Rapid high‐resolution T₁ mapping using a highly accelerated radial steady‐state free‐precession technique

Background T 1 mapping is often used in some clinical protocols. Existing techniques are limited in slice coverage, and/or spatial‐temporal resolution, or require long acquisitions. Here we present a multi‐slice inversion‐recovery (IR) radial steady‐state free precession (radSSFP) pulse sequence combined with a principal component (PC) based reconstruction that overcomes these limitations. Purpose To develop a fast technique for multi‐slice high‐resolution T 1 mapping. Study Type Technical efficacy study done prospectively. Phantom/Subjects IR‐radSSFP was tested in phantoms, five healthy volunteers, and four patients with abdominal lesions. Field Strength/Sequence IR‐radSSFP was implemented at 3T. Assessment Computer simulations were performed to optimize the flip angle for T 1 estimation; testing was done in phantoms using as reference an IR spin‐echo pulse sequence. T 1 mapping with IR‐radSSFP was also assessed in vivo (brain and abdomen) and T 1 values were compared with literature. T 1 maps were also compared with a radial IR‐FLASH technique. Statistical Tests A two‐tailed t‐test was used to compare T 1 values in phantoms. A repeatability study was carried out in vivo using Bland‐Altman analysis. Results Simulations and phantom experiments showed that a flip angle of 20˚ was optimal for T 1 mapping. When comparing single to multi‐slice experiments in phantoms there were no significant differences between the means T 1 values ( P = 0.0475). In vivo results show that T 1 maps with spatial resolution as high as 0.69 mm × 0.69 mm × 2.00 mm (brain) and 0.83 mm × 0.83 mm × 3.00 mm (abdomen) can be generated for 84 brain slices in 3 min and 10 abdominal slices in a breath‐hold; T 1 values were comparable to those reported in literature. The coefficients of variation from the repeatability study were 1.7% for brain and 2.5–2.7% in the abdomen. Data Conclusion A multi‐slice IR‐radSSFP technique combined with a PC‐based reconstruction was demonstrated for higher resolution T 1 mapping. This technique is fast, motion‐insensitive and yields repeatable T 1 values comparable to those in literature. Level of Evidence : 2 Technical Efficacy : Stage 1 J. Magn. Reson. Imaging 2019;49:239–252.