A comparison between visual and quantitative analysis in a prospective evaluation of labelled 111In leucocyte imaging...

In a continuing evaluation of 111In-oxine labelled leucocyte imaging in vascular surgery, we have studied 16 patients with a clinical diagnosis of possible vascular graft infection. We have evaluated both visual and semi-quantitative analysis of the images obtained and have interpreted these in the light of the subsequent clinical outcome. Full length or multifocal uptake was seen in six patients, all of whom eventually required graft excision with two limbs surviving, and one death. These patients had a significantly higher uptake ratio (median = 3.26) than those with either localized (median = 1.12; p = 0.0027) or negative images (median = 0.72; p = 0.0003). Of four patients showing localized uptake only, one required amputation for continuing sepsis. Six patients had negative images, and had normal DSA and CT scans. Uptake ratios could not distinguish between those with localized images and those with negative images. Computer generated vertical profiles aided separation of patients with presumed localized and negative images. Semi-quantitative analysis has proved to be a reliable method which should allow a more direct comparison of the efficacy of various investigative techniques and of the results of therapy, independent of intra-observer subjective bias.