Abstract:
PURPOSE:To improve the specific absorption rate (SAR) compression model capability in parallel transmission (pTx) MRI systems. METHODS:A k-means clustering method is proposed to group voxels with similar SAR behaviors in the scanned object, providing a controlled upper-bounded estimation of peak local SARs. This k-means compression model and the conventional virtual observation point (VOP) model were tested in a pTx MRI framework. The pTx pulse design with different SAR controlling schemes was simulated using a numerical human head model and an eight-channel 7T coil array. Multiple criteria (including RF power, global and peak local SARs, and excitation accuracy) were compared for the performance testing. RESULTS:The k-means compression model generated a narrower overestimation bound, leading to a more accurate local SAR estimation. Among different pTx pulse design approaches, the k-means compression model showed the best trade-off between the SAR and excitation accuracy. CONCLUSIONS:The developed SAR compression model is advantageous for pTx framework given the narrower overestimation bound and control over the compression ratio. Results also illustrate that a moderate increase of maximum RF power can be useful for reducing the maximum local SAR deposition.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Mao X,Bari S,Love DJ,Rispoli JVdoi
10.1002/mrm.28456subject
Has Abstractpub_date
2021-02-01 00:00:00pages
1093-1103issue
2eissn
0740-3194issn
1522-2594journal_volume
85pub_type
杂志文章abstract::A proton NMR relaxation and pulsed field gradient self-diffusion study of water in fibrin gels, plasma, and blood clots has been performed with special emphasis on the effect of the sol-gel and shrinkage transitions. Deuteron NMR in fibrin gels was also studied to supplement the proton data. It is shown that a measure...
journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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pub_type: 临床试验,杂志文章,随机对照试验
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