A 58-year-old man with long-standing type 2 diabetes mellitus and peripheral neuropathy is evaluated in the clinic for a deep ulcer on the plantar aspect of his left foot. On examination, there is surrounding erythema and induration. A sterile metal probe reaches the deep fascia but does not definitively contact bone. Given the high clinical suspicion for underlying osteomyelitis, the physician decides to initiate a stepwise diagnostic imaging workup.
Arrange the following imaging modalities in the standard recommended sequence for evaluating suspected diabetic foot osteomyelitis, starting from the most appropriate initial test to the alternative advanced study reserved for patients with specific contraindications.
- 1Plain radiography of the left foot
- 2Magnetic resonance imaging (MRI) of the left foot
- 3Radiolabeled leukocyte (white blood cell) scan
Answer
The correct sequence is: 1) Plain radiography, 2) Magnetic resonance imaging (MRI), and 3) Radiolabeled leukocyte scan.
The standard diagnostic algorithm for suspected osteomyelitis begins with plain radiography to identify gross abnormalities or alternative diagnoses. When radiographs are nondiagnostic, MRI is the gold standard advanced imaging modality due to its high sensitivity for marrow edema. If MRI cannot be performed (e.g., due to an incompatible pacemaker), a radiolabeled leukocyte scan is the appropriate alternative advanced test.
Step-by-Step Solution
Key Concept
The standard imaging sequence for suspected diabetic foot osteomyelitis begins with plain radiography, followed by MRI for definitive diagnosis, with radiolabeled leukocyte scans reserved for cases where MRI is contraindicated.