Coregistration imaging of the foot - A new localisation technique

We describe a new technique, known as coregistration imaging, which superim poses Tc-99m isotope bone scans on to plain radiographs. We used the technique selectively in cases in which the nuclear medicine ph ysician, who reported the isotope scan, had difficulty in localising the an atomical site of the abnormality. In the forefoot, coregistration of isotope scans did not help to localise p athology; the scan alone gave sufficient detail. In 17 patients with pain in the hind- and midfoot, isotope scanning identif ied eight sites of abnormality in those with normal radiographs. In those w ith more than one abnormality on plain radiographs the isotope scan elimina ted 12 sites of suspicion. Coregistration of the images significantly incre ased the certainty of localisation of disease (p < 0.001). We recommend the selective use of coregistration scanning as a useful techn ique for investigating patients with pain in the foot and ankle.