RAVE-T2/T1 - Feasibility of a new hybrid MR-sequence for free-breathing abdominal MRI in children and adolescents.

Background: The new radial volumetric encoding RAVE-T/T hybrid sequence is a modern three-dimensional sequence with multiparametric approach, which includes T- and T-weighted contrasts obtained in identical slice position during one measurement. However, the RAVE-T/T hybrid sequence is not yet being used in clinical routine.

Purpose: The aim of this study was to evaluate the RAVE-T/T hybrid sequence in a pediatric population with a clinical indication for an abdominal MRI examination to demonstrate that the hybrid imaging may be less challenging to perform on children.

Materials And Methods: Our retrospective observational study included pediatric patients of all age groups and required for an abdominal MRI examination. Non-contrast standard axial T DIXON and non-contrast RAVE-T/T hybrid sequence were obtained at 3 T. MRI studies were analyzed independently by two pediatric radiologists using a 5-point Likert-type scale in five different categories. T- and T-weighted sequences were each compared with the RAVE-T/T-sequence using a Wilcoxon signed-rank test.

Results: The analysis included 15 children (mean age, 11 years and 4 months, 7 girls and 8 boys). The Cohens Kappa of interrater agreement measured 0.62. The T weighted part of the RAVE-T/T sequence was significantly better than the standard T HASTE sequence in four of five image quality categories: overall image quality (2.2 ± 0.7 vs 1.8 ± 0,7, p = 0.03), respiratory motion artefacts (3.8 ± 0.4 vs 2.0 ± 0.7, p <= 0.01), portal vein clarity (3.3 ± 0.8 vs 2.2 ± 0.7, p <= 0.01), hepatic margin sharpness (2.4 ± 1,0 vs 1.8 ± 0.7, p <= 0.01). The T weighted part of the RAVE-T/T sequence was significantly better than the standard T DIXON weighted sequence in three of five image quality categories: respiratory motion artefacts (4.0 ± 0.2 vs 3.6 ± 0.8, p = 0.01), portal vein clarity (2.7 ± 0.9 vs 2.1 ± 0.7, p <= 0.01), hepatic margin sharpness (3.2 ± 0.7 vs 2.6 ± 0.9, p <= 0.01).

Conclusions: The RAVE-T/T hybrid sequence is feasible and equal compared to standard T- and T-weighted sequences in the assessment of abdominal organs in a pediatric population. Due to non-inferiority to the current standard sequences for abdominal imaging, the RAVE-T/T hybrid sequence is a good alternative for children who cannot be examined in breath-hold technique.