MRI RF Pulse Correction via Real-Time Feedback
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Solution Overview
Problem
MRI apparatuses face challenges in accurately applying radio frequency pulses due to fluctuations in output caused by heating, load changes, and aging degradation of elements, leading to deviations in SAR values and image contrast, necessitating real-time correction to ensure safety and image quality.
Innovation Solution
An MRI apparatus with a generating unit for radio frequency pulses, a sequence control unit for applying corrective pulses, and a calculation unit to measure and correct the pulses in real-time, ensuring accurate output based on input/output characteristics measured during each TR, thereby maintaining set imaging conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If radio frequency pulses are applied multiple times in one examination, then imaging can be performed repeatedly to acquire images, but the output fluctuates in real time due to heating, load changes, and aging degradation, causing deviation from expected output
Solution Approach 1:
The patent implements a feedback mechanism where the actual output of radio frequency pulses is measured during each TR interval using a pickup coil and wave detector. The measured output is compared with the expected output, and a correction value is calculated and applied to adjust the generating unit's output for subsequent TR intervals, ensuring consistent pulse application despite heating and load changes
Solution Approach 2:
The system performs self-correction by automatically measuring its own output, calculating correction values, and adjusting its generating unit without external intervention. The correction information is stored and reused to maintain accurate pulse output across multiple imaging sequences
2Measurement precision
If the output of radio frequency pulses deviates from expected values, then SAR values become inaccurate, but correcting the output requires changing imaging conditions which consumes time and effort
Solution Approach 1:
The patent implements continuous correction of radio frequency pulse output during the entire examination by measuring and correcting the generating unit's output at each TR interval. This continuous monitoring and adjustment ensures SAR values remain accurate throughout the examination without requiring interruptions to recalculate imaging conditions
Solution Approach 2:
The patent replaces manual adjustment of imaging conditions with an automated electronic correction system that uses pickup coils, wave detectors, and digital signal processing to automatically measure, calculate, and apply correction values to the radio frequency pulse output
3Object-affected harmful factors
If radio frequency pulses are applied at lower than set output, then SAR values are reduced, but desired image contrast cannot be obtained
Solution Approach 1:
The patent dynamically adjusts the radio frequency pulse output parameters by calculating correction values based on measured deviations from expected output. The correction information modifies the generating unit's parameters in real-time to maintain the intended flip angles and pulse characteristics, ensuring both safety and image quality
Data Source
AI summary
An MRI apparatus includes, a generating unit configured to generate radio frequency pulses applied in a pulse sequence; a sequence control unit configured to apply a radio frequency pulse related to acquisition of an image signal and a corrective radio frequency pulse during execution of one TR of a pulse sequence; and a calculation unit configured to measure the corrective radio frequency pulse and calculate a correction value for the radio frequency pulse. Based on the correction value, the generating unit corrects a radio frequency pulse related to acquisition of an image signal to be applied during a following TR later than a TR during which the corrective radio frequency pulse is measured.