Abstract
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Objectives Positive tagged RBC scans have poor correlation with catheter angiograms. This result in many unnecessary invasive procedure with potential serious complications. We tried to find factors associated with a higher angiogram positivity to potentially improve diagnostic yield of the tagged RBC imaging.
Methods Ninety four consecutive patients with positive RBC scans who also had an angiogram within 24 hours were included in the study. A reader blinded to patients' information and results interpreted the studies. 21 known negative RBC scans were included to reduce the chance of expectation bias for the reader. The result of angiograms were collected from reports and recorded. We looked at the time the RBC scan became positive, how promptly it showed up and correlated with angiogram results. We also compared the rate of angiogram positivity between single readers and two readers concordance.
Results Patients who had a positive angios were more likely to have a prompt bleed rather than a slow bleed, 75% vs 41%(p=0.003). In the negative angio group 59% had a slow bleed and in the positive angio group 25% had slow bleed (p=0.003) In the positive angio group, the bleed was detected in the first 15 minutes 64% compared to 36% in the negative angio group (p=0.02). Only 3% of patients with a positive angio had a positive bleeding scan after 30 minutes of imaging (p=0.4) Angio was more likely to be positive if concordance of two readers was present at a rate of 87%, where only 51 % of negative angio had 2 readers concordance (p=0.002) There was no difference between average delay time of angio after positive RBC scan in the two groups.
Conclusions The tagged RBC scans with visualization of prompt bleed and bleed within the first 15 minutes of the study have a significantly higher correlation with positive angiograms. Considering these factors potentially can reduce the number of unnecessary invasive procedures