Читать книгу Fractures in the Horse - Группа авторов - Страница 86

Fracture is defined by Dorland's Medical Dictionary as ‘a break or discontinuity in bone’. In almost all cases, diagnostic imaging, in its various forms, is necessary to identify, classify and monitor fractures. The goals, independent of modality, are to accurately depict, characterize and quantify bone defects. Ideally, the imaging test would also identify all other injuries including associated soft tissue and vascular damage. Accurate and comprehensive evaluation is important to direct a rational course of action, predict clinical dangers, avoid potential complications and to provide an accurate prognosis.

In its simplest form, the diagnosis of a fracture is binary so with perfect sensitivity and specificity of the diagnostic imaging test, a fracture either is or is not present. The reality of clinical medicine is that numerous and complicated factors are involved in the identification and interpretation of imaging or roentgen findings that lead to a true and fully characterized diagnosis. These include, but may not be limited to, factors associated with the biological system (pathophysiology of fracture genesis, patient health etc.), the utilized imaging modality (‐ies) and the observer. Most diagnostic imaging tests are a representation of the anatomy with some modalities providing a representation of the physiology. All tests require that the observer accurately identifies the pertinent imaging signs and interprets them correctly.

The means by which discontinuity in bone is identified depends on the imaging modality used. Radiography, ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) are morphological or anatomical studies, and nuclear scintigraphy is a functional study. All are commonly used in equine practice and employ different physics to create images. While overlap of principles exists, each has unique characteristics that must be understood to use the technique accurately and to its fullest capacity. Understanding the information provided by individual modalities together with anamnesis and results of the clinical examination are critical in order to choose, utilize and accurately interpret the best diagnostic test(s) for each patient. Similarly, knowledge and understanding of the expected biological behaviour of bone are necessary in order to use diagnostic imaging to monitor fracture healing.