MAGNETIC-RESONANCE-IMAGING FOR EVALUATION OF CHILDHOOD APLASTIC-ANEMIA

Purpose: We prospectively evaluated the ability of magnetic resonance imaging (MRI) of the thoraco-lumbar vertebrae to determine the relativ e amount of red and fatty marrow in children with aplastic anemia. Pat ients and Methods: Twenty pediatric patients (ages 1-19 years) with ap lastic anemia underwent. T1-weighted (T1W, n = 31) and short T1 invers ion recovery (STIR, n = 30) MRI of the midline sagittal thoraco-lumbar spine. Bone marrow (BM) biopsies from the posterior iliac crest (n = 29) were also performed. All studies were evaluated by blinded observe rs; MR grading was based on visual inspection of signal intensity. Bio psy-estimated cellularity was compared with T1W and STIR grading when these were performed within 14 days of each other (n = 16). All studie s were compared to a simultaneous absolute neutrophil count (ANC), abs olute reticulocyte count (ARC), and platelet count. Results: BM cellul arity estimated by BM biopsy was significantly associated with STIR gr ading (p = 0.032, Jonckheere-Terpstra test), as were peripheral ANC (p = 0.044), ARC (p = 0.007), and platelet count (p = 0.003). T1W grade was significantly associated with ANC (P = 0.011) but not ARC (p = 0.0 53) or platelet count (p = 0.377). Biopsy-estimated cellularity was as sociated with ANC (p = 0.032) and ARC (p = 0.036), but not platelet co unt (p = 0.282). Conclusion: In childhood aplastic anemia patients, ST IR (and, to a lesser extent, T1W) MRI of the thoraco-lumbar spine refl ects BM activity, as measured by peripheral blood ANC, ARC, and platel et count, and BM cellularity, as measured by BM biopsy. MRI may thus p rovide a noninvasive measure of hematopoietic status.