SAR measurement in MRI: an improved method

Rocco Romano; Fausto Acernese; Pietro Luigi Indovina; Fabrizio Barone

doi:10.1117/12.814127

9 April 2009 SAR measurement in MRI: an improved method

Rocco Romano, Fausto Acernese, Pietro Luigi Indovina, Fabrizio Barone

Proceedings Volume 7295, Health Monitoring of Structural and Biological Systems 2009; 72952P (2009) https://doi.org/10.1117/12.814127
Event: SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, 2009, San Diego, California, United States

Abstract

During an MR procedure, the patient absorbs a portion of the transmitted RF energy, which may result in tissue heating and other adverse effects, such as alterations in visual, auditory and neural functions. The Specific Absorption Rate (SAR), in W/kg, is the RF power absorbed per unit mass of tissue and is one of the most important parameters related with thermal effects and acts as a guideline for MRI safety. Strict limits to the SAR levels are imposed by patient safety international regulations (CEI - EN 60601 - 2 - 33) and SAR measurements are required in order to verify its respect. The recommended methods for mean SAR measurement are quite problematic and often require a maintenance man intervention and long stop machine. For example, in the CEI recommended pulse energy method, the presence of a maintenance man is required in order to correctly connect the required instrumentation; furthermore, the procedure is complex and requires remarkable processing and calculus. Simpler are the calorimetric methods, also if in this case long acquisition times are required in order to have significant temperature variations and accurate heat capacity knowledge (CEI - EN 60601 - 2- 33). The phase transition method is a new method to measure SAR in MRI which has the advantages to be very simple and to overcome all the typical calorimetric method problems. It does not require in gantry temperature measurements, any specific heat or heat capacity knowledge, but only mass and time measurement. Furthermore, in this method, it is possible to show that all deposited SAR power can be considered acquired and measured.

Citation Download Citation

Rocco Romano, Fausto Acernese, Pietro Luigi Indovina, and Fabrizio Barone "SAR measurement in MRI: an improved method", Proc. SPIE 7295, Health Monitoring of Structural and Biological Systems 2009, 72952P (9 April 2009); https://doi.org/10.1117/12.814127

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KEYWORDS

Synthetic aperture radar

Tissues

Scanners

Magnetic resonance imaging

Temperature metrology

Time metrology

Cesium

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