[Evaluation of the Accuracy of Relaxation Time Measurements Using 3D-QALAS at 3.0 T MRI and Comparison with 2D-MDME].

PURPOSE

Three-dimensional (3D) quantification using an interleaved Look-Locker acquisition sequence with a T preparation pulse (QALAS) is a quantitative sequence used to measure relaxation times. The accuracy of the relaxation time measurement of 3D-QALAS at 3.0 T and the bias of 3D-QALAS have not yet been assessed. The purpose of this study was to clarify the accuracy of the relaxation time measurements using 3D-QALAS at 3.0 T MRI.

METHODS

The accuracy of the T and T values for 3D-QALAS was evaluated using a phantom. Subsequently, the T and T values and proton density of the brain parenchyma in healthy subjects were measured using 3D-QALAS and compared with those of 2D multi-dynamic multi-echo (MDME).

RESULTS

In the phantom study, the average T value of 3D-QALAS was 8.3% prolonged than that for conventional inversion recovery spin-echo; the average T value for 3D-QALAS was 18.4% shorter than that for multi-echo spin-echo. The in vivo assessment showed that the mean T and T values and PD for 3D-QALAS were prolonged by 5.3%, shortened by 9.6%, and increased by 7.0%, respectively, compared with those for 2D-MDME.

CONCLUSION

Although 3D-QALAS at 3.0 T has high accuracy T value, which is less than 1000 ms, the T value could be overestimated for tissues with it longer than that T value. The T value for 3D-QALAS could be underestimated for tissues with T values, and this tendency increases with longer T values.