Diagnosing bone infection in the diabetic foot is challenging and often requires several diagnostic procedures, including advanced imaging. We compared the diagnostic performances of MRI, radiolabeled white blood cell (WBC) scintigraphy (either with 99mTc-hexamethylpropyleneamineoxime [HMPAO] or 111In-oxine), and [18F]fluorodeoxyglucose positron emission tomography (18F-FDG–PET)/computed tomography.
We searched Medline and Embase as of August 2016 for studies of diagnostic tests on patients known or suspected to have diabetes and a foot infection. We performed a systematic review using criteria recommended by the Cochrane Review of a database that included prospective and retrospective diagnostic studies performed on patients with diabetes in whom there was a clinical suspicion of osteomyelitis of the foot. The preferred reference standard was bone biopsy and subsequent pathological (or microbiological) examination.
Our review found 6,649 articles; 3,894 in Medline and 2,755 in Embase. A total of 27 full articles and 2 posters was selected for inclusion in the analysis. The performance characteristics for the 18F-FDG–PET were: sensitivity, 89%; specificity, 92%; diagnostic odds ratio (DOR), 95; positive likelihood ratio (LR), 11; and negative LR, 0.11. For WBC scan with 111In-oxine, the values were: sensitivity, 92%; specificity, 75%; DOR, 34; positive LR, 3.6; and negative LR, 0.1. For WBC scan with 99mTc-HMPAO, the values were: sensitivity, 91%; specificity, 92%; DOR, 118; positive LR, 12; and negative LR, 0.1. Finally, for MRI, the values were: sensitivity, 93%; specificity, 75%; DOR, 37; positive LR, 3.66, and negative LR, 0.10.
The various modalities have similar sensitivity, but 18F-FDG–PET and 99mTc-HMPAO–labeled WBC scintigraphy offer the highest specificity. Larger prospective studies with a direct comparison among the different imaging techniques are required.