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.
Vertebral osteomyelitis
Radiological intervention is often necessary to confirm the presence of vertebral osteomyelitis in the body. Plain-film radiological orders are necessary for all patients displaying symptoms of the disease. This diagnostic approach is often preliminary to other radiological procedures, such as magnetic resonance imaging, or MRI, computed tomography (CT) scan, fine-needle aspiration biopsy, and nuclear scintigraphy. The initial plain-film X-ray images are scanned for any indication of disc compression between two vertebrae or the degeneration of one or more vertebrae. Only when these findings are ambiguous is further testing necessary to diagnose the disease. Other radiological approaches offer more comprehensive imaging of the spinal area, but can often prove inconclusive. MRI scans do not expose the patient to radiation and are highly sensitive to changes in the size and appearance of the intervertebral discs; however, findings on the MRI scan may be confused with other conditions such as the presence of tumors or bone fractures. If MRI imaging is inconclusive, the high sensitivity to erosions in the vertebrae or intervertebral discs of CT scans may be preferred for their ability to indicate signs of the disease more clearly than MRI. Additional tests may be ordered if such preliminary tests cannot confirm a diagnosis; for example, needle biopsies may be needed to take samples of bone surrounding the disc space where the infection is thought to live, or nuclear bone scans may be used to contrast areas of healthy bone with areas of infection.