Affiliation:
1. Department of Radiology University of Pittsburgh Pittsburgh Pennsylvania USA
2. Department of Neurology University of Pittsburgh Pittsburgh Pennsylvania USA
3. Department of Neurobiology University of Pittsburgh Pittsburgh Pennsylvania USA
4. Department of Biostatistics University of Pittsburgh Pittsburgh Pennsylvania USA
Abstract
AbstractPurposepH enhanced (pHenh) CEST imaging combines the pH sensitivity from amide and guanidino signals, but the saturation parameters have not been optimized. We propose pHdual as a variant of pHenh that suppresses background signal variations, while enhancing pH sensitivity and potential for imaging ischemic brain injury of stroke.MethodsSimulation and in vivo rodent stroke experiments of pHenh MRI were performed with varied RF saturation powers for both amide and guanidino protons to optimize the contrast between lesion/normal tissues, while simultaneously minimizing signal variations across different types of normal tissues. In acute stroke, contrast and volume ratio measured by pHdual imaging were compared with an amide‐CEST approach, and perfusion and diffusion MRI.ResultsSimulation experiments indicated that amide and guanidino CEST signals exhibit unique sensitivities across different pH ranges, with pHenh producing greater sensitivity over a broader pH regime. The pHenh data of rodent stroke brain demonstrated that the lesion/normal tissue contrast was maximized for an RF saturation power pair of 0.5 μT at 2.0 ppm and 1.0 μT at 3.6 ppm, whereas an optimal contrast‐to‐variation ratio (CVR) was obtained with a 0.7 μT saturation at 2.0 ppm and 0.8 μT at 3.6 ppm. In acute stroke, CVR optimized pHenh (i.e., pHdual) achieved a higher sensitivity than the three‐point amide‐CEST approach, and distinct patterns of lesion tissue compared to diffusion and perfusion MRI.ConclusionpHdual MRI improves the sensitivity of pH‐weighted imaging and will be a valuable tool for assessing tissue viability in stroke.
Funder
National Institutes of Health
Subject
Radiology, Nuclear Medicine and imaging
Cited by
3 articles.
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