No correlation between tumor R2* and ΔR2*oxygen-air, or between either R2* or ΔR2*oxygen-air and tumor volume, was determined across the cohorts, indicating that the differences in intrinsic susceptibility MRI between tumors in the Th-ALKF1174L/Th-MYCN and Th-MYCN mice were independent of tumor size. The gene discussed is MYCN; the disease is neoplasm.