SPECT/CT signals diabetic bone disease

Hybrid molecular imaging can lead to diagnosis of osteomyelitis in diabetic patients via bedside bone puncture without the need for surgical or image-guided biopsy, according to a study published online in Diabetes Care in March.

The number of people worldwide diagnosed with diabetes is expected to spike to more than 300 million by the year 2025. Of these, about 25 percent will develop a foot ulcer due to complications of the disease, according to Elisabeth Aslangul, MD, PhD, from the Université Paris Descartes, in Paris, and colleagues.

This study evaluated hybrid molecular imaging’s ability to signal diabetic osteomyelitis in patients with foot ulcers but no signs of soft tissue infection. Researchers employed SPECT/CT and the biomarker gallium-67 (67-Ga).

“Coupling of 67Ga SPECT/CT imaging and bedside percutaneous bone puncture appears to be accurate and safe for diagnosing diabetic foot osteomyelitis in patients without signs of soft tissue infection, obviating the need for antibiotic treatment in 55 percent of suspected cases,” wrote Aslangul et al.

This study presented SPECT/CT as potential competition for MRI, considered the gold standard of advanced imaging when radiography is not sufficient for diagnosis. As sensitive as MRI is for tissue contrast, its specificity for osteomyelitis imaging is less than 80 percent. Plain scintigraphy is thought to be “highly sensitive,” but lacking in specificity for the evaluation of diabetic bone disease. SPECT and CT together may provide a more accurate picture of disease combining both physiologic and anatomic information for comprehensive diagnoses.

“The fusion of scintigraphic and morphologic images, using [SPECT/CT], is more accurate than planar scintigraphy alone, correctly differentiating foot osteomyelitis and contiguous soft tissue infection in 97 percent of cases compared with 59 percent for planar scintigraphy,” wrote the authors.

Hybrid molecular imaging was found to have a sensitivity of 88 percent and a specificity of 93.6 percent in the evaluation of osteomyelitis in diabetics presenting a foot ulcer. A total of 55 patients with diabetic foot ulceration underwent 67-Ga SPECT/CT imaging during the course of two years. Those who had negative scans for bone infection recovered without antibiotics and 40 of the 42 subjects with positive scans for osteomyelitis received bone punctures for verification of bone disease. Of these 40, positive biopsies were determined for 24 of the test group and 19 biopsies were negative, with three suspected false-negatives.