n.121 – COMPARING FDG PET/CT AND WBC SCAN IN PATIENTS WITH AND WITHOUT SUSPICION OF VASCULAR GRAFT INFECTION



Abstract

BACKGROUND-AIM
In the literature there are few studies comparing 18F-Fdg PET/TC and scintigraphy with WBC in the diagnosis of vascular prostheses infections. Moreover, the patterns of distribution of FDG and radiobelled WBC in patients with endoprosthesis, in relation to the type of stent and the time of operation, is not well know.
Purpose: aim of the present study was to compare the two techniques in two groups of 6 patients, that underwent operated with endoprosthesis endurant. The first group included patients with suspicion of infection (TC, increased ESR, GB and PCR, fever), while the second group includes patients clinically and biochemically infection free.
METHODS
In the study, 12 patient that underwent an endovascular exclusion of abdominal aortic aneurysm, were recruited. Only patients with endoprosthesis aorto-bisiliaca type endurant were included to avoid differences in uptake due to prosthetic material used.
In each patients scintigraphy with labeled leukocytes was performed. Dynamic images were acquired on the abdomen in the anterior-posterior from time 0 to 2.5 minutes (one frame every 4 seconds for 40 frames) .Planar images were acquired on the abdomen in anteroposterior and oblique front left and right to 45 °. The first set of images was acquired 10 minutes after administration of the radiopharmaceutical (100 seconds of acquisition time), the second set at 3 hours (141 seconds of acquisition) and the third set at 20 hours (1040 seconds acquisition).
18F-Fdg PET was performed after the administration of 185 MBq of 18F-FDG. Patients with diabetes or hyperglycemia received insulin or hypoglycemic drugs before the examination and metformin suspended three days before the exam. The blood glucose before injection was less than 180 mg / dl in all patients. PET / CT in the prosthesis area (from neck to mid-femur) will be performed 60 minutes after intravenous injection of 18F-FDG.
Criteria of positivity were the presence of intra- and extra-vascular uptake inhomogeneous with a SUV max> 3. Positivity criteria for the WBC was the presence of pathological accumulation in the periprosthetic.
The final diagnosiswas made by clinical-surgery follow up
RESULTS
Results showed that in patients with suspected infection ,the two techniques were concordant in 5 cases (3 positive and 2 negative) and discordant in 1 case (Fdg positive and WBC negative). In control patients without suspected infection the two techniques were concordant in 5 cases (all negative) and discordant in only one case (Fdg positive and WBC negative).
CONCLUSION
The PET / CT with FDG seems to be equally sensitive to the WBC but less specific

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