Accurate and precise in vivo liver 3D T1 mapping at 3T.

PURPOSE: To develop an accurate and precise liver 3D T 1 $$ {T}_1 $$ mapping method using only scanner-agnostic sequences. METHODS: While the spoiled gradient-recalled echo sequence is widely available on clinical scanners, variable flip angle T 1 $$ {T}_1 $$ mapping methods based on this sequence provide biased T 1 $$ {T}_1 $$ estimates, with the largest systematic error arising from B 1 + $$ {B}_1^{+} $$ inhomogeneities. To correct for this, the flip angle was mapped using a 2D gradient-echo double-angle method approach. To correct for the confounding effect of fat on liver T 1 $$ {T}_1 $$ and B 1 + $$ {B}_1^{+} $$ , Dixon and fat saturation techniques were used in combination with the variable flip angle and the B 1 + $$ {B}_1^{+} $$ map acquisitions, respectively. The T 1 $$ {T}_1 $$ and B 1 + $$ {B}_1^{+} $$ mapping methods were validated with a T 1 $$ {T}_1 $$ -phantom against gold standard methods. An intra- and inter-repeatability study was conducted at 3T in 10 healthy individuals' livers. RESULTS: The developed 3D T 1 $$ {T}_1 $$ mapping method achieved an excellent agreement with the gold standard, with a weighted root mean squared normalized error below 2.8%. In vivo, a median T 1 $$ {T}_1 $$ standard deviation of 31 ms and an interquartile range of [27, 39] ms was achieved across all measurements, including the intra- and inter-repeatability study data. A within-subject standard deviation for T 1 $$ {T}_1 $$ of 21 ± 5 ms had a corresponding repeatability coefficient of 60 ms. The measured T 1 $$ {T}_1 $$ values agree well with MOLLI and SASHA T 1 $$ {T}_1 $$ mapping methods, with average T 1 $$ {T}_1 $$ differences of 5%. CONCLUSION: Accurate and precise 3D T 1 $$ {T}_1 $$ liver measurements can lead the way to the wider adoption of a clinically feasible T 1 $$ {T}_1 $$ measurement as a marker of hepatic fibro-inflammation.