Diffusion Kurtosis Imaging of Acute Infarction: Comparison with                     Routine Diffusion and Follow-up MR Imaging

Yin, Jianzhong; Sun, Haizhen; Wang, Zhiyun; Ni, Hongbo; Shen, Wen; Sun, Phillip Zhe

doi:10.1148/radiol.2017170553

Cited by 50 publications

(41 citation statements)

References 34 publications

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“…Notably, the CNR of MRAPTR maps determined from CW‐ and pulse‐APT MRI were not significantly different from each other (3.59 ± 0.40 vs. 3.25 ± 0.65, P > .05). As such, highly pH‐specific pulse‐APT MRI is feasible with the generalized MRAPT analysis, which is promising for characterizing the heterogeneous ischemic tissue injury typically characterized by perfusion and diffusion MRI …”

Section: Discussionmentioning

confidence: 99%

Demonstration of magnetization transfer and relaxation normalized pH‐specific pulse‐amide proton transfer imaging in an animal model of acute stroke

Sun

2020

Magnetic Resonance in Med

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Purpose: pH-weighted amide proton transfer (APT) MRI is promising to serve as a new surrogate metabolic imaging biomarker for refined ischemic tissue demarcation.APT MRI with pulse-RF irradiation (pulse-APT) is an alternative to the routine continuous wave (CW-) APT MRI that overcomes the RF duty cycle limit. Our study aimed to generalize the recently developed pH-specific magnetization transfer and relaxationnormalized APT (MRAPT) analysis to pulse-APT MRI in acute stroke imaging. Methods: Multiparametric MRI, including CW-and pulse-APT MRI scans, were performed following middle cerebral artery occlusion in rats. We calculated pH-sensitive MTR asym and pH-specific MRAPT contrast between the ipsilateral diffusion lesion and contralateral normal area. Results: An inversion pulse of 10 to 15 ms maximizes the pH-sensitive MRI contrast for pulse-APT MRI. The contrast-to-noise ratio of pH-specific MRAPT effect between the contralateral normal area and ischemic lesion from both methods are comparable (3.25 ± 0.65 vs. 3.59 ± 0.40, P > .05). pH determined from both methods were in good agreement, with their difference within 0.1. Conclusions: Pulse-APT MRI provides highly pH-specific mapping for acute stroke imaging. K E Y W O R D Sacidosis, acute stroke, amide proton transfer (APT), chemical exchange saturation transfer (CEST), pulse-CEST MRI | 1527 SUN mismatch into perfusion/pH lesion mismatch (benign oligemia) and pH/diffusion lesion mismatch (metabolic penumbra), refining the routine mismatch paradigm. 13,14 Indeed, recent clinical trials have shown that response to endovascular reperfusion is not time dependent in patients with salvageable tissue, underscoring the importance of accurate penumbra mapping. [15][16][17] Although CEST MRI has often been implemented with continuous wave (CW) RF irradiation, the irradiation scheme of an RF pulse train is of reduced RF duty cycle and specific absorption rate (SAR), making it amenable to all scanners. 18 For slow exchangeable protons, it has been shown that pulse-CEST MRI with inversion pulses of intermediate durations provides similar contrast to that of CW-CEST MRI. [19][20][21] The routine magnetization transfer (MT) ratio asymmetry (MTR asym ) analysis, despite its pH sensitivity, is susceptible to the slightly asymmetric magnetization transfer (MT) effects. MTR asym is heterogeneous across the intact white and gray matter despite their little pH difference. 22 It has been shown that in rats, the T 1w -normalized CEST effects for the intact brain WM and GM are 2.08 ± 0.20 vs. 2.00 ± 0.23%/s (APT), −1.79 ± 0.88 vs. −0.89 ± 0.97%/s (MT contrast asymmetry) and 4.42 ± 0.58 vs. 3.38 ± 0.42%/s (nuclear overhauser enhancement, NOE), respectively. 23 Indeed, the noticeable NOE and MT contrast between brain WM and GM despite their little pH difference suggest that NOE and MT effects are not pH specific. The recently developed MT and relaxation-normalized APT (MRAPT) analysis minimizes the intrinsic non-pH related heterogeneity in pH-weighted MTR asym image toward pH-specific im...

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Section: Discussionmentioning

confidence: 99%

Demonstration of magnetization transfer and relaxation normalized pH‐specific pulse‐amide proton transfer imaging in an animal model of acute stroke

Sun

2020

Magnetic Resonance in Med

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“…The swelling and structural destruction of organelles make the water molecule diffusion more limited. The MK value is a more sensitive indicator of damage than the MD value, which suggests that the former can be used to represent the microenvironment complexity index and water molecule heterogeneity in the tissues 16,18,28,29 . In calculating the rate of change of MK and MD values, and to avoid bilateral infarction and the complication of side infarction and the influence of the contralateral perfusion pressure increase, we used measurements in a normal control group, which provided a more accurate scale for lesion evaluation.…”

Section: Discussionmentioning

confidence: 99%

Diffusion kurtosis imaging and pathological comparison of early hypoxic–ischemic brain damage in newborn piglets

Xiao

Tian

et al. 2020

Sci Rep

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To investigate the application value of magnetic resonance diffusion kurtosis imaging (DKI) in hypoxic–ischemic brain damage (HIBD) in newborn piglets and to compare imaging and pathological results. Of 36 piglets investigated, 18 were in the experimental group and 18 in the control group. The HIBD model was established in newborn piglets by ligating the bilateral common carotid arteries and placing them into hypoxic chamber. All piglets underwent conventional MRI and DKI scans at 3, 6, 9, 12, 16, and 24 h postoperatively. Mean kurtosis (MK) and mean diffusivity (MD) maps were constructed. Then, the lesions were examined using light and electron microscopy and compared with DKI images. The MD value of the lesion area gradually decreased and the MK value gradually increased in the experimental group with time. The lesion areas gradually expanded with time; MK lesions were smaller than MD lesions. Light microscopy revealed neuronal swelling in the MK- and MD-matched and mismatched regions. Electron microscopy demonstrated obvious mitochondrial swelling and autophagosomes in the MK- and MD-matched region but normal mitochondrial morphology or mild swelling in the mismatched region. DKI can accurately evaluate early ischemic–hypoxic brain injury in newborn piglets.

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“…Diffusional kurtosis imaging (DKI) has been introduced to measure the degree of non‐Gaussian displacement in disorders such as Parkinson's disease, epilepsy, traumatic brain injury, and stroke . In particular, emerging evidence has suggested that the kurtosis lesion likely provides greater specificity for the infarction core than the routine DWI lesion .…”

Section: Introductionmentioning

confidence: 99%

In vivo microscopic diffusional kurtosis imaging with symmetrized double diffusion encoding EPI

Paulsen

Zhou

et al. 2018

Magnetic Resonance in Med

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Diffusion Kurtosis Imaging of Acute Infarction: Comparison with Routine Diffusion and Follow-up MR Imaging

Cited by 50 publications

References 34 publications

Demonstration of magnetization transfer and relaxation normalized pH‐specific pulse‐amide proton transfer imaging in an animal model of acute stroke

Demonstration of magnetization transfer and relaxation normalized pH‐specific pulse‐amide proton transfer imaging in an animal model of acute stroke

Diffusion kurtosis imaging and pathological comparison of early hypoxic–ischemic brain damage in newborn piglets

In vivo microscopic diffusional kurtosis imaging with symmetrized double diffusion encoding EPI

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