Dynamic diffusion-weighted hyperpolarized ¹³ C imaging based on a slice-selective double spin echo sequence for...

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Hyperpolarized Contrast Agents

Background:

• Dynamic measurement of apparent diffusion coefficient (ADC) is crucial for understanding biological processes.
• Hyperpolarized agents offer enhanced signal for metabolic imaging.
• Existing diffusion-weighted imaging techniques have limitations in dynamic measurements.

Purpose of the Study:

• To develop a novel pulse sequence for dynamic ADC measurement of hyperpolarized substrates.
• To assess substrate perfusion, metabolic conversion, and transport in real-time.

Main Methods:

• A slice-selective double spin echo sequence was designed for dynamic hyperpolarized 13C diffusion-weighted imaging.
• The sequence was optimized using theoretical analysis and simulations on a preclinical scanner.
• Validation was performed in phantom and in vivo studies, including a transgenic mouse model of prostate cancer.

Main Results:

• The optimized sequence demonstrated reduced saturation effects, enabling more dynamic imaging frames and a longer acquisition window.
• Preclinical studies showed an increase in measured ADC over time in prostate tumors, potentially indicating lactate efflux.
• The sequence successfully provided dynamic ADC maps of lactate.

Conclusions:

• The developed pulse sequence significantly improves dynamic diffusion-weighted imaging compared to traditional methods.
• It enables time-resolved ADC mapping of hyperpolarized lactate.
• This advancement aids in studying metabolic and transport dynamics in vivo.