| 1 | Magnetic resonance imaging:Is there a role in clinical management for acute ischemic colitis?显示文摘AIM:To validate the utility of magnetic resonance imaging(MRI) for the clinical management of acute ischemic colitis(IC).METHODS:This is a magnetic resonance(MR) prospective evaluation of 7 patients who were proved to have acute IC on the basis of clinical,endoscopic and computed tomography(CT) findings and who were imaged in our institution between February 2011 and July 2012.The mean age of the patients was 72.28 years.Abdominal CTs were obtained using a 64-detector row configuration for all patients with un-enhanced and contrast-enhanced scans,in the late arterial phase(start delay 45-50 s) and in the portal venous phase(start delay 70-80 s).The MR examinations were performed using a 1.5T superconducting magnet,using Fast Imaging Employing Steady State Acquisition and T2-weighted fast-recovery fast-spin echo sequences in axial and coronal plane.CT and MRI examinations were analysed for the presence of colonic abnormalities and associated findings.RESULTS:Segmental involvement was seen in 6 patients(85.71%),with a mean length of involvement of 412 mm(range 145.5-1000 mm).Wall thickness varied between 6 mm and 17.5 mm(mean 10.52 mm) upon CT examinations and from 5 to 15 mm(mean 8.8 mm) upon MR examinations.The MRI appearance of the colonic wall varied over the time:TypeⅠappearance with a 3 layer sandwich sign was seen in 5 out of 12 examinations(41.66%),patients underwent MR within a mean of 36 h(ranging from 1 to 54 h) after the CT examination.Type Ⅱ and Ⅲ appearance with a 2 layer sign,was seen in 4 examinations(33.33%),patients underwent MR within a mean of 420.5 h(ranging from 121 to 720 h) after the CT examination.In the remaining three MRI examinations,performed within a mean of 410 h(ranging from 99.5 to 720 h) the colonic wall appeared normal.CONCLUSION:MRI,only using precontrast images,may be used as a substitute for invasive procedures in diagnosis and follow-up of acute IC. | Maria Antonietta Mazzei Susanna Guerrini Nevada Cioffi Squitieri Giusi Imbriaco Raffaele Chieca Serenella Civitelli Vinno Savelli Francesco Giuseppe Mazzei Luca Volterrani | 2013 | World Journal of Gastroenterology2013，19，8： | 5 |
| 3 | An in-depth multi-technique characterization of rare earth carbonates-RE_(2)(CO_(3))_(3)·2H_(2)O-owning tengerite-type structure显示文摘The present study has been conducted to contribute,once and for all,filling the lack of structural information for the whole class of rare earth(RE)carbonates owning the tengerite-(Y)structure.A complete structural characterization,carried out by Rietveld refinement of X-ray powder diffraction(XRD)data,was comparatively performed for the first time on several hydrated RE carbonates,having the general chemical formula RE_(2)(CO_(3))_(3)·χH_(2)O,RE=Y,Gd,Tb,Dy,Ho and Er.All samples share the same space group and lattice parameters similar to tengerite-(Y);the structures are also closely related,consisting in all cases of a three-dimensional framework of nine-fold coordinated RE atom polyhedral,linked together by carbonate ions.In addition to relatively minor changes in fractional coordinates of atom sites and corresponding interatomic distances,the only perceivable difference lies in the lattice parameters affected by the ionic radius of RE^(3+).However,in the case of Er,which has the lowest cationic radius among the analyzed RE,the stabilization of tengerite structure is at its limit condition,because the carbonate groups are heavily distorted.Furthermore,FT-IR and Raman spectra confirm the main structural features obtained by Rietveld refinements.The observed morphology of the various samples is almost the same,being characterized by the presence of bidimensional rod-like particles grouped in agglomerates,typical of tengerite crystals,thus indicating that the crystallization mechanism occurring during the hydrothermal synthesis is the same,irrespective of the involved RE cation. | Luca Spiridigliozzi Mauro Bortolotti Grazia Accardo Alessandro Vergara Domenico Frattini Claudio Ferone Raffaele Cioffi Gianfranco Dell'Agli | 2022 | Journal of Rare Earths2022，40，8： | 0 |
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