Simultaneous T₁ and T₂ mapping of the carotid plaque (SIMPLE) with T₂ and inversion recovery prepared 3D radial imaging

Purpose: To propose a technique that can produce different T₁ and T₂ contrasts in a single scan for simultaneous T₁ and T₂ mapping of the carotid plaque (SIMPLE). Methods: An interleaved 3D golden angle radial trajectory was used in conjunction with T₂ preparation with variable duration (TE_prep) and inversion recovery pulses. Sliding window reconstruction was adopted to reconstruct images at different inversion delay time and TE_prep for joint T₁ and T₂ fitting. In the fitting procedure, a rapid B₁ correction method was presented. The accuracy of SIMPLE was investigated in phantom experiments. In vivo scans were performed on 5 healthy volunteers with 2 scans each, and on 5 patients with carotid atherosclerosis. Results: The phantom T₁ and T₂ estimations of SIMPLE agreed well with the standard methods with the percentage difference smaller than 7.1%. In vivo T₁ and T₂ for normal carotid vessel wall were 1213 ± 48.3 ms and 51.1 ± 1.7 ms, with good interscan repeatability. Alternations of T₁ and T₂ in plaque regions were in agreement with the conventional multicontrast imaging findings. Conclusion: The proposed SIMPLE allows simultaneous T₁ and T₂ mapping of the carotid artery in less than 10 minutes, serving as a quantitative tool with good accuracy and reproducibility for plaque characterization.