Synthetic and conventional magnetic resonance imaging for knee assessment in children with leukemia: a comparative...

Magnetic resonance imaging (MRI) is an ideal method for the detection of osteonecrosis in children with acute lymphoblastic leukemia (ALL), but some children struggle to adhere to the procedure due to its lengthy examination time. This study evaluated the feasibility of synthetic MRI for knee examinations in children with ALL.

This prospective study included 33 children with ALL who underwent conventional and synthetic MRI. Participants were categorized into Group A (>8 years, n=23) and Group B (≤8 years, n=10). Scan time, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), motion artifacts, image quality score, lesion detection, and T2 values were compared using paired t-tests, Wilcoxon signed-rank tests, Cohen's kappa, and Bland-Altman analysis, with Bonferroni correction (α=0.003).

Synthetic MRI significantly reduced scan time (Group A: 286±74 vs. 504±64 s, P<0.001; Group B: 254±8 vs. 461±17 s, P=0.002). No significant SNR or CNR differences were found between synthetic and conventional T1-weighted imaging (T1WI) (P>0.003). Synthetic proton density-weighted imaging (PDWI) showed lower SNR (P<0.003) but similar CNR (P>0.003). In T1WI, motion artifacts were comparable between synthetic and conventional MRI in Group A (P=0.166) but were more pronounced with synthetic MRI in Group B (P=0.038). In PDWI, synthetic images exhibited significantly greater motion artifacts in both Group A and Group B (P=0.011 and P=0.023, respectively). Image noise was higher in synthetic T1WI and PDWI (P<0.050). Lesion detection showed excellent agreement (κ=0.86-0.96), though two Group B cases were nondiagnostic. T2 values showed no significant inter-method differences in either group (P>0.003).

For pediatric leukemia patients capable of maintaining stillness, synthetic MRI shortens acquisition time while preserving diagnostic accuracy and quantitative precision. However, due to motion susceptibility, its clinical use should be limited to cooperative children.