Preliminary Study of Confounder-Corrected Fat Fraction and R2* Mapping of Bone Marrow in Children With Acute Leukemia

The bone marrow (BM) evaluation of acute leukemia (AL) mainly depends on invasive BM puncture biopsy. Noninvasive and accurate MR examination technology has potential clinical application value in the BM evaluation of AL patients. Multi-gradient-echo (MGRE) has been found useful to evaluate changes in BM fat and iron content, but has not yet been applied in AL.

To explore the diagnostic capability of BM infiltration of quantitative BM fat fraction (FF) and R2* values obtained from a 3D MGRE sequence in children with primary AL.

Prospective.

Sixty-two pediatric patients with untreated AL and 68 healthy volunteers. AL patients were divided into acute lymphoblastic leukemia (ALL) (n = 39) and acute myeloid leukemia (AML) (n = 23) groups.

3T, 3D chemical-shift-encoded multi-gradient-echo, T1WI, T2WI, T2_STIR.

BM FF and R2* values were assessed by manually drawing regions of interest at the L3, L4, ilium, and 1 cm below the bilateral trochanter of the femur (upper femur).

Independent sample t-tests, variance analysis, Spearman correlation.

BM FF and R2* at L3, L4, ilium, and upper femur, FF_total and R2*_total were significantly lower in the AL than control group. BM FF did not significantly differ between ALL and AML groups (P_L3  = 0.060, P_L4  = 0.086, P_ilium  = 0.179, P_{upper femur}  = 0.149, and P_totle  = 0.097, respectively). The R2* was significantly lower in ALL group than AML group for L3, L4, and R2*_total . BM FF was moderately positively correlated with R2* in ALL group, and strongly positively correlated in AML group. Area under the receiver operating characteristic curves showed that BM FF had higher AUC in AL, ALL, and AML (all AUC = 1.000) than R2* (0.976, 0.996, and 0.941, respectively).

MGRE-MRI mapping can be applied to measure BM FF and R2* values, and help evaluate BM infiltration and iron storage in children with AL.

1 Technical Efficacy: 2.