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4 results

  • Using Magnetic Resonance Perfusion to Stratify Overall Survival in Treated High-Grade Gliomas

  • Crystal Fong, Sameer Parpia, Brian Yemen, Scott Tsai, Jeffrey Greenspoon
  • Journal:
    Canadian Journal of Neurological Sciences / Volume 46 / Issue 5 / September 2019
    Published online by Cambridge University Press:
    24 July 2019, pp. 533-539
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  • Background:

    MR perfusion imaging is a relatively new technique that may aid in identifying recurrent tumor (RT) in those with radically treated high-grade gliomas (HGG). We aim to assess the relationship between dynamic susceptibility contrast-enhanced MR perfusion (DSC-MRP) and overall survival to establish a baseline for future research and to determine the utility of DSC-MRP as a clinical decision-making and prognostic tool.

    Methods:

    We conducted a retrospective cohort study. Adults with pathologically confirmed HGG at the Juravinski Cancer Centre, Ontario between January 2011 and April 2014 with at least one post-treatment DSC-MRP were included. DSC-MRP was interpreted as positive or negative for tumor recurrence by experienced radiologists. The primary outcome was overall survival.

    Results:

    Sixty-one patients were enrolled. Median survival for patients with a positive DSC-MRP scan was 4.5 months compared with 10.2 months for those with a negative DSC-MRP scan (hazard ratio [unadjusted] = 2.51; 95% confidence interval = 1.10–5.67; p-value = 0.03). Multivariable modeling (adjusted) that included all pre-selected variables showed similar results.

    Conclusion:

    Survival time in patients with HGG is generally low, and almost all patients will demonstrate RT. Our data suggest a positive DSC-MRP correlates with lower overall survival and may signify the presence of highly active RT. These results generate a hypothesis that there may be a prognostic role for the use of serial DSC-MRP for tumor surveillance. More importantly, this biomarker may aid in decision making for treatment plans and palliation.

  • CT Perfusion in Acute Stroke Predicts Final Infarct Volume- Inter-observer Study

  • Jai Jai Shiva Shankar, Gavin Langlands, Steve Doucette, Stephen Phillips
  • Journal:
    Canadian Journal of Neurological Sciences / Volume 43 / Issue 1 / January 2016
    Published online by Cambridge University Press:
    20 January 2016, pp. 93-97
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  • Background: Computed tomography perfusion (CTP) is increasingly being used in the setting of acute ischemic stroke (AIS). The aim of the current study was to compare the prognostic utility of, and inter-observer variation between, baseline appearances on non-contrast CT (using Alberta Stroke Program Early CT score(ASPECTS)) and on CTP for predicting final infarct volume. We also assessed impact of training on interpretation of these images. Methods: Retrospectively, plain head computed tomography (CT) and CTP images at presentation and CT or diffusion imaging on follow up of patients with AIS were analyzed. The lesion volume on different CTP parameters was then correlated with the final infarct volume. This analysis was done by a Neuroradiologist, a stroke Neurologist and a medical student. Kappa statistics and Intra-class correlation coefficients were used for agreement between readers. Pearson correlation coefficients were used.Results: Thirty eight patients with AIS met all inclusion criteria. There was very good agreement among all readers for the CTP parameters. There was only fair agreement for ASPECT score. Correlation coefficient (r-square) between CTP parameters and final infarct volume showed that cerebral blood volume was the best parameter to predict the final infarct volume followed by cerebral blood flow and time to peak. The best reader to predict the final infarct volume on the initial CT perfusion study was the neuroradiologist followed by medical student and stroke neurologist. Conclusions: Cerebral blood volume defect correlated the best with the final infarct volume. There was a very good inter-observer agreement for all the CTP maps in predicting the final infarct volume despite the wide variation in the experience of the readers.

  • 15 - The ischemic penumbra: the evolution of a concept

  • Edited by Stephen Davis, Marc Fisher, National Institute of Mental Health, Bethesda, Maryland, Steven Warach, National Institutes of Health, Baltimore
  • Book:
    Magnetic Resonance Imaging in Stroke
    Published online:
    26 August 2009
    Print publication:
    20 March 2003, pp 191-206

  • Summary

    The fundamental importance of the concept of the ischemic penumbra is the recognition that ischemic processes may be reversible. Although founded on the concept of critical changes of blood flow, the ischemic penumbra can also be described in molecular terms. A molecular delineation of the ischemic core employs analyses of appropriate proteins, many of which have a short half-life and hence rapid reductions in concentration. Multitracer PET imaging with 15O allows generation of quantitative brain maps for CBF, CMRO2, OEF, cerebral blood volume (CBV), and regional cerebral metabolic rate of glucose. Evolving MRI techniques are useful for assessment of penumbral tissue in acute stroke. DWI is increasingly available in the setting of acute stroke, and for rapid acquisition it is performed using echoplanar magnetic resonance imaging methods. The blood oxygen level dependent (BOLD) technique has been used to differentiate perfused and non-perfused tissues during experimental ischemia in cats.

  • 1 - Functional brain imaging with PET and SPECT

  • from Part 1 - Techniques of functional neuroimaging
  • Edited by Monique Ernst, National Institutes of Health, Baltimore, Judith M. Rumsey, National Institute of Mental Health, Bethesda, Maryland
  • Foreword by Joseph T. Coyle
  • Book:
    Functional Neuroimaging in Child Psychiatry
    Published online:
    06 January 2010
    Print publication:
    12 October 2000, pp 3-26

  • Summary

    Two nuclear medicine-based approaches to functional brain imaging can be used to study the pediatric population, positron emission tomography (PET) and single-photon emission computed tomography (SPECT). This chapter talks about PET instrumentation, positron-emitting radiotracers, and radiotracer modeling. It describes the PET methods used to measure cerebral blood flow (rCBF) and cerebral blood volume (rCBV) and glucose and oxygen metabolism. Measurements of CBF glucose metabolism are widely used as indices of neuronal activity. The radionuclides used in SPECT decay by emitting a single photon or gamma ray from their nucleus; radioactivity distribution is estimated by detection of gamma rays. To interpret changes in PET and SPECT studies, it is necessary to understand the relationships among CBF, metabolism, and local neuronal activity. Radiation exposure in the context of PET and SPECT is an important consideration when they are used for research rather than diagnostic purposes.