Radionuclide diagnosis of vertebral osteomyelitis: indium-111-leukocyte and technetium-99m-methylene diphosphonate bone scintigraphy.

Seventy-six 111In-labeled leukocyte images performed on 71 patients with possible vertebral osteomyelitis were reviewed. Twenty-eight cases of vertebral osteomyelitis were diagnosed. Vertebral labeled leukocyte activity was normal in 2, increased in 11, and decreased in 15 cases of osteomyelitis. The median duration of symptoms was significantly longer in patients with osteomyelitis and decreased vertebral activity than in patients with osteomyelitis and increased activity (3 mo versus 2 wk; p = 0.019). No significant relationship between the duration of antibiotic therapy and the appearance of vertebral osteomyelitis on leukocyte images was identified (p = 0.62). Increased vertebral activity was highly specific (98%) for osteomyelitis but relatively insensitive (39%). Decreased activity was neither sensitive (54%) nor specific (52%). Seven patients with clinically resolved infection underwent follow-up imaging. Of four patients who initially presented with increased activity, one had normal and three had decreased vertebral activity on follow up studies. All three patients with decreased activity initially had decreased activity on follow-up. Using increased or decreased activity as criteria for infection, the accuracy of leukocyte imaging for diagnosing vertebral osteomyelitis was 66%, similar to that of 99mTc bone imaging (63%) in our population. Leukocyte imaging did however provide important information about extraosseous infection in 12 of the patients studied.