Sh-MOLLI Cardiac T1 Mapping Reduces Imaging Time
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Solution Overview
Problem
Conventional MOLLI techniques require long heart beat breath-holds, making it challenging for cardiac patients, especially those with slowed heart rates or breathlessness, due to prolonged recovery epochs, which increases measurement time and estimation errors.
Innovation Solution
The Sh-MOLLI method involves front-loaded sampling in consecutive inversion-recovery experiments with conditional data processing to include or reject additional samples based on empirical relationships and fit errors, allowing for rapid generation of high-resolution T1 maps in a single short breath-hold, using fewer heartbeats than MOLLI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional MOLLI technique is used with long recovery epochs, then T1 mapping accuracy is maintained, but imaging time and measurement duration are prolonged
Solution Approach 1:
The patent applies preliminary action by performing front-loaded sampling in the first inversion-recovery experiment, where a greater number of samples are acquired early in the sequence when T1 recovery information is most critical. This allows the algorithm to establish accurate T1 mapping parameters from the initial high-density sampling, enabling subsequent experiments to use fewer samples while maintaining overall measurement accuracy.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the number of samples acquired in each subsequent inversion-recovery experiment based on the estimated T1 value from previous experiments. When T1 is estimated to be short, fewer samples are needed in later experiments, allowing the sequence to be truncated early. This adaptive parameter adjustment optimizes the balance between measurement accuracy and imaging time.
2Measurement precision
If long breath-hold duration is required for MOLLI, then sufficient T1 recovery sampling is achieved, but patient comfort and breathability deteriorate
Solution Approach 1:
The patent applies partial action by acquiring the essential T1 mapping information through front-loaded sampling in the first experiment with a higher number of samples, then using conditional sampling in subsequent experiments based on whether additional T1 recovery data is still needed. This partial sampling strategy reduces the total breath-hold duration while maintaining sufficient sampling accuracy for clinical T1 mapping.
3Measurement precision
If more samples are collected in subsequent IR experiments, then T1 mapping precision is improved, but imaging time and heart beat requirements increase
Solution Approach 1:
The patent implements dynamics by making the sampling strategy adaptive rather than static. The number of samples acquired in each inversion-recovery experiment is dynamically determined based on the estimated T1 value from previous experiments and the fit error metrics. This dynamic adjustment allows the system to optimize imaging efficiency by reducing samples when T1 is short while maintaining precision when T1 is long, thereby improving overall productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Sh-MOLLI significantly reduces imaging time, maintains accuracy comparable to MOLLI, and is less susceptible to movement artifacts, providing robust, quantitative T1 maps with minimal underestimation of T1 values, suitable for clinical applications.
Implementation Method 1
tissue contrast is generated by a combination of intrinsic tissue properties such as spin-lattice (T1) and spin-spin (T2) relaxation times
Data Source
AI summary
A shortened version of the MOLLI sequence (Sh-MOLLI) is described which generates rapid and high-resolution myocardial spin-lattice (T1) maps. The Sh-MOLLI technique is based on a significant abbreviation of pre-existing TI sampling scheme combined with the use of processing logic to bypass the major side effects of the above sampling scheme abbreviation and distinguish between long and short T1 relaxation times in order to conditionally utilize available TI samples for non-linear T1 fitting.