1. To become familiar with pathophysiology of infectious diseases pertinent to imaging features.
2. To understand imaging features of infectious diseases and their differential diagnosis.
3. To appreciate the clinical perspective of imaging infectious diseases.
In this lecture, we’ll focus on imaging osteomyelitis of the appendicular and axial skeleton, and their differential diagnosis using radiographs, US, and especially MRI and PET-CT. Understanding the interaction between invading organisms and intact or compromised host response is essential in the interpretation of imaging features. Major routes of infection include hematogeneous or contiguous routes occurring in respectively pediatric-geriatric, or immunocompromised and diabetic, or post-procedure infections. Location in the metaphysis and vertebral body are hallmarks of hematogenous spread. Location in bones close to skin defects, pressure points, and soft tissue infection are hallmarks of contiguous spread, especially in diabetic foot, intensive care patients, and following surgical or image guided procedures. Knowledge of age and the comorbidity-related relationship between vasculature on one-hand and growth plates and discs, on the other hand, is essential in the diagnosis of infection. Also, imaging features of host response depend on the pressure within anatomical compartments. The most relevant differential diagnostic issues including posttraumatic sequelae, degenerative disease, Charcot foot and spine, sterile inflammatory disease (CRMO, SAPHO), tumours, and also the differentiation between mild and life-threatening infection like necrotising fasciitis will be discussed. The impact of imaging on clinical outcome as it depends on treatment options, cost-effectiveness, predictive values of various imaging studies relative to clinical and laboratory tests, is addressed.