ObjectiveTo analyze the association between iterative decomposition of water and fat with echo asymmetry and least-squares estimation quantification sequence (IDEAL-IQ) magnetic resonance imaging (MRI) of bone marrow fat fraction and bone marrow reserve function during concurrent chemoradiotherapy for cervical cancer. MethodsThe study retrospectively analyzed twenty-six patients with stage IB1 to IVA cervical cancer treated between February 2020 and November 2020. All patients received concurrent chemoradiotherapy that included platinum alone or combined paclitaxel and platinum. Pelvic IDEAL-IQ MRI (plain and enhanced) was performed before and after treatment. Regions of interest, including the fifth lumbar vertebra, sacrum, ilium, ischium, and femoral neck, were manually delineated, and the bone marrow fat fraction was measured. Peripheral blood cell counts were recorded during treatment, and the relationship between the fat fraction values and changes in the blood cell counts was explored. ResultsIDEAL-IQ MRI bone marrow fat fraction was associated with platelet nadir and platelet decline during treatment. The average pelvic bone marrow fat fraction before chemoradiotherapy was moderately negatively correlated with platelet count nadir during concurrent chemoradiotherapy (r = −0.450, P = 0.021). The change in average pelvic bone marrow fat fraction through chemoradiotherapy was moderately positively correlated with the degree of thrombocytopenia (r = 0.399, P = 0.044). ConclusionBone marrow fat content quantified by IDEAL-IQ was associated with platelet count nadir and the degree of thrombocytopenia in patients with cervical cancer undergoing concurrent chemoradiotherapy.