[Nuclear medicine in the integrated diagnosis of fatigue fractures]

Nuclear medicine applications deal with the functional and dynamic study of organs and apparatuses in each diagnostic protocol. Bone scintigraphy (diagnostic accuracy: 80%) plays an important role in the differential diagnosis of the various musculoskeletal conditions in sports, mainly in the so-called "stress syndrome". The method is rather simple, including three steps: 1) study of radioactivity in the ROI; 2) capillary phase, with early imaging; 3) bone phase, with a static image 5 hours after injection. Slight differences in marker uptake, with fusiform and elongated marker accumulation areas, can be seen in the tibial stress syndrome, which exhibits no increase in the vascular phase, while in stress fractures, mainly in the late stages, increased activity can be seen in the arteriolar and capillary phases. Stress fractures are divided into 5 stages, from stage 1 = < 20% skeletal involvement to stage 5 = complete fracture, with > 80% bone involvement. The advantages of 3-phase bone scintigraphy can be summarized as follows: 1) it yields objective information, where clinics and radiology are often negative; 2) it allows the differential diagnosis between soft tissue lesions and bone fractures even in an early stage; 3) it allows prognosis to be made and the resumption of sport activity to be planned.