Abstract 5820: The Clinical Value of Absolute Quantification of Myocardial Perfusion in The Detection of Coronary Artery Disease. A Study Using Positron Emission Tomography to Detect Multi-vessel Disease
Background: Perfusion imaging is standard technique in the detection of CAD. However, the analysis is based on assessment of relative perfusion defects that has known limitations in the detection of multi-vessel disease. Typically only the most severe perfusion abnormalities are detected but not less severe defects or balanced disease. PET measures myocardial perfusion in absolute terms potentially being able to avoid these drawbacks but the value of quantitation has not been shown in clinical studies.
Aims: To evaluate the accuracy of absolute quantification of myocardial perfusion in the diagnosis and the detection of multivessel CAD.
Patients and methods: 83 consecutive patients with moderate (30–70%) pretest likelihood of CAD were enrolled. PET perfusion imaging at rest and during adenosine stress were performed using O-15-water. The studies were analyzed using validated quantitative model and software. Both standard relative perfusion images and images that were scaled to known absolute scale (0.0–3.5 ml/min/g) were produced. The images were analyzed by two experienced readers blinded to clinical data, image scaling and invasive coronary angiography (ICA). The regions were classified as normal (>70% of uptake), mildly abnormal (50–70%) and severely abnormal (< 50%) in each vascular territory and compared against ICA.
Results: The PPV, NPV and accuracy of absolute perfusion in the detection of any CAD were 87%, 97%, 92% respectively. The corresponding values in the detection of multi-vessel disease were 94%, 96% and 95%. When standard relative images were used the respective values for multi-vessel disease were 33%, 69% and 60% against ICA. Relative analysis was able to detect only 39% of patients with multi-vessel disease. In addition, regional perfusion was often (31%) falsely interpreted as multi-vessel disease while preserved absolute perfusion was able to exclude significant stenoses.
Conclusions: The measurement of myocardial perfusion in absolute terms has significant impact on the interpretation of myocardial perfusion. Standard relative analysis is able to detect only small fraction of patients with multi-vessel disease and also quite commonly variability in perfusion is falsely interpreted as a sign of multi-vessel disease.