Assessment of ischemic penumbra in patients with hyperacute stroke using amide proton transfer (APT) chemical exchange saturation transfer (CEST) MRI

作者：Tietze Anna^*; Blicher Jakob; Mikkelsen Irene Klaerke; Ostergaard Leif; Strother Megan K; Smith Seth A; Donahue Manus J

来源：NMR in Biomedicine, 2014, 27(2): 163-174.

DOI：10.1002/nbm.3048

• acute stroke
• lactate
• pH
• MRI
• cerebrovascular disease
• chemical exchange saturation transfer (CEST)
• penumbra
• amide proton transfer

Chemical exchange saturation transfer (CEST)-derived, pH-weighted, amide proton transfer (APT) MRI has shown promise in animal studies for the prediction of infarction risk in ischemic tissue. Here, APT MRI was translated to patients with acute stroke (1-24h post-symptom onset), and assessments of APT contrast, perfusion, diffusion, disability and final infarct volume (23-92days post-stroke) are reported. Healthy volunteers (n=5) and patients (n=10) with acute onset of symptoms (0-4h, n=7; uncertain onset <24h, n=3) were scanned with diffusion- and perfusion-weighted MRI, fluid-attenuated inversion recovery (FLAIR) and CEST. Traditional asymmetry and a Lorentzian-based APT index were calculated in the infarct core, at-risk tissue (time-to-peak, TTP; lengthening) and final infarct volume. On average (mean +/- standard deviation), control white matter APT values (asymmetry, 0.019 +/- 0.005; Lorentzian, 0.045 +/- 0.006) were not significantly different (p>0.05) from APT values in normal-appearing white matter (NAWM) of patients (asymmetry, 0.022 +/- 0.003; Lorentzian, 0.048 +/- 0.003); however, ischemic regions in patients showed reduced (p=0.03) APT effects compared with NAWM. Representative cases are presented, whereby the APT contrast is compared quantitatively with contrast from other imaging modalities. The findings vary between patients; in some patients, a trend for a reduction in the APT signal in the final infarct region compared with at-risk tissue was observed, consistent with tissue acidosis. However, in other patients, no relationship was observed in the infarct core and final infarct volume. Larger clinical studies, in combination with focused efforts on sequence development at clinically available field strengths (e.g. 3.0T), are necessary to fully understand the potential of APT imaging for guiding the hyperacute management of patients.

• 出版日期2014-2