The value of SPECT-CT in patients with suspicion of a vascular graft infection

1971 Objectives Vascular graft infection is a rare, but serious complication with a high rate of morbidity and mortality. Labeled leucocytes imaging could ensure specific visualization for an efficient treatment. The aim of the study was to apply SPECT-CT in patients with suspicion of a vascular graft infection. Methods We have examined 25 patients (Pts), of whom 16 were with aortobifemoral, 2-with femorofemaral, 2-with axillofemoral and 5-with ileofemoral bypass. Fourteen of the patients were still under the antibiotic therapy, not enough clinically influenced by it. We have used “in vitro” labeled leukocytes with 99mTc-HMPAO(370MBq) and applied hybrid imaging with SPECT-CT. The results were verified microbiologically, by surgery or by follow-up. An index of accumulation (IA) was used for an objective quantification of the results and for evaluation of the activity of the infection process. IA was calculated as the activity of the suspected area divided by the activity of the contralateral area. Results The infection was ruled out when IA was below 1.1 (in 5 Pts), low grade of activity was considered at IA of 1.1-1.3 (in 12 Pts) and active infection at IA above 1.3 (in 8 Pts). Using CT, exact localization of the infection was possible, differentiating infection along the vascular graft and/or infection in the soft tissues adjacent to the graft (in 5/25 Pts) or superimposed on bone marrow (in 2/25 Pts). As a whole, the sensitivity was 84.2%, specificity of 83.3% and accuracy of 83.9%. For 30% of the patients SPECT-CT contributed important additional information, which changed the therapy. Conclusions We suggest that combining hybrid imaging with quantitative criteria for evaluation of the activity of the vascular graft infection ensures its exact localization and could change the therapy.