Aims and objectives
Radiofrequency energy deposition in MRI is limited to prevent excessive heating of the patient’ organs.
In this poster correlations of the specific absorption rate (SAR) - meaning radiofrequency absorption - on a large dataset of exams (for specific exam protocols) performed with 3 MRI 1.5 Tunits from different manufacturers are investigated.
Methods and materials
Reggio Emilia Diagnostic Imaging Department (REDID) adopts a RIS-PACS integrated dose monitoring system software called “Gray detector”.
It allows to query a huge amount of data from headers of images stored in PACS,
including MR ones (Figure 1).
For radiological exposures (e.g.
CT) reference diagnostic levels (RDL) are defined to optimize patients’ exposures.
In last years documented MRI patient adverse events aremainly related to thermal injuries due to improper patient management (eg.
patient weight uncorrectly inserted in MRI unit) or equipment use.
The SAR describes...
The EN/IEC 1st level limit was never exceeded.
The dynamic T1-weighted (T1) and the T2-weighted fat saturated (T2) sequence were considered for breast exams.
The SAR median values for T1 were 0.49,
0.31 W/kg for GE,
Philips and Siemens respectively and 1.19,
1.77 for T2 (Figure 2).
For brain exams the whole acquisition protocols were considered.
The SAR (W/Kg) median and 75th percentile values were 0.709-1.385 for GE,
1.105-1.732 for Philips,
0.276-0.490 for Siemens (Figure 3).
The analysis and monitoring of SAR values collected from image header stored in PACS is possible and may become a quality index to monitor MR procedures like RDL in radiology.
Further analysis are necessary better iffrom multicentric studies.
A review of thermal MR injuries.
Hardy PT 2nd1,
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ACR guidance document on MR safe practices: 2013.
Expert Panel on MR Safety1,
Bradley WG Jr,
Lester JW Jr,
IEC 60601-2-33:2010 Medical electrical equipment - Part 2-33: Particular requirements for...