CONTRIBUTION OF TC-99M HEXAMETHYLPROPYLENE AMINE OXIME LABELED LEUKOCYTE SCINTIGRAPHY TO THE DIAGNOSIS OF DIABETIC FOOT INFECTION

We conducted a prospective study in order to evaluate the contribution of technetium-99m hexamethylpropylene amine oxime (HAMPAO) labelled l eucocyte scintigraphy to the diagnosis and follow-up of osteomyelitis in the diabetic foot. The study was conducted between October 1992 and November 1996 and included 42 patients (30 men and 12 women; mean age 63 years) with diabetes mellitus (type 1, n = 22, type 2, n = 20) who had a total of 56 diabetic foot ulcers. The initial exploration inclu ded standard radiography, three-phase bone scintigraphy and Tc-99m-HMP AO labelled leucocyte scintigraphy (HMPAO-LS), performed within a 3-da y interval. For the 56 ulceration sites, 26 cases of osteomyelitis wer e diagnosed: ten on the basis of radiographic and histologial/bacterio logical criteria after bone biopsy, 11 after radiographic follow-up an d five on the basis of biopsy results alone. No osteomyelitis was pres ent at 30 sites, there were seven cases of cellulitis. The sensitivity and specificity of Tc-99m-HMPAO-LS were 88.4% and 96.6% respectively (23 true-positives, 29 true-negatives, one false-positive, three false -negatives). The accuracy of radiography, Tc-99m-methylene diphosphona te and HMPAO-LS was 69.6%, 62.5%, and 92.9%, respectively, Follow-up s cintigraphy (n = 14) 4 months after initial diagnosis and I month afte r antibiotic withdrawal confirmed cure of osteomyelitis despite the ab sence of complete clinical regression of the ulcers. In conclusion, Tc -99m-HMPAO labelled leucocyte scintigraphy was found to be an excellen t method for the diagnosis of osteomyelitis in the diabetic foot. It c an contribute to follow-up, particularly when clinical regression of p erforating ulcers is incomplete and cure of osteomyelitis must be conf irmed in order that antibiotic treatment may be discontinued.