Comparing different analysis methods for quantifying the MRI amide proton transfer (APT) effect in hyperacute stroke patients
Journal
NMR in Biomedicine
Journal Volume
27
Journal Issue
9
Pages
1019-1029
Date Issued
2014
Author(s)
Tee Y.K.
Harston G.W.J.
Blockley N.
Okell T.W.
Levman J.
Sheerin F.
Cellerini M.
Jezzard P.
Kennedy J.
Payne S.J.
Chappell M.A.
Abstract
Amide proton transfer (APT) imaging is a pH mapping method based on the chemical exchange saturation transfer phenomenon that has potential for penumbra identification following stroke. The majority of the literature thus far has focused on generating pH-weighted contrast using magnetization transfer ratio asymmetry analysis instead of quantitative pH mapping. In this study, the widely used asymmetry analysis and a model-based analysis were both assessed on APT data collected from healthy subjects (n = 2) and hyperacute stroke patients (n = 6, median imaging time after onset = 2 hours 59 minutes). It was found that the model-based approach was able to quantify the APT effect with the lowest variation in grey and white matter (? 13.8 %) and the smallest average contrast between these two tissue types (3.48 %) in the healthy volunteers. The model-based approach also performed quantitatively better than the other measures in the hyperacute stroke patient APT data, where the quantified APT effect in the infarct core was consistently lower than in the contralateral normal appearing tissue for all the patients recruited, with the group average of the quantified APT effect being 1.5 ± 0.3 % (infarct core) and 1.9 ± 0.4 % (contralateral). Based on the fitted parameters from the model-based analysis and a previously published pH and amide proton exchange rate relationship, quantitative pH maps for hyperacute stroke patients were generated, for the first time, using APT imaging. ? 2014 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.
Subjects
Amides
Chemical analysis
pH
Proton transfer
Saturation magnetization
Amide proton transfers
Chemical exchange saturation transfer
Healthy volunteers
Hyperacute strokes
Magnetization transfer ratio
Model based approach
Model-based analysis
Stroke
Magnetic resonance imaging
tissue plasminogen activator
amide
proton
adult
amide proton transfer
article
brain ischemia
case report
contrast to noise ratio
diffusion weighted imaging
echo planar imaging
gray matter
human
male
nuclear magnetic resonance imaging
nuclear Overhauser effect
priority journal
proton transport
stroke patient
white matter
algorithm
brain chemistry
cerebrovascular accident
chemistry
comparative study
computer assisted diagnosis
female
metabolism
pathology
procedures
reproducibility
sensitivity and specificity
very elderly
Aged, 80 and over
Algorithms
Brain Chemistry
Female
Humans
Image Interpretation, Computer-Assisted
Magnetic Resonance Imaging
Male
Protons
Reproducibility of Results
Sensitivity and Specificity
SDGs
Type
journal article