Acute stroke in cats: comparison of dynamic susceptibility-contrast MR imaging with T2- and diffusion-weighted MR imaging.

Abstract

This dynamic method can advance the time of detection of early ischemia in comparison with T2-weighted MR imaging and provides functional information about hemodynamics not provided by other methods of MR imaging.

Dynamic Gd-DTPA-Enhanced MR Imaging of the Kidney: Comparison between T1 – and T2*-Weighted Sequences

“…In order to understand the changes in contrast en hancement in the kidneys, it is important to consider the effects of Gd-DTPA concentration and distribution on signal intensity in the Tl-weighted and T2*-weighted imagings [4,5,[12][13][14][15], During the first pass of Gd-DTPA in the tissue, the bolus of Gd-DTPA is predominantly in the intravascular space. During this very early phase, the increase in signal intensity in the Tl-weighted imaging is caused mainly by the shortening of T1 relaxation time in the intravascular space.…”

“…The T2*-weighted dynamic MR imaging has already been applied to evaluate the vascularity of normal and abnormal brain tissues, and it has been supposed that the T2*-weighted imaging may be more accurate in the evalu ation of the regional cerebral blood flow than the T lweighted imaging when the blood-brain barrier is intact [12][13][14][15], When the tissue lacks barrier function, the cere bral blood flow obtained by the T2*-weighted imaging is D ynam ic MR Imaging: T l-and T2*-Weighted Sequences underestimated, because the induced field gradient may be reduced as contrast material leaves the intravascular space and makes T l shortening, resulting in an increase in signal intensity. In fact, the enhancement pattern of the renal cell carcinoma showed an evident Tl shortening effect ( fig.…”

“…T2*-weighted dynamic MR imaging has been already applied for evaluating the vascularity of normal and abnormal brain tissues. The dynamic enhancement pat tern ofT2*-weighted MR imaging correlates with regional cerebral blood volume when the blood-brain barrier is intact [12][13][14][15], The goal of studies into the dynamic MR imaging of the kidney is to establish MR renography using Gd-DTPA, but it remains to be determined whether T lweighted or T2*-weighted sequences are more informa tive and practical for the evaluation of the renal blood flow and function. We employed a Tl-weighted Turbo-FLASH (Fast Low-Angle SHot) sequence and a T2*-weighted FLASH sequence, and compared the enhance ment patterns of the kidneys in humans.…”

Diffusion and Perfusion MRI, Measurements of Acute Stroke Events and Outcome: Present Practice and Future Hope

“…Nevertheless, this numbra, whereas it is difficult to distinguish normal regions from penumbra using DWI because of the small needs reassessment in the light of the new developments with MRI. Diffusion imaging is quite recent and is the ma-difference in ADC [5]. A combination of diffusion-and perfusion-sensitive MRI may play a significant role in jor current reason for the need to reassess the value of MRI.…”

“…The haemodynamic consequence useful to predict the histological outcome of the affected tissues in terms of cell recovery or necrosis. Comparison on the perfused but compressed part of an injured hemisphere is a delayed and prolonged signal loss compared of diffusion and perfusion MRI could be of major prognostic value because their discrepancies in location of with the contralateral normal hemisphere [5]. Relative quantification of cerebral blood volume may be obtained their abnormalities could correspond to the penumbra.…”