From the RSNA refresher courses - Evaluation of the marrow space in the adult hip

The adult pelvis and hip contain extensive marrow space in which a variety of processes may occur. Evaluation of this space requires an understanding of normal maturation and recognition that the marrow of the pelvis (axial s keleton) and that of the proximal femurs (appendicular skeleton) contain va riable amounts of red and yellow marrow. At magnetic resonance (MR) imaging , this variability yields patterns in normal marrow ranging from very unifo rm and homogeneous signal intensity to patchy and heterogeneous signal inte nsity. The marrow space serves as a reflection of patient health and may he rald developing anemia with reconversion of inactive to active marrow. Path ologic processes to be considered include marrow edema related to trauma, t umors, or infection; marrow ischemia and infarction; marrow infiltration fr om primary or secondary neoplasms or from infection; or complete loss of no rmal myeloid tissue in the marrow space. Each process can be effectively st udied with MR imaging.