Conventional MR imaging

Influence of several nitrosyl-iron complexes on relaxation rates was assessed to establish a MR imaging technique for nitric oxide (NO). " To induce formation of nitrosyl-ion complexes in a biological tissue, isolated rat liver was perfused with a saline solution of the NO donor sodium nitroprus-side (SNP), and the MR signal intensity was examined thereafter. Nitrosyl-iron complexes exhibit a contrast effect at MR imaging that can be exploited for NO imaging in living animals and patients with conventional MR imaging. 

Posterior reversible encephalopathy syndrome Hyperperfusion syndrome post carotid endarterectomy Conventional MR imaging findings... 

With conventional MR imaging techniques, lymph nodes are visualized vdien they have a size of at least 1.0-1.5 cm [10]. Optimized imaging techniques (body phased-array coil, 512 matrix, 3D acquisition) or state-of-the-art spiral or multislice CT scanners depict lymph nodes as small at about 3-5 mm [7,8]. These techniques usually allow good evaluation of the lymph nodes adjacent to the straight great vessels (Fig. 15.1). 

Caoili EM, Inampudi P, Cohan RH et al (2005b) Optimization of multi-detector row CT urography effect of compression, saline administration, and prolongation of acquisition delay. Radiology 235 116-123 Catalano C, Pavone P, Laghi A et al (1999) MR pyelography and conventional MR imaging in urinary tract obstruction. Acta Radiol 40 198-202... 

Gadolinium has been complexed with dendrimers and it was observed that this complex enhanced conventional MR images in a dendrimer molecular weight dependent way and substantially better, compared with conventional diethylenetri-aminepentaacetic acid Gd (III) chelates [82]. 

Mullins ME, Schaefer PW, Sorensen AG, Halpern EF, Ay H, He J, Koroshetz WJ, Gonzalez RG. CT and conventional and diffusion-weighted MR imaging in acute stroke study in 691 patients at presentation to the emergency department. Radiology 2002 224 353-360. 

As we have seen, conventional spin echo imaging (Section II.E) typically takes approximately a few minutes because an independent r.f. excitation is required for acquisition of each row of k-space data. Hence, sampling of the complete raster is limited by the repetition/recycle time of the pulse sequence used, which in turn is governed by the inherent 7) relaxation time(s) of the system under study. In general, the acquisition speed of an MR image may be improved by two basic methods ... 

Yamada, 1., S. Suzuki, and Y. Matsushima, Moyamoya disease comparison of assessment with MR angiography and MR imaging versus conventional angiography. Radiology,... 

Conventional CT and MR imaging cannot reliably detect infarction at early time points (less than 6 h) because detection of hypoattenuation on CT and hyperintensity on T2-weighted and ELAIR MR images requires substantial increases in tissue water. Eor infarctions imaged within 6 h after stroke onset, reported sensitivities are 38 5% for CT and 18 6% for MRI [30, 31]. Eor infarctions imaged within 24 h, one study reported a sensitivity of 58% for CT and 82% for MRI [32]. 

The particles were shown to be multimodal in their capacity to provide both CT and MR contrast. Synchrotron radiation computed tomography (SRCT) phantom imaging was obtained at a gold concentration of 1.4mg mLr which is lower than the detection threshold of a conventional CT scanner. In vivo SRCT images of mice and rats were obtained at a concentration of 10 mg mL7 which corresponds to a 5mM Gd. MR images were enhanced by the presence of the particles. Postmortem ICP mass spectrometry showed the particles to distribute mostly to the kidneys of the animals, where they were readily cleared in the urine. Interestingly,... 

MRI is methodologically limited in that it does not reliably show intralesional calcifications, which are frequently identified on conventional radiographs or CT scans hy their popcorn-like appearance [169]. Occasionally, calcifications take the form of a peripheral rim after hemorrhagic infarction and can he identified on Tl-weighted MR images (Fig. 5.20). 

CT, fibrofatty proliferation shows a slightly increased attenuation. In MRl, the signal intensity is decreased compared with normal fat separating the bowel loops. Phlegmon and abscesses can occur in the small bowel mesentery, abdominal wall, or psoas muscle or perianally. They are well demonstrated on CT and fat-saturated TlW MR imaging [59]. Fistulas and sinus tracts are also depicted however, the reported sensitivity of MR imaging for depicting sinus tracts is 50%-75% compared to a conventional enteroclysis study [63]. 

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