Transit delay and flow quantification in muscle with continuous arterial spin labeling perfusion-MRI

Area of Science:

• Physiology
• Medical Imaging

Background:

• Muscle blood flow assessment is crucial for diagnosing various conditions.
• Continuous arterial spin labeling (CASL) magnetic resonance imaging (MRI) offers a non-invasive method for quantifying tissue perfusion.

Purpose of the Study:

• To investigate the dependency of CASL muscle flow measurements on transit delay.
• To evaluate the repeatability of CASL measurements in healthy subjects.

Main Methods:

• CASL MRI of calf, foot, and forearm in 23 healthy subjects.
• Varying postlabeling delays (PLD) of 1000, 1500, and 1900 msec were used.
• Ischemia induced by tourniquet followed by hyperemia, with imaging before, during, and after ischemia.

Main Results:

• CASL successfully resolved the hyperemic flow time course.
• Flow measurements increased with PLD, suggesting significant transit delay in muscle.
• Peak hyperemic flow measurements were comparable to contrast-enhanced MRI.
• Region-of-interest based measurements showed ~20% variability over one hour.

Conclusions:

• Muscle blood flow measurements using CASL are influenced by transit delay.
• CASL is a viable technique for assessing hyperemia in muscle, though repeatability requires consideration.