Technical Note: Fully automatic segmental relaxometry (FASTR) for cardiac magnetic resonance T1 mapping.

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Radiology

Background:

• Cardiac relaxometry, especially T1 mapping, is crucial for diagnosing various heart conditions.
• Manual segmentation of left ventricular regions for T1 and extracellular volume calculation is time-consuming and labor-intensive.
• Automated solutions are needed for efficient analysis in high-volume clinical settings.

Purpose of the Study:

• To introduce a fully automated relaxometry framework (FASTR) for segmental analysis of cardiac T1 maps.
• To enable automated calculation of native and postcontrast myocardial T1 and partition coefficient (λ).

Main Methods:

• Developed FASTR for automatic myocardial segmentation using CINE images and T1 maps.
• Applied FASTR to T1 maps from 11 patients post-myocardial infarction using Modified Look-Locker Inversion (MOLLI) sequence.
• Compared FASTR-derived T1 and λ values with those from two expert observers.

Main Results:

• FASTR achieved robust myocardial segmentation on T1 maps, even with infarcted tissue.
• FASTR's Dice coefficients for segmentation accuracy were comparable to inter-observer variability.
• Strong correlations were found between FASTR and expert measurements for T1 and λ, similar to inter-expert correlations.

Conclusions:

• FASTR provides accurate myocardial segmentation for native and postcontrast MOLLI T1 analysis without manual input.
• The automated nature of FASTR is highly beneficial for high-volume clinical cardiac imaging protocols.