Document Type : Full Research Paper
Author
Biomedical engineering Department, Hamedan University of Technology, , Hamedan, Iran
Abstract
The chemical exchange due to saturation transfer by applying an electromagnetic radio frequency (RF) pulse to a magnetic resonance scanner is called the CEST effect. The CEST effect depends mainly on relaxation times, chemical exchange rate, concentration of the contrast agent and RF pulse properties. Dependence of chemical exchange rate on some clinical indicators such as pH, temperature and glucose consumption, allows diagnosis diseases non-invasively. The chemical exchange rate is determined through presenting new objective function of the CEST effect in the mathematical closed form quantitatively. A new description of the optimal amplitude of the rectangular RF pulse is obtained by applying gradient-based methods on the proposed convex objective function. Chemical exchange rate is proposed at the simple representation form independent to contrast agent by reversing the optimal amplitude description for large shift frequency contrast agents. Evaluation of the objective function and the proposed relations are performed by comparing them with valid methods derived solving Bloch-McConnell equations through parametric and real data. The mean relative square error of the objective function based on the parametric data is 7.25% and for the proposed the optimal amplitude and chemical exchange rate based on the real data are 6.3% and 4.2%, respectively.
Keywords
- "؛ Saturation transfer"؛ Optimization"؛ CEST Contrast agent"؛ CEST spectrum processing"؛
- "؛ Chemical exchange rate"؛ ."؛ Magnetization transfer"
Main Subjects
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