MSK Tumors and Marrow Evaluation Bone Marrow

(i) Introduction Bone marrow consists of trabecular bone and a variety of cells including hematopoetic, fat, stroma and reticuloendothelial system cells as well as sinsusoids. The weight of the bone marrow is approximately 5% of the whole body weight. Bone marrow composition changes with age, which is reflected in a change in signal characteristics in MR images. Red marrow, which is found in younger individuals is composed of approximately 40% fat and 40% water, while yellow bone marrow contains approximately 80% fat and 15% water. MRI is a very sensitive technique to assess physiological changes in bone marrow composition and to detect bone marrow abnormalities. Intimate knowledge of age-related morphology as well as reactive physiological changes is required to evaluate bone marrow pathology.