Susceptibility contrast

For a given object immersed in an environment with different magnetic susceptibility the image distortion depends on the shape of the object, that is, on the tensorial properties of 

9 [Ben 1) Siisceplibiliiy effects In NMR imaginji. (a) Phanioni of iwo coaxial glass cylinders, The omer one is tilled with distilled water, the inner one with a copper sulfate solution. 

10 Susceptibility contrast in commercial EPDM samples, (a) 2D projection acquireil by spin-warp imaging, (b) 2D projection acquired by gradient-echo imaging. The images were measured at a temperature of 363 K. Adapted from BIUR with permission from Hiithig Gmbh. 

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The second application was checked in a feasibility study. The preliminary results show that segregations in Inconnel IN 718 can be detected within the volume. It can be assumed that segregations also in other type of material can be detected by this method. Several details, however, have to be checked before a routine use of this susceptibility based method. Among these details are to determine the susceptibility contrast of v ious segregations in various matrix materials as well as sizing and localisation procedures of the segrations. 

FIGURE 2.6 Dynamic susceptibility contrast imaging. Axial images of the brain are acquired repeatedly, in this case every 1.5 seconds. As a bolus of intravenously injected contrast material enters the brain, first arteries, then brain parenchyma, and finally veins demonstrate a transient loss of signal intensity. In this acute stroke patient, hypoperfusion of the left middle cerebral artery territory results in delayed arrival of the contrast bolus and prolonged stasis of contrast within the tissue. 

Rempp KA, Brix G, Wenz F, Becker CR, Guckel F, Lorenz WJ. Quantification of regional cerebral blood flow and volume with dynamic susceptibility contrast-enhanced MR imaging. Radiology 1994 193 637-641. 

Speck O, Chang L, DeSilva NM, Ernst T. Perfusion MRI of the human brain with dynamic susceptibility contrast gradient-echo versus spin-echo techniques. J Magn Reson Imaging 2000 12 381-387. 

Kaufman, M.J., Levin. J.M., Maas, L.C., et. al. Cocaine decreases relative cerebral blood volume in humans a dynamic susceptibility contrast magnetic resonance imaging study. Psychopharmacology 138(1), 76-81, 1998. 

Figure 7.5 [15] Susceptibility contrast in EPDM samples at 363 K (a) 2D Hahn-echo image acquired with the sequence of Figure 7.4a (b) 2D gradient-echo image acquired...

Perfusion Measurements with the Dynamic Susceptibility Contrast-Enhanced Method 103... 

Sequences for Dynamic Susceptibility Contrast-Enhanced Imaging 104... 

Postprocessing of Dynamic Susceptibility Contrast-Enhanced Data 105... 

Fig. 6.1. Source images of a dynamic susceptibility contrast-enhanced series in a healthy volunteer, acquired 20-50 s after bolus injection during the bolus passage the signal decrease in gray matter is more prominent than that in white matter. After the bolus passage, the signal returns to normal...

Benner T, Heiland S, Erb G et al (1997) Accuracy of gamma-variate fits to concentration-time curves from dynamic susceptibility-contrast enhanced MRI influence of time resolution, maximal signal drop and signal-to-noise. Magn Reson Imaging 15 307-317... 

Butcher K, Parsons M, Baird T et al (2003) Perfusion thresholds in acute stroke thrombolysis. Stroke 34 2159-2164 Calamante F, Gadian DG, Connelly A (2000) Delay and dispersion effects in dynamic susceptibility contrast MRI simulations using singular value decomposition. Magn Reson Med 44 466-473... 

For the exact description of hemodynamic stroke and identification of individual hemodynamic risk zones, as mentioned earlier, the assessment of the hemodynamic situation is essential. PI offers a means to obtain semiquantitative hemodynamic information in cerebral ischemia with relatively high resolution and short acquisition times covering all cerebral vascular territories. In acute cerebral ischemia dynamic susceptibility contrast... 

Guckel FJ, Brix G, Schmiedek P et al (1996) Cerebrovascular reserve capacity in patients with occlusive cerebrovascular disease assessment with dynamic susceptibility contrast-enhanced MR imaging and the acetazolamide stimulation test. Radiology 201 405-412... 

Holmes TM, Petrella JR, Provenzale JM (2004) Distinction between cerebral abscesses and high-grade neoplasms by dynamic susceptibility contrast perfusion MRI. AJR Am J Roentgenol 183 1247-1252. 

Law M, Yang S, Babb JS, Knopp EA, Golfinos JG, Zagzag D, Johnson G (2004) Comparison of cerebral blood volume and vascular permeability from dynamic susceptibility contrast-enhanced perfusion MR imaging with glioma grade. AJNR Am J Neuroradiol 25 746-755. 

Haraldseth O, Jones RA, Muller TB, Fahlvik AK, Oksendal AN. Comparison of dysprosium DTPA BMA and superparamagnetic iron oxide particles as susceptibility contrast agents for perfusion imaging of regional... 

Quantitation and Resolution. While CTP and MR-PWl both attempt to evaluate the intricacies of capillary-level hemodynamics, the differences in technique create several important differences that should be considered (Table 5.5). While dynamic susceptibility contrast (DSC) MR-PWI techniques rely on the indirect T2 effect induced in adjacent tissues by high concentrations of rv gadolinium, CTP relies on direct visualization of the contrast material. The linear relationship between contrast concentration and attenuation in CT more readily lends itself to quantitation, which is not possible with MR-PWI techniques. Comparison with a positron emission tomography reference standard resulted in an accurate CBF calculation with CTP [92], but overestimation of CBF and... 

Wirestam, R., et al.. Assessment of regional cerebral blood flow by dynamic susceptibility contrast MRI using different deconvolution techniques. Magn Reson Med, 2000. 43(5) p. 691-700. 

Ibaraki, M., et al., Tracer delay correction of cerebral blood flow with dynamic susceptibility contrast-enhanced MRI. J Cereb Blood Elow Metab, 2005. 25(3) p. 378-90. 

Hatazawa, J., et al.. Cerebral blood volume in acute brain infarction A combined study with dynamic susceptibility contrast MRI and 99mTc-HMPAO-SPECT. Stroke, 1999. 30(4) p. 800-6. 

Xaylor, M.B., A. Jackson, and J.M. Weller, Dynamic susceptibility contrast enhanced MRI in reversible posterior leukoencephalopathy syndrome associated with haemolytic uraemic syndrome. Br J Radiol, 2000. 73(868) p. 438-42. 

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