High‐sensitivity CEST mapping using a spatiotemporal correlation‐enhanced method

• Published in: Magnetic resonance in medicine Vol. 84; no. 6; pp. 3342 - 3350
• Main Authors: Chen, Lin, Cao, Suyi, Koehler, Raymond C., Zijl, Peter C. M., Xu, Jiadi
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.12.2020
• Subjects: amide; Amides; amine; Animals; Brain; Brain mapping; chemical exchange saturation transfer (CEST); Correlation; creatine (Cr); Decomposition; Ischemia; ischemic stroke; Magnetic fields; Magnetic Resonance Imaging; Mapping; Mice; multilinear singular value decomposition (MLSVD); Noise; Noise reduction; pH effects; pH mapping; polynomial and Lorentzian line‐shape fitting (PLOF); Random noise; Sensitivity; Singular value decomposition; singular value decomposition (SVD); amide; pH mapping; polynomial and Lorentzian line-shape fitting (PLOF); creatine (Cr); chemical exchange saturation transfer (CEST); multilinear singular value decomposition (MLSVD); amine; ischemic stroke; singular value decomposition (SVD)
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.28380

Purpose To obtain high‐sensitivity CEST maps by exploiting the spatiotemporal correlation between CEST images. Methods A postprocessing method accomplished by multilinear singular value decomposition (MLSVD) was used to enhance the CEST SNR by exploiting the correlation between the Z‐spectrum for each voxel and the low‐rank property of the overall CEST data. The performance of this method was evaluated using CrCEST in ischemic mouse brain at 11.7 tesla. Then, MLSVD CEST was applied to obtain Cr, amide, and amine CEST maps of the ischemic mouse brain to demonstrate its general applications. Results Complex‐valued Gaussian noise was added to CEST k‐space data to mimic a low SNR situation. MLSVD CEST analysis was able to suppress the noise, recover the degraded CEST peak, and provide better CrCEST quality compared to the smoothing and singular value decomposition (SVD)‐based denoising methods. High‐resolution Cr, amide, and amine CEST maps of an ischemic stroke using MLSVD CEST suggest that CrCEST is also a sensitive pH mapping method, and a wide range of pH changes can be detected by combing CrCEST with amine CEST at high magnetic fields. Conclusion MLSVD CEST provides a simple and efficient way to improve the SNR of CEST images.