Lameness (equine)
Magnetic Resonance Imaging (MRI) produces a 3-dimensional image that allows for exceptional evaluation of soft tissue structures, as well as the detection of boney change and the presence of excessive fluid accumulation associated with inflammation. Like CT, an MRI image may be viewed in various planes of orientation, improving visualization of anatomic structures and any associated pathologic change. MRI is considered the gold standard for diagnosing soft tissue injury within the foot. While it can provide a definitive diagnosis in cases where other imaging modalities have failed, it does have several limitations. Available magnet size restricts imaging to the level of the stifle or elbow, or below. MRI takes a significant amount of time acquire an image, which translates to long anesthesia times and therefore reduces the size of the area that may be imaged in a single session. The area thought to be associated with lameness must be placed in the MRI. MRI is therefore inappropriate for any lameness that can not be localized to a specific region of the limb. Additionally, MRI has limited availability and high cost compared to the other imaging modalities.
Marrow adipose tissue
To improve quantification of MAT, novel imaging techniques have been developed as a means to visualize and quantify MAT. Although proton magnetic resonance spectroscopy (1H-MRS) has been used with success to quantify vertebral MAT in humans, it is difficult to employ in laboratory animals. Magnetic resonance imaging (MRI) provides MAT assessment in the vertebral skeleton in conjunction with μCT-based marrow density measurements. A volumetric method to identify, quantify, and localize MAT in rodent bone has been recently developed, requiring osmium staining of bones and μCT imaging, followed by advanced image analysis of osmium-bound lipid volume (in mm) relative to bone volume. This technique provides reproducible quantification and visualization of MAT, enabling the ability to consistently quantify changes in MAT with diet, exercise, and agents that constrain precursor lineage allocation. Although the osmium method is quantitatively precise, osmium is toxic and cannot be compared across batched experiments. Recently, researchers developed and validated a 9.4T MRI scanner technique that allows localization and volumetric (3D) quantification that can be compared across experiments. 
Hematopoietic cells (also known as blood cells) reside in the bone marrow along with marrow adipocytes. These hematopoietic cells are derived from hematopoietic stem cells (HSC) which give rise to diverse cells: cells of the blood, immune system, as well as cells that break down bone (osteoclasts). HSC renewal occurs in the marrow stem cell niche, a microenvironment that contains cells and secreted factors that promote appropriate renewal and differentiation of HSC. The study of the stem cell niche is relevant to the field of oncology in order to improve therapy for multiple hematologic cancers. As such cancers are often treated with bone marrow transplantation, there is interest in improving the renewal of HSC. Recent work demonstrates that marrow adipocytes secrete factors that promote HSC renewal in most bones.