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Advanced Imaging of the Diabetic Foot and Its
Complications
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The imaging characteristics of osteomyelitis are not specific, and a differential diagnosis should always be considered. The superior soft tissue visualization of MR imaging compared to CT and nuclear medicine allows for increased specificity and more accurate diagnosis. Differential diagnosis
Reactive bone marrow edema refers to signal changes secondary to adjacent soft tissue inflammation without osteomyelitis. The signal patterns overlap those of osteomyelitis. Differentiating reactive bone marrow edema from osteomyelitis may be difficult. In general, the greater the signal intensity on T2 and STIR sequences, the more likely osteomyelitis is present [Craig et al]. Additionally, finding other signs of osteomyelitis such as cortical destruction, abscess and sinus tract formation, and deep ulceration lead to a more confident diagnosis of osteomyelitis. Traumatic or stress fractures may occur in diabetic feet secondary weakened bone and altered biomechanics. Fracture lines are readily visualized by MR imaging. Inflammatory arthridites in the active phase may present with soft tissue swelling, dactylitis, and reactive bone marrow edema. Knowledge of these preexisting conditions will help to minimize error. Lack of adjacent soft tissue ulcer formation makes osteomyelitis unlikely. Healed osteomyelitis. Little has been written about the imaging features of treated and healed osteomyelitis. Erdman et al had difficulty distinguishing healed osteomyelitis from active disease. Unger et al have reported normalization of signal on T2 weighted sequences with increased signal on T1 weighted sequences presumably related to fatty replacement of marrow. |
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