On‐ and off‐resonance <i>T</i><sub>1ρ</sub> MRI in acute cerebral ischemia of the rat

Gröhn, Olli; Mäkelä, Heidi I.; Lukkarinen, Jouko A.; DelaBarre, Lance; Lin, Joseph; Garwood, Michael; Kauppinen, Risto A.

doi:10.1002/mrm.10356

Cited by 39 publications

(40 citation statements)

References 19 publications

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“…The decrease observed at 40 min complicates the interpretation of single time point measures of 23 Na by T 2 *-weighted imaging as signal intensity is not single valued, however this limitation could be overcome by reducing the T 2 *-weighting, as has been previously reported [23]. Further studies are required to determine whether decreased 23 Na T 2 *-weighted signal intensity has specific biological significance and/or advantages for detection of acute ischemic lesions compared to other imaging contrasts such as diffusion, perfusion, T 2 , T 1 , and/or lactate metabolic imaging [42][43][44][45].…”

Section: Discussionmentioning

confidence: 92%

Sodium T2*-weighted MR imaging of acute focal cerebral ischemia in rabbits

Bartha¹,

Lee²,

Hogan³

et al. 2004

Magnetic Resonance Imaging

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Section: Discussionmentioning

confidence: 92%

Sodium T2*-weighted MR imaging of acute focal cerebral ischemia in rabbits

Bartha¹,

Lee²,

Hogan³

et al. 2004

Magnetic Resonance Imaging

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“…Our data demonstrate that rotating frame relaxation in vivo is indeed influenced by the choice of pulse modulation functions. Specifically, the effective spin-lock frequency with the HS n pulses ( ω eff ( t )) is off- resonance during a significant portion of the pulse duration, so the method therefore probes more of the shorter correlation time regime of molecular motion than the on-resonance CW-type technique (Gröhn et al 2003). …”

Section: Discussionmentioning

confidence: 99%

Quantitative Assessment of Water Pools by T_1p and T_2p MRI in Acute Cerebral Ischemia of the Rat

Jokivarsi

Niskanen

Michaeli

et al. 2008

J Cereb Blood Flow Metab

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The rotating frame longitudinal relaxation MRI contrast, T1ρ, obtained with on-resonance continuous wave (CW) spin-lock field is a sensitive indicator of tissue changes associated with hyperacute stroke. Here, the rotating frame relaxation concept was extended by acquiring both T1ρ and transverse rotating frame (T2ρ) MRI data using both CW and adiabatic hyperbolic secant (HSn, n = 1, 4, or 8) pulses in a rat stroke model of middle cerebral artery occlusion (MCAo). The results demonstrate differences in the sensitivity of spin-lock T1ρ and T2ρ MRI to detect hyperacute ischemia. The most sensitive techniques were CW-T1ρ and T1ρ using HS4 or HS8 pulses. Fitting a two-pool exchange model to the T1ρ and T2ρ MRI data acquired from the infarcting brain indicated time-dependent increase in free water fraction, decrease in the correlation time of water fraction associated with macromolecules and increase in the exchange correlation time. These findings are consistent with known pathology in acute stroke, including vasogenic edema, destructive processes and tissue acidification. Our results demonstrate that the sensitivity of the spin-lock MRI contrast in vivo can be modified using different spin-lock preparation blocks, and that physico-chemical models of the rotating frame relaxation may provide insight into progression of ischemia in vivo.

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“…The relaxation of magnetization parallel to the longitudinal axis (Z 0 ) of that reference frame is characterized with the time constant T 1q , while that of magnetization in the plane perpendicular to Z 0 with the time constant T 2q . These reports have shown T 1q -related contrast in, for example, rat cerebral ischemia [1] and human knee cartilage [2] and T 2q -related contrast in the human brain [3,4].…”

Section: Introductionmentioning

confidence: 95%