Proposal for local SAR safety margin in pediatric neuro-imaging using 7 T MRI and parallel transmission.

Ultra-high field MRI with parallel transmission (pTx) provides a powerful neuroimaging tool with potential application in paediatrics. The use of pTx, however, necessitates a dedicated local specific absorption rate (SAR) management strategy, able to predict and monitor the peak local SAR (pSAR). In this work, we address the pSARassessment for an in-house built 7 Tesla 16Tx32Rx pediatric head coil, using the concept of Virtual Observation Points (VOPs) for SAR estimation.

A Mathematical Analysis of Clustering-Free Local SAR Compression Algorithms for MRI Safety in Parallel Transmission.

Parallel transmission (pTX) is a versatile solution to enable UHF MRI of the human body, where radiofrequency (RF) field inhomogeneity appears very challenging. Today, state of the art monitoring of the local SAR in pTX consists in evaluating the RF power deposition on specific SAR matrices called Virtual Observation Points (VOPs). It essentially relies on accurate electromagnetic simulations able to return the local SAR distribution inside the body in response to any applied pTX RF waveform.