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  • Wiley  (2)
  • Semmineh, Natenael B.  (2)
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  • Wiley  (2)
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  • 1
    In: Magnetic Resonance in Medicine, Wiley, Vol. 83, No. 1 ( 2020-01), p. 109-123
    Abstract: Brain tumor dynamic susceptibility contrast (DSC) MRI is adversely impacted by T 1 and contrast agent leakage effects that result in inaccurate hemodynamic metrics. While multi‐echo acquisitions remove T 1 leakage effects, there is no consensus on the optimal set of acquisition parameters. Using a computational approach, we systematically evaluated a wide range of acquisition strategies to determine the optimal multi‐echo DSC‐MRI perfusion protocol. Methods Using a population‐based DSC‐MRI digital reference object (DRO), we assessed the influence of preload dosing (no preload and full dose preload), field strength (1.5 and 3T), pulse sequence parameters (echo time, repetition time, and flip angle), and leakage correction on relative cerebral blood volume (rCBV) and flow (rCBF) accuracy. We also compared multi‐echo DSC‐MRI protocols with standard single‐echo protocols. Results Multi‐echo DSC‐MRI is highly consistent across all protocols, and multi‐echo rCBV (with or without use of a preload dose) had higher accuracy than single‐echo rCBV. Regression analysis showed that choice of repetition time and flip angle had minimal impact on multi‐echo rCBV and rCBV, indicating the potential for significant flexibility in acquisition parameters. The echo time combination had minimal impact on rCBV, though longer echo times should be avoided, particularly at higher field strengths. Leakage correction improved rCBV accuracy in all cases. Multi‐echo rCBF was less biased than single‐echo rCBF, although rCBF accuracy was reduced overall relative to rCBV. Conclusions Multi‐echo acquisitions were more robust than single‐echo, essentially decoupling both repetition time and flip angle from rCBV accuracy. Multi‐echo acquisitions obviate the need for preload dosing, although leakage correction to remove residual leakage effects remains compulsory for high rCBV accuracy.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 1493786-4
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  • 2
    In: Magnetic Resonance in Medicine, Wiley, Vol. 74, No. 3 ( 2015-09), p. 772-784
    Abstract: In brain tumor dynamic susceptibility contrast (DSC)‐MRI studies, multiecho acquisition methods are used to quantify the dynamic changes in T 1 and T 2 * that occur when contrast agent (CA) extravasates. Such methods also enable the estimation of the effective tissue CA transverse relaxivity. The goal of this study was to evaluate the sensitivity of the transverse relaxivity at tracer equilibrium (TRATE) to tumor cytoarchitecture. Methods Computational and in vitro studies were used to evaluate the biophysical basis of TRATE. In 9L, C6, and human brain tumors, TRATE, the apparent diffusion coefficient ( ADC) , the CA transfer constant ( K trans ), the extravascular extracellular volume fraction ( v e ), and histological data were compared. Results Simulations and in vitro results indicate that TRATE is highly sensitive to variations in cellular properties such as cell size and density. The histologic cell density and TRATE values were significantly higher in 9L tumors as compared to C6 tumors. In animal and human tumors, a voxel‐wise comparison of TRATE with ADC , v e , and K trans maps showed low spatial correlation. Conclusion The assessment of TRATE is clinically feasible and its sensitivity to tissue cytoarchitectural features not present in other imaging methods indicate that it could potentially serve as a unique structural signature or “trait” of cancer. Magn Reson Med 74:772–784, 2015. © 2014 Wiley Periodicals, Inc.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 1493786-4
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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