Navigator-gated free-breathing joint T 1 -T 2 mapping of the kidney

Authors:
Preprint
Publisher website
Google Scholar
Abstract
Purpose: To develop and evaluate a free-breathing 2D radial joint T₁-T₂ mapping technique for the kidneys at 3T, and to assess the impact of navigator gating parameters on mapping precision and accuracy. Methods: The PARMANav sequence (PArametric Radial MApping with Navigator gating) was implemented for renal imaging, using 25 single-shot radial gradient echo acquisitions with five repeated magnetization preparations and lung-liver navigator gating to avoid through-plane motion. Virtual compressed coil and compressed sensing with spatial and contrast regularization was used for image reconstruction, followed by a model-based registration. An acquisition-specific joint T₁-T₂ dictionary was generated using extended phase graph simulations. T 1 and T 2 accuracies were quantified in a phantom study versus gold standard spin-echo-based sequences. The influence of the navigator acceptance window width (NAWW) and navigator rejection on T 1 and T 2 precision were established in 10 healthy volunteers and were compared to routine T 1 and T 2 mapping. Three patients were scanned to demonstrate clinical feasibility. Results: In the phantom, PARMANav T 1 and T 2 values showed high accuracy with the gold standard T 1 and T 2 values and were insensitive to rejected navigators (< 5% variation for T 1 and T 2 ). As expected from previous studies, in-vivo renal PARMANav T 1 and T 2 values were higher than routine values but showed lower variability, both per subject and between subjects: in the cortex PARMANav T 1 =1601±48ms/T 2 =90.8±5.0ms vs routine T 1 =1307±108ms/T 2 =73.3±8.0ms, while in the medulla PARMANav T 1 =2044±82ms/T 2 =90.3±5.4ms and routine T 1 =1560±122ms/T 2 =67.6±5.8ms. No T 1 or T 2 trend was observed for the different NAWW. Feasibility was demonstrated in patients, where high-quality maps were obtained. Conclusion: PARMANav allows for precise and accurate joint T 1 -T 2 mapping of the kidneys without requiring breath holding. Through-plane motion artifacts were avoided with a navigator, which did not impact the accuracy or precision of the resulting maps.

This publication has 27 references indexed in Scilit: