Quantitative magnetic resonance imaging assessment of cerebral ischemia in rat using on-resonance T1 in the rotating frame

Gröhn, Olli; Lukkarinen, Jouko A.; Silvennoinen, Martti; Pitkänen, Asla; Zijl, Peter C.M. van; Kauppinen, Risto A.

doi:10.1002/(sici)1522-2594(199908)42:2<268::aid-mrm8>3.0.co;2-a

Cited by 70 publications

(63 citation statements)

References 40 publications

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“…An almost immediate drop of temperature by 2 - 3°C in the ischemic core (Gröhn et al 1999) and acidification of tissue is expected to decrease contributions of the anisochronous mechanisms to the relaxation. Anisochronous effects may not be significant for the T 1ρ relaxation (Abragam 1961; Michaeli et al 2006), but they may contribute to the T 2ρ relaxation.…”

Section: Discussionmentioning

confidence: 99%

“…It should be noted that this is typically the earliest time point when stroke patients are examined with MRI and often shows significant diffusion perfusion mismatch (Baird et al 1997; Meng et al 2004; Shen et al 2003) as a sign of tissue at risk of infarction. It has been shown both in animal models (Gröhn et al 1999; Minematsu et al 1992) and in human stroke patients (Doege et al 2000) that the original diffusion abnormality can transiently recover, notwithstanding the evolving lesion. Also, T 1ρ measured during the early hours of ischemia has been shown to better correlate with cell death (Gröhn et al 1999).…”

Section: Discussionmentioning

confidence: 99%

“…It has been shown both in animal models (Gröhn et al 1999; Minematsu et al 1992) and in human stroke patients (Doege et al 2000) that the original diffusion abnormality can transiently recover, notwithstanding the evolving lesion. Also, T 1ρ measured during the early hours of ischemia has been shown to better correlate with cell death (Gröhn et al 1999). Furthermore, T 1ρ progressively increases during the first hours of stroke, while diffusion remains at a constant low value, showing that these two MR contrasts probe different aspects of ischemia.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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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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“…Recent studies indicate that one can predict the degree of irreversible neuronal damage in the early moments of focal ischemia with quantitative T 1 MRI before T 2 hyperintensity is evident (37,39). In the present study, we observed that incomplete recovery of R 1 after ischemia was associated with imminent cell loss in the brain cortex, and that conventional T 2 -weighted MRI did not highlight the damaged tissue a day later, even when both absolute R 1 and CP R 2 MRI showed pathological values.…”

Section: Discussionmentioning

confidence: 99%

Acute cerebral ischemia in rats studied by Carr‐Purcell spin‐echo magnetic resonance imaging: Assessment of blood oxygenation level‐dependent and tissue effects on the transverse relaxation

Kavec¹,

Gröhn²,

Kettunen³

et al. 2004

Magnetic Resonance in Med

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Acute cerebral ischemia has been shown to be associated with an enhanced transverse relaxation rate in rat brain parenchyma, chiefly due to the blood oxygenation level-dependent (BOLD) effect. In this study, Carr-Purcell R 2 (CP R 2 ), acquired both with short and long time intervals between centers of adiabatic -pulses ( CP ), was used to assess the contributions of BOLD and tissue effects to the transverse relaxation in two brain ischemia models of rat at 4.7 T. R 1 and diffusion MR images were also acquired in the same animals. During the first minutes of global ischemia, the long CP R 2 in brain parenchyma increased, whereas the short CP R 2 was unchanged. Based on the simulations, and using constraints of intravascular BOLD effect on parenchymal R 2 , the former observation was ascribed to be due to susceptibility changes arising in the extravascular compartment. R 1 declined almost immediately after the onset of focal cerebral ischemia, and further declined during the evolution of ischemic damage. Interestingly, short CP CP R 2 started to decline after some 20 min of focal ischemia and declined over a time course similar to that of Several recent studies have shown that in the early minutes of cerebral ischemia the transverse relaxation rate in brain parenchyma increases, leading to negative T* 2 (1,2) and T 2 (3-5) MR signal change. A shortening of transverse relaxation time has been observed in animal models of hypoperfusion (6), and global (7,8) and focal (1,3) ischemia, as well as in human stroke victims (9), at field strengths ranging from 1.5 to 9.4 T. This observation has been generally attributed to the blood oxygenation leveldependent (BOLD) effect, and the known hemodynamic and metabolic adaptations to reduced cerebral perfusion pressure (CPP) support this conclusion. At lowered CPP levels, cerebral blood volume (CBV) and oxygen extraction increase (10), resulting in a situation in which the accumulation of deoxyhemoglobin (Hb) is favored. Increased Hb levels generate local susceptibility gradients, resulting in enhanced transverse relaxation expressed as a negative BOLD effect.The negative BOLD effect in focal cerebral ischemia is interesting as regards tissue assignment, since BOLD is generated only by tissue that is capable of mitochondrial oxidation. On the basis of this mechanism underlying the generation of T 2 /T* 2 change, it has been proposed that the negative BOLD effect may have a role in the assessment of tissue viability in focally ischemic brain (11). Before the role of decreased T 2 and/or T* 2 in acute cerebral ischemia can be explicitly assigned, a deeper understanding of the underlying physiological and physical phenomena must be obtained. Recent studies in our laboratory have suggested that the T 2 changes associated with focal and global rat brain ischemia can be explained by intravascular susceptibility effects at both 1.5 T (6) and 4.7 T (12). These observations are in line with data from human brain BOLD experiments at 1.5 T (13-15) and 4 T (16), as well as with relaxation ...

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“…While some of the elevated values in infiltrative edema can be explained by lower cellularity and greater water content, other physiologic processes may underlie the observed T1ρ values. For example, studies of cerebral ischemia have suggested that T1ρ prolongation in ischemic regions relates to higher acidity caused by ischemic or infarcted tissue leading to altered proton exchange and macromolecular integrity [24,29]. Acidic extracellular pH from tumor catabolism has been observed in brain tumors and as such we postulate that proton exchange may play a central role in the observations [30,31].…”

Section: Discussionmentioning

confidence: 89%

Differentiation of brain tumor-related edema based on 3D T1rho imaging

Villanueva-Meyer

Barajas

Mabray

et al. 2017

European Journal of Radiology

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Background and purpose Cerebral edema associated with brain tumors is an important source of morbidity. Its type depends largely on the capillary ultra-structures of the histopathologic subtype of underlying brain tumor. The purpose of our study was to differentiate vasogenic edema associated with brain metastases and infiltrative edema related to diffuse gliomas using quantitative 3D T1 rho (T1ρ) imaging. Materials and methods Preoperative MR examination including whole brain 3D T1ρ imaging was performed in 23 patients with newly diagnosed brain tumors (9 with metastasis, 8 with lower grade glioma, LGG, 6 with glioblastoma, GBM). Mean T1ρ values were measured in regions of peritumoral non-enhancing T2 signal hyperintensity, excluding both enhancing and necrotic or cystic component, and normal-appearing white matter. Results Mean T1ρ values were significantly elevated in the vasogenic edema surrounding intracranial metastases when compared to the infiltrative edema associated with either LGG or GBM (p = 0.02 and < 0.01, respectively). No significant difference was noted between T1ρ values of infiltrative edema between LGG and GBM (p = 0.84 and 0.96, respectively). Conclusion Our study demonstrates the feasibility and potential diagnostic role of T1ρ in the quantitative differentiation between edema related to intracranial metastases and gliomas and as a potentially complementary tool to standard MR techniques in further characterizing pathophysiology of vasogenic and infiltrative edema.

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Quantitative magnetic resonance imaging assessment of cerebral ischemia in rat using on-resonance T1 in the rotating frame

Cited by 70 publications

References 40 publications

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

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

Acute cerebral ischemia in rats studied by Carr‐Purcell spin‐echo magnetic resonance imaging: Assessment of blood oxygenation level‐dependent and tissue effects on the transverse relaxation

Differentiation of brain tumor-related edema based on 3D T1rho imaging

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Quantitative magnetic resonance imaging assessment of cerebral ischemia in rat using on-resonance T1 in the rotating frame

Cited by 70 publications

References 40 publications

Quantitative Assessment of Water Pools by T1p and T2p MRI in Acute Cerebral Ischemia of the Rat

Quantitative Assessment of Water Pools by T1p and T2p MRI in Acute Cerebral Ischemia of the Rat

Acute cerebral ischemia in rats studied by Carr‐Purcell spin‐echo magnetic resonance imaging: Assessment of blood oxygenation level‐dependent and tissue effects on the transverse relaxation

Differentiation of brain tumor-related edema based on 3D T1rho imaging

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

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