The diagnostic value of single photon-emission computed tomography bone scans combined with CT (SPECT-CT) in diseases of the foot and ankle

Abstract

A radionuclide bone scan with single photon-emission computed tomography and CT (SPECT-CT) is a new imaging modality which combines highly detailed CT with the functional information from a triple phase radionuclide bone scan. Little has been published about its diagnostic accuracy and usefulness in foot and ankle pathology. The aim of this study is to evaluate whether bone scans with SPECT-CT provide a useful contribution to the management of patients with foot and ankle pain, and whether it results in changes to clinical management. A retrospective study involving 50 patients was conducted between March 2010 and April 2011. SPECT-CT was requested in cases where definitive clinical diagnosis could not be achieved after clinical examination and plain radiography. Pathology as highlighted on SPECT-CT was taken as the definitive diagnosis in these patients and was treated accordingly. Patients were subsequently seen in the follow up clinic to evaluate the outcome of their treatment. In 11 patients (22%), the provisional clinical diagnosis matched with the findings of the SPECT-CT and no change in treatment was necessary. In 39 patients (78%) the findings of the SPECT-CT did not correlate exactly with the initial clinical diagnosis and led to a modified treatment plan. The accuracy, sensitivity, specificity, positive predictive and negative predictive value of SPECT-CT in this series was 94%, 95.45%, 83.3%, 97.6% and 71.43% respectively. SPECT-CT is a useful investigation tool in foot and ankle pathologies. The present study shows a high diagnostic accuracy and we recommend its use in cases with diagnostic uncertainty.