On the fat saturation effect in quantitative ultrashort TE MR imaging

Area of Science:

• Magnetic Resonance Imaging
• Biomaterials Science
• Orthopedics

Background:

• Quantitative ultrashort echo time (UTE) imaging offers valuable insights into knee tissue composition.
• Fat saturation (FatSat) is a common technique to improve image quality by suppressing fat signal.
• The impact of FatSat on quantitative UTE biomarkers in knee joint tissues requires detailed investigation.

Purpose of the Study:

• To evaluate the effect of FatSat on quantitative measurements obtained using three different UTE sequences at 3T.
• To assess the differences, correlations, and agreements of UTE biomarkers with and without FatSat in knee cartilage, meniscus, and whole cadaveric specimens.

Main Methods:

• Three quantitative UTE sequences were employed: multi-echo for T1 measurement, adiabatic T1ρ prepared UTE for T1ρ measurement, and MT-prepared UTE for MTR and MMF.
• Cartilage, meniscus samples, and whole knee cadaveric specimens were imaged with and without FatSat.
• Quantitative difference ratio (QDR), correlation, and agreement analyses were performed to compare FatSat and non-FatSat scans.

Main Results:

• Fat suppression was effective across all three UTE sequences with FatSat.
• QDR values ranged from 0.2% to 12.6%, indicating generally small differences between FatSat and non-FatSat scans.
• Most quantitative biomarkers (T1ρ, MTR, MMF) showed statistically significant differences (p < 0.05) with FatSat, except for T1ρ in muscle and MMF in meniscus.
• T1 measurements showed no significant differences (p > 0.05) between FatSat and non-FatSat scans.
• Strong correlations were observed for all biomarkers between scans with and without FatSat.

Conclusions:

• Quantitative UTE biomarkers demonstrate good correlation and agreement between scans with and without FatSat.
• While slight differences exist, FatSat can be reliably used in quantitative UTE imaging of knee tissues.
• These findings support the utility of FatSat in enhancing UTE imaging protocols for knee joint assessment.