Exemplary patient from the OPAL trial. On coronal images of knees, short tau inversion recovery images (top row) show diffuse hyperintense inhomogeneous signals, and T1-weighted images (bottom row) show diffuse hypointense signals revealing extensive leukemic infiltration of bone at diagnosis. At the 6-month follow-up examination, the hyperintense signal in short tau inversion recovery decreased and the hypointense signal in T1 increased toward normal appearance. At 9 months into treatment, MRI shows asymptomatic lesions in the metaphyses, which shows spontaneous regression beginning at 12 months into treatment.