MRI SAR Monitoring With Prefix-Free Memory Encoding

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Solution Overview

Problem

Magnetic resonance imaging systems with multiple transmit channels face memory constraints in calculating moving averages for specific absorption rate (SAR) due to the need for larger memory spaces, which are not available in small embedded systems.

Innovation Solution

A memory-efficient method using prefix-free codes to store monitoring measured values, allowing for efficient SAR monitoring by quantizing and digitizing data, reducing memory requirements through variable-length codewords and prefix-free encoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If moving average calculation is performed for multiple SAR variables in multi-channel MRI systems, then monitoring accuracy is improved, but memory space requirement increases significantly

Engineering Contradiction:

ImproveSAR monitoring accuracyVSAvoidmemory space

Core Design Contradiction:

Measurement precisionVSVolume of stationary object

Solution Approach 1:

The patent extracts only the essential information needed for SAR monitoring by quantizing measured values to discrete levels and storing only the necessary historical data points. This selective extraction reduces memory requirements while maintaining monitoring accuracy for detecting SAR limit violations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter representation from continuous floating-point values to discrete quantized levels. By transforming SAR measured values into discrete quantization levels and using variable-length encoding, the system reduces memory space requirements while preserving the ability to accurately monitor SAR compliance.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If fixed-length encoding is used for storing monitoring values, then data processing is simplified, but memory usage increases

Engineering Contradiction:

Improvedata processing complexityVSAvoidmemory space

Core Design Contradiction:

Device complexityVSVolume of stationary object

Solution Approach 1:

The patent introduces dynamic variable-length encoding where the number of bits required to store each quantization level varies. This dynamic encoding approach allows the system to use fewer bits for frequently occurring quantization levels and more bits only when necessary, reducing overall memory usage while maintaining manageable processing complexity through standardized encoding rules.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20250389797A1Memory-efficient monitoring of a magnetic resonance scan using a prefix-free code

Publication Date: 2025.12.25 SIEMENS HEALTHINEERS AG

AI summary

A method for monitoring a magnetic resonance scan, a magnetic resonance apparatus, and a computer program product are provided. Herein, monitoring measured values are captured during the magnetic resonance scan. Monitoring memory values are generated by quantizing the monitoring measured values. The monitoring memory values are stored as prefix-free code in a memory unit. The stored monitoring measured values are used to monitor the magnetic resonance scan for compliance with a monitoring limit value.