Magnetic resonance perfusion imaging without contrast media

Area of Science:

• Magnetic Resonance Imaging
• Medical Imaging Techniques
• Physiology

Background:

• Perfusion imaging traditionally requires contrast media administration.
• Non-invasive methods for assessing tissue perfusion are highly sought after in clinical diagnostics.
• Arterial spin labelling (ASL) presents a promising alternative for contrast-free perfusion assessment.

Purpose of the Study:

• To systematically analyze magnetic resonance imaging (MRI) techniques for contrast-free perfusion imaging.
• To detail arterial spin labelling (ASL) approaches for quantitative perfusion rate assessment.
• To evaluate the potential of ASL for perfusion imaging across diverse tissue types.

Main Methods:

• Systematic comparison of continuous and pulsed ASL techniques.
• Application of a standard kinetic model and analysis of tissue properties influencing perfusion measurements.
• Development and implementation of a flow-sensitive alternating inversion recovery (FAIR) ASL sequence with true fast imaging with steady precession (true FISP) on 0.2, 1.5, and 3 T scanners.

Main Results:

• ASL imaging enables non-invasive, in vivo assessment of tissue perfusion rates.
• High spatial resolution (millimeter range) and sufficient signal-to-noise ratio in perfusion maps were achieved for kidney, lung, brain, salivary, and thyroid glands.
• Examination times for perfusion maps ranged from 2-5 minutes.

Conclusions:

• Newly developed ASL techniques yield high image quality and quantitative perfusion maps, particularly in tissues with high perfusion rates like tumors.
• Averaging acquisitions and image subtraction are necessary for optimal results.
• Synchronization of data acquisition to respiration is crucial for abdominal and thoracic organ imaging.