among dyspneic patients in all 9 cases. Compared with MRA, the sensitivities and specificities of RT sequences for PE were 93 and 100% (per examination), 96 and 100% (lobar artery PE), and 97 and 100% (segmental artery PE), respectively. Compared with scintigraphy, the sensitivity and specificity of RT-MRI were 83 and 100%, respectively. The MRA reached 100% sensitivity and specificity in this subgroup. The RT-MRI proved to be very robust and undisturbed by respiratory movements and patient cooperation. Its image quality assured fast diagnostic examinations, and its sensitivity and specificity, compared with MRA and scintigraphy, were sufficient to allow the diagnosis of acute central, lobar, and segmental PE; therefore, the emergency diagnosis of PE using RT-MRI is feasible and reliable.

Purpose: To evaluate the signal-enhancing characteristics of monomer-coated very small superparamagnetic iron oxide (SPIO) particles used as a blood pool contrast medium for magnetic resonance (MR) angiography in the coronary arteries., Materials and Methods: The particles used in this study were coated with citrate as the monomer (VSOP-C91). The particles have a total diameter of 7 nm and show the following relaxivities at 0.47 T: T1, 19 L/mmol. sec(-1); T2, 29 L/mmol. sec(-1). Fifteen cardiac MR examinations were performed at 1.5 T in five pigs. Images were acquired from immediately to 35 minutes (equilibrium phase) after intravenous injection of gadopentetate dimeglumine, gadobenate dimeglumine, and the very small SPIO particles (n = 5 for each substance)., Results: Immediately after administration of gadopentetate dimeglumine, gadobenate dimeglumine, and the very small SPIO particles, respectively, increases in the signal-to-noise ratio in blood were 94%, 103%, and 102% and in myocardium were 83%, 83%, and 29% (P <.05, very small SPIO particles versus the low-molecular-weight gadolinium-based compounds). Differences in the blood-to-myocardium contrast-to-noise ratio and visualization of the coronary arteries and their branches were also significant., Conclusion: VSOP-C91 significantly improves visualization of the coronary arteries at MR angiography from immediately to 35 minutes after injection.

Rationale and Objectives: Magnetic resonance (MR) is limited by artifacts in vessels after stenting. An active MR imaging stent (AMRIS) allows for artifact-free imaging with local improvement in signal-to-noise ratio (SNR). In a rabbit model, we evaluated the imaging properties by MR angiography (MRA) and flow measurements., Methods: The AMRIS was placed in the abdominal aorta of five rabbits. At 1.5 T, MRA (three-dimensional fast low-angle shot) was performed before and after intravenous injection of an iron oxide-based, blood-pool contrast medium (dose, 50 micromol Fe/kg), and flow measurements were performed (electrocardiographically triggered phase-contrast cine gradient-echo sequence). Mean SNRs were calculated and flow volume curves were generated., Results: The SNR was 6.0 +/- 0.6 (outside the stent) versus 12.3 +/- 1.1 (inside the stent, P < 0.05) for plain MRA, 21.2 +/- 0.6 versus 40.6 +/- 5.2 (P < 0.05) for contrast-enhanced MRA, and 5.4 +/- 0.4 versus 13.7 +/- 2.1 (P < 0.05) for the magnitude images of flow measurements. Flow volume curves within and distal to the stent were comparable., Conclusions: By using the AMRIS as a vascular stent, the stented vessel segment can be examined with enhanced signal intensity on MRI.

Purpose: An animal model is used to investigate whether MR angiography combined with super-paramagnetic particles of iron oxide (SPIO) is suitable for detecting thromboses., Methods: 42 rats in groups of 7 each were examined on days 1, 3, 5, 7, 9 and 11, respectively, after mechanical/chemical thrombus induction in a 1.5 Tesla magnet with a FISP sequence (TR/TE/FA 50 ms/6 ms/40 degrees). Imaging was performed before and up to 90 minutes after intravenous injection of 30 mumol FE/kg BW of the experimental SPIO (hydrodynamic diameter, 34 +/- 17 nm LLS; R1 and R2 relaxivity at 0.47 T, 31 and 57 L/(mmol*s)). MIP reconstructions of MR angiographies were submitted to consensus assessment by two examiners. using histology as the gold standard., Results: The image quality of MIP reconstructions was rated as good in 38 of 42 cases. With regard to thrombotic vessel occlusion, MR angiography coincided with histology in 17 of 42 cases and differed in 25, lumen narrowing being overestimated by MRI in 4 cases and underestimated in 21. In these 21 cases, the histologically observed recanalization could not be detected by MR angiography., Conclusions: SPIO-enhanced MR angiography achieves adequate vessel contrast and reliable thrombus detection in animal experiments. Partial volume effects prevent microscopically observed recanalization from being detected by clinical MRI.

Hydroxamate siderophores of virulent Bordetella pertussis and Bordetella bronchiseptica strains were purified using a simple large-scale isolation procedure, and identified by various spectroscopic techniques as the macrocyclic dihydroxamate siderophore trivially known as alcaligin, 1,8(S),11,18(S)- tetrahydroxy-1,6,11,16-tetraazacycloeicosane-2,5,12,15-tetrone+ ++, which was previously isolated from the taxonomically-related bacterial species Alcaligenes denitrificans subsp. xylosoxydans. Alcaligin purified from iron-depleted cultures of B. pertussis and B. bronchiseptica exhibited specific growth-promoting activity under iron-restricted conditions for Bordetella indicator strains, and ere active in [55Fe]ferric alcaligin transport assays. Evidence suggests that several C2-symmetric conformations of alcaligin exist simultaneously in both methanolic and aqueous solution.

Radial artery cannulation for constant monitoring of arterial pressure and blood gases has become commonplace in the care of the seriously ill. The radial artery is readily accessible and is often regarded as carrying a negligible complication risk, because there is extensive collateral arterial flow in the hand. To the rarely reported cases of gangrene of the hand secondary to cannulation of the radial artery, this publication adds two, both survivors. One, a 46-year-old female with a clinical picture suggestive of mild Raynaud's disease, was treated by closed mitral commissurotomy; the second, a 44-year-old female, was treated for drug overdose complicated by cardiac arrest and renal shutdown.

Cephalometric roentgenography in nonhuman primates requires more precise head positioning than that afforded by commonly used ear rod techniques. A standard cephalometric headholder was therefore modified and a technique was developed to implant an attachment that permit precise positioning of the head in all three planes of spce. This method has been used in 36 animals, and at 35 months postsurgery the implants have remained stable and tissue compatiblity is generally excellent. Roentgenograms obtained with this technique offer a high degree of accuracy in documenting growth changes and response to orthodontic treatment.

Superior thyroid artery cannulation during carotid endarterectomy and coupling the cannula to a three-way stopcock with an anaeroid manometer allows the surgical team in the operating field to monitor mean pressures and to draw blood samples for gas analysis from the common, the internal, or the external carotid artery. The technique has been applied in 118 patients without related complications.