Objectives: Diabetic foot osteomyelitis (DFO) is a leading cause of non-traumatic lower limb amputations. While magnetic resonance imaging (MRI) and plain radiographs are common, their specificity is often limited by neuroarthropathic changes (Charcot foot). This prospective study evaluated the diagnostic utility of Tc-99m HMPAO labelled leucocyte scintigraphy combined with single photon emission computed tomography - computed tomography (SPECT-CT) in identifying DFO, using bone biopsy as the reference standard. Material and Methods: The study was conducted between 2015 and 2017 at a tertiary care hospital in South India. Thirty diabetic patients with 35 suspected infected foot ulcers were enrolled. Patients underwent plain radiography followed by labelled leucocyte scintigraphy. Images were acquired at 30 minutes (quality check), 4 hours (planar and SPECT-CT), and 24 hours. Bone biopsies were performed on 17 ulcers for histopathological and microbiological confirmation. Results: The median labelling efficiency of the leucocytes was 42.3%. SPECT-CT demonstrated superior contrast and localisation compared to planar imaging, identifying focal uptake in four ulcers that appeared negative on 4-hour planar scans. Of the 17 biopsied ulcers, 5 were confirmed as osteomyelitis via histopathology. The combined WBC scintigraphy and SPECT-CT yielded a sensitivity of 60% and a specificity of 100%. Conclusion: Labelled leucocyte scintigraphy with SPECT-CT is a highly specific, non-invasive imaging modality for DFO. Its ability to accurately differentiate soft tissue infection from bone involvement makes it a powerful tool for ruling out osteomyelitis and guiding surgical biopsies, particularly when conventional radiological findings are ambiguous.
Angamuthu et al. (Fri,) studied this question.